[Android WebView] Update SW rendering to use SkPicture and fix scrolling cases.

android_webview/native/aw_contents.cc

Index: android_webview/native/aw_contents.cc
diff --git a/android_webview/native/aw_contents.cc b/android_webview/native/aw_contents.cc
index 778400ef776ec363460d0d7a0ed7a02df37a27ac..c32940decc7eca6b943a19398cec3c6f9b411fb2 100644
--- a/android_webview/native/aw_contents.cc
+++ b/android_webview/native/aw_contents.cc
@@ -160,7 +160,6 @@ AwContents::AwContents(JNIEnv* env,
       view_visible_(false),
       compositor_visible_(false),
       is_composite_pending_(false),
-      last_scroll_x_(0), last_scroll_y_(0),
       last_frame_context_(NULL) {
   RendererPictureMap::CreateInstance();
   android_webview::AwBrowserDependencyFactory* dependency_factory =
@@ -313,7 +312,6 @@ void AwContents::DrawGL(AwDrawGLInfo* draw_info) {
     last_frame_context_ = current_context;
   }
 
-  gfx::Transform transform;
   compositor_->SetWindowBounds(gfx::Size(draw_info->width, draw_info->height));
 
   if (draw_info->is_layer) {
@@ -322,6 +320,7 @@ void AwContents::DrawGL(AwDrawGLInfo* draw_info) {
     // The Android framework will composite us afterwards.
     compositor_->SetHasTransparentBackground(false);
     view_clip_layer_->setMasksToBounds(false);
+    transform_layer_->setTransform(gfx::Transform());
     scissor_clip_layer_->setMasksToBounds(false);
     scissor_clip_layer_->setPosition(gfx::PointF());
     scissor_clip_layer_->setBounds(gfx::Size());
@@ -346,15 +345,17 @@ void AwContents::DrawGL(AwDrawGLInfo* draw_info) {
     undo_clip_position.Translate(-clip_rect.x(), -clip_rect.y());
     scissor_clip_layer_->setSublayerTransform(undo_clip_position);
 
+    gfx::Transform transform;
     transform.matrix().setColMajorf(draw_info->transform);
+
+    // The scrolling values of the Android Framework affect the transformation
+    // matrix. This needs to be undone to let the compositor handle scrolling.
+    transform.Translate(hw_rendering_scroll_.x(), hw_rendering_scroll_.y());
+    transform_layer_->setTransform(transform);
+
     view_clip_layer_->setMasksToBounds(true);
   }
 
-  // The scrolling values of the Android Framework affect the transformation
-  // matrix. This needs to be undone to let the compositor handle scrolling.
-  transform.Translate(last_scroll_x_, last_scroll_y_);
-  transform_layer_->setTransform(transform);
-
   compositor_->Composite();
   is_composite_pending_ = false;
 
@@ -421,7 +422,8 @@ void AwContents::DrawGL(AwDrawGLInfo* draw_info) {
   // ---------------------------------------------------------------------------
 }
 
-bool AwContents::DrawSW(JNIEnv* env, jobject obj, jobject java_canvas) {
+bool AwContents::DrawSW(JNIEnv* env, jobject obj, jobject java_canvas,
+                        jint scroll_x, jint scroll_y) {
   scoped_refptr<cc::PicturePileImpl> picture =
       RendererPictureMap::GetInstance()->GetRendererPicture(
           web_contents_->GetRoutingID());
@@ -450,6 +452,9 @@ bool AwContents::DrawSW(JNIEnv* env, jobject obj, jobject java_canvas) {
     }
     canvas.setMatrix(matrix);
 
+    // Scroll needs to be undone to let the Chrome compositor handle scrolling.
+    canvas.translate(scroll_x, scroll_y);

[Leandro Graciá Gil, 2013/01/04 21:21:24]

As part of the review of https://codereview.chromium.org/11731002/ I'll be
replacing all PicturePileImpl directly with SkPictures. It happens that then we
will translate the scroll to immediately undo that as PicturePileImpl::Raster
did to position itself correctly within the content.

So, apparently this translate and any references to scroll offsets in SW mode
can be removed and scroll will be automatically fixed when adopting SkPictures.
I'll update the patch.

+
     SkRegion clip;
     if (pixels->clip_region_size) {
       size_t bytes_read = clip.readFromMemory(pixels->clip_region);
@@ -459,12 +464,10 @@ bool AwContents::DrawSW(JNIEnv* env, jobject obj, jobject java_canvas) {
       clip.setRect(SkIRect::MakeWH(pixels->width, pixels->height));
     }
 
-    SkIRect sk_clip_rect = clip.getBounds();
-    gfx::Rect clip_rect(sk_clip_rect.x(), sk_clip_rect.y(),
-                        sk_clip_rect.width(), sk_clip_rect.height());
-
     cc::RenderingStats stats;
-    picture->Raster(&canvas, clip_rect, 1.0, &stats);
+    gfx::Rect content_rect(scroll_x, scroll_y, view_size_.width(),
+                           view_size_.height());
+    picture->Raster(&canvas, content_rect, 1.0, &stats);
   }
 
   g_draw_sw_functions->release_pixels(pixels);
@@ -860,8 +863,7 @@ jboolean AwContents::RestoreFromOpaqueState(
 
 void AwContents::SetScrollForHWFrame(JNIEnv* env, jobject obj,
                                      int scroll_x, int scroll_y) {
-  last_scroll_x_ = scroll_x;
-  last_scroll_y_ = scroll_y;
+  hw_rendering_scroll_ = gfx::Point(scroll_x, scroll_y);
 }
 
 void AwContents::SetPendingWebContentsForPopup(