Use nine-patch resource for drawing Aura overlay scrollbar thumb.

cc/layers/painted_overlay_scrollbar_layer_impl.cc

+// Copyright 2016 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/layers/painted_overlay_scrollbar_layer_impl.h"
+
+#include <algorithm>
+
+#include "base/memory/ptr_util.h"
+#include "cc/input/scrollbar_animation_controller.h"
+#include "cc/layers/layer.h"
+#include "cc/quads/solid_color_draw_quad.h"
+#include "cc/quads/texture_draw_quad.h"
+#include "cc/trees/layer_tree_impl.h"
+#include "cc/trees/layer_tree_settings.h"
+#include "cc/trees/occlusion.h"
+#include "ui/gfx/geometry/rect_conversions.h"
+
+namespace cc {
+
+std::unique_ptr<PaintedOverlayScrollbarLayerImpl>
+PaintedOverlayScrollbarLayerImpl::Create(LayerTreeImpl* tree_impl,
+                                         int id,
+                                         ScrollbarOrientation orientation,
+                                         bool is_left_side_vertical_scrollbar) {
+  return base::WrapUnique(new PaintedOverlayScrollbarLayerImpl(
+      tree_impl, id, orientation, is_left_side_vertical_scrollbar));
+}
+
+PaintedOverlayScrollbarLayerImpl::PaintedOverlayScrollbarLayerImpl(
+    LayerTreeImpl* tree_impl,
+    int id,
+    ScrollbarOrientation orientation,
+    bool is_left_side_vertical_scrollbar)
+    : ScrollbarLayerImplBase(tree_impl,
+                             id,
+                             orientation,
+                             is_left_side_vertical_scrollbar,
+                             true),
+      thumb_ui_resource_id_(0),
+      thumb_thickness_(0),
+      thumb_length_(0),
+      track_start_(0),
+      track_length_(0) {}
+
+PaintedOverlayScrollbarLayerImpl::~PaintedOverlayScrollbarLayerImpl() {}
+
+std::unique_ptr<LayerImpl> PaintedOverlayScrollbarLayerImpl::CreateLayerImpl(
+    LayerTreeImpl* tree_impl) {
+  return PaintedOverlayScrollbarLayerImpl::Create(
+      tree_impl, id(), orientation(), is_left_side_vertical_scrollbar());
+}
+
+void PaintedOverlayScrollbarLayerImpl::PushPropertiesTo(LayerImpl* layer) {
+  ScrollbarLayerImplBase::PushPropertiesTo(layer);
+
+  PaintedOverlayScrollbarLayerImpl* scrollbar_layer =
+      static_cast<PaintedOverlayScrollbarLayerImpl*>(layer);
+
+  scrollbar_layer->SetThumbThickness(thumb_thickness_);
+  scrollbar_layer->SetThumbLength(thumb_length_);
+  scrollbar_layer->SetTrackStart(track_start_);
+  scrollbar_layer->SetTrackLength(track_length_);
+
+  scrollbar_layer->SetImageBounds(image_bounds_);
+  scrollbar_layer->SetAperture(aperture_);
+
+  scrollbar_layer->set_thumb_ui_resource_id(thumb_ui_resource_id_);
+}
+
+bool PaintedOverlayScrollbarLayerImpl::WillDraw(
+    DrawMode draw_mode,
+    ResourceProvider* resource_provider) {
+  DCHECK(draw_mode != DRAW_MODE_RESOURCELESS_SOFTWARE);
+  return LayerImpl::WillDraw(draw_mode, resource_provider);
+}
+
+void PaintedOverlayScrollbarLayerImpl::AppendQuads(

[aelias_OOO_until_Jul13, 2017/02/28 23:23:51]

There's still a bit of code duplication here with NinePatchLayerImpl, is there
some way of sharing code for some of this method too?

[bokan, 2017/03/01 00:44:21]

Ok, I've moved as much as I could into NinePatchGenerator::AppendQuads. WDYT?

