From 32b080261845c7508581f9c452d48ffd2401c450 Mon Sep 17 00:00:00 2001 From: Arne Schwabe Date: Fri, 2 Aug 2019 12:50:57 +0200 Subject: Add skeleton build variant --- .../support/v4n/app/FragmentStatePagerAdapter.java | 232 ++ .../android/support/v4n/view/PagerAdapter.java | 320 +++ .../java/android/support/v4n/view/ViewPager.java | 2895 ++++++++++++++++++++ 3 files changed, 3447 insertions(+) create mode 100644 main/src/ui/java/android/support/v4n/app/FragmentStatePagerAdapter.java create mode 100644 main/src/ui/java/android/support/v4n/view/PagerAdapter.java create mode 100644 main/src/ui/java/android/support/v4n/view/ViewPager.java (limited to 'main/src/ui/java/android/support/v4n') diff --git a/main/src/ui/java/android/support/v4n/app/FragmentStatePagerAdapter.java b/main/src/ui/java/android/support/v4n/app/FragmentStatePagerAdapter.java new file mode 100644 index 00000000..4ffec519 --- /dev/null +++ b/main/src/ui/java/android/support/v4n/app/FragmentStatePagerAdapter.java @@ -0,0 +1,232 @@ +/* + * Copyright (C) 2011 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package android.support.v4n.app; + +import java.util.ArrayList; + +import android.annotation.TargetApi; +import android.app.Fragment; +import android.app.FragmentManager; +import android.app.FragmentTransaction; +import android.os.Build; +import android.os.Bundle; +import android.os.Parcelable; +import android.support.v4n.view.PagerAdapter; +import android.util.Log; +import android.view.View; +import android.view.ViewGroup; + +/** + * Implementation of {@link android.support.v4.view.PagerAdapter} that + * uses a {@link Fragment} to manage each page. This class also handles + * saving and restoring of fragment's state. + * + *

This version of the pager is more useful when there are a large number + * of pages, working more like a list view. When pages are not visible to + * the user, their entire fragment may be destroyed, only keeping the saved + * state of that fragment. This allows the pager to hold on to much less + * memory associated with each visited page as compared to + * {@link FragmentPagerAdapter} at the cost of potentially more overhead when + * switching between pages. + * + *

When using FragmentPagerAdapter the host ViewPager must have a + * valid ID set.

+ * + *

Subclasses only need to implement {@link #getItem(int)} + * and {@link #getCount()} to have a working adapter. + * + *

Here is an example implementation of a pager containing fragments of + * lists: + * + * {@sample development/samples/Support13Demos/src/com/example/android/supportv13/app/FragmentStatePagerSupport.java + * complete} + * + *

The R.layout.fragment_pager resource of the top-level fragment is: + * + * {@sample development/samples/Support13Demos/res/layout/fragment_pager.xml + * complete} + * + *

The R.layout.fragment_pager_list resource containing each + * individual fragment's layout is: + * + * {@sample development/samples/Support13Demos/res/layout/fragment_pager_list.xml + * complete} + */ +public abstract class FragmentStatePagerAdapter extends PagerAdapter { + private static final String TAG = "FragmentStatePagerAdptr"; + private static final boolean DEBUG = false; + + private final FragmentManager mFragmentManager; + private FragmentTransaction mCurTransaction = null; + + private ArrayList mSavedState = new ArrayList(); + private ArrayList mFragments = new ArrayList(); + private Fragment mCurrentPrimaryItem = null; + + public FragmentStatePagerAdapter(FragmentManager fm) { + mFragmentManager = fm; + } + + /** + * Return the Fragment associated with a specified position. + */ + public abstract Fragment getItem(int position); + + @Override + public void startUpdate(ViewGroup container) { + } + + @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1) + @Override + public Object instantiateItem(ViewGroup container, int position) { + // If we already have this item instantiated, there is nothing + // to do. This can happen when we are restoring the entire pager + // from its saved state, where the fragment manager has already + // taken care of restoring the fragments we previously had instantiated. + if (mFragments.size() > position) { + Fragment f = mFragments.get(position); + if (f != null) { + return f; + } + } + + if (mCurTransaction == null) { + mCurTransaction = mFragmentManager.beginTransaction(); + } + + Fragment fragment = getItem(position); + if (DEBUG) Log.v(TAG, "Adding item #" + position + ": f=" + fragment); + if (mSavedState.size() > position) { + Fragment.SavedState fss = mSavedState.get(position); + if (fss != null) { + fragment.setInitialSavedState(fss); + } + } + while (mFragments.size() <= position) { + mFragments.add(null); + } + fragment.setMenuVisibility(false); + fragment.setUserVisibleHint(false); + mFragments.set(position, fragment); + mCurTransaction.add(container.getId(), fragment); + + return fragment; + } + + @Override + public void destroyItem(ViewGroup container, int position, Object object) { + Fragment fragment = (Fragment)object; + + if (mCurTransaction == null) { + mCurTransaction = mFragmentManager.beginTransaction(); + } + if (DEBUG) Log.v(TAG, "Removing item #" + position + ": f=" + object + + " v=" + ((Fragment)object).getView()); + while (mSavedState.size() <= position) { + mSavedState.add(null); + } + mSavedState.set(position, mFragmentManager.saveFragmentInstanceState(fragment)); + mFragments.set(position, null); + + mCurTransaction.remove(fragment); + } + + @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1) + @Override + public void setPrimaryItem(ViewGroup container, int position, Object object) { + Fragment fragment = (Fragment)object; + if (fragment != mCurrentPrimaryItem) { + if (mCurrentPrimaryItem != null) { + mCurrentPrimaryItem.setMenuVisibility(false); + mCurrentPrimaryItem.setUserVisibleHint(false); + } + if (fragment != null) { + fragment.setMenuVisibility(true); + fragment.setUserVisibleHint(true); + } + mCurrentPrimaryItem = fragment; + } + } + + @Override + public void finishUpdate(ViewGroup container) { + if (mCurTransaction != null) { + mCurTransaction.commitAllowingStateLoss(); + mCurTransaction = null; + mFragmentManager.executePendingTransactions(); + } + } + + @Override + public boolean isViewFromObject(View view, Object object) { + return ((Fragment)object).getView() == view; + } + + @Override + public Parcelable saveState() { + Bundle state = null; + if (mSavedState.size() > 0) { + state = new Bundle(); + Fragment.SavedState[] fss = new Fragment.SavedState[mSavedState.size()]; + mSavedState.toArray(fss); + state.putParcelableArray("states", fss); + } + for (int i=0; i keys = bundle.keySet(); + for (String key: keys) { + if (key.startsWith("f")) { + int index = Integer.parseInt(key.substring(1)); + Fragment f = mFragmentManager.getFragment(bundle, key); + if (f != null) { + while (mFragments.size() <= index) { + mFragments.add(null); + } + f.setMenuVisibility(false); + mFragments.set(index, f); + } else { + Log.w(TAG, "Bad fragment at key " + key); + } + } + } + } + } +} diff --git a/main/src/ui/java/android/support/v4n/view/PagerAdapter.java b/main/src/ui/java/android/support/v4n/view/PagerAdapter.java new file mode 100644 index 00000000..70ed75f3 --- /dev/null +++ b/main/src/ui/java/android/support/v4n/view/PagerAdapter.java @@ -0,0 +1,320 @@ +/* + * Copyright (C) 2011 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package android.support.v4n.view; + +import android.database.DataSetObservable; +import android.database.DataSetObserver; +import android.os.Parcelable; +import android.view.View; +import android.view.ViewGroup; + +/** + * Base class providing the adapter to populate pages inside of + * a {@link ViewPager}. You will most likely want to use a more + * specific implementation of this, such as + * {@link android.support.v4n.app.FragmentPagerAdapter} or + * {@link android.support.v4.app.FragmentStatePagerAdapter}. + * + *

When you implement a PagerAdapter, you must override the following methods + * at minimum:

+ * + * + *

PagerAdapter is more general than the adapters used for + * {@link android.widget.AdapterView AdapterViews}. Instead of providing a + * View recycling mechanism directly ViewPager uses callbacks to indicate the + * steps taken during an update. A PagerAdapter may implement a form of View + * recycling if desired or use a more sophisticated method of managing page + * Views such as Fragment transactions where each page is represented by its + * own Fragment.

+ * + *

ViewPager associates each page with a key Object instead of working with + * Views directly. This key is used to track and uniquely identify a given page + * independent of its position in the adapter. A call to the PagerAdapter method + * {@link #startUpdate(ViewGroup)} indicates that the contents of the ViewPager + * are about to change. One or more calls to {@link #instantiateItem(ViewGroup, int)} + * and/or {@link #destroyItem(ViewGroup, int, Object)} will follow, and the end + * of an update will be signaled by a call to {@link #finishUpdate(ViewGroup)}. + * By the time {@link #finishUpdate(ViewGroup) finishUpdate} returns the views + * associated with the key objects returned by + * {@link #instantiateItem(ViewGroup, int) instantiateItem} should be added to + * the parent ViewGroup passed to these methods and the views associated with + * the keys passed to {@link #destroyItem(ViewGroup, int, Object) destroyItem} + * should be removed. The method {@link #isViewFromObject(View, Object)} identifies + * whether a page View is associated with a given key object.

+ * + *

A very simple PagerAdapter may choose to use the page Views themselves + * as key objects, returning them from {@link #instantiateItem(ViewGroup, int)} + * after creation and adding them to the parent ViewGroup. A matching + * {@link #destroyItem(ViewGroup, int, Object)} implementation would remove the + * View from the parent ViewGroup and {@link #isViewFromObject(View, Object)} + * could be implemented as return view == object;.

+ * + *

PagerAdapter supports data set changes. Data set changes must occur on the + * main thread and must end with a call to {@link #notifyDataSetChanged()} similar + * to AdapterView adapters derived from {@link android.widget.BaseAdapter}. A data + * set change may involve pages being added, removed, or changing position. The + * ViewPager will keep the current page active provided the adapter implements + * the method {@link #getItemPosition(Object)}.

