Support showing previews in the photo viewer.

The photo viewer now supports the notion of a
preview of the full image. The preview is not
pinchable in any manner and displays a circular
progress bar over top of it while we are downloading
the full version of the image.

To enable this functionality, there is a new column
in the PhotoContract API called thumbnailUri. If it is
not set to null and if the attempted load of the contentUri
is unsuccessful, we will attempt to load a thumbnail version
that will show until the contentUri is finished loading.

Change-Id: I5547a5fc6a30ee6a30f137dc1dee76a77fb5b304

5 files changed, 69 insertions, 44 deletions

diff --git a/photoviewer/src/com/android/ex/photo/Intents.java b/photoviewer/src/com/android/ex/photo/Intents.java
index 18c626e..7e31169 100644
--- a/photoviewer/src/com/android/ex/photo/Intents.java
+++ b/photoviewer/src/com/android/ex/photo/Intents.java
@@ -35,6 +35,7 @@ public class Intents {
     public static final String EXTRA_RESOLVED_PHOTO_URI = "resolved_photo_uri";
     public static final String EXTRA_PHOTO_NAME = "photo_name";
     public static final String EXTRA_PROJECTION = "projection";
+    public static final String EXTRA_THUMBNAIL_URI = "thumbnail_uri";
 
     /**
      * Gets a photo view intent builder to display the photos from phone activity.
@@ -76,6 +77,8 @@ public class Intents {
         private String mResolvedPhotoUri;
         /** The projection for the query to use; optional */
         private String[] mProjection;
+        /** The URI of a thumbnail of the photo to display */
+        private String mThumbnailUri;
 
         private PhotoViewIntentBuilder(Context context, Class<?> cls) {
             mIntent = new Intent(context, cls);
@@ -115,6 +118,14 @@ public class Intents {
             return this;
         }
 
+        /**
+         * Sets the URI for a thumbnail preview of the photo.
+         */
+        public PhotoViewIntentBuilder setThumbnailUri(String thumbnailUri) {
+            mThumbnailUri = thumbnailUri;
+            return this;
+        }
+
         /** Build the intent */
         public Intent build() {
             if (TextUtils.isEmpty(mPhotosUri) && TextUtils.isEmpty(mResolvedPhotoUri)) {
@@ -146,6 +157,10 @@ public class Intents {
                 mIntent.putExtra(EXTRA_PROJECTION, mProjection);
             }
 
+            if (mThumbnailUri != null) {
+                mIntent.putExtra(EXTRA_THUMBNAIL_URI, mThumbnailUri);
+            }
+
             return mIntent;
         }
     }
diff --git a/photoviewer/src/com/android/ex/photo/adapters/PhotoPagerAdapter.java b/photoviewer/src/com/android/ex/photo/adapters/PhotoPagerAdapter.java
index 41b146e..0c7ba63 100644
--- a/photoviewer/src/com/android/ex/photo/adapters/PhotoPagerAdapter.java
+++ b/photoviewer/src/com/android/ex/photo/adapters/PhotoPagerAdapter.java
@@ -33,6 +33,7 @@ import com.android.ex.photo.provider.PhotoContract;
 public class PhotoPagerAdapter extends BaseCursorPagerAdapter {
     private int mContentUriIndex;
     private int mPhotoNameIndex;
+    private int mThumbnailUriIndex;
 
     public PhotoPagerAdapter(Context context, FragmentManager fm, Cursor c) {
         super(context, fm, c);
@@ -42,13 +43,15 @@ public class PhotoPagerAdapter extends BaseCursorPagerAdapter {
     public Fragment getItem(Context context, Cursor cursor, int position) {
         final String photoUri = cursor.getString(mContentUriIndex);
         final String photoName = cursor.getString(mPhotoNameIndex);
+        final String thumbnailUri = cursor.getString(mThumbnailUriIndex);
 
         // create new PhotoViewFragment
         final PhotoViewIntentBuilder builder =
                 Intents.newPhotoViewFragmentIntentBuilder(mContext);
           builder
             .setPhotoName(photoName)
-            .setResolvedPhotoUri(photoUri);
+            .setResolvedPhotoUri(photoUri)
+            .setThumbnailUri(thumbnailUri);
 
         return new PhotoViewFragment(builder.build(), position, this);
     }
@@ -57,6 +60,8 @@ public class PhotoPagerAdapter extends BaseCursorPagerAdapter {
     public Cursor swapCursor(Cursor newCursor) {
         mContentUriIndex =
                 newCursor.getColumnIndex(PhotoContract.PhotoViewColumns.CONTENT_URI);
+        mThumbnailUriIndex =
+                newCursor.getColumnIndex(PhotoContract.PhotoViewColumns.THUMBNAIL_URI);
         mPhotoNameIndex =
                 newCursor.getColumnIndex(PhotoContract.PhotoViewColumns.NAME);
 
