Android WebView: Make a custom Picture subclass

android_webview/java/src/org/chromium/android_webview/AwPicture.java

Index: android_webview/java/src/org/chromium/android_webview/AwPicture.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwPicture.java b/android_webview/java/src/org/chromium/android_webview/AwPicture.java
new file mode 100644
index 0000000000000000000000000000000000000000..2636a3184c15b598d8e8d320a31b5d3fcffcd9de
--- /dev/null
+++ b/android_webview/java/src/org/chromium/android_webview/AwPicture.java
@@ -0,0 +1,116 @@
+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.android_webview;
+
+import android.graphics.Canvas;
+import android.graphics.Picture;
+import android.graphics.Rect;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+import org.chromium.content.common.CleanupReference;
+
+import java.io.OutputStream;
+
+// A simple wrapper around a SkPicture, that allows final rendering to be performed using the
+// chromium skia library.
+@JNINamespace("android_webview")
+class AwPicture extends Picture {
+
+    private int mNativeAwPicture;
+    private boolean mCompatibilityMode;
+
+    // There is no explicit destroy method on Picture base-class, so cleanup is always
+    // handled via the CleanupReference.
+    private static final class DestroyRunnable implements Runnable {
+        private int mNativeAwPicture;
+        private DestroyRunnable(int nativeAwPicture) {
+            mNativeAwPicture = nativeAwPicture;
+        }
+        @Override
+        public void run() {
+            nativeDestroy(mNativeAwPicture);
+        }
+    }
+
+    private CleanupReference mCleanupReference;
+
+    /**
+     * @param nativeAwPicture is an instance of the AwPicture native class. Ownership is
+     *                        taken by this java instance.
+     * @param compatibilityMode if true, unsupported methods are a no-op rather than throw.
+     */
+    AwPicture(int nativeAwPicture, boolean compatibilityMode) {
+        mNativeAwPicture = nativeAwPicture;
+        mCompatibilityMode = compatibilityMode;
+        mCleanupReference = new CleanupReference(this, new DestroyRunnable(nativeAwPicture));
+    }
+
+    @Override
+    public Canvas beginRecording(int width, int height) {
+        checkCompat();
+        if (mCleanupReference != null) {
+            mCleanupReference.cleanupNow();
+            mCleanupReference = null;
+        }
+        mNativeAwPicture = 0;
+        return super.beginRecording(width, height);
+    }
+
+    @Override
+    public void endRecording() {
+        super.endRecording();
+    }
+
+    @Override
+    public int getWidth() {
+        if (mNativeAwPicture != 0) {
+            return nativeGetWidth(mNativeAwPicture);
+        } else {
+            return super.getWidth();
+        }
+    }
+
+    @Override
+    public int getHeight() {
+        if (mNativeAwPicture != 0) {
+            return nativeGetHeight(mNativeAwPicture);
+        } else {
+            return super.getHeight();
+        }
+    }
+
+    Rect mClipBoundsTemporary = new Rect();

[sgurun-gerrit only, 2013/08/08 22:11:19]

Is this intentional? why is it not private and defined at the top?

+    @Override
+    public void draw(Canvas canvas) {
+        if (mNativeAwPicture != 0) {
+            canvas.getClipBounds(mClipBoundsTemporary);
+            nativeDraw(mNativeAwPicture, canvas,
+                    mClipBoundsTemporary.left, mClipBoundsTemporary.top,
+                    mClipBoundsTemporary.right, mClipBoundsTemporary.bottom);
+        } else {
+            super.draw(canvas);
+        }
+    }
+
+    @Override
+    public void writeToStream(OutputStream stream) {
+        if (stream == null) throw new NullPointerException();
+        checkCompat();
+    }
+
+    private void checkCompat() {
+        if (!mCompatibilityMode) {
+            throw new IllegalStateException("Unsupported in WebView Picture");
+        }

[joth, 2013/08/03 17:38:12]

else Log.e ?

[Kristian Monsen, 2013/08/08 21:28:59]

It would potentially crash the app. It either happens all the time or never on a
system as far as I understand? Maybe best the keep the exception.

[joth, 2013/08/08 22:39:01]

As per verbal discussion, I'll remove the mCompatibilityMode and change to
always throw for incorrect usage at this layer

[boliu, 2013/08/08 23:05:10]

What is that discussion? It's probably a bad idea for apps to call these
methods, but they didn't through exception before?

+    }
+
+    private static native void nativeDestroy(int nativeAwPicture);
+    private native int nativeGetWidth(int nativeAwPicture);
+    private native int nativeGetHeight(int nativeAwPicture);
+    private native void nativeDraw(int nativeAwPicture, Canvas canvas,
+            int left, int top, int right, int bottom);
+}
+