cc/layers/viewport.cc

   1 // Copyright 2015 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/layers/viewport.h"
   6
   7 #include "base/logging.h"
   8 #include "cc/input/top_controls_manager.h"
   9 #include "cc/trees/layer_tree_host_impl.h"
  10 #include "cc/trees/layer_tree_impl.h"
  11 #include "ui/gfx/geometry/vector2d_conversions.h"
  12 #include "ui/gfx/geometry/vector2d_f.h"
  13
  14 namespace cc {
  15
  16 // static
  17 scoped_ptr<Viewport> Viewport::Create(
  18     LayerTreeHostImpl* host_impl) {
  19   return make_scoped_ptr(new Viewport(host_impl));
  20 }
  21
  22 Viewport::Viewport(LayerTreeHostImpl* host_impl)
  23     : host_impl_(host_impl)
  24     , pinch_zoom_active_(false) {
  25   DCHECK(host_impl_);
  26 }
  27
  28 void Viewport::Pan(const gfx::Vector2dF& delta) {
  29   gfx::Vector2dF pending_delta = delta;
  30   float page_scale = host_impl_->active_tree()->current_page_scale_factor();
  31   pending_delta.Scale(1 / page_scale);
  32   InnerScrollLayer()->ScrollBy(pending_delta);
  33 }
  34
  35 Viewport::ScrollResult Viewport::ScrollBy(const gfx::Vector2dF& delta,
  36                                           const gfx::Point& viewport_point,
  37                                           bool is_direct_manipulation,
  38                                           bool affect_top_controls) {
  39   gfx::Vector2dF content_delta = delta;
  40
  41   if (affect_top_controls && ShouldTopControlsConsumeScroll(delta))
  42     content_delta -= ScrollTopControls(delta);
  43
  44   gfx::Vector2dF pending_content_delta = content_delta;
  45
  46   bool invert_scroll_order =
  47       host_impl_->settings().invert_viewport_scroll_order;
  48   LayerImpl* primary_layer =
  49       invert_scroll_order ? InnerScrollLayer() : OuterScrollLayer();
  50   LayerImpl* secondary_layer =
  51       invert_scroll_order ? OuterScrollLayer() : InnerScrollLayer();
  52
  53   pending_content_delta -= host_impl_->ScrollLayer(primary_layer,
  54                                                    pending_content_delta,
  55                                                    viewport_point,
  56                                                    is_direct_manipulation);
  57
  58   ScrollResult result;
  59
  60   // TODO(bokan): This shouldn't be needed but removing it causes subtle
  61   // viewport movement during top controls manipulation.
  62   if (gfx::ToRoundedVector2d(pending_content_delta).IsZero()) {
  63     result.consumed_delta = delta;
  64   } else {
  65     pending_content_delta -= host_impl_->ScrollLayer(secondary_layer,
  66                                                      pending_content_delta,
  67                                                      viewport_point,
  68                                                      is_direct_manipulation);
  69     result.consumed_delta = delta - AdjustOverscroll(pending_content_delta);
  70   }
  71
  72   result.content_scrolled_delta = content_delta - pending_content_delta;
  73   return result;
  74 }
  75
  76 void Viewport::SnapPinchAnchorIfWithinMargin(const gfx::Point& anchor) {
  77   gfx::SizeF viewport_size =
  78       host_impl_->active_tree()->InnerViewportContainerLayer()->bounds();
  79
  80   if (anchor.x() < kPinchZoomSnapMarginDips)
  81     pinch_anchor_adjustment_.set_x(-anchor.x());
  82   else if (anchor.x() > viewport_size.width() - kPinchZoomSnapMarginDips)
  83     pinch_anchor_adjustment_.set_x(viewport_size.width() - anchor.x());
  84
  85   if (anchor.y() < kPinchZoomSnapMarginDips)
  86     pinch_anchor_adjustment_.set_y(-anchor.y());
  87   else if (anchor.y() > viewport_size.height() - kPinchZoomSnapMarginDips)
  88     pinch_anchor_adjustment_.set_y(viewport_size.height() - anchor.y());
  89 }
  90
  91 void Viewport::PinchUpdate(float magnify_delta, const gfx::Point& anchor) {
  92   if (!pinch_zoom_active_) {
  93     // If this is the first pinch update and the pinch is within a margin-
  94     // length of the screen edge, offset all updates by the amount so that we
  95     // effectively snap the pinch zoom to the edge of the screen. This makes it
  96     // easy to zoom in on position: fixed elements.