+ */ +public abstract class PagerAdapter { + private DataSetObservable mObservable = new DataSetObservable(); + + public static final int POSITION_UNCHANGED = -1; + public static final int POSITION_NONE = -2; + + /** + * Return the number of views available. + */ + public abstract int getCount(); + + /** + * Called when a change in the shown pages is going to start being made. + * @param container The containing View which is displaying this adapter's + * page views. + */ + public void startUpdate(ViewGroup container) { + startUpdate((View) container); + } + + /** + * Create the page for the given position. The adapter is responsible + * for adding the view to the container given here, although it only + * must ensure this is done by the time it returns from + * {@link #finishUpdate(ViewGroup)}. + * + * @param container The containing View in which the page will be shown. + * @param position The page position to be instantiated. + * @return Returns an Object representing the new page. This does not + * need to be a View, but can be some other container of the page. + */ + public Object instantiateItem(ViewGroup container, int position) { + return instantiateItem((View) container, position); + } + + /** + * Remove a page for the given position. The adapter is responsible + * for removing the view from its container, although it only must ensure + * this is done by the time it returns from {@link #finishUpdate(ViewGroup)}. + * + * @param container The containing View from which the page will be removed. + * @param position The page position to be removed. + * @param object The same object that was returned by + * {@link #instantiateItem(View, int)}. + */ + public void destroyItem(ViewGroup container, int position, Object object) { + destroyItem((View) container, position, object); + } + + /** + * Called to inform the adapter of which item is currently considered to + * be the "primary", that is the one show to the user as the current page. + * + * @param container The containing View from which the page will be removed. + * @param position The page position that is now the primary. + * @param object The same object that was returned by + * {@link #instantiateItem(View, int)}. + */ + public void setPrimaryItem(ViewGroup container, int position, Object object) { + setPrimaryItem((View) container, position, object); + } + + /** + * Called when the a change in the shown pages has been completed. At this + * point you must ensure that all of the pages have actually been added or + * removed from the container as appropriate. + * @param container The containing View which is displaying this adapter's + * page views. + */ + public void finishUpdate(ViewGroup container) { + finishUpdate((View) container); + } + + /** + * Called when a change in the shown pages is going to start being made. + * @param container The containing View which is displaying this adapter's + * page views. + * + * @deprecated Use {@link #startUpdate(ViewGroup)} + */ + public void startUpdate(View container) { + } + + /** + * Create the page for the given position. The adapter is responsible + * for adding the view to the container given here, although it only + * must ensure this is done by the time it returns from + * {@link #finishUpdate(ViewGroup)}. + * + * @param container The containing View in which the page will be shown. + * @param position The page position to be instantiated. + * @return Returns an Object representing the new page. This does not + * need to be a View, but can be some other container of the page. + * + * @deprecated Use {@link #instantiateItem(ViewGroup, int)} + */ + public Object instantiateItem(View container, int position) { + throw new UnsupportedOperationException( + "Required method instantiateItem was not overridden"); + } + + /** + * Remove a page for the given position. The adapter is responsible + * for removing the view from its container, although it only must ensure + * this is done by the time it returns from {@link #finishUpdate(View)}. + * + * @param container The containing View from which the page will be removed. + * @param position The page position to be removed. + * @param object The same object that was returned by + * {@link #instantiateItem(View, int)}. + * + * @deprecated Use {@link #destroyItem(ViewGroup, int, Object)} + */ + public void destroyItem(View container, int position, Object object) { + throw new UnsupportedOperationException("Required method destroyItem was not overridden"); + } + + /** + * Called to inform the adapter of which item is currently considered to + * be the "primary", that is the one show to the user as the current page. + * + * @param container The containing View from which the page will be removed. + * @param position The page position that is now the primary. + * @param object The same object that was returned by + * {@link #instantiateItem(View, int)}. + * + * @deprecated Use {@link #setPrimaryItem(ViewGroup, int, Object)} + */ + public void setPrimaryItem(View container, int position, Object object) { + } + + /** + * Called when the a change in the shown pages has been completed. At this + * point you must ensure that all of the pages have actually been added or + * removed from the container as appropriate. + * @param container The containing View which is displaying this adapter's + * page views. + * + * @deprecated Use {@link #finishUpdate(ViewGroup)} + */ + public void finishUpdate(View container) { + } + + /** + * Determines whether a page View is associated with a specific key object + * as returned by {@link #instantiateItem(ViewGroup, int)}. This method is + * required for a PagerAdapter to function properly. + * + * @param view Page View to check for association with object + * @param object Object to check for association with view + * @return true if view is associated with the key object object + */ + public abstract boolean isViewFromObject(View view, Object object); + + /** + * Save any instance state associated with this adapter and its pages that should be + * restored if the current UI state needs to be reconstructed. + * + * @return Saved state for this adapter + */ + public Parcelable saveState() { + return null; + } + + /** + * Restore any instance state associated with this adapter and its pages + * that was previously saved by {@link #saveState()}. + * + * @param state State previously saved by a call to {@link #saveState()} + * @param loader A ClassLoader that should be used to instantiate any restored objects + */ + public void restoreState(Parcelable state, ClassLoader loader) { + } + + /** + * Called when the host view is attempting to determine if an item's position + * has changed. Returns {@link #POSITION_UNCHANGED} if the position of the given + * item has not changed or {@link #POSITION_NONE} if the item is no longer present + * in the adapter. + * + *

The default implementation assumes that items will never + * change position and always returns {@link #POSITION_UNCHANGED}. + * + * @param object Object representing an item, previously returned by a call to + * {@link #instantiateItem(View, int)}. + * @return object's new position index from [0, {@link #getCount()}), + * {@link #POSITION_UNCHANGED} if the object's position has not changed, + * or {@link #POSITION_NONE} if the item is no longer present. + */ + public int getItemPosition(Object object) { + return POSITION_UNCHANGED; + } + + /** + * This method should be called by the application if the data backing this adapter has changed + * and associated views should update. + */ + public void notifyDataSetChanged() { + mObservable.notifyChanged(); + } + + /** + * Register an observer to receive callbacks related to the adapter's data changing. + * + * @param observer The {@link android.database.DataSetObserver} which will receive callbacks. + */ + public void registerDataSetObserver(DataSetObserver observer) { + mObservable.registerObserver(observer); + } + + /** + * Unregister an observer from callbacks related to the adapter's data changing. + * + * @param observer The {@link android.database.DataSetObserver} which will be unregistered. + */ + public void unregisterDataSetObserver(DataSetObserver observer) { + mObservable.unregisterObserver(observer); + } + + /** + * This method may be called by the ViewPager to obtain a title string + * to describe the specified page. This method may return null + * indicating no title for this page. The default implementation returns + * null. + * + * @param position The position of the title requested + * @return A title for the requested page + */ + public CharSequence getPageTitle(int position) { + return null; + } + + /** + * Returns the proportional width of a given page as a percentage of the + * ViewPager's measured width from (0.f-1.f] + * + * @param position The position of the page requested + * @return Proportional width for the given page position + */ + public float getPageWidth(int position) { + return 1.f; + } +} diff --git a/main/src/ui/java/android/support/v4n/view/ViewPager.java b/main/src/ui/java/android/support/v4n/view/ViewPager.java new file mode 100644 index 00000000..6009af62 --- /dev/null +++ b/main/src/ui/java/android/support/v4n/view/ViewPager.java @@ -0,0 +1,2895 @@ +/* + * Copyright (C) 2011 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package android.support.v4n.view; + +import android.annotation.TargetApi; +import android.content.Context; +import android.content.res.Resources; +import android.content.res.TypedArray; +import android.database.DataSetObserver; +import android.graphics.Canvas; +import android.graphics.Rect; +import android.graphics.drawable.Drawable; +import android.os.Build; +import android.os.Bundle; +import android.os.Parcel; +import android.os.Parcelable; +import android.os.SystemClock; +import android.support.annotation.DrawableRes; +import android.support.v4.os.ParcelableCompat; +import android.support.v4.os.ParcelableCompatCreatorCallbacks; +import android.support.v4.view.AccessibilityDelegateCompat; +import android.support.v4.view.MotionEventCompat; +import android.support.v4.view.VelocityTrackerCompat; +import android.support.v4.view.ViewCompat; +import android.support.v4.view.ViewConfigurationCompat; +import android.support.v4.view.accessibility.AccessibilityEventCompat; +import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat; +import android.support.v4.view.accessibility.AccessibilityRecordCompat; +import android.support.v4.widget.EdgeEffectCompat; +import android.util.AttributeSet; +import android.util.Log; +import android.view.FocusFinder; +import android.view.Gravity; +import android.view.KeyEvent; +import android.view.MotionEvent; +import android.view.SoundEffectConstants; +import android.view.VelocityTracker; +import android.view.View; +import android.view.ViewConfiguration; +import android.view.ViewGroup; +import android.view.ViewParent; +import android.view.accessibility.AccessibilityEvent; +import android.view.animation.Interpolator; +import android.widget.Scroller; + +import java.lang.reflect.Method; +import java.util.ArrayList; +import java.util.Collections; +import java.util.Comparator; + +/** + * Layout manager that allows the user to flip left and right + * through pages of data. You supply an implementation of a + * {@link PagerAdapter} to generate the pages that the view shows. + * + *

Note this class is currently under early design and + * development. The API will likely change in later updates of + * the compatibility library, requiring changes to the source code + * of apps when they are compiled against the newer version.

+ * + *

ViewPager is most often used in conjunction with {@link android.app.Fragment}, + * which is a convenient way to supply and manage the lifecycle of each page. + * There are standard adapters implemented for using fragments with the ViewPager, + * which cover the most common use cases. These are + * {@link android.support.v4n.app.FragmentPagerAdapter} and + * {@link android.support.v4.app.FragmentStatePagerAdapter}; each of these + * classes have simple code showing how to build a full user interface + * with them. + * + *

For more information about how to use ViewPager, read Creating Swipe Views with + * Tabs.

+ * + *

Below is a more complicated example of ViewPager, using it in conjunction + * with {@link android.app.ActionBar} tabs. You can find other examples of using + * ViewPager in the API 4+ Support Demos and API 13+ Support Demos sample code. + * + * {@sample development/samples/Support13Demos/src/com/example/android/supportv13/app/ActionBarTabsPager.java + * complete} + */ +public class ViewPager extends ViewGroup { + private static final String TAG = "ViewPager"; + private static final boolean DEBUG = false; + + private static final boolean USE_CACHE = false; + + private static final int DEFAULT_OFFSCREEN_PAGES = 1; + private static final int MAX_SETTLE_DURATION = 600; // ms + private static final int MIN_DISTANCE_FOR_FLING = 25; // dips + + private static final int DEFAULT_GUTTER_SIZE = 16; // dips + + private static final int MIN_FLING_VELOCITY = 400; // dips + + private static final int[] LAYOUT_ATTRS = new int[] { + android.R.attr.layout_gravity + }; + + /** + * Used to track what the expected number of items in the adapter should be. + * If the app changes this when we don't expect it, we'll throw a big obnoxious exception. + */ + private int mExpectedAdapterCount; + + static class ItemInfo { + Object object; + int position; + boolean scrolling; + float widthFactor; + float offset; + } + + private static final Comparator COMPARATOR = new Comparator(){ + @Override + public int compare(ItemInfo lhs, ItemInfo rhs) { + return lhs.position - rhs.position; + } + }; + + private static final Interpolator sInterpolator = new Interpolator() { + public float getInterpolation(float t) { + t -= 1.0f; + return t * t * t * t * t + 1.0f; + } + }; + + private final ArrayList mItems = new ArrayList(); + private final ItemInfo mTempItem = new ItemInfo(); + + private final Rect mTempRect = new Rect(); + + private PagerAdapter mAdapter; + private int mCurItem; // Index of currently displayed page. + private int mRestoredCurItem = -1; + private Parcelable mRestoredAdapterState = null; + private ClassLoader mRestoredClassLoader = null; + private Scroller mScroller; + private PagerObserver mObserver; + + private int mPageMargin; + private Drawable mMarginDrawable; + private int mTopPageBounds; + private int mBottomPageBounds; + + // Offsets of the first and last items, if known. + // Set during population, used to determine if we are at the beginning + // or end of the pager data set during touch scrolling. + private float mFirstOffset = -Float.MAX_VALUE; + private float mLastOffset = Float.MAX_VALUE; + + private int mChildWidthMeasureSpec; + private int mChildHeightMeasureSpec; + private boolean mInLayout; + + private boolean mScrollingCacheEnabled; + + private boolean mPopulatePending; + private int mOffscreenPageLimit = DEFAULT_OFFSCREEN_PAGES; + + private boolean mIsBeingDragged; + private boolean mIsUnableToDrag; + private boolean mIgnoreGutter; + private int mDefaultGutterSize; + private int mGutterSize; + private int mTouchSlop; + /** + * Position of the last motion event. + */ + private float mLastMotionX; + private float mLastMotionY; + private float mInitialMotionX; + private float mInitialMotionY; + /** + * ID of the active pointer. This is used to retain consistency during + * drags/flings if multiple pointers are used. + */ + private int mActivePointerId = INVALID_POINTER; + /** + * Sentinel value for no current active pointer. + * Used by {@link #mActivePointerId}. + */ + private static final int INVALID_POINTER = -1; + + /** + * Determines speed during touch scrolling + */ + private VelocityTracker mVelocityTracker; + private int mMinimumVelocity; + private int mMaximumVelocity; + private int mFlingDistance; + private int mCloseEnough; + + // If the pager is at least this close to its final position, complete the scroll + // on touch down and let the user interact with the content inside instead of + // "catching" the flinging pager. + private static final int CLOSE_ENOUGH = 2; // dp + + private boolean mFakeDragging; + private long mFakeDragBeginTime; + + private EdgeEffectCompat mLeftEdge; + private EdgeEffectCompat mRightEdge; + + private boolean mFirstLayout = true; + private boolean mNeedCalculatePageOffsets = false; + private boolean mCalledSuper; + private int mDecorChildCount; + + private OnPageChangeListener mOnPageChangeListener; + private OnPageChangeListener mInternalPageChangeListener; + private OnAdapterChangeListener mAdapterChangeListener; + private PageTransformer mPageTransformer; + private Method mSetChildrenDrawingOrderEnabled; + + private static final int DRAW_ORDER_DEFAULT = 0; + private static final int DRAW_ORDER_FORWARD = 1; + private static final int DRAW_ORDER_REVERSE = 2; + private int mDrawingOrder; + private ArrayList mDrawingOrderedChildren; + private static final ViewPositionComparator sPositionComparator = new ViewPositionComparator(); + + /** + * Indicates that the pager is in an idle, settled state. The current page + * is fully in view and no animation is in progress. + */ + public static final int SCROLL_STATE_IDLE = 0; + + /** + * Indicates that the pager is currently being dragged by the user. + */ + public static final int SCROLL_STATE_DRAGGING = 1; + + /** + * Indicates that the pager is in the process of settling to a final position. + */ + public static final int SCROLL_STATE_SETTLING = 2; + + private final Runnable mEndScrollRunnable = new Runnable() { + public void run() { + setScrollState(SCROLL_STATE_IDLE); + populate(); + } + }; + + private int mScrollState = SCROLL_STATE_IDLE; + + /** + * Callback interface for responding to changing state of the selected page. + */ + public interface OnPageChangeListener { + + /** + * This method will be invoked when the current page is scrolled, either as part + * of a programmatically initiated smooth scroll or a user initiated touch scroll. + * + * @param position Position index of the first page currently being displayed. + * Page position+1 will be visible if positionOffset is nonzero. + * @param positionOffset Value from [0, 1) indicating the offset from the page at position. + * @param positionOffsetPixels Value in pixels indicating the offset from position. + */ + public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels); + + /** + * This method will be invoked when a new page becomes selected. Animation is not + * necessarily complete. + * + * @param position Position index of the new selected page. + */ + public void onPageSelected(int position); + + /** + * Called when the scroll state changes. Useful for discovering when the user + * begins dragging, when the pager is automatically settling to the current page, + * or when it is fully stopped/idle. + * + * @param state The new scroll state. + * @see ViewPager#SCROLL_STATE_IDLE + * @see ViewPager#SCROLL_STATE_DRAGGING + * @see ViewPager#SCROLL_STATE_SETTLING + */ + public void onPageScrollStateChanged(int state); + } + + /** + * Simple implementation of the {@link OnPageChangeListener} interface with stub + * implementations of each method. Extend this if you do not intend to override + * every method of {@link OnPageChangeListener}. + */ + public static class SimpleOnPageChangeListener implements OnPageChangeListener { + @Override + public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { + // This space for rent + } + + @Override + public void onPageSelected(int position) { + // This space for rent + } + + @Override + public void onPageScrollStateChanged(int state) { + // This space for rent + } + } + + /** + * A PageTransformer is invoked whenever a visible/attached page is scrolled. + * This offers an opportunity for the application to apply a custom transformation + * to the page views using animation properties. + * + *