diff --git a/photoviewer/src/com/android/ex/photo/fragments/PhotoViewFragment.java b/photoviewer/src/com/android/ex/photo/fragments/PhotoViewFragment.java
index 726dca4..36dd9da 100644
--- a/photoviewer/src/com/android/ex/photo/fragments/PhotoViewFragment.java
+++ b/photoviewer/src/com/android/ex/photo/fragments/PhotoViewFragment.java
@@ -77,13 +77,15 @@ public class PhotoViewFragment extends Fragment implements
             "com.android.mail.photo.fragments.PhotoViewFragment.INTENT";
 
     // Loader IDs
-    private final static int LOADER_ID_PHOTO = 2;
+    private final static int LOADER_ID_PHOTO = 1;
+    private final static int LOADER_ID_THUMBNAIL = 2;
 
     /** The size of the photo */
     public static Integer sPhotoSize;
 
     /** The URL of a photo to display */
     private String mResolvedPhotoUri;
+    private String mThumbnailUri;
     /** The intent we were launched with */
     private Intent mIntent;
     private PhotoViewActivity mCallback;
@@ -95,6 +97,8 @@ public class PhotoViewFragment extends Fragment implements
     /** Whether or not the fragment should make the photo full-screen */
     private boolean mFullScreen;
 
+    private boolean mShowingThumbnail;
+
     public PhotoViewFragment() {
         mPosition = -1;
     }
@@ -103,6 +107,7 @@ public class PhotoViewFragment extends Fragment implements
         mIntent = intent;
         mPosition = position;
         mAdapter = adapter;
+        mShowingThumbnail = false;
     }
 
     @Override
@@ -151,8 +156,7 @@ public class PhotoViewFragment extends Fragment implements
         }
 
         mResolvedPhotoUri = mIntent.getStringExtra(Intents.EXTRA_RESOLVED_PHOTO_URI);
-
-        setHasOptionsMenu(true);
+        mThumbnailUri = mIntent.getStringExtra(Intents.EXTRA_THUMBNAIL_URI);
     }
 
     @Override
@@ -161,9 +165,6 @@ public class PhotoViewFragment extends Fragment implements
         final View view = inflater.inflate(R.layout.photo_fragment_view, container, false);
 
         mPhotoView = (PhotoView) view.findViewById(R.id.photo_view);
-
-        mPhotoView.setPhotoLoading(true);
-
         mPhotoView.setOnClickListener(this);
         mPhotoView.setFullScreen(mFullScreen, false);
 
@@ -214,10 +215,13 @@ public class PhotoViewFragment extends Fragment implements
 
     @Override
     public Loader<Bitmap> onCreateLoader(int id, Bundle args) {
-        if (id == LOADER_ID_PHOTO) {
-            return new PhotoBitmapLoader(getActivity(), mResolvedPhotoUri);
-        } else {
-            return null;
+        switch (id) {
+            case LOADER_ID_PHOTO:
+                return new PhotoBitmapLoader(getActivity(), mResolvedPhotoUri);
+            case LOADER_ID_THUMBNAIL:
+                return new PhotoBitmapLoader(getActivity(), mThumbnailUri);
+            default:
+                return null;
         }
     }
 
@@ -229,14 +233,31 @@ public class PhotoViewFragment extends Fragment implements
         }
 
         final int id = loader.getId();
-        if (id == LOADER_ID_PHOTO) {
-            if (data == null) {
-                return;
-            }
+        switch (id) {
+            case LOADER_ID_PHOTO:
+                if (data == null) {
+                    getLoaderManager().initLoader(LOADER_ID_THUMBNAIL, null, this);
+                    return;
+                }
+
+                mShowingThumbnail = false;
+                bindPhoto(data);
+                mCallback.setViewActivated();
+                setViewVisibility();
+                break;
+            case LOADER_ID_THUMBNAIL:
+                if (data == null || isPhotoBound()) {
+                    return;
+                }
 
-            bindPhoto(data);
-            mCallback.setViewActivated();
-            setViewVisibility();
+                mShowingThumbnail = true;
+                bindPhoto(data);
+                mCallback.setViewActivated();
+                setViewVisibility();
+                mPhotoView.enableImageTransforms(false);
+                break;
+            default:
+                break;
         }
     }
 
