Bug 816547: Make sure the Bitmap is accessed in UI thread in LWTheme. [r=mfinkle]

--HG--
extra : rebase_source : 7f99818a2395fdc4f03b24927f706a4f81197038

mobile/android/base/LightweightTheme.java

@@ -18,13 +18,17 @@ import android.graphics.drawable.BitmapDrawable;
 import android.graphics.Rect;
 import android.graphics.Shader;
 import android.os.Build;
+import android.os.Looper;
+import android.os.Handler;
 import android.util.DisplayMetrics;
 import android.view.Gravity;
 import android.view.View;
 import android.view.ViewParent;
 
-import java.net.URL;
 import java.io.InputStream;
+import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URL;
 import java.util.List;
 import java.util.ArrayList;
 
@@ -34,15 +38,13 @@ public class LightweightTheme implements GeckoEventListener {
     private static final String LOGTAG = "GeckoLightweightTheme";
 
     private Application mApplication;
+    private Handler mHandler;
+
     private Bitmap mBitmap;
     private int mColor;
     private boolean mIsLight;
 
     public static interface OnChangeListener {
-        // This is the View's default post.
-        // This is required to post the change/rest on UI thread.
-        public boolean post(Runnable action);
-
         // The View should change its background/text color. 
         public void onLightweightThemeChanged();
 
@@ -54,8 +56,10 @@ public class LightweightTheme implements GeckoEventListener {
     
     public LightweightTheme(Application application) {
         mApplication = application;
+        mHandler = new Handler(Looper.getMainLooper());
         mListeners = new ArrayList<OnChangeListener>();
 
+        // unregister isn't needed as the lifetime is same as the application.
         GeckoAppShell.getEventDispatcher().registerEventListener("LightweightTheme:Update", this);
         GeckoAppShell.getEventDispatcher().registerEventListener("LightweightTheme:Disable", this);
     }
@@ -70,15 +74,50 @@ public class LightweightTheme implements GeckoEventListener {
         mListeners.remove(listener);
     }
 
-    public void setLightweightTheme(String headerURL) {
+    @Override
+    public void handleMessage(String event, JSONObject message) {
+        try {
+            if (event.equals("LightweightTheme:Update")) {
+                JSONObject lightweightTheme = message.getJSONObject("data");
+                String headerURL = lightweightTheme.getString("headerURL"); 
+                int mark = headerURL.indexOf('?');
+                if (mark != -1)
+                    headerURL = headerURL.substring(0, mark);
                 try {
                     // Get the image and convert it to a bitmap.
                     URL url = new URL(headerURL);
                     InputStream stream = url.openStream();
-            mBitmap = BitmapFactory.decodeStream(stream);
+                    final Bitmap bitmap = BitmapFactory.decodeStream(stream);
                     stream.close();
+                    mHandler.post(new Runnable() {
+                        public void run() {
+                            setLightweightTheme(bitmap);
+                        }
+                    });
+                } catch(MalformedURLException e) {
+                } catch(IOException e) {
+                }
+            } else if (event.equals("LightweightTheme:Disable")) {
+                mHandler.post(new Runnable() {
+                    public void run() {
+                        resetLightweightTheme();
+                    }
+                });
+            }
+        } catch (Exception e) {
+            Log.e(LOGTAG, "Exception handling message \"" + event + "\":", e);
+        }
+    }
 
-            // The download could be HTTP for previews, so let's be sure we have a bitmap
+    /**
+     * Set a new lightweight theme with the given bitmap.
+     * Note: This should be called on the UI thread to restrict accessing the
+     * bitmap to a single thread.
+     *
+     * @param bitmap The bitmap used for the lightweight theme.
+     */
+    private void setLightweightTheme(Bitmap bitmap) {
+        mBitmap = bitmap;
         if (mBitmap == null || mBitmap.getWidth() == 0 || mBitmap.getHeight() == 0) {
             mBitmap = null;
             return;
@@ -98,66 +137,24 @@ public class LightweightTheme implements GeckoEventListener {
                            (0.0721 * (mColor &0x000000FF));
         mIsLight = (luminance > 110) ? true : false;
 
-            notifyListeners();
-        } catch(java.net.MalformedURLException e) {
-            mBitmap = null;
-        } catch(java.io.IOException e) {
-            mBitmap = null;
-        }
+        for (OnChangeListener listener : mListeners)
+            listener.onLightweightThemeChanged();
     }
 
-    public void resetLightweightTheme() {
+    /**
+     * Reset the lightweight theme.
+     * Note: This should be called on the UI thread to restrict accessing the
+     * bitmap to a single thread.
+     */
+    private void resetLightweightTheme() {
         if (mBitmap != null) {
             // Reset the bitmap.
             mBitmap = null;
 
-            // Post the reset on the UI thread.
-            for (OnChangeListener listener : mListeners) {
-                 final OnChangeListener oneListener = listener;
-                 oneListener.post(new Runnable() {
-                     @Override
-                     public void run() {
-                         oneListener.onLightweightThemeReset();
-                     }
-                 });
+            for (OnChangeListener listener : mListeners)
+                listener.onLightweightThemeReset();
         }
     }
-    }
-
-    public void notifyListeners() {
-        if (mBitmap == null)
-            return;
-
-        // Post the change on the UI thread.
-        for (OnChangeListener listener : mListeners) {
-             final OnChangeListener oneListener = listener;
-             oneListener.post(new Runnable() {
-                 @Override
-                 public void run() {
-                     oneListener.onLightweightThemeChanged();
-                 }
-             });
-        }
-    }
-
-    @Override
-    public void handleMessage(String event, JSONObject message) {
-        try {
-            if (event.equals("LightweightTheme:Update")) {
-                JSONObject lightweightTheme = message.getJSONObject("data");
-                String headerURL = lightweightTheme.getString("headerURL"); 
-                int mark = headerURL.indexOf('?');
-                if (mark != -1)
-                    headerURL = headerURL.substring(0, mark);
-                setLightweightTheme(headerURL);
-            } else if (event.equals("LightweightTheme:Disable")) {
-                resetLightweightTheme();
-            }
-        } catch (Exception e) {
-            Log.e(LOGTAG, "Exception handling message \"" + event + "\":", e);
-        }
-    }
-
 
     /**
      * A lightweight theme is enabled only if there is an active bitmap.