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   SetPaintToLayer(true);
  18   SetFillsBoundsOpaquely(false);
  19 }
  20
  21 SlideOutView::~SlideOutView() {
  22 }
  23
  24 void SlideOutView::OnGestureEvent(ui::GestureEvent* event) {
  25   if (event->type() == ui::ET_SCROLL_FLING_START) {
  26     // The threshold for the fling velocity is computed empirically.
  27     // The unit is in pixels/second.
  28     const float kFlingThresholdForClose = 800.f;
  29     if (fabsf(event->details().velocity_x()) > kFlingThresholdForClose) {
  30       SlideOutAndClose(event->details().velocity_x() < 0 ? SLIDE_LEFT :
  31                        SLIDE_RIGHT);
  32       event->StopPropagation();
  33       return;
  34     }
  35     RestoreVisualState();
  36     return;
  37   }
  38
  39   if (!event->IsScrollGestureEvent())
  40     return;
  41
  42   if (event->type() == ui::ET_GESTURE_SCROLL_BEGIN) {
  43     gesture_scroll_amount_ = 0.f;
  44   } else if (event->type() == ui::ET_GESTURE_SCROLL_UPDATE) {
  45     // The scroll-update events include the incremental scroll amount.
  46     gesture_scroll_amount_ += event->details().scroll_x();
  47
  48     gfx::Transform transform;
  49     transform.Translate(gesture_scroll_amount_, 0.0);
  50     layer()->SetTransform(transform);
  51     layer()->SetOpacity(
  52         1.f - std::min(fabsf(gesture_scroll_amount_) / width(), 1.f));
  53
  54   } else if (event->type() == ui::ET_GESTURE_SCROLL_END) {
  55     const float kScrollRatioForClosingNotification = 0.5f;
  56     float scrolled_ratio = fabsf(gesture_scroll_amount_) / width();
  57     if (scrolled_ratio >= kScrollRatioForClosingNotification) {
  58       SlideOutAndClose(gesture_scroll_amount_ < 0 ? SLIDE_LEFT : SLIDE_RIGHT);
  59       event->StopPropagation();
  60       return;
  61     }
  62     RestoreVisualState();
  63   }
  64
  65   event->SetHandled();
  66 }
  67
  68 void SlideOutView::RestoreVisualState() {
  69   // Restore the layer state.
  70   const int kSwipeRestoreDurationMS = 150;
  71   ui::ScopedLayerAnimationSettings settings(layer()->GetAnimator());
  72   settings.SetTransitionDuration(
  73       base::TimeDelta::FromMilliseconds(kSwipeRestoreDurationMS));
  74   layer()->SetTransform(gfx::Transform());
  75   layer()->SetOpacity(1.f);
  76 }
  77
  78 void SlideOutView::SlideOutAndClose(SlideDirection direction) {
  79   const int kSwipeOutTotalDurationMS = 150;
  80   int swipe_out_duration = kSwipeOutTotalDurationMS * layer()->opacity();
  81   ui::ScopedLayerAnimationSettings settings(layer()->GetAnimator());
  82   settings.SetTransitionDuration(
  83       base::TimeDelta::FromMilliseconds(swipe_out_duration));
  84   settings.AddObserver(this);
  85
  86   gfx::Transform transform;
  87   transform.Translate(direction == SLIDE_LEFT ? -width() : width(), 0.0);
  88   layer()->SetTransform(transform);
  89   layer()->SetOpacity(0.f);
  90 }
  91
  92 void SlideOutView::OnImplicitAnimationsCompleted() {
  93   OnSlideOut();
  94 }
  95
  96 }  // namespace views