Bug 803299 - Enable 32-bit colour on Android. r=kats

mobile/android/base/GeckoAppShell.java

@@ -38,6 +38,7 @@ import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.ImageFormat;
 import android.graphics.Paint;
+import android.graphics.PixelFormat;
 import android.graphics.Rect;
 import android.graphics.RectF;
 import android.graphics.SurfaceTexture;
@@ -135,6 +136,7 @@ public class GeckoAppShell
     static private final boolean LOGGING = false;
 
     static private int sDensityDpi = 0;
+    static private int sScreenDepth = 0;
 
     private static final EventDispatcher sEventDispatcher = new EventDispatcher();
 
@@ -1379,6 +1381,27 @@ public class GeckoAppShell
         return sDensityDpi;
     }
 
+    /**
+     * Returns the colour depth of the default screen. This will either be
+     * 24 or 16.
+     */
+    public static int getScreenDepth() {
+        if (sScreenDepth == 0 && getGeckoInterface() != null) {
+            switch (getGeckoInterface().getActivity().getWindowManager().getDefaultDisplay().getPixelFormat()) {
+            case PixelFormat.RGBA_8888 :
+            case PixelFormat.RGBX_8888 :
+            case PixelFormat.RGB_888 :
+                sScreenDepth = 24;
+                break;
+            default:
+                sScreenDepth = 16;
+                break;
+            }
+        }
+
+        return sScreenDepth;
+    }
+
     public static void setFullScreen(boolean fullscreen) {
         if (getGeckoInterface() != null)
             getGeckoInterface().setFullScreen(fullscreen);