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..30ec57b7ff1df481d2fa5cd28e526fb5881593a1
--- /dev/null
+++ b/android_webview/java/src/org/chromium/android_webview/AwPicture.java
@@ -0,0 +1,95 @@
+// 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;
+
+    // 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.
+     */
+    AwPicture(int nativeAwPicture) {
+        mNativeAwPicture = nativeAwPicture;
+        mCleanupReference = new CleanupReference(this, new DestroyRunnable(nativeAwPicture));
+    }
+
+    @Override
+    public Canvas beginRecording(int width, int height) {
+        unsupportedOperation();
+        return null;
+    }
+
+    @Override
+    public void endRecording() {
+        // Intentional no-op. The native picture ended recording prior to java c'tor call.
+    }
+
+    @Override
+    public int getWidth() {
+        return nativeGetWidth(mNativeAwPicture);
+    }
+
+    @Override
+    public int getHeight() {
+        return nativeGetHeight(mNativeAwPicture);
+    }
+
+    // Effectively a local variable of draw(), but held as a member to avoid GC churn.
+    private Rect mClipBoundsTemporary = new Rect();
+
+    @Override
+    public void draw(Canvas canvas) {
+        canvas.getClipBounds(mClipBoundsTemporary);
+        nativeDraw(mNativeAwPicture, canvas,
+                mClipBoundsTemporary.left, mClipBoundsTemporary.top,
+                mClipBoundsTemporary.right, mClipBoundsTemporary.bottom);
+    }
+
+    @Override
+    public void writeToStream(OutputStream stream) {
+        unsupportedOperation();
+    }
+
+    private void unsupportedOperation() {
+        throw new IllegalStateException("Unsupported in AwPicture");
+    }
+
+    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);
+}
+