Instantiating background image of preview video in

Magnification Gesture screen using ImageView, also
set GlobalLayoutListener to adjust its position.
Bug: 27992162
Bug: 27901691

Change-Id: I9563eb2776bcde3d7edeb4a420a9b3c02481baf8

res/layout/video_preference.xml

@@ -15,13 +15,22 @@
 -->
 <RelativeLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
-    android:id="@+id/video_background"
     android:layout_width="match_parent"
     android:layout_height="wrap_content">
 
+    <ImageView
+        android:id="@+id/video_background"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:src="@drawable/accessibility_screen_magnification_background"
+        android:scaleType="fitXY"
+        android:adjustViewBounds="true" />
+
     <VideoView
         android:id="@+id/video"
         android:layout_width="wrap_content"
-        android:layout_height="wrap_content" />
+        android:layout_height="wrap_content"
+        android:layout_alignTop="@id/video_background"
+        android:layout_centerHorizontal="true" />
 
 </RelativeLayout>

src/com/android/settings/accessibility/ToggleScreenMagnificationPreferenceFragment.java

@@ -30,20 +30,24 @@ import android.support.v7.preference.Preference;
 import android.support.v7.preference.PreferenceScreen;
 import android.support.v7.preference.PreferenceViewHolder;
 import android.view.Display;
-import android.view.Gravity;
+import android.view.ViewTreeObserver;
+import android.view.ViewTreeObserver.OnGlobalLayoutListener;
 import android.view.WindowManager;
+import android.widget.ImageView;
 import android.widget.MediaController;
-import android.widget.RelativeLayout;
+import android.widget.RelativeLayout.LayoutParams;
 import android.widget.VideoView;
 import com.android.internal.logging.MetricsProto.MetricsEvent;
 import com.android.settings.R;
 import com.android.settings.widget.ToggleSwitch;
 import com.android.settings.widget.ToggleSwitch.OnBeforeCheckedChangeListener;
 
-public class ToggleScreenMagnificationPreferenceFragment
+public class ToggleScreenMagnificationPreferenceFragment extends ToggleFeaturePreferenceFragment {
-        extends ToggleFeaturePreferenceFragment {
 
     protected class VideoPreference extends Preference {
+        private ImageView mVideoBackgroundView;
+        private OnGlobalLayoutListener mLayoutListener;
+
         public VideoPreference(Context context) {
             super(context);
         }
@@ -51,40 +55,19 @@ public class ToggleScreenMagnificationPreferenceFragment
         @Override
         public void onBindViewHolder(PreferenceViewHolder view) {
             super.onBindViewHolder(view);
+            Resources res = getPrefContext().getResources();
+            final int backgroundAssetWidth = res.getDimensionPixelSize(
+                    R.dimen.screen_magnification_video_background_width);
+            final int videoAssetWidth = res
+                    .getDimensionPixelSize(R.dimen.screen_magnification_video_width);
+            final int videoAssetHeight = res
+                    .getDimensionPixelSize(R.dimen.screen_magnification_video_height);
+            final int videoAssetMarginTop = res.getDimensionPixelSize(
+                    R.dimen.screen_magnification_video_margin_top);
             view.setDividerAllowedAbove(false);
             view.setDividerAllowedBelow(false);
-            final RelativeLayout background =
+            mVideoBackgroundView = (ImageView) view.findViewById(R.id.video_background);
-                    (RelativeLayout) view.findViewById(R.id.video_background);
+            final VideoView videoView = (VideoView) view.findViewById(R.id.video);
-            VideoView videoView = (VideoView) view.findViewById(R.id.video);
-
-            // Hacky adjustment for using VideoView in recycle view and positioning
-            // it on the background image
-            Resources res = getPrefContext().getResources();
-            final int backgroundWidth = res.getDimensionPixelSize(
-                    R.dimen.screen_magnification_video_background_width);
-            final int backgroundHeight = res.getDimensionPixelSize(
-                    R.dimen.screen_magnification_video_background_height);
-            final int videoWidth = res.getDimensionPixelSize(
-                    R.dimen.screen_magnification_video_width);
-            final int videoHeight = res.getDimensionPixelSize(
-                    R.dimen.screen_magnification_video_height);
-            final int videoMarginTop = res.getDimensionPixelSize(
-                    R.dimen.screen_magnification_video_margin_top);
-            final int screenWidth = getScreenWidth(getPrefContext());
-
-            RelativeLayout.LayoutParams videoLp = new RelativeLayout.LayoutParams(
-                    screenWidth * videoWidth / backgroundWidth,
-                    screenWidth * videoHeight / backgroundWidth);
-            videoLp.setMargins(0, screenWidth * videoMarginTop / backgroundWidth, 0, 0);
-            videoView.setLayoutParams(videoLp);
-
-            RelativeLayout.LayoutParams backgroundLp = new RelativeLayout.LayoutParams(
-                    screenWidth,
-                    screenWidth * backgroundHeight / backgroundWidth);
-            background.setLayoutParams(backgroundLp);
-            background.setBackgroundResource(
-                    R.drawable.accessibility_screen_magnification_background);
-            background.setGravity(Gravity.CENTER_HORIZONTAL);
 
             // Loop the video.
             videoView.setOnPreparedListener(new OnPreparedListener() {
@@ -100,7 +83,31 @@ public class ToggleScreenMagnificationPreferenceFragment
                     R.raw.accessibility_screen_magnification)));
             // Make sure video controls (e.g. for pausing) are not displayed.
             videoView.setMediaController(null);
-            videoView.start();
+
+            // LayoutListener for adjusting the position of the VideoView on the background image.
+            mLayoutListener = new OnGlobalLayoutListener() {
+                @Override
+                public void onGlobalLayout() {
+                    final int backgroundViewWidth = mVideoBackgroundView.getWidth();
+
+                    LayoutParams videoLp = (LayoutParams) videoView.getLayoutParams();
+                    videoLp.width = videoAssetWidth * backgroundViewWidth / backgroundAssetWidth;
+                    videoLp.height = videoAssetHeight * backgroundViewWidth / backgroundAssetWidth;
+                    videoLp.setMargins(0,
+                            videoAssetMarginTop * backgroundViewWidth / backgroundAssetWidth, 0, 0);
+                    videoView.setLayoutParams(videoLp);
+                    videoView.invalidate();
+                    videoView.start();
+                }
+            };
+
+            mVideoBackgroundView.getViewTreeObserver().addOnGlobalLayoutListener(mLayoutListener);
+        }
+
+        @Override
+        protected void onPrepareForRemoval() {
+            mVideoBackgroundView.getViewTreeObserver()
+                    .removeOnGlobalLayoutListener(mLayoutListener);
         }
     }