As property animation is only supported as of Android 3.0 and forward, + * setting a PageTransformer on a ViewPager on earlier platform versions will + * be ignored.

+ */ + public interface PageTransformer { + /** + * Apply a property transformation to the given page. + * + * @param page Apply the transformation to this page + * @param position Position of page relative to the current front-and-center + * position of the pager. 0 is front and center. 1 is one full + * page position to the right, and -1 is one page position to the left. + */ + public void transformPage(View page, float position); + } + + /** + * Used internally to monitor when adapters are switched. + */ + interface OnAdapterChangeListener { + public void onAdapterChanged(PagerAdapter oldAdapter, PagerAdapter newAdapter); + } + + /** + * Used internally to tag special types of child views that should be added as + * pager decorations by default. + */ + interface Decor {} + + public ViewPager(Context context) { + super(context); + initViewPager(); + } + + public ViewPager(Context context, AttributeSet attrs) { + super(context, attrs); + initViewPager(); + } + + void initViewPager() { + setWillNotDraw(false); + setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); + setFocusable(true); + final Context context = getContext(); + mScroller = new Scroller(context, sInterpolator); + final ViewConfiguration configuration = ViewConfiguration.get(context); + final float density = context.getResources().getDisplayMetrics().density; + + mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(configuration); + mMinimumVelocity = (int) (MIN_FLING_VELOCITY * density); + mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); + mLeftEdge = new EdgeEffectCompat(context); + mRightEdge = new EdgeEffectCompat(context); + + mFlingDistance = (int) (MIN_DISTANCE_FOR_FLING * density); + mCloseEnough = (int) (CLOSE_ENOUGH * density); + mDefaultGutterSize = (int) (DEFAULT_GUTTER_SIZE * density); + + ViewCompat.setAccessibilityDelegate(this, new MyAccessibilityDelegate()); + + if (ViewCompat.getImportantForAccessibility(this) + == ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_AUTO) { + ViewCompat.setImportantForAccessibility(this, + ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_YES); + } + } + + @Override + protected void onDetachedFromWindow() { + removeCallbacks(mEndScrollRunnable); + super.onDetachedFromWindow(); + } + + private void setScrollState(int newState) { + if (mScrollState == newState) { + return; + } + + mScrollState = newState; + if (mPageTransformer != null) { + // PageTransformers can do complex things that benefit from hardware layers. + enableLayers(newState != SCROLL_STATE_IDLE); + } + if (mOnPageChangeListener != null) { + mOnPageChangeListener.onPageScrollStateChanged(newState); + } + } + + /** + * Set a PagerAdapter that will supply views for this pager as needed. + * + * @param adapter Adapter to use + */ + public void setAdapter(PagerAdapter adapter) { + if (mAdapter != null) { + mAdapter.unregisterDataSetObserver(mObserver); + mAdapter.startUpdate(this); + for (int i = 0; i < mItems.size(); i++) { + final ItemInfo ii = mItems.get(i); + mAdapter.destroyItem(this, ii.position, ii.object); + } + mAdapter.finishUpdate(this); + mItems.clear(); + removeNonDecorViews(); + mCurItem = 0; + scrollTo(0, 0); + } + + final PagerAdapter oldAdapter = mAdapter; + mAdapter = adapter; + mExpectedAdapterCount = 0; + + if (mAdapter != null) { + if (mObserver == null) { + mObserver = new PagerObserver(); + } + mAdapter.registerDataSetObserver(mObserver); + mPopulatePending = false; + final boolean wasFirstLayout = mFirstLayout; + mFirstLayout = true; + mExpectedAdapterCount = mAdapter.getCount(); + if (mRestoredCurItem >= 0) { + mAdapter.restoreState(mRestoredAdapterState, mRestoredClassLoader); + setCurrentItemInternal(mRestoredCurItem, false, true); + mRestoredCurItem = -1; + mRestoredAdapterState = null; + mRestoredClassLoader = null; + } else if (!wasFirstLayout) { + populate(); + } else { + requestLayout(); + } + } + + if (mAdapterChangeListener != null && oldAdapter != adapter) { + mAdapterChangeListener.onAdapterChanged(oldAdapter, adapter); + } + } + + private void removeNonDecorViews() { + for (int i = 0; i < getChildCount(); i++) { + final View child = getChildAt(i); + final LayoutParams lp = (LayoutParams) child.getLayoutParams(); + if (!lp.isDecor) { + removeViewAt(i); + i--; + } + } + } + + /** + * Retrieve the current adapter supplying pages. + * + * @return The currently registered PagerAdapter + */ + public PagerAdapter getAdapter() { + return mAdapter; + } + + void setOnAdapterChangeListener(OnAdapterChangeListener listener) { + mAdapterChangeListener = listener; + } + + private int getClientWidth() { + return getMeasuredWidth() - getPaddingLeft() - getPaddingRight(); + } + + /** + * Set the currently selected page. If the ViewPager has already been through its first + * layout with its current adapter there will be a smooth animated transition between + * the current item and the specified item. + * + * @param item Item index to select + */ + public void setCurrentItem(int item) { + mPopulatePending = false; + setCurrentItemInternal(item, !mFirstLayout, false); + } + + /** + * Set the currently selected page. + * + * @param item Item index to select + * @param smoothScroll True to smoothly scroll to the new item, false to transition immediately + */ + public void setCurrentItem(int item, boolean smoothScroll) { + mPopulatePending = false; + setCurrentItemInternal(item, smoothScroll, false); + } + + public int getCurrentItem() { + return mCurItem; + } + + void setCurrentItemInternal(int item, boolean smoothScroll, boolean always) { + setCurrentItemInternal(item, smoothScroll, always, 0); + } + + void setCurrentItemInternal(int item, boolean smoothScroll, boolean always, int velocity) { + if (mAdapter == null || mAdapter.getCount() <= 0) { + setScrollingCacheEnabled(false); + return; + } + if (!always && mCurItem == item && mItems.size() != 0) { + setScrollingCacheEnabled(false); + return; + } + + if (item < 0) { + item = 0; + } else if (item >= mAdapter.getCount()) { + item = mAdapter.getCount() - 1; + } + final int pageLimit = mOffscreenPageLimit; + if (item > (mCurItem + pageLimit) || item < (mCurItem - pageLimit)) { + // We are doing a jump by more than one page. To avoid + // glitches, we want to keep all current pages in the view + // until the scroll ends. + for (int i=0; iNote: Prior to Android 3.0 the property animation APIs did not exist. + * As a result, setting a PageTransformer prior to Android 3.0 (API 11) will have no effect.

+ * + * @param reverseDrawingOrder true if the supplied PageTransformer requires page views + * to be drawn from last to first instead of first to last. + * @param transformer PageTransformer that will modify each page's animation properties + */ + public void setPageTransformer(boolean reverseDrawingOrder, PageTransformer transformer) { + if (Build.VERSION.SDK_INT >= 11) { + final boolean hasTransformer = transformer != null; + final boolean needsPopulate = hasTransformer != (mPageTransformer != null); + mPageTransformer = transformer; + setChildrenDrawingOrderEnabledCompat(hasTransformer); + if (hasTransformer) { + mDrawingOrder = reverseDrawingOrder ? DRAW_ORDER_REVERSE : DRAW_ORDER_FORWARD; + } else { + mDrawingOrder = DRAW_ORDER_DEFAULT; + } + if (needsPopulate) populate(); + } + } + + void setChildrenDrawingOrderEnabledCompat(boolean enable) { + if (Build.VERSION.SDK_INT >= 7) { + if (mSetChildrenDrawingOrderEnabled == null) { + try { + mSetChildrenDrawingOrderEnabled = ViewGroup.class.getDeclaredMethod( + "setChildrenDrawingOrderEnabled", new Class[] { Boolean.TYPE }); + } catch (NoSuchMethodException e) { + Log.e(TAG, "Can't find setChildrenDrawingOrderEnabled", e); + } + } + try { + mSetChildrenDrawingOrderEnabled.invoke(this, enable); + } catch (Exception e) { + Log.e(TAG, "Error changing children drawing order", e); + } + } + } + + @Override + protected int getChildDrawingOrder(int childCount, int i) { + final int index = mDrawingOrder == DRAW_ORDER_REVERSE ? childCount - 1 - i : i; + final int result = ((LayoutParams) mDrawingOrderedChildren.get(index).getLayoutParams()).childIndex; + return result; + } + + /** + * Set a separate OnPageChangeListener for internal use by the support library. + * + * @param listener Listener to set + * @return The old listener that was set, if any. + */ + OnPageChangeListener setInternalPageChangeListener(OnPageChangeListener listener) { + OnPageChangeListener oldListener = mInternalPageChangeListener; + mInternalPageChangeListener = listener; + return oldListener; + } + + /** + * Returns the number of pages that will be retained to either side of the + * current page in the view hierarchy in an idle state. Defaults to 1. + * + * @return How many pages will be kept offscreen on either side + * @see #setOffscreenPageLimit(int) + */ + public int getOffscreenPageLimit() { + return mOffscreenPageLimit; + } + + /** + * Set the number of pages that should be retained to either side of the + * current page in the view hierarchy in an idle state. Pages beyond this + * limit will be recreated from the adapter when needed. + * + *

This is offered as an optimization. If you know in advance the number + * of pages you will need to support or have lazy-loading mechanisms in place + * on your pages, tweaking this setting can have benefits in perceived smoothness + * of paging animations and interaction. If you have a small number of pages (3-4) + * that you can keep active all at once, less time will be spent in layout for + * newly created view subtrees as the user pages back and forth.

+ * + *

You should keep this limit low, especially if your pages have complex layouts. + * This setting defaults to 1.

