src/ui/views/controls/slide_out_view.cc

   1 // Copyright (c) 2012 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 "ui/views/controls/slide_out_view.h"
   6
   7 #include "ui/compositor/layer.h"
   8 #include "ui/compositor/scoped_layer_animation_settings.h"
   9 #include "ui/gfx/transform.h"
  10
  11 namespace views {
  12
  13 SlideOutView::SlideOutView()
  14     : gesture_scroll_amount_(0.f) {
  15   // If accelerated compositing is not available, this widget tracks the
  16   // OnSlideOut event but does not render any visible changes.
  17   if (get_use_acceleration_when_possible()) {
  18     SetPaintToLayer(true);
  19     SetFillsBoundsOpaquely(false);
  20   }
  21 }
  22
  23 SlideOutView::~SlideOutView() {
  24 }
  25
  26 void SlideOutView::OnGestureEvent(ui::GestureEvent* event) {
  27   if (event->type() == ui::ET_SCROLL_FLING_START) {
  28     // The threshold for the fling velocity is computed empirically.
  29     // The unit is in pixels/second.
  30     const float kFlingThresholdForClose = 800.f;
  31     if (fabsf(event->details().velocity_x()) > kFlingThresholdForClose) {
  32       SlideOutAndClose(event->details().velocity_x() < 0 ? SLIDE_LEFT :
  33                        SLIDE_RIGHT);
  34       event->StopPropagation();
  35       return;
  36     }
  37     RestoreVisualState();
  38     return;
  39   }
  40
  41   if (!event->IsScrollGestureEvent())
  42     return;
  43
  44   if (event->type() == ui::ET_GESTURE_SCROLL_BEGIN) {
  45     gesture_scroll_amount_ = 0.f;
  46   } else if (event->type() == ui::ET_GESTURE_SCROLL_UPDATE) {
  47     // The scroll-update events include the incremental scroll amount.
  48     gesture_scroll_amount_ += event->details().scroll_x();
  49
  50     if (get_use_acceleration_when_possible()) {
  51       gfx::Transform transform;
  52       transform.Translate(gesture_scroll_amount_, 0.0);
  53       layer()->SetTransform(transform);
  54       layer()->SetOpacity(
  55           1.f - std::min(fabsf(gesture_scroll_amount_) / width(), 1.f));
  56     }
  57
  58   } else if (event->type() == ui::ET_GESTURE_SCROLL_END) {
  59     const float kScrollRatioForClosingNotification = 0.5f;
  60     float scrolled_ratio = fabsf(gesture_scroll_amount_) / width();
  61     if (scrolled_ratio >= kScrollRatioForClosingNotification) {
  62       SlideOutAndClose(gesture_scroll_amount_ < 0 ? SLIDE_LEFT : SLIDE_RIGHT);
  63       event->StopPropagation();
  64       return;
  65     }
  66     RestoreVisualState();
  67   }
  68
  69   event->SetHandled();
  70 }
  71
  72 void SlideOutView::RestoreVisualState() {
  73   if (!get_use_acceleration_when_possible())
  74     return;
  75
  76   // Restore the layer state.
  77   const int kSwipeRestoreDurationMS = 150;
  78   ui::ScopedLayerAnimationSettings settings(layer()->GetAnimator());
  79   settings.SetTransitionDuration(
  80       base::TimeDelta::FromMilliseconds(kSwipeRestoreDurationMS));
  81   layer()->SetTransform(gfx::Transform());
  82   layer()->SetOpacity(1.f);
  83 }
  84
  85 void SlideOutView::SlideOutAndClose(SlideDirection direction) {
  86   if (!get_use_acceleration_when_possible()) {
  87     // No animations, so don't wait to fire the OnSlideOut event.
  88     OnSlideOut();
  89     return;
  90   }
  91   const int kSwipeOutTotalDurationMS = 150;
  92   int swipe_out_duration = kSwipeOutTotalDurationMS * layer()->opacity();
  93   ui::ScopedLayerAnimationSettings settings(layer()->GetAnimator());
  94   settings.SetTransitionDuration(
  95       base::TimeDelta::FromMilliseconds(swipe_out_duration));
  96   settings.AddObserver(this);
  97
  98   gfx::Transform transform;
  99   transform.Translate(direction == SLIDE_LEFT ? -width() : width(), 0.0);
 100   layer()->SetTransform(transform);
 101   layer()->SetOpacity(0.f);
 102 }
 103
 104 void SlideOutView::OnImplicitAnimationsCompleted() {
 105   OnSlideOut();
 106 }
 107
 108 }  // namespace views