@@ -245,7 +266,6 @@ public class PhotoViewFragment extends Fragment implements
      */
     private void bindPhoto(Bitmap bitmap) {
         if (mPhotoView != null) {
-            mPhotoView.setPhotoLoading(false);
             mPhotoView.bindPhoto(bitmap);
         }
     }
@@ -255,7 +275,6 @@ public class PhotoViewFragment extends Fragment implements
      */
     private void resetPhotoView() {
         if (mPhotoView != null) {
-            mPhotoView.setPhotoLoading(true);
             mPhotoView.bindPhoto(null);
         }
     }
@@ -322,7 +341,7 @@ public class PhotoViewFragment extends Fragment implements
      * Returns {@code true} if a photo has been bound. Otherwise, returns {@code false}.
      */
     public boolean isPhotoBound() {
-        return (mPhotoView != null && mPhotoView.isPhotoBound());
+        return (mPhotoView != null && mPhotoView.isPhotoBound() && !mShowingThumbnail);
     }
 
     /**
diff --git a/photoviewer/src/com/android/ex/photo/provider/PhotoContract.java b/photoviewer/src/com/android/ex/photo/provider/PhotoContract.java
index 51ce893..0a9a43a 100644
--- a/photoviewer/src/com/android/ex/photo/provider/PhotoContract.java
+++ b/photoviewer/src/com/android/ex/photo/provider/PhotoContract.java
@@ -21,7 +21,7 @@ import android.net.Uri;
 import android.provider.OpenableColumns;
 
 public final class PhotoContract {
-    /** Columns for the view {@link #PHOTO_VIEW} */
+    /** Columns for the view */
     public static interface PhotoViewColumns {
         /**
          * This column is a {@link Uri} that can be queried
@@ -39,6 +39,12 @@ public final class PhotoContract {
          */
         public static final String CONTENT_URI = "contentUri";
         /**
+         * This column is a {@link Uri} that points to a thumbnail of the image
+         * that ideally is a local file.
+         * This value is undefined in any other state.
+         */
+        public static final String THUMBNAIL_URI = "thumbnailUri";
+        /**
          * This string column is the MIME type.
          */
         public static final String CONTENT_TYPE = "contentType";
@@ -51,13 +57,9 @@ public final class PhotoContract {
             PhotoViewColumns.URI,
             PhotoViewColumns.NAME,
             PhotoViewColumns.CONTENT_URI,
+            PhotoViewColumns.THUMBNAIL_URI,
             PhotoViewColumns.CONTENT_TYPE,
         };
-
-        public final static int INDEX_URI = 0;
-        public final static int INDEX_NAME = 1;
-        public final static int INDEX_CONTENT_URI = 2;
-        public final static int INDEX_CONTENT_TYPE = 3;
     }
 
     public static final class ContentTypeParameters {
diff --git a/photoviewer/src/com/android/ex/photo/views/PhotoView.java b/photoviewer/src/com/android/ex/photo/views/PhotoView.java
index f6b8315..1de5ff4 100644
--- a/photoviewer/src/com/android/ex/photo/views/PhotoView.java
+++ b/photoviewer/src/com/android/ex/photo/views/PhotoView.java
@@ -86,8 +86,6 @@ public class PhotoView extends View implements GestureDetector.OnGestureListener
 
     /** The photo to display */
     private BitmapDrawable mDrawable;
-    /** Whether or not the photo is in the process of loading */
-    private boolean mLoading;
     /** The matrix used for drawing; this may be {@code null} */
     private Matrix mDrawMatrix;
     /** A matrix to apply the scaling of the photo */
@@ -469,20 +467,6 @@ public class PhotoView extends View implements GestureDetector.OnGestureListener
     }
 
     /**
-     * Returns {@code true} if a photo has been bound. Otherwise, {@code false}.
-     */
-    public boolean isPhotoLoading() {
-        return mLoading;
-    }
-
-    /**
-     * Sets whether the photo is being loaded.
-     */
-    public void setPhotoLoading(boolean loading) {
-        mLoading = loading;
-    }
-
-    /**
      * Hides the photo info portion of the header. As a side effect, this automatically enables
      * or disables image transformations [eg zoom, pan, etc...] depending upon the value of
      * fullScreen. If this is not desirable, enable / disable image transformations manually.
@@ -550,7 +534,7 @@ public class PhotoView extends View implements GestureDetector.OnGestureListener
         // snap transformations; we don't animate
         mMatrix.set(mOriginalMatrix);
 
-        // Invalidate the view because if you move off this PhotoHeaderView
+        // Invalidate the view because if you move off this PhotoView
         // to another one and come back, you want it to draw from scratch
         // in case you were zoomed in or translated (since those settings
         // are not preserved and probably shouldn't be).