Refactor cc scrollbar layers architecture.

This CL separates the solid-color scrollbar functionality into its own class structure, resulting in the following hierarchy:

ScrollbarLayerInterface (pure-virtual)
 |
 --------  PaintedScrollbarLayer (for outer-viewport)
 |
 --------- SolidColorScrollbarLayer (for inner-viewport)            
                                    (Android, pinch-zoom)

ScrollbarLayerImplBase
 |
 ----- PaintedScrollbarLayerImpl (for outer-viewport)
 |
 ----- SolidColorScrollbarLayerImpl (for inner-viewport)
                                    (Android, pinch-zoom)

In this architecture, solid-color scrollbars can live side-by side with regular desktop scrollbars, and no longer require a WebScrollbar in order to be created. The scrolling LayerImpl's only know about ScrollbarLayerImplBase, and the TreeSynchronizer & LTI only deal with *Base layer types.

The ScrollbarLayerImplBase layer is not pure virtual, but rather attempts to collect any common functionality, and the result is much simpler classes for SolidColorScrollbarLayerImpl.

Work remaining:

1) Once the pinch-viewport layers are in place in CC, we can get rid of vertical adjust (I think), and so LTI::UpdateSolidColorScrollbars() can go away. When this goes away, some of the interface for ScrollbarLayerImplBase can be simplified as well.

Review URL: https://chromiumcodereview.appspot.com/18341009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@220637 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 23 insertions, 164 deletions

diff --git a/cc/layers/painted_scrollbar_layer_impl.cc b/cc/layers/painted_scrollbar_layer_impl.cc
index 621cf39..83685c3 100644
--- a/cc/layers/painted_scrollbar_layer_impl.cc
+++ b/cc/layers/painted_scrollbar_layer_impl.cc
@@ -29,35 +29,26 @@ PaintedScrollbarLayerImpl::PaintedScrollbarLayerImpl(
     LayerTreeImpl* tree_impl,
     int id,
     ScrollbarOrientation orientation)
-    : LayerImpl(tree_impl, id),
+    : ScrollbarLayerImplBase(tree_impl, id, orientation),
       track_ui_resource_id_(0),
       thumb_ui_resource_id_(0),
-      current_pos_(0.f),
-      maximum_(0),
       thumb_thickness_(0),
       thumb_length_(0),
       track_start_(0),
       track_length_(0),
-      orientation_(orientation),
       vertical_adjust_(0.f),
-      visible_to_total_length_ratio_(1.f),
-      scroll_layer_id_(Layer::INVALID_ID),
-      is_overlay_scrollbar_(false) {}
+      scroll_layer_id_(Layer::INVALID_ID) {}
 
 PaintedScrollbarLayerImpl::~PaintedScrollbarLayerImpl() {}
 
-PaintedScrollbarLayerImpl* PaintedScrollbarLayerImpl::ToScrollbarLayer() {
-  return this;
-}
-
 scoped_ptr<LayerImpl> PaintedScrollbarLayerImpl::CreateLayerImpl(
     LayerTreeImpl* tree_impl) {
-  return PaintedScrollbarLayerImpl::Create(tree_impl, id(), orientation_)
+  return PaintedScrollbarLayerImpl::Create(tree_impl, id(), orientation())
       .PassAs<LayerImpl>();
 }
 
 void PaintedScrollbarLayerImpl::PushPropertiesTo(LayerImpl* layer) {
-  LayerImpl::PushPropertiesTo(layer);
+  ScrollbarLayerImplBase::PushPropertiesTo(layer);
 
   PaintedScrollbarLayerImpl* scrollbar_layer =
       static_cast<PaintedScrollbarLayerImpl*>(layer);
@@ -66,7 +57,6 @@ void PaintedScrollbarLayerImpl::PushPropertiesTo(LayerImpl* layer) {
   scrollbar_layer->SetThumbLength(thumb_length_);
   scrollbar_layer->SetTrackStart(track_start_);
   scrollbar_layer->SetTrackLength(track_length_);
-  scrollbar_layer->set_is_overlay_scrollbar(is_overlay_scrollbar_);
 
   scrollbar_layer->set_track_ui_resource_id(track_ui_resource_id_);
   scrollbar_layer->set_thumb_ui_resource_id(thumb_ui_resource_id_);
@@ -74,9 +64,7 @@ void PaintedScrollbarLayerImpl::PushPropertiesTo(LayerImpl* layer) {
 
 bool PaintedScrollbarLayerImpl::WillDraw(DrawMode draw_mode,
                                   ResourceProvider* resource_provider) {
-  if (draw_mode == DRAW_MODE_RESOURCELESS_SOFTWARE &&
-      !layer_tree_impl()->settings().solid_color_scrollbars)
-    return false;
+  DCHECK(draw_mode != DRAW_MODE_RESOURCELESS_SOFTWARE);
   return LayerImpl::WillDraw(draw_mode, resource_provider);
 }
 