+ * + * @param limit How many pages will be kept offscreen in an idle state. + */ + public void setOffscreenPageLimit(int limit) { + if (limit < DEFAULT_OFFSCREEN_PAGES) { + Log.w(TAG, "Requested offscreen page limit " + limit + " too small; defaulting to " + + DEFAULT_OFFSCREEN_PAGES); + limit = DEFAULT_OFFSCREEN_PAGES; + } + if (limit != mOffscreenPageLimit) { + mOffscreenPageLimit = limit; + populate(); + } + } + + /** + * Set the margin between pages. + * + * @param marginPixels Distance between adjacent pages in pixels + * @see #getPageMargin() + * @see #setPageMarginDrawable(Drawable) + * @see #setPageMarginDrawable(int) + */ + public void setPageMargin(int marginPixels) { + final int oldMargin = mPageMargin; + mPageMargin = marginPixels; + + final int width = getWidth(); + recomputeScrollPosition(width, width, marginPixels, oldMargin); + + requestLayout(); + } + + /** + * Return the margin between pages. + * + * @return The size of the margin in pixels + */ + public int getPageMargin() { + return mPageMargin; + } + + /** + * Set a drawable that will be used to fill the margin between pages. + * + * @param d Drawable to display between pages + */ + public void setPageMarginDrawable(Drawable d) { + mMarginDrawable = d; + if (d != null) refreshDrawableState(); + setWillNotDraw(d == null); + invalidate(); + } + + /** + * Set a drawable that will be used to fill the margin between pages. + * + * @param resId Resource ID of a drawable to display between pages + */ + public void setPageMarginDrawable(@DrawableRes int resId) { + setPageMarginDrawable(getContext().getResources().getDrawable(resId)); + } + + @Override + protected boolean verifyDrawable(Drawable who) { + return super.verifyDrawable(who) || who == mMarginDrawable; + } + + @Override + protected void drawableStateChanged() { + super.drawableStateChanged(); + final Drawable d = mMarginDrawable; + if (d != null && d.isStateful()) { + d.setState(getDrawableState()); + } + } + + // We want the duration of the page snap animation to be influenced by the distance that + // the screen has to travel, however, we don't want this duration to be effected in a + // purely linear fashion. Instead, we use this method to moderate the effect that the distance + // of travel has on the overall snap duration. + float distanceInfluenceForSnapDuration(float f) { + f -= 0.5f; // center the values about 0. + f *= 0.3f * Math.PI / 2.0f; + return (float) Math.sin(f); + } + + /** + * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. + * + * @param x the number of pixels to scroll by on the X axis + * @param y the number of pixels to scroll by on the Y axis + */ + void smoothScrollTo(int x, int y) { + smoothScrollTo(x, y, 0); + } + + /** + * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. + * + * @param x the number of pixels to scroll by on the X axis + * @param y the number of pixels to scroll by on the Y axis + * @param velocity the velocity associated with a fling, if applicable. (0 otherwise) + */ + void smoothScrollTo(int x, int y, int velocity) { + if (getChildCount() == 0) { + // Nothing to do. + setScrollingCacheEnabled(false); + return; + } + int sx = getScrollX(); + int sy = getScrollY(); + int dx = x - sx; + int dy = y - sy; + if (dx == 0 && dy == 0) { + completeScroll(false); + populate(); + setScrollState(SCROLL_STATE_IDLE); + return; + } + + setScrollingCacheEnabled(true); + setScrollState(SCROLL_STATE_SETTLING); + + final int width = getClientWidth(); + final int halfWidth = width / 2; + final float distanceRatio = Math.min(1f, 1.0f * Math.abs(dx) / width); + final float distance = halfWidth + halfWidth * + distanceInfluenceForSnapDuration(distanceRatio); + + int duration = 0; + velocity = Math.abs(velocity); + if (velocity > 0) { + duration = 4 * Math.round(1000 * Math.abs(distance / velocity)); + } else { + final float pageWidth = width * mAdapter.getPageWidth(mCurItem); + final float pageDelta = (float) Math.abs(dx) / (pageWidth + mPageMargin); + duration = (int) ((pageDelta + 1) * 100); + } + duration = Math.min(duration, MAX_SETTLE_DURATION); + + mScroller.startScroll(sx, sy, dx, dy, duration); + ViewCompat.postInvalidateOnAnimation(this); + } + + ItemInfo addNewItem(int position, int index) { + ItemInfo ii = new ItemInfo(); + ii.position = position; + ii.object = mAdapter.instantiateItem(this, position); + ii.widthFactor = mAdapter.getPageWidth(position); + if (index < 0 || index >= mItems.size()) { + mItems.add(ii); + } else { + mItems.add(index, ii); + } + return ii; + } + + void dataSetChanged() { + // This method only gets called if our observer is attached, so mAdapter is non-null. + + final int adapterCount = mAdapter.getCount(); + mExpectedAdapterCount = adapterCount; + boolean needPopulate = mItems.size() < mOffscreenPageLimit * 2 + 1 && + mItems.size() < adapterCount; + int newCurrItem = mCurItem; + + boolean isUpdating = false; + for (int i = 0; i < mItems.size(); i++) { + final ItemInfo ii = mItems.get(i); + final int newPos = mAdapter.getItemPosition(ii.object); + + if (newPos == PagerAdapter.POSITION_UNCHANGED) { + continue; + } + + if (newPos == PagerAdapter.POSITION_NONE) { + mItems.remove(i); + i--; + + if (!isUpdating) { + mAdapter.startUpdate(this); + isUpdating = true; + } + + mAdapter.destroyItem(this, ii.position, ii.object); + needPopulate = true; + + if (mCurItem == ii.position) { + // Keep the current item in the valid range + newCurrItem = Math.max(0, Math.min(mCurItem, adapterCount - 1)); + needPopulate = true; + } + continue; + } + + if (ii.position != newPos) { + if (ii.position == mCurItem) { + // Our current item changed position. Follow it. + newCurrItem = newPos; + } + + ii.position = newPos; + needPopulate = true; + } + } + + if (isUpdating) { + mAdapter.finishUpdate(this); + } + + Collections.sort(mItems, COMPARATOR); + + if (needPopulate) { + // Reset our known page widths; populate will recompute them. + final int childCount = getChildCount(); + for (int i = 0; i < childCount; i++) { + final View child = getChildAt(i); + final LayoutParams lp = (LayoutParams) child.getLayoutParams(); + if (!lp.isDecor) { + lp.widthFactor = 0.f; + } + } + + setCurrentItemInternal(newCurrItem, false, true); + requestLayout(); + } + } + + void populate() { + populate(mCurItem); + } + + void populate(int newCurrentItem) { + ItemInfo oldCurInfo = null; + int focusDirection = View.FOCUS_FORWARD; + if (mCurItem != newCurrentItem) { + focusDirection = mCurItem < newCurrentItem ? View.FOCUS_RIGHT : View.FOCUS_LEFT; + oldCurInfo = infoForPosition(mCurItem); + mCurItem = newCurrentItem; + } + + if (mAdapter == null) { + sortChildDrawingOrder(); + return; + } + + // Bail now if we are waiting to populate. This is to hold off + // on creating views from the time the user releases their finger to + // fling to a new position until we have finished the scroll to + // that position, avoiding glitches from happening at that point. + if (mPopulatePending) { + if (DEBUG) Log.i(TAG, "populate is pending, skipping for now..."); + sortChildDrawingOrder(); + return; + } + + // Also, don't populate until we are attached to a window. This is to + // avoid trying to populate before we have restored our view hierarchy + // state and conflicting with what is restored. + if (getWindowToken() == null) { + return; + } + + mAdapter.startUpdate(this); + + final int pageLimit = mOffscreenPageLimit; + final int startPos = Math.max(0, mCurItem - pageLimit); + final int N = mAdapter.getCount(); + final int endPos = Math.min(N-1, mCurItem + pageLimit); + + if (N != mExpectedAdapterCount) { + String resName; + try { + resName = getResources().getResourceName(getId()); + } catch (Resources.NotFoundException e) { + resName = Integer.toHexString(getId()); + } + throw new IllegalStateException("The application's PagerAdapter changed the adapter's" + + " contents without calling PagerAdapter#notifyDataSetChanged!" + + " Expected adapter item count: " + mExpectedAdapterCount + ", found: " + N + + " Pager id: " + resName + + " Pager class: " + getClass() + + " Problematic adapter: " + mAdapter.getClass()); + } + + // Locate the currently focused item or add it if needed. + int curIndex = -1; + ItemInfo curItem = null; + for (curIndex = 0; curIndex < mItems.size(); curIndex++) { + final ItemInfo ii = mItems.get(curIndex); + if (ii.position >= mCurItem) { + if (ii.position == mCurItem) curItem = ii; + break; + } + } + + if (curItem == null && N > 0) { + curItem = addNewItem(mCurItem, curIndex); + } + + // Fill 3x the available width or up to the number of offscreen + // pages requested to either side, whichever is larger. + // If we have no current item we have no work to do. + if (curItem != null) { + float extraWidthLeft = 0.f; + int itemIndex = curIndex - 1; + ItemInfo ii = itemIndex >= 0 ? mItems.get(itemIndex) : null; + final int clientWidth = getClientWidth(); + final float leftWidthNeeded = clientWidth <= 0 ? 0 : + 2.f - curItem.widthFactor + (float) getPaddingLeft() / (float) clientWidth; + for (int pos = mCurItem - 1; pos >= 0; pos--) { + if (extraWidthLeft >= leftWidthNeeded && pos < startPos) { + if (ii == null) { + break; + } + if (pos == ii.position && !ii.scrolling) { + mItems.remove(itemIndex); + mAdapter.destroyItem(this, pos, ii.object); + if (DEBUG) { + Log.i(TAG, "populate() - destroyItem() with pos: " + pos + + " view: " + ii.object); + } + itemIndex--; + curIndex--; + ii = itemIndex >= 0 ? mItems.get(itemIndex) : null; + } + } else if (ii != null && pos == ii.position) { + extraWidthLeft += ii.widthFactor; + itemIndex--; + ii = itemIndex >= 0 ? mItems.get(itemIndex) : null; + } else { + ii = addNewItem(pos, itemIndex + 1); + extraWidthLeft += ii.widthFactor; + curIndex++; + ii = itemIndex >= 0 ? mItems.get(itemIndex) : null; + } + } + + float extraWidthRight = curItem.widthFactor; + itemIndex = curIndex + 1; + if (extraWidthRight < 2.f) { + ii = itemIndex < mItems.size() ? mItems.get(itemIndex) : null; + final float rightWidthNeeded = clientWidth <= 0 ? 