Define public inteface for accessing Canvas pixels

The embedder can supply implementations of the declared functions, allowing
the software draw path to have direct access to the pixels underlying
the java Canvas object from native code.

BUG=


Review URL: https://chromiumcodereview.appspot.com/11665020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@174592 0039d316-1c4b-4281-b951-d872f2087c98

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

@@ -7,6 +7,7 @@
 import android.content.res.Configuration;
 import android.graphics.Bitmap;
 import android.graphics.Canvas;
+import android.graphics.Color;
 import android.graphics.Rect;
 import android.net.http.SslCertificate;
 import android.os.AsyncTask;
@@ -330,6 +331,10 @@ public void destroy() {
         mNativeAwContents = 0;
     }
 
+    public static void setAwDrawSWFunctionTable(int functionTablePointer) {
+        nativeSetAwDrawSWFunctionTable(functionTablePointer);
+    }
+
     public static int getAwDrawGLFunction() {
         return nativeGetAwDrawGLFunction();
     }
@@ -349,8 +354,11 @@ public boolean onPrepareDrawGL(Canvas canvas) {
     }
 
     public void onDraw(Canvas canvas) {
-        // TODO(joth): Implement. For now, just clear the canvas to red.
-        canvas.drawRGB(200, 1, 4);
+        if (!nativeDrawSW(mNativeAwContents, canvas)) {
+            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));
+        }
     }
 
     public int findAllSync(String searchString) {
@@ -929,6 +937,7 @@ private void handleJsPrompt(String url, String message, String defaultValue,
     private native int nativeInit(AwWebContentsDelegate webViewWebContentsDelegate,
             boolean privateBrowsing);
     private static native void nativeDestroy(int nativeAwContents);
+    private static native void nativeSetAwDrawSWFunctionTable(int functionTablePointer);
     private static native int nativeGetAwDrawGLFunction();
 
     private native int nativeGetWebContents(int nativeAwContents);
@@ -944,6 +953,7 @@ private native void nativeSetIoThreadClient(int nativeAwContents,
     private native void nativeSetInterceptNavigationDelegate(int nativeAwContents,
             InterceptNavigationDelegate navigationInterceptionDelegate);
 
+    private native boolean nativeDrawSW(int nativeAwContents, Canvas canvas);
     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);

android_webview/native/DEPS

@@ -3,4 +3,7 @@ include_rules = [
   "+content/public/browser",
   "+ui/gfx",
   "+ui/gl",
+
+  # TODO(joth): Remove if we can move the compositor driver into ../browser/
+  "+third_party/skia/include",
 ]

android_webview/native/aw_contents.cc

@@ -15,6 +15,7 @@
 #include "android_webview/native/aw_contents_io_thread_client_impl.h"
 #include "android_webview/native/aw_web_contents_delegate.h"
 #include "android_webview/native/state_serializer.h"
+#include "android_webview/public/browser/draw_sw.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
@@ -35,6 +36,9 @@
 #include "content/public/common/ssl_status.h"
 #include "jni/AwContents_jni.h"
 #include "net/base/x509_certificate.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "third_party/skia/include/core/SkDevice.h"
 #include "ui/gfx/transform.h"
 #include "ui/gl/gl_bindings.h"
 
@@ -78,6 +82,8 @@ namespace android_webview {
 
 namespace {
 
+AwDrawSWFunctionTable* g_draw_sw_functions = NULL;
+
 const void* kAwContentsUserDataKey = &kAwContentsUserDataKey;
 
 class AwContentsUserData : public base::SupportsUserData::Data {
@@ -410,6 +416,43 @@ void AwContents::DrawGL(AwDrawGLInfo* draw_info) {
   // ---------------------------------------------------------------------------
 }
 
