Implement pinch-zoom scaling for main-frame scrollbars and pinch-zoom overlay scrollbars.

cc/pinch_zoom_scrollbar_layer_impl.cc

Index: cc/pinch_zoom_scrollbar_layer_impl.cc
diff --git a/cc/pinch_zoom_scrollbar_layer_impl.cc b/cc/pinch_zoom_scrollbar_layer_impl.cc
new file mode 100644
index 0000000000000000000000000000000000000000..dc592911e3f28884cc3d66c75e960432705cb950
--- /dev/null
+++ b/cc/pinch_zoom_scrollbar_layer_impl.cc
@@ -0,0 +1,248 @@
+// Copyright 2013 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/pinch_zoom_scrollbar_layer_impl.h"
+
+#include "cc/layer_tree_host_impl.h"
+#include "cc/layer_tree_impl.h"
+#include "cc/quad_sink.h"
+#include "cc/renderer.h"
+#include "cc/texture_draw_quad.h"
+#include "skia/ext/platform_canvas.h"
+#include "ui/gfx/rect.h"
+#include "ui/gfx/rect_conversions.h"
+
+namespace cc {
+
+PinchZoomScrollbarState::PinchZoomScrollbarState(
+    WebKit::WebScrollbar::Orientation orientation, PinchZoomViewport* owner)
+    : owner_(owner),
+      orientation_(orientation) {
+  DCHECK(owner_);
+}
+
+PinchZoomScrollbarState::~PinchZoomScrollbarState() {}
+
+gfx::SizeF PinchZoomScrollbarState::layout_viewport_size() const {
+  return owner_->layout_viewport_size();
+}
+
+gfx::Vector2dF PinchZoomScrollbarState::zoomed_viewport_offset() const {
+  return owner_->zoomed_viewport_offset();
+}
+
+float PinchZoomScrollbarState::total_page_scale_factor() const {
+  return owner_->total_page_scale_factor();
+}
+
+float PinchZoomScrollbarState::device_scale_factor() const {
+  return owner_->device_scale_factor();
+}
+
+LayerImpl* PinchZoomScrollbarState::root_scroll_layer() {
+  return owner_->root_scroll_layer();
+}
+
+void PinchZoomScrollbarState::RefreshSizeAndPosition(LayerImpl* layer_impl)
+{
+    gfx::SizeF size = owner_->layout_viewport_size();
+    if (orientation_ == WebKit::WebScrollbar::Vertical) {
+        gfx::Size bounds = gfx::Size(kTrackWidth, size.height());
+        layer_impl->setContentBounds(bounds);
+        layer_impl->setBounds(bounds);
+        layer_impl->setPosition(gfx::Point(size.width() - kTrackWidth, 0));
+    } else {
+        gfx::Size bounds = gfx::Size(size.width(), kTrackWidth);
+        layer_impl->setContentBounds(bounds);
+        layer_impl->setBounds(bounds);
+        layer_impl->setPosition(gfx::Point(0, size.height() - kTrackWidth));
+    }
+}
+
+bool PinchZoomScrollbarState::ShouldDisplayPinchZoomScrollbars() {
+  return owner_->total_page_scale_factor() > 1 && owner_->currently_scrolling_layer();
+}
+
+scoped_ptr<PinchZoomScrollbarLayerImpl> PinchZoomScrollbarLayerImpl::create(
+    LayerTreeImpl* treeImpl,
+    int id,
+    PinchZoomScrollbarState* state) {
+  return make_scoped_ptr(new PinchZoomScrollbarLayerImpl(treeImpl, id, state));
+}
+
+PinchZoomScrollbarLayerImpl::PinchZoomScrollbarLayerImpl(
+    LayerTreeImpl* treeImpl,
+    int id, PinchZoomScrollbarState* state)
+    : ScrollbarLayerImplBase(treeImpl, id),
+      state_(state) {
+  DCHECK(state_);
+  std::string debugName = "Layer for Pinch Zoom Scrollbar ";
+  debugName += ((state_->orientation() == WebKit::WebScrollbar::Vertical) ?
