ui/views/controls/scrollbar/overlay_scroll_bar.cc

   1 // Copyright 2013 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/scrollbar/overlay_scroll_bar.h"
   6
   7 #include "third_party/skia/include/core/SkColor.h"
   8 #include "third_party/skia/include/core/SkXfermode.h"
   9 #include "ui/gfx/canvas.h"
  10 #include "ui/views/background.h"
  11 #include "ui/views/border.h"
  12 #include "ui/views/controls/scrollbar/base_scroll_bar_thumb.h"
  13
  14 namespace views {
  15 namespace {
  16
  17 const int kScrollbarWidth = 10;
  18 const int kThumbInsetInside = 3;
  19 const int kThumbInsetFromEdge = 1;
  20 const int kThumbCornerRadius = 2;
  21 const int kThumbMinimumSize = kScrollbarWidth;
  22 const int kThumbHoverAlpha = 128;
  23 const int kThumbDefaultAlpha = 64;
  24
  25 class OverlayScrollBarThumb : public BaseScrollBarThumb,
  26                               public gfx::AnimationDelegate {
  27  public:
  28   explicit OverlayScrollBarThumb(BaseScrollBar* scroll_bar);
  29   ~OverlayScrollBarThumb() override;
  30
  31  protected:
  32   // View overrides:
  33   gfx::Size GetPreferredSize() const override;
  34   void OnPaint(gfx::Canvas* canvas) override;
  35
  36   // gfx::AnimationDelegate overrides:
  37   void AnimationProgressed(const gfx::Animation* animation) override;
  38
  39  private:
  40   double animation_opacity_;
  41   DISALLOW_COPY_AND_ASSIGN(OverlayScrollBarThumb);
  42 };
  43
  44 OverlayScrollBarThumb::OverlayScrollBarThumb(BaseScrollBar* scroll_bar)
  45     : BaseScrollBarThumb(scroll_bar),
  46       animation_opacity_(0.0) {
  47   // This is necessary, otherwise the thumb will be rendered below the views if
  48   // those views paint to their own layers.
  49   SetPaintToLayer(true);
  50   SetFillsBoundsOpaquely(false);
  51 }
  52
  53 OverlayScrollBarThumb::~OverlayScrollBarThumb() {
  54 }
  55
  56 gfx::Size OverlayScrollBarThumb::GetPreferredSize() const {
  57   return gfx::Size(kThumbMinimumSize, kThumbMinimumSize);
  58 }
  59
  60 void OverlayScrollBarThumb::OnPaint(gfx::Canvas* canvas) {
  61   gfx::Rect local_bounds(GetLocalBounds());
  62   SkPaint paint;
  63   int alpha = kThumbDefaultAlpha * animation_opacity_;
  64   if (GetState() == CustomButton::STATE_HOVERED) {
  65     alpha = kThumbHoverAlpha * animation_opacity_;
  66   } else if(GetState() == CustomButton::STATE_PRESSED) {
  67     // If we are in pressed state, no need to worry about animation,
  68     // just display the deeper color.
  69     alpha = kThumbHoverAlpha;
  70   }
  71
  72   paint.setStyle(SkPaint::kFill_Style);
  73   paint.setColor(SkColorSetARGB(alpha, 0, 0, 0));
  74   canvas->DrawRoundRect(local_bounds, kThumbCornerRadius, paint);
  75 }
  76
  77 void OverlayScrollBarThumb::AnimationProgressed(
  78     const gfx::Animation* animation) {
  79   animation_opacity_ = animation->GetCurrentValue();
  80   SchedulePaint();
  81 }
  82
  83 }  // namespace
  84
  85 OverlayScrollBar::OverlayScrollBar(bool horizontal)
  86     : BaseScrollBar(horizontal, new OverlayScrollBarThumb(this)),
  87       animation_(static_cast<OverlayScrollBarThumb*>(GetThumb())) {
  88   set_notify_enter_exit_on_child(true);
  89 }
  90
  91 OverlayScrollBar::~OverlayScrollBar() {
  92 }
  93
  94 gfx::Rect OverlayScrollBar::GetTrackBounds() const {
  95   gfx::Rect local_bounds(GetLocalBounds());
  96   if (IsHorizontal()) {
  97     local_bounds.Inset(kThumbInsetFromEdge, kThumbInsetInside,
  98                        kThumbInsetFromEdge, kThumbInsetFromEdge);
  99   } else {
 100     local_bounds.Inset(kThumbInsetInside, kThumbInsetFromEdge,
 101                        kThumbInsetFromEdge, kThumbInsetFromEdge);
 102   }
 103   gfx::Size track_size = local_bounds.size();
 104   track_size.SetToMax(GetThumb()->size());
 105   local_bounds.set_size(track_size);
 106   return local_bounds;
 107 }
 108
 109 int OverlayScrollBar::GetLayoutSize() const {
 110   return 0;
 111 }
 112
 113 int OverlayScrollBar::GetContentOverlapSize() const {
 114   return kScrollbarWidth;
 115 }
 116
 117 void OverlayScrollBar::OnMouseEnteredScrollView(const ui::MouseEvent& event) {
 118   animation_.Show();
 119 }
 120
 121 void OverlayScrollBar::OnMouseExitedScrollView(const ui::MouseEvent& event) {
 122   animation_.Hide();
 123 }
 124
 125 void OverlayScrollBar::OnGestureEvent(ui::GestureEvent* event) {
 126   switch (event->type()) {
 127     case ui::ET_GESTURE_SCROLL_BEGIN:
 128       animation_.Show();
 129       break;
 130     case ui::ET_GESTURE_SCROLL_END:
 131     case ui::ET_SCROLL_FLING_START:
 132     case ui::ET_GESTURE_END:
 133       animation_.Hide();
 134       break;
 135     default:
 136       break;
 137   }
 138   BaseScrollBar::OnGestureEvent(event);
 139 }
 140
 141 gfx::Size OverlayScrollBar::GetPreferredSize() const {
 142   return gfx::Size();
 143 }
 144
 145 void OverlayScrollBar::Layout() {
 146   gfx::Rect thumb_bounds = GetTrackBounds();
 147   BaseScrollBarThumb* thumb = GetThumb();
 148   if (IsHorizontal()) {
 149     thumb_bounds.set_x(thumb->x());
 150     thumb_bounds.set_width(thumb->width());
 151   } else {
 152     thumb_bounds.set_y(thumb->y());
 153     thumb_bounds.set_height(thumb->height());
 154   }
 155   thumb->SetBoundsRect(thumb_bounds);
 156 }
 157
 158 void OverlayScrollBar::OnPaint(gfx::Canvas* canvas) {
 159 }
 160
 161 }  // namespace views