+bool AwContents::DrawSW(JNIEnv* env, jobject obj, jobject java_canvas) {
+  AwPixelInfo* pixels;
+  if (!g_draw_sw_functions ||
+      (pixels = g_draw_sw_functions->access_pixels(env, java_canvas)) == NULL) {
+    // TODO(joth): Fall back to slow path rendering via temporary bitmap.
+    return false;
+  }
+
+  {
+    SkBitmap bitmap;
+    bitmap.setConfig(static_cast<SkBitmap::Config>(pixels->config),
+                     pixels->width,
+                     pixels->height,
+                     pixels->row_bytes);
+    bitmap.setPixels(pixels->pixels);
+    SkDevice device(bitmap);
+    SkCanvas canvas(&device);
+    SkMatrix matrix;
+    for (int i = 0; i < 9; i++) {
+      matrix.set(i, pixels->matrix[i]);
+    }
+    canvas.setMatrix(matrix);
+    SkRegion clip;
+    if (pixels->clip_region_size) {
+      size_t bytes_read = clip.readFromMemory(pixels->clip_region);
+      DCHECK_EQ(pixels->clip_region_size, bytes_read);
+      canvas.setClipRegion(clip);
+    }
+
+    // TODO(joth): Implement real drawing. For now, fill the view in blue.
+    canvas.drawARGB(128, 1, 30, 250);
+  }
+
+  g_draw_sw_functions->release_pixels(pixels);
+  return true;
+}
+
 jint AwContents::GetWebContents(JNIEnv* env, jobject obj) {
   return reinterpret_cast<jint>(web_contents_.get());
 }
@@ -446,6 +489,12 @@ void AwContents::Destroy(JNIEnv* env, jobject obj) {
   delete this;
 }
 
+// static
+void SetAwDrawSWFunctionTable(JNIEnv* env, jclass, jint function_table) {
+  g_draw_sw_functions =
+      reinterpret_cast<AwDrawSWFunctionTable*>(function_table);
+}
+
 // static
 jint GetAwDrawGLFunction(JNIEnv* env, jclass) {
   return reinterpret_cast<jint>(&DrawGLFunction);

android_webview/native/aw_contents.h

@@ -51,6 +51,7 @@ class AwContents : public FindHelper::Listener,
   virtual ~AwContents();
 
   void DrawGL(AwDrawGLInfo* draw_info);
+  bool DrawSW(JNIEnv* env, jobject obj, jobject canvas);
 
   void RunJavaScriptDialog(
       content::JavaScriptMessageType message_type,

android_webview/public/browser/draw_sw.h

@@ -0,0 +1,44 @@
+// Copyright (c) 2012 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.
+
+#ifndef ANDROID_WEBVIEW_PUBLIC_BROWSER_DRAW_SW_H_
+#define ANDROID_WEBVIEW_PUBLIC_BROWSER_DRAW_SW_H_
+
+#include <jni.h>
+#include <stddef.h>
+
+#ifndef __cplusplus
+#error "Can't mix C and C++ when using jni.h"
+#endif
+
+// Holds the information required to implement the SW draw to system canvas.
+struct AwPixelInfo {
+  int config;         // In SkBitmap::Config format.
+  int width;          // In pixels.
+  int height;         // In pixels.
+  int row_bytes;      // Number of bytes from start of one line to next.
+  void* pixels;       // The pixels, all (height * row_bytes) of them.
+  float matrix[9];    // The matrix currently in effect on the canvas.
+  void* clip_region;  // Flattened clip region.
+  size_t clip_region_size;   // Number of bytes in |clip_region|.
+};
+
+// Function that can be called to fish out the underlying native pixel data
+// from a Java canvas object, for optimized rendering path.
+// Returns the pixel info on success, which must be freed via a call to
+// AwReleasePixelsFunction, or NULL.
+typedef AwPixelInfo* (AwAccessPixelsFunction)(JNIEnv* env, jobject canvas);
+
+// Must be called to balance every *successful* call to AwAccessPixelsFunction
+// (i.e. that returned true).
+typedef void (AwReleasePixelsFunction)(AwPixelInfo* pixels);
+
+// "vtable" for the functions declared in this file. An instance must be set via
+// AwContents.setAwDrawSWFunctionTable
+struct AwDrawSWFunctionTable {
+  AwAccessPixelsFunction* access_pixels;
+  AwReleasePixelsFunction* release_pixels;
+};
+
+#endif  // ANDROID_WEBVIEW_PUBLIC_BROWSER_DRAW_SW_H_