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