@@ -96,16 +84,6 @@ void PaintedScrollbarLayerImpl::AppendQuads(
 
   gfx::Rect thumb_quad_rect = ComputeThumbQuadRect();
 
-  if (layer_tree_impl()->settings().solid_color_scrollbars) {
-    scoped_ptr<SolidColorDrawQuad> quad = SolidColorDrawQuad::Create();
-    quad->SetNew(shared_quad_state,
-                 thumb_quad_rect,
-                 layer_tree_impl()->settings().solid_color_scrollbar_color,
-                 false);
-    quad_sink->Append(quad.PassAs<DrawQuad>(), append_quads_data);
-    return;
-  }
-
   ResourceProvider::ResourceId thumb_resource_id =
       layer_tree_impl()->ResourceIdForUIResource(thumb_ui_resource_id_);
   ResourceProvider::ResourceId track_resource_id =
@@ -147,26 +125,9 @@ void PaintedScrollbarLayerImpl::AppendQuads(
   }
 }
 
-ScrollbarOrientation PaintedScrollbarLayerImpl::Orientation() const {
-  return orientation_;
-}
-
-float PaintedScrollbarLayerImpl::CurrentPos() const {
-  return current_pos_;
-}
-
-int PaintedScrollbarLayerImpl::Maximum() const {
-  return maximum_;
-}
-
-gfx::Rect PaintedScrollbarLayerImpl::ScrollbarLayerRectToContentRect(
-    gfx::RectF layer_rect) const {
-  // Don't intersect with the bounds as in layerRectToContentRect() because
-  // layer_rect here might be in coordinates of the containing layer.
-  gfx::RectF content_rect = gfx::ScaleRect(layer_rect,
-                                           contents_scale_x(),
-                                           contents_scale_y());
-  return gfx::ToEnclosingRect(content_rect);
+void PaintedScrollbarLayerImpl::DidLoseOutputSurface() {
+  track_ui_resource_id_ = 0;
+  thumb_ui_resource_id_ = 0;
 }
 
 void PaintedScrollbarLayerImpl::SetThumbThickness(int thumb_thickness) {
@@ -176,12 +137,21 @@ void PaintedScrollbarLayerImpl::SetThumbThickness(int thumb_thickness) {
   NoteLayerPropertyChanged();
 }
 
+int PaintedScrollbarLayerImpl::ThumbThickness() const {
+  return thumb_thickness_;
+}
+
 void PaintedScrollbarLayerImpl::SetThumbLength(int thumb_length) {
   if (thumb_length_ == thumb_length)
     return;
   thumb_length_ = thumb_length;
   NoteLayerPropertyChanged();
 }
+
+int PaintedScrollbarLayerImpl::ThumbLength() const {
+  return thumb_length_;
+}
+
 void PaintedScrollbarLayerImpl::SetTrackStart(int track_start) {
   if (track_start_ == track_start)
     return;
@@ -189,6 +159,10 @@ void PaintedScrollbarLayerImpl::SetTrackStart(int track_start) {
   NoteLayerPropertyChanged();
 }
 
+int PaintedScrollbarLayerImpl::TrackStart() const {
+  return track_start_;
+}
+
 void PaintedScrollbarLayerImpl::SetTrackLength(int track_length) {
   if (track_length_ == track_length)
     return;
@@ -196,123 +170,8 @@ void PaintedScrollbarLayerImpl::SetTrackLength(int track_length) {
   NoteLayerPropertyChanged();
 }
 
