[Android WebView] Implement the capture picture API.

android_webview/java/src/org/chromium/android_webview/AwContents.java

Index: android_webview/java/src/org/chromium/android_webview/AwContents.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index 2c08909808e6315ada2167ce6c6c036fe08dc544..ced27a82425991c74b629e232eb8c119ce6f2427 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -8,6 +8,7 @@ import android.content.res.Configuration;
 import android.graphics.Bitmap;
 import android.graphics.Canvas;
 import android.graphics.Color;
+import android.graphics.Picture;
 import android.graphics.Rect;
 import android.net.http.SslCertificate;
 import android.os.AsyncTask;
@@ -39,6 +40,7 @@ import org.chromium.net.X509Util;
 import org.chromium.ui.gfx.NativeWindow;
 
 import java.io.File;
+import java.lang.ref.SoftReference;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.security.KeyStoreException;
@@ -104,6 +106,9 @@ public class AwContents {
     // Must call nativeUpdateLastHitTestData first to update this before use.
     private final HitTestData mPossiblyStaleHitTestData;
 
+    // Cached bitmap used for auxiliary rasterization in rendering fallback modes.
+    private static SoftReference<Bitmap> sBitmapCache;
+
     private static final class DestroyRunnable implements Runnable {
         private int mNativeAwContents;
         private DestroyRunnable(int nativeAwContents) {
@@ -393,7 +398,9 @@ public class AwContents {
 
     public void onDraw(Canvas canvas) {
         if (mNativeAwContents == 0) return;
-        if (!nativeDrawSW(mNativeAwContents, canvas)) {
+        Rect clip = canvas.getClipBounds();
+        if (!nativeDrawSW(mNativeAwContents, canvas, clip.left, clip.top,
+                clip.right - clip.left, clip.bottom - clip.top)) {
             Log.w(TAG, "Native DrawSW failed; clearing to background color.");
             int c = mContentViewCore.getBackgroundColor();
             canvas.drawRGB(Color.red(c), Color.green(c), Color.blue(c));
@@ -404,6 +411,19 @@ public class AwContents {
         mLayoutSizer.onMeasure(widthMeasureSpec, heightMeasureSpec);
     }
 
+    public Picture capturePicture() {
+        return nativeCapturePicture(mNativeAwContents);
+    }
+
+    /**
+     * Enable the OnNewPicture callback.
+     * @param enabled Flag to enable the callback.
+     * @param invalidationOnly Flag to call back only on invalidation without providing a picture.
+     */
+    public void enableOnNewPicture(boolean enabled, boolean invalidationOnly) {
+        nativeEnableOnNewPicture(mNativeAwContents, enabled, invalidationOnly);
+    }
+
     public int findAllSync(String searchString) {
         if (mNativeAwContents == 0) return 0;
         return nativeFindAllSync(mNativeAwContents, searchString);
@@ -909,6 +929,11 @@ public class AwContents {
         mContentsClient.onFindResultReceived(activeMatchOrdinal, numberOfMatches, isDoneCounting);
     }
 
+    @CalledByNative
+    public void onNewPicture(Picture picture) {
+        mContentsClient.onNewPicture(picture);
+    }
+
     // Called as a result of nativeUpdateLastHitTestData.
     @CalledByNative
     private void updateHitTestData(
@@ -981,6 +1006,42 @@ public class AwContents {
         return null;
     }
 
+    /**
+     * Provides a Bitmap object with a given width and height used for auxiliary rasterization.
+     * Might reuse cached bitmaps.
+     */
+    @CalledByNative
+    private static Bitmap createBitmap(int width, int height) {
+        Bitmap bitmap = sBitmapCache != null ? sBitmapCache.get() : null;
+        if (bitmap == null || bitmap.getWidth() != width || bitmap.getHeight() != height) {
+            bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+            bitmap.eraseColor(Color.BLACK);
+            sBitmapCache = new SoftReference<Bitmap>(bitmap);

[joth, 2013/01/22 00:05:41]

looks like I read these patches out of order...
sBitmapCache is complex as it's used by two different flows now, one of which
(capturePicture fallback) holds potentially long-lived references to the bitmap.
we shouldn't really cache the bitmap in that case.  maybe we don't care as it's
just a fallback mode? But maybe all round easiest just to get rid of this cache

[Leandro Graciá Gil, 2013/01/22 02:11:13]

I think you're right. This caching can cause problems like, for example, when
we're provided a Picture-backed Canvas in onDraw and we re-use the bitmap later.
Probably will be best if we remove the soft reference.

+        }
+        return bitmap;
+    }
+
+    /**
+     * Draws a provided bitmap into a canvas.
+     * Used for convenience from the native side and other static helper methods.
+     */
+    @CalledByNative
+    private static void drawBitmapIntoCanvas(Bitmap bitmap, Canvas canvas) {
+        canvas.drawBitmap(bitmap, 0, 0, null);
+    }
+
+    /**
+     * Creates a new Picture that records drawing a provided bitmap.
+     */
+    @CalledByNative
+    private static Picture recordRasterizedBitmap(Bitmap bitmap) {

[joth, 2013/01/22 00:05:41]

recordBitmapIntoPicture ? 

[Leandro Graciá Gil, 2013/01/22 02:11:13]

Yes, much better. Done.

+        Picture picture = new Picture();
+        Canvas recordingCanvas = picture.beginRecording(bitmap.getWidth(), bitmap.getHeight());
+        drawBitmapIntoCanvas(bitmap, recordingCanvas);
+        picture.endRecording();
+        return picture;
+    }
+
     @CalledByNative
     private void handleJsAlert(String url, String message, JsResultReceiver receiver) {
         mContentsClient.handleJsAlert(url, message, receiver);
@@ -1024,7 +1085,8 @@ public class AwContents {
     private native void nativeSetInterceptNavigationDelegate(int nativeAwContents,
             InterceptNavigationDelegate navigationInterceptionDelegate);
 
-    private native boolean nativeDrawSW(int nativeAwContents, Canvas canvas);
+    private native boolean nativeDrawSW(int nativeAwContents, Canvas canvas, int clipX, int clipY,
+            int clipW, int clipH);
     private native void nativeSetScrollForHWFrame(int nativeAwContents, int scrollX, int scrollY);
     private native int nativeFindAllSync(int nativeAwContents, String searchString);
     private native void nativeFindAllAsync(int nativeAwContents, String searchString);
@@ -1049,4 +1111,8 @@ public class AwContents {
     private native int nativeReleasePopupWebContents(int nativeAwContents);
     private native void nativeSetWebContents(int nativeAwContents, int nativeNewWebContents);
     private native void nativeFocusFirstNode(int nativeAwContents);
+
+    private native Picture nativeCapturePicture(int nativeAwContents);
+    private native void nativeEnableOnNewPicture(int nativeAwContents, boolean enabled,
+            boolean invalidationOnly);
 }