0 : + (float) getPaddingRight() / (float) clientWidth + 2.f; + for (int pos = mCurItem + 1; pos < N; pos++) { + if (extraWidthRight >= rightWidthNeeded && pos > endPos) { + if (ii == null) { + break; + } + if (pos == ii.position && !ii.scrolling) { + mItems.remove(itemIndex); + mAdapter.destroyItem(this, pos, ii.object); + if (DEBUG) { + Log.i(TAG, "populate() - destroyItem() with pos: " + pos + + " view: " + (ii.object)); + } + ii = itemIndex < mItems.size() ? mItems.get(itemIndex) : null; + } + } else if (ii != null && pos == ii.position) { + extraWidthRight += ii.widthFactor; + itemIndex++; + ii = itemIndex < mItems.size() ? mItems.get(itemIndex) : null; + } else { + ii = addNewItem(pos, itemIndex); + itemIndex++; + extraWidthRight += ii.widthFactor; + ii = itemIndex < mItems.size() ? mItems.get(itemIndex) : null; + } + } + } + + calculatePageOffsets(curItem, curIndex, oldCurInfo); + } + + if (DEBUG) { + Log.i(TAG, "Current page list:"); + for (int i=0; i(); + } else { + mDrawingOrderedChildren.clear(); + } + final int childCount = getChildCount(); + for (int i = 0; i < childCount; i++) { + final View child = getChildAt(i); + mDrawingOrderedChildren.add(child); + } + Collections.sort(mDrawingOrderedChildren, sPositionComparator); + } + } + + private void calculatePageOffsets(ItemInfo curItem, int curIndex, ItemInfo oldCurInfo) { + final int N = mAdapter.getCount(); + final int width = getClientWidth(); + final float marginOffset = width > 0 ? (float) mPageMargin / width : 0; + // Fix up offsets for later layout. + if (oldCurInfo != null) { + final int oldCurPosition = oldCurInfo.position; + // Base offsets off of oldCurInfo. + if (oldCurPosition < curItem.position) { + int itemIndex = 0; + ItemInfo ii = null; + float offset = oldCurInfo.offset + oldCurInfo.widthFactor + marginOffset; + for (int pos = oldCurPosition + 1; + pos <= curItem.position && itemIndex < mItems.size(); pos++) { + ii = mItems.get(itemIndex); + while (pos > ii.position && itemIndex < mItems.size() - 1) { + itemIndex++; + ii = mItems.get(itemIndex); + } + while (pos < ii.position) { + // We don't have an item populated for this, + // ask the adapter for an offset. + offset += mAdapter.getPageWidth(pos) + marginOffset; + pos++; + } + ii.offset = offset; + offset += ii.widthFactor + marginOffset; + } + } else if (oldCurPosition > curItem.position) { + int itemIndex = mItems.size() - 1; + ItemInfo ii = null; + float offset = oldCurInfo.offset; + for (int pos = oldCurPosition - 1; + pos >= curItem.position && itemIndex >= 0; pos--) { + ii = mItems.get(itemIndex); + while (pos < ii.position && itemIndex > 0) { + itemIndex--; + ii = mItems.get(itemIndex); + } + while (pos > ii.position) { + // We don't have an item populated for this, + // ask the adapter for an offset. + offset -= mAdapter.getPageWidth(pos) + marginOffset; + pos--; + } + offset -= ii.widthFactor + marginOffset; + ii.offset = offset; + } + } + } + + // Base all offsets off of curItem. + final int itemCount = mItems.size(); + float offset = curItem.offset; + int pos = curItem.position - 1; + mFirstOffset = curItem.position == 0 ? curItem.offset : -Float.MAX_VALUE; + mLastOffset = curItem.position == N - 1 ? + curItem.offset + curItem.widthFactor - 1 : Float.MAX_VALUE; + // Previous pages + for (int i = curIndex - 1; i >= 0; i--, pos--) { + final ItemInfo ii = mItems.get(i); + while (pos > ii.position) { + offset -= mAdapter.getPageWidth(pos--) + marginOffset; + } + offset -= ii.widthFactor + marginOffset; + ii.offset = offset; + if (ii.position == 0) mFirstOffset = offset; + } + offset = curItem.offset + curItem.widthFactor + marginOffset; + pos = curItem.position + 1; + // Next pages + for (int i = curIndex + 1; i < itemCount; i++, pos++) { + final ItemInfo ii = mItems.get(i); + while (pos < ii.position) { + offset += mAdapter.getPageWidth(pos++) + marginOffset; + } + if (ii.position == N - 1) { + mLastOffset = offset + ii.widthFactor - 1; + } + ii.offset = offset; + offset += ii.widthFactor + marginOffset; + } + + mNeedCalculatePageOffsets = false; + } + + /** + * This is the persistent state that is saved by ViewPager. Only needed + * if you are creating a sublass of ViewPager that must save its own + * state, in which case it should implement a subclass of this which + * contains that state. + */ + public static class SavedState extends BaseSavedState { + int position; + Parcelable adapterState; + ClassLoader loader; + + public SavedState(Parcelable superState) { + super(superState); + } + + @Override + public void writeToParcel(Parcel out, int flags) { + super.writeToParcel(out, flags); + out.writeInt(position); + out.writeParcelable(adapterState, flags); + } + + @Override + public String toString() { + return "FragmentPager.SavedState{" + + Integer.toHexString(System.identityHashCode(this)) + + " position=" + position + "}"; + } + + public static final Parcelable.Creator CREATOR + = ParcelableCompat.newCreator(new ParcelableCompatCreatorCallbacks() { + @TargetApi(24) + @Override + public SavedState createFromParcel(Parcel in, ClassLoader loader) { + return new SavedState(in, loader); + } + + @Override + public SavedState[] newArray(int size) { + return new SavedState[size]; + } + }); + + SavedState(Parcel in, ClassLoader loader) { + super(in); + if (loader == null) { + loader = getClass().getClassLoader(); + } + position = in.readInt(); + adapterState = in.readParcelable(loader); + this.loader = loader; + } + } + + @Override + public Parcelable onSaveInstanceState() { + Parcelable superState = super.onSaveInstanceState(); + SavedState ss = new SavedState(superState); + ss.position = mCurItem; + if (mAdapter != null) { + ss.adapterState = mAdapter.saveState(); + } + return ss; + } + + @Override + public void onRestoreInstanceState(Parcelable state) { + if (!(state instanceof SavedState)) { + super.onRestoreInstanceState(state); + return; + } + + SavedState ss = (SavedState)state; + super.onRestoreInstanceState(ss.getSuperState()); + + if (mAdapter != null) { + mAdapter.restoreState(ss.adapterState, ss.loader); + setCurrentItemInternal(ss.position, false, true); + } else { + mRestoredCurItem = ss.position; + mRestoredAdapterState = ss.adapterState; + mRestoredClassLoader = ss.loader; + } + } + + @Override + public void addView(View child, int index, ViewGroup.LayoutParams params) { + if (!checkLayoutParams(params)) { + params = generateLayoutParams(params); + } + final LayoutParams lp = (LayoutParams) params; + lp.isDecor |= child instanceof Decor; + if (mInLayout) { + if (lp != null && lp.isDecor) { + throw new IllegalStateException("Cannot add pager decor view during layout"); + } + lp.needsMeasure = true; + addViewInLayout(child, index, params); + } else { + super.addView(child, index, params); + } + + if (USE_CACHE) { + if (child.getVisibility() != GONE) { + child.setDrawingCacheEnabled(mScrollingCacheEnabled); + } else { + child.setDrawingCacheEnabled(false); + } + } + } + + @Override + public void removeView(View view) { + if (mInLayout) { + removeViewInLayout(view); + } else { + super.removeView(view); + } + } + + ItemInfo infoForChild(View child) { + for (int i=0; i 0 && !mItems.isEmpty()) { + final int widthWithMargin = width - getPaddingLeft() - getPaddingRight() + margin; + final int oldWidthWithMargin = oldWidth - getPaddingLeft() - getPaddingRight() + + oldMargin; + final int xpos = getScrollX(); + final float pageOffset = (float) xpos / oldWidthWithMargin; + final int newOffsetPixels = (int) (pageOffset * widthWithMargin); + + scrollTo(newOffsetPixels, getScrollY()); + if (!mScroller.isFinished()) { + // We now return to your regularly scheduled scroll, already in progress. + final int newDuration = mScroller.getDuration() - mScroller.timePassed(); + ItemInfo targetInfo = infoForPosition(mCurItem); + mScroller.startScroll(newOffsetPixels, 0, + (int) (targetInfo.offset * width), 0, newDuration); + } + } else { + final ItemInfo ii = infoForPosition(mCurItem); + final float scrollOffset = ii != null ? Math.min(ii.offset, mLastOffset) : 0; + final int scrollPos = (int) (scrollOffset * + (width - getPaddingLeft() - getPaddingRight())); + if (scrollPos != getScrollX()) { + completeScroll(false); + scrollTo(scrollPos, getScrollY()); + } + } + } + + @Override + protected void onLayout(boolean changed, int l, int t, int r, int b) { + final int count = getChildCount(); + int width = r - l; + int height = b - t; + int paddingLeft = getPaddingLeft(); + int paddingTop = getPaddingTop(); + int paddingRight = getPaddingRight(); + int paddingBottom = getPaddingBottom(); + final int scrollX = getScrollX(); + + int decorCount = 0; + + // First pass - decor views. We need to do this in two passes so that + // we have the proper offsets for non-decor views later. + for (int i = 0; i < count; i++) { + final View child = getChildAt(i); + if (child.getVisibility() != GONE) { + final LayoutParams lp = (LayoutParams) child.getLayoutParams(); + int childLeft = 0; + int childTop = 0; + if (lp.isDecor) { + final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK; + final int vgrav = lp.gravity & Gravity.VERTICAL_GRAVITY_MASK; + switch (hgrav) { + default: + childLeft = paddingLeft; + break; + case Gravity.LEFT: + childLeft = paddingLeft; + paddingLeft += child.getMeasuredWidth(); + break; + case Gravity.CENTER_HORIZONTAL: + childLeft = Math.max((width - child.getMeasuredWidth()) / 2, + paddingLeft); + break; + case Gravity.RIGHT: + childLeft = width - paddingRight - child.getMeasuredWidth(); + paddingRight += child.getMeasuredWidth(); + break; + } + switch (vgrav) { + default: + childTop = paddingTop; + break; + case Gravity.TOP: + childTop = paddingTop; + paddingTop += child.getMeasuredHeight(); + break; + case Gravity.CENTER_VERTICAL: + childTop = Math.max((height - child.getMeasuredHeight()) / 2, + paddingTop); + break; + case Gravity.BOTTOM: + childTop = height - paddingBottom - child.getMeasuredHeight(); + paddingBottom += child.getMeasuredHeight(); + break; + } + childLeft += scrollX; + child.layout(childLeft, childTop, + childLeft + child.getMeasuredWidth(), + childTop + child.getMeasuredHeight()); + decorCount++; + } + } + } + + final int childWidth = width - paddingLeft - paddingRight; + // Page views. Do this once we have the right padding offsets from above. + for (int i = 0; i < count; i++) { + final View child = getChildAt(i); + if (child.getVisibility() != GONE) { + final LayoutParams lp = (LayoutParams) child.getLayoutParams(); + ItemInfo ii; + if (!lp.isDecor && (ii = infoForChild(child)) != null) { + int loff = (int) (childWidth * ii.offset); + int childLeft = paddingLeft + loff; + int childTop = paddingTop; + if (lp.needsMeasure) { + // This was added during layout and needs measurement. + // Do it now that we know what we're working with. + lp.needsMeasure = false; + final int widthSpec = MeasureSpec.makeMeasureSpec( + (int) (childWidth * lp.widthFactor), + MeasureSpec.EXACTLY); + final int heightSpec = MeasureSpec.makeMeasureSpec( + (int) (height - paddingTop - paddingBottom), + MeasureSpec.EXACTLY); + child.measure(widthSpec, heightSpec); + } + int id = -1; + + if (DEBUG) Log.v(TAG, "Positioning #" + i + " " + child + " f=" + ii.object + + ":" + childLeft + "," + childTop + " " + child.getMeasuredWidth() + + "x" + child.getMeasuredHeight()); + + child.layout(childLeft, childTop, + childLeft + child.getMeasuredWidth(), + childTop + child.getMeasuredHeight()); + } + } + } + mTopPageBounds = paddingTop; + mBottomPageBounds = height - paddingBottom; + mDecorChildCount = decorCount; + + if (mFirstLayout) { + scrollToItem(mCurItem, false, 0, false); + } + mFirstLayout = false; + } + + @Override + public void computeScroll() { + if (!mScroller.isFinished() && mScroller.computeScrollOffset()) { + int oldX = getScrollX(); + int oldY = getScrollY(); + int x = mScroller.getCurrX(); + int y = mScroller.getCurrY(); + + if (oldX != x || oldY != y) { + scrollTo(x, y); + if (!pageScrolled(x)) { + mScroller.abortAnimation(); + scrollTo(0, y); + } + } + + // Keep on drawing until the animation has finished. + ViewCompat.postInvalidateOnAnimation(this); + return; + } + + // Done with scroll, clean up state. + completeScroll(true); + } + + private boolean pageScrolled(int xpos) { + if (mItems.size() == 0) { + mCalledSuper = false; + onPageScrolled(0, 0, 0); + if (!mCalledSuper) { + throw new IllegalStateException( + "onPageScrolled did not call superclass implementation"); + } + return false; + } + final ItemInfo ii = infoForCurrentScrollPosition(); + final int width = getClientWidth(); + final int widthWithMargin = width + mPageMargin; + final float marginOffset = (float) mPageMargin / width; + final int currentPage = ii.position; + final float pageOffset = (((float) xpos / width) - ii.offset) / + (ii.widthFactor + marginOffset); + final int offsetPixels = (int) (pageOffset * widthWithMargin); + + mCalledSuper = false; + onPageScrolled(currentPage, pageOffset, offsetPixels); + if (!mCalledSuper) { + throw new IllegalStateException( + "onPageScrolled did not call superclass implementation"); + } + return true; + } + + /** + * This method will be invoked when the current page is scrolled, either as part + * of a programmatically initiated smooth scroll or a user initiated touch scroll. + * If you override this method you must call through to the superclass implementation + * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled + * returns. + * + * @param position Position index of the first page currently being displayed. + * Page position+1 will be visible if positionOffset is nonzero. + * @param offset Value from [0, 1) indicating the offset from the page at position. + * @param offsetPixels Value in pixels indicating the offset from position. + */ + protected void onPageScrolled(int position, float offset, int offsetPixels) { + // Offset any decor views if needed - keep them on-screen at all times. + if (mDecorChildCount > 0) { + final int scrollX = getScrollX(); + int paddingLeft = getPaddingLeft(); + int paddingRight = getPaddingRight(); + final int width = getWidth(); + final int childCount = getChildCount(); + for (int i = 0; i < childCount; i++) { + final View child = getChildAt(i); + final LayoutParams lp = (LayoutParams) child.getLayoutParams(); + if (!lp.isDecor) continue; + + final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK; + int childLeft = 0; + switch (hgrav) { + default: + childLeft = paddingLeft; + break; + case Gravity.LEFT: + childLeft = paddingLeft; + paddingLeft += child.getWidth(); + break; + case Gravity.CENTER_HORIZONTAL: + childLeft = Math.max((width - child.getMeasuredWidth()) / 2, + paddingLeft); + break; + case Gravity.RIGHT: + childLeft = width - paddingRight - child.getMeasuredWidth(); + paddingRight += child.getMeasuredWidth(); + break; + } + childLeft += scrollX; + + final int childOffset = childLeft - child.getLeft(); + if (childOffset != 0) { + child.offsetLeftAndRight(childOffset); + } + } + } + + if (mOnPageChangeListener != null) { + mOnPageChangeListener.onPageScrolled(position, offset, offsetPixels); + } + if (mInternalPageChangeListener != null) { + mInternalPageChangeListener.onPageScrolled(position, offset, offsetPixels); + } + + if (mPageTransformer != null) { + final int scrollX = getScrollX(); + final int childCount = getChildCount(); + for (int i = 0; i < childCount; i++) { + final View child = getChildAt(i); + final LayoutParams lp = (LayoutParams) child.getLayoutParams(); + + if (lp.isDecor) continue; + + final float transformPos = (float) (child.getLeft() - scrollX) / getClientWidth(); + mPageTransformer.transformPage(child, transformPos); + } + } + + mCalledSuper = true; + } + + private void completeScroll(boolean postEvents) { + boolean needPopulate = mScrollState == SCROLL_STATE_SETTLING; + if (needPopulate) { + // Done with scroll, no longer want to cache view drawing. + setScrollingCacheEnabled(false); + mScroller.abortAnimation(); + int oldX = getScrollX(); + int oldY = getScrollY(); + int x = mScroller.getCurrX(); + int y = mScroller.getCurrY(); + if (oldX != x || oldY != y) { + scrollTo(x, y); + } + } + mPopulatePending = false; + for (int i=0; i 0) || (x > getWidth() - mGutterSize && dx < 0); + } + + private void enableLayers(boolean enable) { + final int childCount = getChildCount(); + for (int i = 0; i < childCount; i++) { + final int layerType = enable ? + ViewCompat.LAYER_TYPE_HARDWARE : ViewCompat.LAYER_TYPE_NONE; + ViewCompat.setLayerType(getChildAt(i), layerType, null); + } + } + + @Override + public boolean onInterceptTouchEvent(MotionEvent ev) { + /* + * This method JUST determines whether we want to intercept the motion. + * If we return true, onMotionEvent will be called and we do the actual + * scrolling there. + */ + + final int action = ev.getAction() & MotionEventCompat.ACTION_MASK; + + // Always take care of the touch gesture being complete. + if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) { + // Release the drag. + if (DEBUG) Log.v(TAG, "Intercept done!"); + mIsBeingDragged = false; + mIsUnableToDrag = false; + mActivePointerId = INVALID_POINTER; + if (mVelocityTracker != null) { + mVelocityTracker.recycle(); + mVelocityTracker = null; + } + return false; + } + + // Nothing more to do here if we have decided whether or not we + // are dragging. + if (action != MotionEvent.ACTION_DOWN) { + if (mIsBeingDragged) { + if (DEBUG) Log.v(TAG, "Intercept returning true!"); + return true; + } + if (mIsUnableToDrag) { + if (DEBUG) Log.v(TAG, "Intercept returning false!"); + return false; + } + } + + switch (action) { + case MotionEvent.ACTION_MOVE: { + /* + * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check + * whether the user has moved far enough from his original down touch. + */ + + /* + * Locally do absolute value. mLastMotionY is set to the y value + * of the down event. + */ + final int activePointerId = mActivePointerId; + if (activePointerId == INVALID_POINTER) { + // If we don't have a valid id, the touch down wasn't on content. + break; + } + + final int pointerIndex = MotionEventCompat.findPointerIndex(ev, activePointerId); + final float x = MotionEventCompat.getX(ev, pointerIndex); + final float dx = x - mLastMotionX; + final float xDiff = Math.abs(dx); + final float y = MotionEventCompat.getY(ev, pointerIndex); + final float yDiff = Math.abs(y - mInitialMotionY); + if (DEBUG) Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + "," + yDiff); + + if (dx != 0 && !isGutterDrag(mLastMotionX, dx) && + canScroll(this, false, (int) dx, (int) x, (int) y)) { + // Nested view has scrollable area under this point. Let it be handled there. + mLastMotionX = x; + mLastMotionY = y; + mIsUnableToDrag = true; + return false; + } + if (xDiff > mTouchSlop && xDiff * 0.5f > yDiff) { + if (DEBUG) Log.v(TAG, "Starting drag!"); + mIsBeingDragged = true; + requestParentDisallowInterceptTouchEvent(true); + setScrollState(SCROLL_STATE_DRAGGING); + mLastMotionX = dx > 0 ? mInitialMotionX + mTouchSlop : + mInitialMotionX - mTouchSlop; + mLastMotionY = y; + setScrollingCacheEnabled(true); + } else if (yDiff > mTouchSlop) { + // The finger has moved enough in the vertical + // direction to be counted as a drag... abort + // any attempt to drag horizontally, to work correctly + // with children that have scrolling containers. + if (DEBUG) Log.v(TAG, "Starting unable to drag!"); + mIsUnableToDrag = true; + } + if (mIsBeingDragged) { + // Scroll to follow the motion event + if (performDrag(x)) { + ViewCompat.postInvalidateOnAnimation(this); + } + } + break; + } + + case MotionEvent.ACTION_DOWN: { + /* + * Remember location of down touch. + * ACTION_DOWN always refers to pointer index 0. + */ + mLastMotionX = mInitialMotionX = ev.getX(); + mLastMotionY = mInitialMotionY = ev.getY(); + mActivePointerId = MotionEventCompat.getPointerId(ev, 0); + mIsUnableToDrag = false; + + mScroller.computeScrollOffset(); + if (mScrollState == SCROLL_STATE_SETTLING && + Math.abs(mScroller.getFinalX() - mScroller.getCurrX()) > mCloseEnough) { + // Let the user 'catch' the pager as it animates. + mScroller.abortAnimation(); + mPopulatePending = false; + populate(); + mIsBeingDragged = true; + requestParentDisallowInterceptTouchEvent(true); + setScrollState(SCROLL_STATE_DRAGGING); + } else { + completeScroll(false); + mIsBeingDragged = false; + } + + if (DEBUG) Log.v(TAG, "Down at " + mLastMotionX + "," + mLastMotionY + + " mIsBeingDragged=" + mIsBeingDragged + + "mIsUnableToDrag=" + mIsUnableToDrag); + break; + } + + case MotionEventCompat.ACTION_POINTER_UP: + onSecondaryPointerUp(ev); + break; + } + + if (mVelocityTracker == null) { + mVelocityTracker = VelocityTracker.obtain(); + } + mVelocityTracker.addMovement(ev); + + /* + * The only time we want to intercept motion events is if we are in the + * drag mode. + */ + return mIsBeingDragged; + } + + @Override + public boolean onTouchEvent(MotionEvent ev) { + if (mFakeDragging) { + // A fake drag is in progress already, ignore this