  97     if (host_impl_->settings().invert_viewport_scroll_order)
  98       SnapPinchAnchorIfWithinMargin(anchor);
  99
 100     pinch_zoom_active_ = true;
 101   }
 102
 103   LayerTreeImpl* active_tree = host_impl_->active_tree();
 104
 105   // Keep the center-of-pinch anchor specified by (x, y) in a stable
 106   // position over the course of the magnify.
 107   gfx::Point adjusted_anchor = anchor + pinch_anchor_adjustment_;
 108   float page_scale = active_tree->current_page_scale_factor();
 109   gfx::PointF previous_scale_anchor =
 110       gfx::ScalePoint(adjusted_anchor, 1.f / page_scale);
 111   active_tree->SetPageScaleOnActiveTree(page_scale * magnify_delta);
 112   page_scale = active_tree->current_page_scale_factor();
 113   gfx::PointF new_scale_anchor =
 114       gfx::ScalePoint(adjusted_anchor, 1.f / page_scale);
 115   gfx::Vector2dF move = previous_scale_anchor - new_scale_anchor;
 116
 117   // Scale back to viewport space since that's the coordinate space ScrollBy
 118   // uses.
 119   move.Scale(page_scale);
 120
 121   // If clamping the inner viewport scroll offset causes a change, it should
 122   // be accounted for from the intended move.
 123   move -= InnerScrollLayer()->ClampScrollToMaxScrollOffset();
 124
 125   if (host_impl_->settings().invert_viewport_scroll_order) {
 126     Pan(move);
 127   } else {
 128     gfx::Point viewport_point;
 129     bool is_wheel_event = false;
 130     bool affect_top_controls = false;
 131     ScrollBy(move, viewport_point, is_wheel_event, affect_top_controls);
 132   }
 133 }
 134
 135 void Viewport::PinchEnd() {
 136   pinch_anchor_adjustment_ = gfx::Vector2d();
 137   pinch_zoom_active_ = false;
 138 }
 139
 140 gfx::Vector2dF Viewport::ScrollTopControls(const gfx::Vector2dF& delta) {
 141   gfx::Vector2dF excess_delta =
 142       host_impl_->top_controls_manager()->ScrollBy(delta);
 143
 144   return delta - excess_delta;
 145 }
 146
 147 bool Viewport::ShouldTopControlsConsumeScroll(
 148     const gfx::Vector2dF& scroll_delta) const {
 149   // Always consume if it's in the direction to show the top controls.
 150   if (scroll_delta.y() < 0)
 151     return true;
 152
 153   if (TotalScrollOffset().y() < MaxTotalScrollOffset().y())
 154     return true;
 155
 156   return false;
 157 }
 158
 159 gfx::Vector2dF Viewport::AdjustOverscroll(const gfx::Vector2dF& delta) const {
 160   // TODO(tdresser): Use a more rational epsilon. See crbug.com/510550 for
 161   // details.
 162   const float kEpsilon = 0.1f;
 163   gfx::Vector2dF adjusted = delta;
 164
 165   if (std::abs(adjusted.x()) < kEpsilon)
 166     adjusted.set_x(0.0f);
 167   if (std::abs(adjusted.y()) < kEpsilon)
 168     adjusted.set_y(0.0f);
 169
 170   return adjusted;
 171 }
 172
 173 gfx::ScrollOffset Viewport::MaxTotalScrollOffset() const {
 174   gfx::ScrollOffset offset;
 175
 176   offset += InnerScrollLayer()->MaxScrollOffset();
 177
 178   if (OuterScrollLayer())
 179     offset += OuterScrollLayer()->MaxScrollOffset();
 180
 181   return offset;
 182 }
 183
 184 gfx::ScrollOffset Viewport::TotalScrollOffset() const {
 185   gfx::ScrollOffset offset;
 186
 187   offset += InnerScrollLayer()->CurrentScrollOffset();
 188
 189   if (OuterScrollLayer())
 190     offset += OuterScrollLayer()->CurrentScrollOffset();
 191
 192   return offset;
 193 }
 194
 195 LayerImpl* Viewport::InnerScrollLayer() const {
 196   return host_impl_->InnerViewportScrollLayer();
 197 }
 198
 199 LayerImpl* Viewport::OuterScrollLayer() const {
 200   return host_impl_->OuterViewportScrollLayer();
 201 }
 202
 203 }  // namespace cc