+    RenderPass* render_pass,
+    AppendQuadsData* append_quads_data) {
+  // For overlay scrollbars, the border should match the inset of the aperture
+  // and be symmetrical.
+  gfx::Rect border(aperture_.x(), aperture_.y(), aperture_.x() * 2,
+                   aperture_.y() * 2);
+  gfx::Rect thumb_quad_rect(ComputeThumbQuadRect());
+  gfx::Rect layer_occlusion;
+  bool fill_center = true;
+  bool nearest_neighbor = false;
+
+  quad_generator_.SetLayout(image_bounds_, thumb_quad_rect.size(), aperture_,
+                            border, layer_occlusion, fill_center);
+
+  SharedQuadState* shared_quad_state =
+      render_pass->CreateAndAppendSharedQuadState();
+  PopulateSharedQuadState(shared_quad_state);
+
+  AppendDebugBorderQuad(render_pass, bounds(), shared_quad_state,
+                        append_quads_data);
+
+  if (!thumb_ui_resource_id_)
+    return;
+
+  ResourceId resource =
+      layer_tree_impl()->ResourceIdForUIResource(thumb_ui_resource_id_);
+
+  if (!resource)
+    return;
+
+  std::vector<NinePatchGenerator::Patch> patches =
+      quad_generator_.GeneratePatches();
+
+  const float vertex_opacity[] = {1.0f, 1.0f, 1.0f, 1.0f};
+  const bool opaque =
+      layer_tree_impl()->IsUIResourceOpaque(thumb_ui_resource_id_);
+  static const bool flipped = false;
+  static const bool premultiplied_alpha = true;
+
+  gfx::Vector2dF offset = thumb_quad_rect.OffsetFromOrigin();
+
+  for (const auto& patch : patches) {
+    gfx::Rect output_rect = gfx::ToEnclosingRect(patch.output_rect + offset);
+    gfx::Rect visible_rect =
+        draw_properties().occlusion_in_content_space.GetUnoccludedContentRect(
+            output_rect);
+    gfx::Rect opaque_rect = opaque ? visible_rect : gfx::Rect();
+    if (!visible_rect.IsEmpty()) {
+      gfx::RectF image_rect = patch.normalized_image_rect;
+      TextureDrawQuad* quad =
+          render_pass->CreateAndAppendDrawQuad<TextureDrawQuad>();
+      quad->SetNew(shared_quad_state, output_rect, opaque_rect, visible_rect,
+                   resource, premultiplied_alpha, image_rect.origin(),
+                   image_rect.bottom_right(), SK_ColorTRANSPARENT,
+                   vertex_opacity, flipped, nearest_neighbor, false);
+      ValidateQuadResources(quad);
+    }
+  }
+}
+
+void PaintedOverlayScrollbarLayerImpl::SetThumbThickness(int thumb_thickness) {
+  if (thumb_thickness_ == thumb_thickness)
+    return;
+  thumb_thickness_ = thumb_thickness;
+  NoteLayerPropertyChanged();
+}
+
+int PaintedOverlayScrollbarLayerImpl::ThumbThickness() const {
+  return thumb_thickness_;
+}
+
+void PaintedOverlayScrollbarLayerImpl::SetThumbLength(int thumb_length) {
+  if (thumb_length_ == thumb_length)
+    return;
+  thumb_length_ = thumb_length;
+  NoteLayerPropertyChanged();
+}
+
+int PaintedOverlayScrollbarLayerImpl::ThumbLength() const {
+  return thumb_length_;
+}
+
+void PaintedOverlayScrollbarLayerImpl::SetTrackStart(int track_start) {
+  if (track_start_ == track_start)
+    return;
+  track_start_ = track_start;
+  NoteLayerPropertyChanged();
+}
+
+int PaintedOverlayScrollbarLayerImpl::TrackStart() const {
+  return track_start_;
+}
+
+void PaintedOverlayScrollbarLayerImpl::SetTrackLength(int track_length) {
+  if (track_length_ == track_length)
+    return;
+  track_length_ = track_length;
+  NoteLayerPropertyChanged();
+}
+
+void PaintedOverlayScrollbarLayerImpl::SetImageBounds(const gfx::Size& bounds) {
+  if (image_bounds_ == bounds)
+    return;
+  image_bounds_ = bounds;
+  NoteLayerPropertyChanged();
+}
+
+void PaintedOverlayScrollbarLayerImpl::SetAperture(const gfx::Rect& aperture) {
+  if (aperture_ == aperture)
+    return;
+  aperture_ = aperture;
+  NoteLayerPropertyChanged();
+}
+
+float PaintedOverlayScrollbarLayerImpl::TrackLength() const {
+  return track_length_ + (orientation() == VERTICAL ? vertical_adjust() : 0);
+}
+
+bool PaintedOverlayScrollbarLayerImpl::IsThumbResizable() const {
+  return false;
+}
+
+const char* PaintedOverlayScrollbarLayerImpl::LayerTypeAsString() const {
+  return "cc::PaintedOverlayScrollbarLayerImpl";
+}
+
+}  // namespace cc