+                "(vertical)" : "(horizontal)");
+  setDebugName(debugName);
+
+  state_->RefreshSizeAndPosition(this);
+}
+
+PinchZoomScrollbarLayerImpl::~PinchZoomScrollbarLayerImpl() {}
+
+float PinchZoomScrollbarLayerImpl::currentPos() const {
+    return state_->thumb_position();
+}
+
+int PinchZoomScrollbarLayerImpl::totalSize() const {
+    return state_->track_length();
+}
+
+int PinchZoomScrollbarLayerImpl::maximum() const {
+    return state_->maximum_position();
+}
+
+WebKit::WebScrollbar::Orientation PinchZoomScrollbarLayerImpl::orientation()
+    const {
+  return state_->orientation();
+}
+
+void PinchZoomScrollbarLayerImpl::appendQuads(
+    QuadSink& quad_sink, AppendQuadsData& append_quads_data) {
+  if (!state_->ShouldDisplayPinchZoomScrollbars())
+    return;
+
+  if (state_->thumb_rect().IsEmpty() || !state_->thumb_texture()->id())
+    return;
+
+  bool premultipled_alpha = false;
+  bool flipped = false;
+  gfx::RectF uv_rect(0, 0, 1, 1);
+
+  SharedQuadState* shared_quad_state =
+      quad_sink.useSharedQuadState(createSharedQuadState());
+  appendDebugBorderQuad(quad_sink, shared_quad_state, append_quads_data);
+
+  gfx::Rect quad_rect(gfx::ToEnclosingRect(
+      gfx::ScaleRect(state_->thumb_rect(),
+                     contentsScaleX(), contentsScaleY())));
+
+  gfx::Rect opaque_rect;
+  const float opacity[] = {1.0f, 1.0f, 1.0f, 1.0f};
+  scoped_ptr<TextureDrawQuad> quad = TextureDrawQuad::Create();
+  quad->SetNew(shared_quad_state, quad_rect, opaque_rect,
+               state_->thumb_texture()->id(),
+               premultipled_alpha, uv_rect, opacity, flipped);
+  quad_sink.append(quad.PassAs<DrawQuad>(), append_quads_data);
+}
+
+void PinchZoomScrollbarLayerImpl::willDraw(
+    ResourceProvider* resource_provider) {
+  LayerImpl::willDraw(resource_provider);
+
+  if (!state_->ShouldDisplayPinchZoomScrollbars())
+    return;
+
+  gfx::Size layout_document_size(layerTreeImpl()->ContentSize());
+
+  gfx::SizeF layout_viewport_size = state_->layout_viewport_size();
+  gfx::Vector2dF layout_viewport_position = state_->zoomed_viewport_offset();
+  float page_scale_factor = state_->total_page_scale_factor();
+  float device_scale_factor = state_->device_scale_factor();
+
+  DCHECK(!layout_document_size.IsEmpty());
+
+  gfx::Vector2d root_scroll_offset;
+  gfx::Vector2d root_max_scroll_offset;
+  LayerImpl* root_scroll_layer = state_->root_scroll_layer();
+  if (root_scroll_layer) {
+    root_scroll_offset = root_scroll_layer->scrollOffset();
+    root_max_scroll_offset = root_scroll_layer->maxScrollOffset();
+  }
+
+  gfx::Rect new_thumb_rect;
+  int& track_length = state_->track_length();
+  float& thumb_position = state_->thumb_position();
+  int& maximum_position = state_->maximum_position();
+  int track_width = state_->track_width();
+
+  int thumb_length;
+  if (state_->orientation() == WebKit::WebScrollbar::Vertical) {
+    track_length = layout_viewport_size.height() - track_width;
+    thumb_length = layout_viewport_size.height() /
+      layout_document_size.height() * device_scale_factor * track_length;
+    maximum_position = state_->track_length() - thumb_length;
+
+    float max_offset = root_max_scroll_offset.y() + (page_scale_factor - 1)
+                      / page_scale_factor * layout_viewport_size.height();
+    float offset = (max_offset >= 1) ? root_scroll_offset.y() +
+                   layout_viewport_position.y() : 0;
+    thumb_position = offset / max_offset * maximum_position;
+
+    // Thumb rect position is with respect to the layer, so the x-coordinate
+    // should be 0.