real one + // but still eat the touch events. + // (It is likely that the user is multi-touching the screen.) + return true; + } + + if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { + // Don't handle edge touches immediately -- they may actually belong to one of our + // descendants. + return false; + } + + if (mAdapter == null || mAdapter.getCount() == 0) { + // Nothing to present or scroll; nothing to touch. + return false; + } + + if (mVelocityTracker == null) { + mVelocityTracker = VelocityTracker.obtain(); + } + mVelocityTracker.addMovement(ev); + + final int action = ev.getAction(); + boolean needsInvalidate = false; + + switch (action & MotionEventCompat.ACTION_MASK) { + case MotionEvent.ACTION_DOWN: { + mScroller.abortAnimation(); + mPopulatePending = false; + populate(); + + // Remember where the motion event started + mLastMotionX = mInitialMotionX = ev.getX(); + mLastMotionY = mInitialMotionY = ev.getY(); + mActivePointerId = MotionEventCompat.getPointerId(ev, 0); + break; + } + case MotionEvent.ACTION_MOVE: + if (!mIsBeingDragged) { + final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId); + final float x = MotionEventCompat.getX(ev, pointerIndex); + final float xDiff = Math.abs(x - mLastMotionX); + final float y = MotionEventCompat.getY(ev, pointerIndex); + final float yDiff = Math.abs(y - mLastMotionY); + if (DEBUG) Log.v(TAG, "Moved x to " + x + "," + y + " diff=" + xDiff + "," + yDiff); + if (xDiff > mTouchSlop && xDiff > yDiff) { + if (DEBUG) Log.v(TAG, "Starting drag!"); + mIsBeingDragged = true; + requestParentDisallowInterceptTouchEvent(true); + mLastMotionX = x - mInitialMotionX > 0 ? mInitialMotionX + mTouchSlop : + mInitialMotionX - mTouchSlop; + mLastMotionY = y; + setScrollState(SCROLL_STATE_DRAGGING); + setScrollingCacheEnabled(true); + + // Disallow Parent Intercept, just in case + ViewParent parent = getParent(); + if (parent != null) { + parent.requestDisallowInterceptTouchEvent(true); + } + } + } + // Not else! Note that mIsBeingDragged can be set above. + if (mIsBeingDragged) { + // Scroll to follow the motion event + final int activePointerIndex = MotionEventCompat.findPointerIndex( + ev, mActivePointerId); + final float x = MotionEventCompat.getX(ev, activePointerIndex); + needsInvalidate |= performDrag(x); + } + break; + case MotionEvent.ACTION_UP: + if (mIsBeingDragged) { + final VelocityTracker velocityTracker = mVelocityTracker; + velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); + int initialVelocity = (int) VelocityTrackerCompat.getXVelocity( + velocityTracker, mActivePointerId); + mPopulatePending = true; + final int width = getClientWidth(); + final int scrollX = getScrollX(); + final ItemInfo ii = infoForCurrentScrollPosition(); + final int currentPage = ii.position; + final float pageOffset = (((float) scrollX / width) - ii.offset) / ii.widthFactor; + final int activePointerIndex = + MotionEventCompat.findPointerIndex(ev, mActivePointerId); + final float x = MotionEventCompat.getX(ev, activePointerIndex); + final int totalDelta = (int) (x - mInitialMotionX); + int nextPage = determineTargetPage(currentPage, pageOffset, initialVelocity, + totalDelta); + setCurrentItemInternal(nextPage, true, true, initialVelocity); + + mActivePointerId = INVALID_POINTER; + endDrag(); + needsInvalidate = mLeftEdge.onRelease() | mRightEdge.onRelease(); + } + break; + case MotionEvent.ACTION_CANCEL: + if (mIsBeingDragged) { + scrollToItem(mCurItem, true, 0, false); + mActivePointerId = INVALID_POINTER; + endDrag(); + needsInvalidate = mLeftEdge.onRelease() | mRightEdge.onRelease(); + } + break; + case MotionEventCompat.ACTION_POINTER_DOWN: { + final int index = MotionEventCompat.getActionIndex(ev); + final float x = MotionEventCompat.getX(ev, index); + mLastMotionX = x; + mActivePointerId = MotionEventCompat.getPointerId(ev, index); + break; + } + case MotionEventCompat.ACTION_POINTER_UP: + onSecondaryPointerUp(ev); + mLastMotionX = MotionEventCompat.getX(ev, + MotionEventCompat.findPointerIndex(ev, mActivePointerId)); + break; + } + if (needsInvalidate) { + ViewCompat.postInvalidateOnAnimation(this); + } + return true; + } + + private void requestParentDisallowInterceptTouchEvent(boolean disallowIntercept) { + final ViewParent parent = getParent(); + if (parent != null) { + parent.requestDisallowInterceptTouchEvent(disallowIntercept); + } + } + + private boolean performDrag(float x) { + boolean needsInvalidate = false; + + final float deltaX = mLastMotionX - x; + mLastMotionX = x; + + float oldScrollX = getScrollX(); + float scrollX = oldScrollX + deltaX; + final int width = getClientWidth(); + + float leftBound = width * mFirstOffset; + float rightBound = width * mLastOffset; + boolean leftAbsolute = true; + boolean rightAbsolute = true; + + final ItemInfo firstItem = mItems.get(0); + final ItemInfo lastItem = mItems.get(mItems.size() - 1); + if (firstItem.position != 0) { + leftAbsolute = false; + leftBound = firstItem.offset * width; + } + if (lastItem.position != mAdapter.getCount() - 1) { + rightAbsolute = false; + rightBound = lastItem.offset * width; + } + + if (scrollX < leftBound) { + if (leftAbsolute) { + float over = leftBound - scrollX; + needsInvalidate = mLeftEdge.onPull(Math.abs(over) / width); + } + scrollX = leftBound; + } else if (scrollX > rightBound) { + if (rightAbsolute) { + float over = scrollX - rightBound; + needsInvalidate = mRightEdge.onPull(Math.abs(over) / width); + } + scrollX = rightBound; + } + // Don't lose the rounded component + mLastMotionX += scrollX - (int) scrollX; + scrollTo((int) scrollX, getScrollY()); + pageScrolled((int) scrollX); + + return needsInvalidate; + } + + /** + * @return Info about the page at the current scroll position. + * This can be synthetic for a missing middle page; the 'object' field can be null. + */ + private ItemInfo infoForCurrentScrollPosition() { + final int width = getClientWidth(); + final float scrollOffset = width > 0 ? (float) getScrollX() / width : 0; + final float marginOffset = width > 0 ? (float) mPageMargin / width : 0; + int lastPos = -1; + float lastOffset = 0.f; + float lastWidth = 0.f; + boolean first = true; + + ItemInfo lastItem = null; + for (int i = 0; i < mItems.size(); i++) { + ItemInfo ii = mItems.get(i); + float offset; + if (!first && ii.position != lastPos + 1) { + // Create a synthetic item for a missing page. + ii = mTempItem; + ii.offset = lastOffset + lastWidth + marginOffset; + ii.position = lastPos + 1; + ii.widthFactor = mAdapter.getPageWidth(ii.position); + i--; + } + offset = ii.offset; + + final float leftBound = offset; + final float rightBound = offset + ii.widthFactor + marginOffset; + if (first || scrollOffset >= leftBound) { + if (scrollOffset < rightBound || i == mItems.size() - 1) { + return ii; + } + } else { + return lastItem; + } + first = false; + lastPos = ii.position; + lastOffset = offset; + lastWidth = ii.widthFactor; + lastItem = ii; + } + + return lastItem; + } + + private int determineTargetPage(int currentPage, float pageOffset, int velocity, int deltaX) { + int targetPage; + if (Math.abs(deltaX) > mFlingDistance && Math.abs(velocity) > mMinimumVelocity) { + targetPage = velocity > 0 ? currentPage : currentPage + 1; + } else { + final float truncator = currentPage >= mCurItem ? 0.4f : 0.6f; + targetPage = (int) (currentPage + pageOffset + truncator); + } + + if (mItems.size() > 0) { + final ItemInfo firstItem = mItems.get(0); + final ItemInfo lastItem = mItems.get(mItems.size() - 1); + + // Only let the user target pages we have items for + targetPage = Math.max(firstItem.position, Math.min(targetPage, lastItem.position)); + } + + return targetPage; + } + + @Override + public void draw(Canvas canvas) { + super.draw(canvas); + boolean needsInvalidate = false; + + final int overScrollMode = ViewCompat.getOverScrollMode(this); + if (overScrollMode == ViewCompat.OVER_SCROLL_ALWAYS || + (overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && + mAdapter != null && mAdapter.getCount() > 1)) { + if (!mLeftEdge.isFinished()) { + final int restoreCount = canvas.save(); + final int height = getHeight() - getPaddingTop() - getPaddingBottom(); + final int width = getWidth(); + + canvas.rotate(270); + canvas.translate(-height + getPaddingTop(), mFirstOffset * width); + mLeftEdge.setSize(height, width); + needsInvalidate |= mLeftEdge.draw(canvas); + canvas.restoreToCount(restoreCount); + } + if (!mRightEdge.isFinished()) { + final int restoreCount = canvas.save(); + final int width = getWidth(); + final int height = getHeight() - getPaddingTop() - getPaddingBottom(); + + canvas.rotate(90); + canvas.translate(-getPaddingTop(), -(mLastOffset + 1) * width); + mRightEdge.setSize(height, width); + needsInvalidate |= mRightEdge.draw(canvas); + canvas.restoreToCount(restoreCount); + } + } else { + mLeftEdge.finish(); + mRightEdge.finish(); + } + + if (needsInvalidate) { + // Keep animating + ViewCompat.postInvalidateOnAnimation(this); + } + } + + @Override + protected void onDraw(Canvas canvas) { + super.onDraw(canvas); + + // Draw the margin drawable between pages if needed. + if (mPageMargin > 0 && mMarginDrawable != null && mItems.size() > 0 && mAdapter != null) { + final int scrollX = getScrollX(); + final int width = getWidth(); + + final float marginOffset = (float) mPageMargin / width; + int itemIndex = 0; + ItemInfo ii = mItems.get(0); + float offset = ii.offset; + final int itemCount = mItems.size(); + final int firstPos = ii.position; + final int lastPos = mItems.get(itemCount - 1).position; + for (int pos = firstPos; pos < lastPos; pos++) { + while (pos > ii.position && itemIndex < itemCount) { + ii = mItems.get(++itemIndex); + } + + float drawAt; + if (pos == ii.position) { + drawAt = (ii.offset + ii.widthFactor) * width; + offset = ii.offset + ii.widthFactor + marginOffset; + } else { + float widthFactor = mAdapter.getPageWidth(pos); + drawAt = (offset + widthFactor) * width; + offset += widthFactor + marginOffset; + } + + if (drawAt + mPageMargin > scrollX) { + mMarginDrawable.setBounds((int) drawAt, mTopPageBounds, + (int) (drawAt + mPageMargin + 0.5f), mBottomPageBounds); + mMarginDrawable.draw(canvas); + } + + if (drawAt > scrollX + width) { + break; // No more visible, no sense in continuing + } + } + } + } + + /** + * Start a fake drag of the pager. + * + *

