[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..9de4bc7b75e2af0408f1c2d2ad7e443e3eab5dd6 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 rasterizing Pictures.
+    private SoftReference<Bitmap> mPictureBitmapCache;
+
     private static final class DestroyRunnable implements Runnable {
         private int mNativeAwContents;
         private DestroyRunnable(int nativeAwContents) {
@@ -404,6 +409,19 @@ 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 +927,11 @@ 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 +1004,28 @@ 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 = mPictureBitmapCache != null ? mPictureBitmapCache.get() : null;
+        if (bitmap == null || bitmap.getWidth() != width || bitmap.getHeight() != height) {
+            bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+            bitmap.eraseColor(Color.BLACK);
+            mPictureBitmapCache = new SoftReference<Bitmap>(bitmap);
+        }
+
+        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);
@@ -1010,6 +1055,7 @@ 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,
@@ -1049,4 +1095,8 @@ 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);
 }