+    new_thumb_rect = gfx::Rect(0, thumb_position, track_width, thumb_length);
+  } else {
+    track_length = layout_viewport_size.width() - track_width;
+    thumb_length = layout_viewport_size.width() / layout_document_size.width() *
+      device_scale_factor * track_length;
+    maximum_position = track_length - thumb_length;
+
+    float max_offset = root_max_scroll_offset.x() + (page_scale_factor - 1)
+                      / page_scale_factor * layout_viewport_size.width();
+    float offset = (max_offset >= 1) ? root_scroll_offset.x() +
+      layout_viewport_position.x() : 0;
+    thumb_position = offset / max_offset * maximum_position;
+
+    // Thumb rect position is with respect to the layer, so the y-coordinate
+    // should be 0.
+    new_thumb_rect = gfx::Rect(thumb_position, 0, thumb_length, track_width);
+  }
+
+  gfx::Rect& thumb_rect = state_->thumb_rect();
+  scoped_ptr<ScopedResource>& thumb_texture = state_->thumb_texture();
+
+  bool thumb_size_not_changed = thumb_rect.size() == new_thumb_rect.size();
+  thumb_rect = new_thumb_rect;
+  if (thumb_size_not_changed && thumb_texture)
+    return;
+
+  // Does texture exist, if not, create it.
+  if (!thumb_texture)
+    thumb_texture = ScopedResource::create(resource_provider);
+
+  if (thumb_texture->size() != thumb_rect.size())
+    thumb_texture->Free();
+
+  if (!thumb_texture->id())
+    thumb_texture->Allocate(thumb_rect.size(), GL_RGBA,
+                            ResourceProvider::TextureUsageAny);
+
+  // Paint canvas and upload to texture.
+  scoped_ptr<SkCanvas> canvas = make_scoped_ptr(
+    skia::CreateBitmapCanvas(thumb_rect.width(), thumb_rect.height(),
+                             false /* opaque */));
+  canvas->clear(SkColorSetARGB(0, 0, 0, 0));
+  SkPaint paint;
+  // Below 255 refers to blue, not red, but we do this to avoid an
+  // explicit swizzle.
+  paint.setColor(SkColorSetARGB(128, 255, 0, 0));
+  SkScalar border = device_scale_factor;
+  SkScalar corner_radius = device_scale_factor * (track_width / 3);
+  DCHECK(corner_radius);
+  SkRect rect = SkRect::MakeXYWH(border, border,
+                                 thumb_rect.width() - 2 * border,
+                                 thumb_rect.height() - 2 * border);
+  canvas->drawRoundRect(rect, corner_radius, corner_radius, paint);
+
+  const SkBitmap* bitmap = &canvas->getDevice()->accessBitmap(false);
+  SkAutoLockPixels locker(*bitmap);
+  gfx::Rect layer_rect(gfx::Point(), thumb_rect.size());
+  DCHECK(bitmap->config() == SkBitmap::kARGB_8888_Config);
+  resource_provider->setPixels(thumb_texture->id(), static_cast<const uint8_t*>(
+                               bitmap->getPixels()), layer_rect, layer_rect,
+                               gfx::Vector2d());
+}
+
+void PinchZoomScrollbarLayerImpl::didLoseOutputSurface() {
+  state_->thumb_texture().reset(0);;
+}
+
+} // namespace cc