A fake drag can be useful if you want to synchronize the motion of the ViewPager + * with the touch scrolling of another view, while still letting the ViewPager + * control the snapping motion and fling behavior. (e.g. parallax-scrolling tabs.) + * Call {@link #fakeDragBy(float)} to simulate the actual drag motion. Call + * {@link #endFakeDrag()} to complete the fake drag and fling as necessary. + * + *

During a fake drag the ViewPager will ignore all touch events. If a real drag + * is already in progress, this method will return false. + * + * @return true if the fake drag began successfully, false if it could not be started. + * + * @see #fakeDragBy(float) + * @see #endFakeDrag() + */ + public boolean beginFakeDrag() { + if (mIsBeingDragged) { + return false; + } + mFakeDragging = true; + setScrollState(SCROLL_STATE_DRAGGING); + mInitialMotionX = mLastMotionX = 0; + if (mVelocityTracker == null) { + mVelocityTracker = VelocityTracker.obtain(); + } else { + mVelocityTracker.clear(); + } + final long time = SystemClock.uptimeMillis(); + final MotionEvent ev = MotionEvent.obtain(time, time, MotionEvent.ACTION_DOWN, 0, 0, 0); + mVelocityTracker.addMovement(ev); + ev.recycle(); + mFakeDragBeginTime = time; + return true; + } + + /** + * End a fake drag of the pager. + * + * @see #beginFakeDrag() + * @see #fakeDragBy(float) + */ + public void endFakeDrag() { + if (!mFakeDragging) { + throw new IllegalStateException("No fake drag in progress. Call beginFakeDrag first."); + } + + final VelocityTracker velocityTracker = mVelocityTracker; + velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); + int initialVelocity = (int) VelocityTrackerCompat.getXVelocity( + velocityTracker, mActivePointerId); + mPopulatePending = true; + final int width = getClientWidth(); + final int scrollX = getScrollX(); + final ItemInfo ii = infoForCurrentScrollPosition(); + final int currentPage = ii.position; + final float pageOffset = (((float) scrollX / width) - ii.offset) / ii.widthFactor; + final int totalDelta = (int) (mLastMotionX - mInitialMotionX); + int nextPage = determineTargetPage(currentPage, pageOffset, initialVelocity, + totalDelta); + setCurrentItemInternal(nextPage, true, true, initialVelocity); + endDrag(); + + mFakeDragging = false; + } + + /** + * Fake drag by an offset in pixels. You must have called {@link #beginFakeDrag()} first. + * + * @param xOffset Offset in pixels to drag by. + * @see #beginFakeDrag() + * @see #endFakeDrag() + */ + public void fakeDragBy(float xOffset) { + if (!mFakeDragging) { + throw new IllegalStateException("No fake drag in progress. Call beginFakeDrag first."); + } + + mLastMotionX += xOffset; + + float oldScrollX = getScrollX(); + float scrollX = oldScrollX - xOffset; + final int width = getClientWidth(); + + float leftBound = width * mFirstOffset; + float rightBound = width * mLastOffset; + + final ItemInfo firstItem = mItems.get(0); + final ItemInfo lastItem = mItems.get(mItems.size() - 1); + if (firstItem.position != 0) { + leftBound = firstItem.offset * width; + } + if (lastItem.position != mAdapter.getCount() - 1) { + rightBound = lastItem.offset * width; + } + + if (scrollX < leftBound) { + scrollX = leftBound; + } else if (scrollX > rightBound) { + scrollX = rightBound; + } + // Don't lose the rounded component + mLastMotionX += scrollX - (int) scrollX; + scrollTo((int) scrollX, getScrollY()); + pageScrolled((int) scrollX); + + // Synthesize an event for the VelocityTracker. + final long time = SystemClock.uptimeMillis(); + final MotionEvent ev = MotionEvent.obtain(mFakeDragBeginTime, time, MotionEvent.ACTION_MOVE, + mLastMotionX, 0, 0); + mVelocityTracker.addMovement(ev); + ev.recycle(); + } + + /** + * Returns true if a fake drag is in progress. + * + * @return true if currently in a fake drag, false otherwise. + * + * @see #beginFakeDrag() + * @see #fakeDragBy(float) + * @see #endFakeDrag() + */ + public boolean isFakeDragging() { + return mFakeDragging; + } + + private void onSecondaryPointerUp(MotionEvent ev) { + final int pointerIndex = MotionEventCompat.getActionIndex(ev); + final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex); + if (pointerId == mActivePointerId) { + // This was our active pointer going up. Choose a new + // active pointer and adjust accordingly. + final int newPointerIndex = pointerIndex == 0 ? 1 : 0; + mLastMotionX = MotionEventCompat.getX(ev, newPointerIndex); + mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex); + if (mVelocityTracker != null) { + mVelocityTracker.clear(); + } + } + } + + private void endDrag() { + mIsBeingDragged = false; + mIsUnableToDrag = false; + + if (mVelocityTracker != null) { + mVelocityTracker.recycle(); + mVelocityTracker = null; + } + } + + private void setScrollingCacheEnabled(boolean enabled) { + if (mScrollingCacheEnabled != enabled) { + mScrollingCacheEnabled = enabled; + if (USE_CACHE) { + final int size = getChildCount(); + for (int i = 0; i < size; ++i) { + final View child = getChildAt(i); + if (child.getVisibility() != GONE) { + child.setDrawingCacheEnabled(enabled); + } + } + } + } + } + + public boolean canScrollHorizontally(int direction) { + if (mAdapter == null) { + return false; + } + + final int width = getClientWidth(); + final int scrollX = getScrollX(); + if (direction < 0) { + return (scrollX > (int) (width * mFirstOffset)); + } else if (direction > 0) { + return (scrollX < (int) (width * mLastOffset)); + } else { + return false; + } + } + + /** + * Tests scrollability within child views of v given a delta of dx. + * + * @param v View to test for horizontal scrollability + * @param checkV Whether the view v passed should itself be checked for scrollability (true), + * or just its children (false). + * @param dx Delta scrolled in pixels + * @param x X coordinate of the active touch point + * @param y Y coordinate of the active touch point + * @return true if child views of v can be scrolled by delta of dx. + */ + protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) { + if (v instanceof ViewGroup) { + final ViewGroup group = (ViewGroup) v; + final int scrollX = v.getScrollX(); + final int scrollY = v.getScrollY(); + final int count = group.getChildCount(); + // Count backwards - let topmost views consume scroll distance first. + for (int i = count - 1; i >= 0; i--) { + // TODO: Add versioned support here for transformed views. + // This will not work for transformed views in Honeycomb+ + final View child = group.getChildAt(i); + if (x + scrollX >= child.getLeft() && x + scrollX < child.getRight() && + y + scrollY >= child.getTop() && y + scrollY < child.getBottom() && + canScroll(child, true, dx, x + scrollX - child.getLeft(), + y + scrollY - child.getTop())) { + return true; + } + } + } + + return checkV && ViewCompat.canScrollHorizontally(v, -dx); + } + + @Override + public boolean dispatchKeyEvent(KeyEvent event) { + // Let the focused view and/or our descendants get the key first + return super.dispatchKeyEvent(event) || executeKeyEvent(event); + } + + /** + * You can call this function yourself to have the scroll view perform + * scrolling from a key event, just as if the event had been dispatched to + * it by the view hierarchy. + * + * @param event The key event to execute. + * @return Return true if the event was handled, else false. + */ + public boolean executeKeyEvent(KeyEvent event) { + boolean handled = false; + if (event.getAction() == KeyEvent.ACTION_DOWN) { + switch (event.getKeyCode()) { + case KeyEvent.KEYCODE_DPAD_LEFT: + handled = arrowScroll(FOCUS_LEFT); + break; + case KeyEvent.KEYCODE_DPAD_RIGHT: + handled = arrowScroll(FOCUS_RIGHT); + break; + } + } + return handled; + } + + public boolean arrowScroll(int direction) { + View currentFocused = findFocus(); + if (currentFocused == this) { + currentFocused = null; + } else if (currentFocused != null) { + boolean isChild = false; + for (ViewParent parent = currentFocused.getParent(); parent instanceof ViewGroup; + parent = parent.getParent()) { + if (parent == this) { + isChild = true; + break; + } + } + if (!isChild) { + // This would cause the focus search down below to fail in fun ways. + final StringBuilder sb = new StringBuilder(); + sb.append(currentFocused.getClass().getSimpleName()); + for (ViewParent parent = currentFocused.getParent(); parent instanceof ViewGroup; + parent = parent.getParent()) { + sb.append(" => ").append(parent.getClass().getSimpleName()); + } + Log.e(TAG, "arrowScroll tried to find focus based on non-child " + + "current focused view " + sb.toString()); + currentFocused = null; + } + } + + boolean handled = false; + + View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, + direction); + if (nextFocused != null && nextFocused != currentFocused) { + if (direction == View.FOCUS_LEFT) { + // If there is nothing to the left, or this is causing us to + // jump to the right, then what we really want to do is page left. + final int nextLeft = getChildRectInPagerCoordinates(mTempRect, nextFocused).left; + final int currLeft = getChildRectInPagerCoordinates(mTempRect, currentFocused).left; + if (currentFocused != null && nextLeft >= currLeft) { + handled = pageLeft(); + } else { + handled = nextFocused.requestFocus(); + } + } else if (direction == View.FOCUS_RIGHT) { + // If there is nothing to the right, or this is causing us to + // jump to the left, then what we really want to do is page right. + final int nextLeft = getChildRectInPagerCoordinates(mTempRect, nextFocused).left; + final int currLeft = getChildRectInPagerCoordinates(mTempRect, currentFocused).left; + if (currentFocused != null && nextLeft <= currLeft) { + handled = pageRight(); + } else { + handled = nextFocused.requestFocus(); + } + } + } else if (direction == FOCUS_LEFT || direction == FOCUS_BACKWARD) { + // Trying to move left and nothing there; try to page. + handled = pageLeft(); + } else if (direction == FOCUS_RIGHT || direction == FOCUS_FORWARD) { + // Trying to move right and nothing there; try to page. + handled = pageRight(); + } + if (handled) { + playSoundEffect(SoundEffectConstants.getContantForFocusDirection(direction)); + } + return handled; + } + + private Rect getChildRectInPagerCoordinates(Rect outRect, View child) { + if (outRect == null) { + outRect = new Rect(); + } + if (child == null) { + outRect.set(0, 0, 0, 0); + return outRect; + } + outRect.left = child.getLeft(); + outRect.right = child.getRight(); + outRect.top = child.getTop(); + outRect.bottom = child.getBottom(); + + ViewParent parent = child.getParent(); + while (parent instanceof ViewGroup && parent != this) { + final ViewGroup group = (ViewGroup) parent; + outRect.left += group.getLeft(); + outRect.right += group.getRight(); + outRect.top += group.getTop(); + outRect.bottom += group.getBottom(); + + parent = group.getParent(); + } + return outRect; + } + + boolean pageLeft() { + if (mCurItem > 0) { + setCurrentItem(mCurItem-1, true); + return true; + } + return false; + } + + boolean pageRight() { + if (mAdapter != null && mCurItem < (mAdapter.getCount()-1)) { + setCurrentItem(mCurItem+1, true); + return true; + } + return false; + } + + /** + * We only want the current page that is being shown to be focusable. + */ + @Override + public void addFocusables(ArrayList views, int direction, int focusableMode) { + final int focusableCount = views.size(); + + final int descendantFocusability = getDescendantFocusability(); + + if (descendantFocusability != FOCUS_BLOCK_DESCENDANTS) { + for (int i = 0; i < getChildCount(); i++) { + final View child = getChildAt(i); + if (child.getVisibility() == VISIBLE) { + ItemInfo ii = infoForChild(child); + if (ii != null && ii.position == mCurItem) { + child.addFocusables(views, direction, focusableMode); + } + } + } + } + + // we add ourselves (if focusable) in all cases except for when we are + // FOCUS_AFTER_DESCENDANTS and there are some descendants focusable. this is + // to avoid the focus search finding layouts when a more precise search + // among the focusable children would be more interesting. + if ( + descendantFocusability != FOCUS_AFTER_DESCENDANTS || + // No focusable descendants + (focusableCount == views.size())) { + // Note that we can't call the superclass here, because it will + // add all views in. So we need to do the same thing View does. + if (!isFocusable()) { + return; + } + if ((focusableMode & FOCUSABLES_TOUCH_MODE) == FOCUSABLES_TOUCH_MODE && + isInTouchMode() && !isFocusableInTouchMode()) { + return; + } + if (views != null) { + views.add(this); + } + } + } + + /** + * We only want the current page that is being shown to be touchable. + */ + @Override + public void addTouchables(ArrayList views) { + // Note that we don't call super.addTouchables(), which means that + // we don't call View.addTouchables(). This is okay because a ViewPager + // is itself not touchable. + for (int i = 0; i < getChildCount(); i++) { + final View child = getChildAt(i); + if (child.getVisibility() == VISIBLE) { + ItemInfo ii = infoForChild(child); + if (ii != null && ii.position == mCurItem) { + child.addTouchables(views); + } + } + } + } + + /** + * We only want the current page that is being shown to be focusable. + */ + @Override + protected boolean onRequestFocusInDescendants(int direction, + Rect previouslyFocusedRect) { + int index; + int increment; + int end; + int count = getChildCount(); + if ((direction & FOCUS_FORWARD) != 0) { + index = 0; + increment = 1; + end = count; + } else { + index = count - 1; + increment = -1; + end = -1; + } + for (int i = index; i != end; i += increment) { + View child = getChildAt(i); + if (child.getVisibility() == VISIBLE) { + ItemInfo ii = infoForChild(child); + if (ii != null && ii.position == mCurItem) { + if (child.requestFocus(direction, previouslyFocusedRect)) { + return true; + } + } + } + } + return false; + } + + @Override + public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) { + // Dispatch scroll events from this ViewPager. + if (event.getEventType() == AccessibilityEvent.TYPE_VIEW_SCROLLED) { + return super.dispatchPopulateAccessibilityEvent(event); + } + + // Dispatch all other accessibility events from the current page. + final int childCount = getChildCount(); + for (int i = 0; i < childCount; i++) { + final View child = getChildAt(i); + if (child.getVisibility() == VISIBLE) { + final ItemInfo ii = infoForChild(child); + if (ii != null && ii.position == mCurItem && + child.dispatchPopulateAccessibilityEvent(event)) { + return true; + } + } + } + + return false; + } + + @Override + protected ViewGroup.LayoutParams generateDefaultLayoutParams() { + return new LayoutParams(); + } + + @Override + protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) { + return generateDefaultLayoutParams(); + } + + @Override + protected boolean checkLayoutParams(ViewGroup.LayoutParams p) { + return p instanceof LayoutParams && super.checkLayoutParams(p); + } + + @Override + public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) { + return new LayoutParams(getContext(), attrs); + } + + class MyAccessibilityDelegate extends AccessibilityDelegateCompat { + + @Override + public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) { + super.onInitializeAccessibilityEvent(host, event); + event.setClassName(ViewPager.class.getName()); + final AccessibilityRecordCompat recordCompat = AccessibilityRecordCompat.obtain(); + recordCompat.setScrollable(canScroll()); + if (event.getEventType() == AccessibilityEvent.TYPE_VIEW_SCROLLED + && mAdapter != null) { + recordCompat.setItemCount(mAdapter.getCount()); + recordCompat.setFromIndex(mCurItem); + recordCompat.setToIndex(mCurItem); + } + } + + @Override + public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) { + super.onInitializeAccessibilityNodeInfo(host, info); + info.setClassName(ViewPager.class.getName()); + info.setScrollable(canScroll()); + if (canScrollHorizontally(1)) { + info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD); + } + if (canScrollHorizontally(-1)) { + info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD); + } + } + + @Override + public boolean performAccessibilityAction(View host, int action, Bundle args) { + if (super.performAccessibilityAction(host, action, args)) { + return true; + } + switch (action) { + case AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD: { + if (canScrollHorizontally(1)) { + setCurrentItem(mCurItem + 1); + return true; + } + } return false; + case AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD: { + if (canScrollHorizontally(-1)) { + setCurrentItem(mCurItem - 1); + return true; + } + } return false; + } + return false; + } + + private boolean canScroll() { + return (mAdapter != null) && (mAdapter.getCount() > 1); + } + } + + private class PagerObserver extends DataSetObserver { + @Override + public void onChanged() { + dataSetChanged(); + } + @Override + public void onInvalidated() { + dataSetChanged(); + } + } + + /** + * Layout parameters that should be supplied for views added to a + * ViewPager. + */ + public static class LayoutParams extends ViewGroup.LayoutParams { + /** + * true if this view is a decoration on the pager itself and not + * a view supplied by the adapter. + */ + public boolean isDecor; + + /** + * Gravity setting for use on decor views only: + * Where to position the view page within the overall ViewPager + * container; constants are defined in {@link android.view.Gravity}. + */ + public int gravity; + + /** + * Width as a 0-1 multiplier of the measured pager width + */ + float widthFactor = 0.f; + + /** + * true if this view was added during layout and needs to be measured + * before being positioned. + */ + boolean needsMeasure; + + /** + * Adapter position this view is for if !isDecor + */ + int position; + + /** + * Current child index within the ViewPager that this view occupies + */ + int childIndex; + + public LayoutParams() { + super(FILL_PARENT, FILL_PARENT); + } + + public LayoutParams(Context context, AttributeSet attrs) { + super(context, attrs); + + final TypedArray a = context.obtainStyledAttributes(attrs, LAYOUT_ATTRS); + gravity = a.getInteger(0, Gravity.TOP); + a.recycle(); + } + } + + static class ViewPositionComparator implements Comparator { + @Override + public int compare(View lhs, View rhs) { + final LayoutParams llp = (LayoutParams) lhs.getLayoutParams(); + final LayoutParams rlp = (LayoutParams) rhs.getLayoutParams(); + if (llp.isDecor != rlp.isDecor) { + return llp.isDecor ? 1 : -1; + } + return llp.position - rlp.position; + } + } +} -- cgit v1.2.3