1 files changed, 232 insertions, 0 deletions
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.
+ *
+ * <p>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.
+ *
+ * <p>When using FragmentPagerAdapter the host ViewPager must have a
+ * valid ID set.</p>
+ *
+ * <p>Subclasses only need to implement {@link #getItem(int)}
+ * and {@link #getCount()} to have a working adapter.
+ *
+ * <p>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}
+ *
+ * <p>The <code>R.layout.fragment_pager</code> resource of the top-level fragment is:
+ *
+ * {@sample development/samples/Support13Demos/res/layout/fragment_pager.xml
+ *      complete}
+ *
+ * <p>The <code>R.layout.fragment_pager_list</code> 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<Fragment.SavedState> mSavedState = new ArrayList<Fragment.SavedState>();
+    private ArrayList<Fragment> mFragments = new ArrayList<Fragment>();
+    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<mFragments.size(); i++) {
+            Fragment f = mFragments.get(i);
+            if (f != null) {
+                if (state == null) {
+                    state = new Bundle();
+                }
+                String key = "f" + i;
+                mFragmentManager.putFragment(state, key, f);
+            }
+        }
+        return state;
+    }
+
+    @Override
+    public void restoreState(Parcelable state, ClassLoader loader) {
+        if (state != null) {
+            Bundle bundle = (Bundle)state;
+            bundle.setClassLoader(loader);
+            Parcelable[] fss = bundle.getParcelableArray("states");
+            mSavedState.clear();
+            mFragments.clear();
+            if (fss != null) {
+                for (int i=0; i<fss.length; i++) {
+                    mSavedState.add((Fragment.SavedState)fss[i]);
+                }
+            }
+            Iterable<String> 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);
+                    }
+                }
+            }
+        }
+    }
+}