[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 93a78d483f5664bf64b4ffcf8fb23f9667b728ce..5cada2a3cdba2529aad472587175efa901295f7b 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;
@@ -379,6 +380,19 @@ public class AwContents {
         }
     }
 
+    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);
@@ -884,6 +898,11 @@ 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(
@@ -956,6 +975,22 @@ public class AwContents {
         return null;
     }
 
+    /**
+     * Rasterizes the latest available picture into a bitmap and draws it into a new Picture.
+     * This approach has performance issues and should only be used as a fallback mechanism.
+     */
+    @CalledByNative
+    private Picture rasterizeIntoPicture(int nativePicture, int width, int height) {
+        Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);

[joth, 2013/01/12 02:36:28]

maybe add a comment for the obvious: we could cache the bitmap to slightly
reduce cost of this approach if necessary (e.g. put it in a static
SoftReference<>).

 (but I agree with your comment above that this isn't worth it now).

[Leandro Graciá Gil, 2013/01/12 17:59:14]

Interesting, I didn't know about soft references. Done.

+        if (!nativeRasterizePicture(bitmap, nativePicture)) return null;
+
+        Picture picture = new Picture();
+        Canvas recordingCanvas = picture.beginRecording(width, height);
+        recordingCanvas.drawBitmap(bitmap, 0, 0, null);
+        picture.endRecording();
+        return picture;
+    }
+
     @CalledByNative
     private void handleJsAlert(String url, String message, JsResultReceiver receiver) {
         mContentsClient.handleJsAlert(url, message, receiver);
@@ -985,6 +1020,7 @@ public class AwContents {
     private static native void nativeDestroy(int nativeAwContents);
     private static native void nativeSetAwDrawSWFunctionTable(int functionTablePointer);
     private static native int nativeGetAwDrawGLFunction();
+    private static native boolean nativeRasterizePicture(Bitmap bitmap, int nativePicture);
 
     private native int nativeGetWebContents(int nativeAwContents);
     private native void nativeDidInitializeContentViewCore(int nativeAwContents,
@@ -1024,4 +1060,8 @@ 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);
 }