Make new-style page scale work on Android.

cc/layer_tree_impl.cc

 // Copyright 2011 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.
 
 #include "cc/layer_tree_impl.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/layer_tree_host_common.h"
 #include "cc/layer_tree_host_impl.h"
 #include "ui/gfx/vector2d_conversions.h"
@@ skipping 67 matching lines @@
 
 void LayerTreeImpl::ClearCurrentlyScrollingLayer() {
   currently_scrolling_layer_ = NULL;
   scrolling_layer_id_from_previous_tree_ = 0;
 }
 
 void LayerTreeImpl::UpdateMaxScrollOffset() {
   if (!root_scroll_layer() || !root_scroll_layer()->children().size())
     return;
 
-  gfx::SizeF view_bounds = device_viewport_size();
-  if (LayerImpl* clip_layer = root_scroll_layer()->parent()) {
-    // Compensate for non-overlay scrollbars.
-    if (clip_layer->masksToBounds())
-      view_bounds = gfx::ScaleSize(clip_layer->bounds(), device_scale_factor());
+  gfx::SizeF view_bounds;
+  if (!settings().pageScalePinchZoomEnabled) {
+    view_bounds = device_viewport_size();
+    if (LayerImpl* clip_layer = root_scroll_layer()->parent()) {
+      // Compensate for non-overlay scrollbars.
+      if (clip_layer->masksToBounds())
+        view_bounds = gfx::ScaleSize(clip_layer->bounds(), device_scale_factor());

[danakj, 2013/01/17 18:02:49]

This bound here (and above) is in physical pixels, but the else{} clause is in
logical pixels? It seems like this code could be using the layout viewport size
and not scaling the clip layer's bounds?

[aelias_OOO_until_Jul13, 2013/01/17 19:59:46]

This clause is for the old coordinate space so it uses totally different
assumptions about the semantics.  I'm just leaving it unchanged to avoid
breaking Android before the transition is complete.

+    }
+    view_bounds.Scale(1 / pinch_zoom_viewport().page_scale_delta());
+  } else {
+    view_bounds = layout_viewport_size();
   }
 
-  gfx::Size content_bounds = ContentSize();
-  if (settings().pageScalePinchZoomEnabled) {
-    // Pinch with pageScale scrolls entirely in layout space.  ContentSize
-    // returns the bounds including the page scale factor, so calculate the
-    // pre page-scale layout size here.
-    float page_scale_factor = pinch_zoom_viewport().page_scale_factor();
-    content_bounds.set_width(content_bounds.width() / page_scale_factor);
-    content_bounds.set_height(content_bounds.height() / page_scale_factor);
-  } else {
-    view_bounds.Scale(1 / pinch_zoom_viewport().page_scale_delta());
-  }
-
-  gfx::Vector2dF max_scroll = gfx::Rect(content_bounds).bottom_right() -
+  gfx::Vector2dF max_scroll = gfx::Rect(ScrollableSize()).bottom_right() -

[danakj, 2013/01/17 18:02:49]

I do like this :)

       gfx::RectF(view_bounds).bottom_right();
-  max_scroll.Scale(1 / device_scale_factor());
 
   // The viewport may be larger than the contents in some cases, such as
   // having a vertical scrollbar but no horizontal overflow.
   max_scroll.ClampToMin(gfx::Vector2dF());
 
   root_scroll_layer()->setMaxScrollOffset(gfx::ToFlooredVector2d(max_scroll));
 }
 
 void LayerTreeImpl::UpdateDrawProperties() {
   render_surface_layer_list_.clear();
@@ skipping 48 matching lines @@
 
   return true;
 }
 
 const LayerTreeImpl::LayerList& LayerTreeImpl::RenderSurfaceLayerList() const {
   // If this assert triggers, then the list is dirty.
   DCHECK(!layer_tree_host_impl_->needsUpdateDrawProperties());
   return render_surface_layer_list_;
 }
 
-gfx::Size LayerTreeImpl::ContentSize() const {
-  // TODO(aelias): Hardcoding the first child here is weird. Think of
-  // a cleaner way to get the contentBounds on the Impl side.
+gfx::Size LayerTreeImpl::ScrollableSize() const {
   if (!root_scroll_layer() || root_scroll_layer()->children().empty())
     return gfx::Size();
-  return root_scroll_layer()->children()[0]->contentBounds();
+  return root_scroll_layer()->children()[0]->bounds();
 }
 
 LayerImpl* LayerTreeImpl::LayerById(int id) {
   LayerIdMap::iterator iter = layer_id_map_.find(id);
   return iter != layer_id_map_.end() ? iter->second : NULL;
 }
 
 void LayerTreeImpl::RegisterLayer(LayerImpl* layer) {
   DCHECK(!LayerById(layer->id()));
   layer_id_map_[layer->id()] = layer;
@@ skipping 105 matching lines @@
 
 AnimationRegistrar* LayerTreeImpl::animationRegistrar() const {
   return layer_tree_host_impl_->animationRegistrar();
 }
 
 const PinchZoomViewport& LayerTreeImpl::pinch_zoom_viewport() const {
   return layer_tree_host_impl_->pinchZoomViewport();
 }
 
 } // namespace cc