Pinch/Zoom Infrastructure & Plumbing CL

cc/layers/scrollbar_layer_impl_base.cc

Index: cc/layers/scrollbar_layer_impl_base.cc
diff --git a/cc/layers/scrollbar_layer_impl_base.cc b/cc/layers/scrollbar_layer_impl_base.cc
index 55f46f51d846fe0fe074735abd315c6007dd49f7..22583a141806a053565c955dd51d940949d6507f 100644
--- a/cc/layers/scrollbar_layer_impl_base.cc
+++ b/cc/layers/scrollbar_layer_impl_base.cc
@@ -5,7 +5,7 @@
 #include "cc/layers/scrollbar_layer_impl_base.h"
 
 #include <algorithm>
-#include "cc/layers/layer.h"
+#include "cc/trees/layer_tree_impl.h"
 #include "ui/gfx/rect_conversions.h"
 
 namespace cc {
@@ -14,10 +14,12 @@ ScrollbarLayerImplBase::ScrollbarLayerImplBase(
     LayerTreeImpl* tree_impl,
     int id,
     ScrollbarOrientation orientation,
-    bool is_left_side_vertical_scrollbar)
+    bool is_left_side_vertical_scrollbar,
+    bool is_overlay)
     : LayerImpl(tree_impl, id),
-      scroll_layer_id_(Layer::INVALID_ID),
-      is_overlay_scrollbar_(false),
+      scroll_layer_(NULL),
+      clip_layer_(NULL),
+      is_overlay_scrollbar_(is_overlay),
       thumb_thickness_scale_factor_(1.f),
       current_pos_(0.f),
       maximum_(0),
@@ -26,14 +28,50 @@ ScrollbarLayerImplBase::ScrollbarLayerImplBase(
       vertical_adjust_(0.f),
       visible_to_total_length_ratio_(1.f) {}
 
+ScrollbarLayerImplBase::~ScrollbarLayerImplBase() {

[aelias_OOO_until_Jul13, 2014/01/16 03:44:04]

This should make sure to call RemoveScrollbar() to avoid leaving dangling
pointers.

[wjmaclean, 2014/01/16 15:07:32]

Done.

+}
+
 void ScrollbarLayerImplBase::PushPropertiesTo(LayerImpl* layer) {
   LayerImpl::PushPropertiesTo(layer);
+  DCHECK(layer->ToScrollbarLayer());
+  layer->ToScrollbarLayer()->set_is_overlay_scrollbar(is_overlay_scrollbar_);
+  PushScrollClipPropertiesTo(layer);
+}
+
+void ScrollbarLayerImplBase::PushScrollClipPropertiesTo(LayerImpl* layer) {
+  DCHECK(layer->ToScrollbarLayer());
+  layer->ToScrollbarLayer()->SetScrollLayerById(ScrollLayerId());
+  layer->ToScrollbarLayer()->SetClipLayerById(ClipLayerId());
 }
 
 ScrollbarLayerImplBase* ScrollbarLayerImplBase::ToScrollbarLayer() {
   return this;
 }
 
+void ScrollbarLayerImplBase::SetScrollLayerById(int id) {
+  LayerImpl* scroll_layer = layer_tree_impl()->LayerById(id);
+  if (scroll_layer_ == scroll_layer)
+    return;
+
+  if (scroll_layer_)
+    scroll_layer_->RemoveScrollbar(this);
+  scroll_layer_ = scroll_layer;
+  if (scroll_layer_)
+    scroll_layer_->AddScrollbar(this);
+}
+
+void ScrollbarLayerImplBase::SetClipLayerById(int id) {
+  LayerImpl* clip_layer = layer_tree_impl()->LayerById(id);
+  if (clip_layer_ == clip_layer)
+    return;
+
+  if (clip_layer_)
+    clip_layer_->RemoveScrollbar(this);
+  clip_layer_ = clip_layer;
+  if (clip_layer_)
+    clip_layer_->AddScrollbar(this);

[aelias_OOO_until_Jul13, 2014/01/16 03:44:04]

It's weird that the clip layer is getting called AddScrollbar just like the
scroll layer even though the semantic relationship is very different.  What does
the clip layer need this for?  Isn't it enough for the scrollbar to have one-way
knowledge of the clip?

[wjmaclean, 2014/01/16 15:07:32]

The scrollbar should not have to rely on polling the clip layer to know when
changes have occurred. Thereforefore both the scroll layer and the scroll clip
layer will push notifications to any registered scrollbars when relevant
geometry changes.

+}
+
 gfx::Rect ScrollbarLayerImplBase::ScrollbarLayerRectToContentRect(
     const gfx::RectF& layer_rect) const {
   // Don't intersect with the bounds as in LayerRectToContentRect() because
@@ -177,4 +215,11 @@ gfx::Rect ScrollbarLayerImplBase::ComputeThumbQuadRect() const {
   return ScrollbarLayerRectToContentRect(thumb_rect);
 }
 
+void ScrollbarLayerImplBase::ScrollbarParametersDidChange() {
+  if (!clip_layer_ || !scroll_layer_)
+    return;
+
+  scroll_layer_->SetScrollbarPosition(this, clip_layer_);
+}
+
 }  // namespace cc