cc/input/scroll_elasticity_helper.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/input/scroll_elasticity_helper.h"
   6
   7 #include "cc/layers/layer_impl.h"
   8 #include "cc/trees/layer_tree_host_impl.h"
   9 #include "cc/trees/layer_tree_impl.h"
  10
  11 namespace cc {
  12
  13 class ScrollElasticityHelperImpl : public ScrollElasticityHelper {
  14  public:
  15   explicit ScrollElasticityHelperImpl(LayerTreeHostImpl* layer_tree_host_impl);
  16   ~ScrollElasticityHelperImpl() override;
  17
  18   bool IsUserScrollable() const override;
  19   gfx::Vector2dF StretchAmount() const override;
  20   void SetStretchAmount(const gfx::Vector2dF& stretch_amount) override;
  21   gfx::ScrollOffset ScrollOffset() const override;
  22   gfx::ScrollOffset MaxScrollOffset() const override;
  23   void ScrollBy(const gfx::Vector2dF& delta) override;
  24   void RequestAnimate() override;
  25
  26  private:
  27   LayerTreeHostImpl* layer_tree_host_impl_;
  28 };
  29
  30 ScrollElasticityHelperImpl::ScrollElasticityHelperImpl(
  31     LayerTreeHostImpl* layer_tree)
  32     : layer_tree_host_impl_(layer_tree) {
  33 }
  34
  35 ScrollElasticityHelperImpl::~ScrollElasticityHelperImpl() {
  36 }
  37
  38 bool ScrollElasticityHelperImpl::IsUserScrollable() const {
  39   LayerImpl* layer = layer_tree_host_impl_->OuterViewportScrollLayer();
  40   if (!layer)
  41     return false;
  42   return layer->user_scrollable_horizontal() ||
  43          layer->user_scrollable_vertical();
  44 }
  45
  46 gfx::Vector2dF ScrollElasticityHelperImpl::StretchAmount() const {
  47   return layer_tree_host_impl_->active_tree()->elastic_overscroll()->Current(
  48       true);
  49 }
  50
  51 void ScrollElasticityHelperImpl::SetStretchAmount(
  52     const gfx::Vector2dF& stretch_amount) {
  53   if (stretch_amount == StretchAmount())
  54     return;
  55
  56   layer_tree_host_impl_->active_tree()->elastic_overscroll()->SetCurrent(
  57       stretch_amount);
  58   layer_tree_host_impl_->active_tree()->set_needs_update_draw_properties();
  59   layer_tree_host_impl_->SetNeedsCommit();
  60   layer_tree_host_impl_->SetNeedsRedraw();
  61   layer_tree_host_impl_->SetFullRootLayerDamage();
  62 }
  63
  64 gfx::ScrollOffset ScrollElasticityHelperImpl::ScrollOffset() const {
  65   return layer_tree_host_impl_->active_tree()->TotalScrollOffset();
  66 }
  67
  68 gfx::ScrollOffset ScrollElasticityHelperImpl::MaxScrollOffset() const {
  69   return layer_tree_host_impl_->active_tree()->TotalMaxScrollOffset();
  70 }
  71
  72 void ScrollElasticityHelperImpl::ScrollBy(const gfx::Vector2dF& delta) {
  73   LayerImpl* root_scroll_layer =
  74       layer_tree_host_impl_->OuterViewportScrollLayer()
  75           ? layer_tree_host_impl_->OuterViewportScrollLayer()
  76           : layer_tree_host_impl_->InnerViewportScrollLayer();
  77   if (root_scroll_layer)
  78     root_scroll_layer->ScrollBy(delta);
  79 }
  80
  81 void ScrollElasticityHelperImpl::RequestAnimate() {
  82   layer_tree_host_impl_->SetNeedsAnimate();
  83 }
  84
  85 // static
  86 ScrollElasticityHelper* ScrollElasticityHelper::CreateForLayerTreeHostImpl(
  87     LayerTreeHostImpl* layer_tree_host_impl) {
  88   return new ScrollElasticityHelperImpl(layer_tree_host_impl);
  89 }
  90
  91 }  // namespace cc