-void PaintedScrollbarLayerImpl::SetVerticalAdjust(float vertical_adjust) {
-  if (vertical_adjust_ == vertical_adjust)
-    return;
-  vertical_adjust_ = vertical_adjust;
-  NoteLayerPropertyChanged();
-}
-
-void PaintedScrollbarLayerImpl::SetVisibleToTotalLengthRatio(float ratio) {
-  if (visible_to_total_length_ratio_ == ratio)
-    return;
-  visible_to_total_length_ratio_ = ratio;
-  NoteLayerPropertyChanged();
-}
-
-void PaintedScrollbarLayerImpl::SetCurrentPos(float current_pos) {
-  if (current_pos_ == current_pos)
-    return;
-  current_pos_ = current_pos;
-  NoteLayerPropertyChanged();
-}
-
-void PaintedScrollbarLayerImpl::SetMaximum(int maximum) {
-  if (maximum_ == maximum)
-    return;
-  maximum_ = maximum;
-  NoteLayerPropertyChanged();
-}
-
-gfx::Rect PaintedScrollbarLayerImpl::ComputeThumbQuadRect() const {
-  // Thumb extent is the length of the thumb in the scrolling direction, thumb
-  // thickness is in the perpendicular direction. Here's an example of a
-  // horizontal scrollbar - inputs are above the scrollbar, computed values
-  // below:
-  //
-  //    |<------------------- track_length_ ------------------->|
-  //
-  // |--| <-- start_offset
-  //
-  // +--+----------------------------+------------------+-------+--+
-  // |<||                            |##################|       ||>|
-  // +--+----------------------------+------------------+-------+--+
-  //
-  //                                 |<- thumb_length ->|
-  //
-  // |<------- thumb_offset -------->|
-  //
-  // For painted, scrollbars, the length is fixed. For solid color scrollbars we
-  // have to compute it. The ratio of the thumb's length to the track's length
-  // is the same as that of the visible viewport to the total viewport, unless
-  // that would make the thumb's length less than its thickness.
-  //
-  // vertical_adjust_ is used when the layer geometry from the main thread is
-  // not in sync with what the user sees. For instance on Android scrolling the
-  // top bar controls out of view reveals more of the page content. We want the
-  // root layer scrollbars to reflect what the user sees even if we haven't
-  // received new layer geometry from the main thread.  If the user has scrolled
-  // down by 50px and the initial viewport size was 950px the geometry would
-  // look something like this:
-  //
-  // vertical_adjust_ = 50, scroll position 0, visible ratios 99%
-  // Layer geometry:             Desired thumb positions:
-  // +--------------------+-+   +----------------------+   <-- 0px
-  // |                    |v|   |                     #|
-  // |                    |e|   |                     #|
-  // |                    |r|   |                     #|
-  // |                    |t|   |                     #|
-  // |                    |i|   |                     #|
-  // |                    |c|   |                     #|
-  // |                    |a|   |                     #|
-  // |                    |l|   |                     #|
-  // |                    | |   |                     #|
-  // |                    |l|   |                     #|
-  // |                    |a|   |                     #|
-  // |                    |y|   |                     #|
-  // |                    |e|   |                     #|
-  // |                    |r|   |                     #|
-  // +--------------------+-+   |                     #|
-  // | horizontal  layer  | |   |                     #|
-  // +--------------------+-+   |                     #|  <-- 950px
-  // |                      |   |                     #|
-  // |                      |   |##################### |
-  // +----------------------+   +----------------------+  <-- 1000px
-  //
-  // The layer geometry is set up for a 950px tall viewport, but the user can
-  // actually see down to 1000px. Thus we have to move the quad for the
-  // horizontal scrollbar down by the vertical_adjust_ factor and lay the
-  // vertical thumb out on a track lengthed by the vertical_adjust_ factor. This
-  // means the quads may extend outside the layer's bounds.
-
-  int thumb_length = thumb_length_;
-  float track_length = track_length_;
-  if (orientation_ == VERTICAL)
-    track_length += vertical_adjust_;
-
-  if (layer_tree_impl()->settings().solid_color_scrollbars) {
-    thumb_length = std::max(
-        static_cast<int>(visible_to_total_length_ratio_ * track_length),
-        thumb_thickness_);
-  }
-
-  // With the length known, we can compute the thumb's position.
-  float clamped_current_pos =
-      std::min(std::max(current_pos_, 0.f), static_cast<float>(maximum_));
-  float ratio = clamped_current_pos / maximum_;
-  float max_offset = track_length - thumb_length;
-  int thumb_offset = static_cast<int>(ratio * max_offset) + track_start_;
-
-  gfx::RectF thumb_rect;
-  if (orientation_ == HORIZONTAL) {
-    thumb_rect = gfx::RectF(thumb_offset, vertical_adjust_,
-                            thumb_length, thumb_thickness_);
-  } else {
-    thumb_rect = gfx::RectF(0.f, thumb_offset,
-                            thumb_thickness_, thumb_length);
-  }
-
-  return ScrollbarLayerRectToContentRect(thumb_rect);
+float PaintedScrollbarLayerImpl::TrackLength() const {
+  return track_length_ + (orientation() == VERTICAL ? vertical_adjust() : 0);
 }
 
 const char* PaintedScrollbarLayerImpl::LayerTypeAsString() const {