athena/util/drag_handle.cc

   1 // Copyright 2014 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 "athena/util/drag_handle.h"
   6
   7 #include "ui/views/background.h"
   8 #include "ui/views/view.h"
   9
  10 namespace athena {
  11 namespace {
  12
  13 const SkColor kDragHandleColorNormal = SK_ColorGRAY;
  14 const SkColor kDragHandleColorHot = SK_ColorWHITE;
  15
  16 // This view notifies its delegate of the touch scroll gestures performed on it.
  17 class DragHandleView : public views::View {
  18  public:
  19   DragHandleView(DragHandleScrollDirection scroll_direction,
  20                  DragHandleScrollDelegate* delegate,
  21                  int preferred_width,
  22                  int preferred_height);
  23   virtual ~DragHandleView();
  24
  25  private:
  26   void SetColor(SkColor color);
  27
  28   void SetIsScrolling(bool scrolling);
  29
  30   // views::View:
  31   virtual gfx::Size GetPreferredSize() const OVERRIDE;
  32   virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
  33
  34   bool scroll_in_progress_;
  35   DragHandleScrollDelegate* delegate_;
  36   DragHandleScrollDirection scroll_direction_;
  37   SkColor color_;
  38   float scroll_start_location_;
  39   const int preferred_width_;
  40   const int preferred_height_;
  41
  42   DISALLOW_COPY_AND_ASSIGN(DragHandleView);
  43 };
  44
  45 DragHandleView::DragHandleView(DragHandleScrollDirection scroll_direction,
  46                                DragHandleScrollDelegate* delegate,
  47                                int preferred_width,
  48                                int preferred_height)
  49     : scroll_in_progress_(false),
  50       delegate_(delegate),
  51       scroll_direction_(scroll_direction),
  52       color_(SK_ColorTRANSPARENT),
  53       preferred_width_(preferred_width),
  54       preferred_height_(preferred_height) {
  55   SetColor(kDragHandleColorNormal);
  56 }
  57
  58 DragHandleView::~DragHandleView() {
  59 }
  60
  61 void DragHandleView::SetColor(SkColor color) {
  62   if (color_ == color)
  63     return;
  64   color_ = color;
  65   set_background(views::Background::CreateSolidBackground(color_));
  66   SchedulePaint();
  67 }
  68
  69 void DragHandleView::SetIsScrolling(bool scrolling) {
  70   if (scroll_in_progress_ == scrolling)
  71     return;
  72   scroll_in_progress_ = scrolling;
  73   if (!scroll_in_progress_)
  74     scroll_start_location_ = 0;
  75 }
  76
  77 // views::View:
  78 gfx::Size DragHandleView::GetPreferredSize() const {
  79   return gfx::Size(preferred_width_, preferred_height_);
  80 }
  81
  82 void DragHandleView::OnGestureEvent(ui::GestureEvent* event) {
  83   SkColor change_color = SK_ColorTRANSPARENT;
  84   if (event->type() == ui::ET_GESTURE_BEGIN &&
  85       event->details().touch_points() == 1) {
  86     change_color = kDragHandleColorHot;
  87   } else if (event->type() == ui::ET_GESTURE_END &&
  88              event->details().touch_points() == 1) {
  89     change_color = kDragHandleColorNormal;
  90   }
  91
  92   if (change_color != SK_ColorTRANSPARENT) {
  93     SetColor(change_color);
  94     event->SetHandled();
  95     return;
  96   }
  97
  98   if (event->type() == ui::ET_GESTURE_SCROLL_BEGIN) {
  99     if (scroll_in_progress_)
 100       return;
 101     float delta;
 102     if (scroll_direction_ == DRAG_HANDLE_VERTICAL) {
 103       delta = event->details().scroll_y_hint();
 104       scroll_start_location_ = event->root_location().y();
 105     } else {
 106       delta = event->details().scroll_x_hint();
 107       scroll_start_location_ = event->root_location().x();
 108     }
 109     delegate_->HandleScrollBegin(delta);
 110     SetIsScrolling(true);
 111     event->SetHandled();
 112   } else if (event->type() == ui::ET_GESTURE_SCROLL_END ||
 113              event->type() == ui::ET_SCROLL_FLING_START) {
 114     if (!scroll_in_progress_)
 115       return;
 116     delegate_->HandleScrollEnd();
 117     SetColor(kDragHandleColorNormal);
 118     SetIsScrolling(false);
 119     event->SetHandled();
 120   } else if (event->type() == ui::ET_GESTURE_SCROLL_UPDATE) {
 121     if (!scroll_in_progress_)
 122       return;
 123     float delta = scroll_direction_ == DRAG_HANDLE_VERTICAL
 124                       ? event->root_location().y() - scroll_start_location_
 125                       : event->root_location().x() - scroll_start_location_;
 126     delegate_->HandleScrollUpdate(delta);
 127     event->SetHandled();
 128   }
 129 }
 130
 131 }  // namespace
 132
 133 views::View* CreateDragHandleView(DragHandleScrollDirection scroll_direction,
 134                                   DragHandleScrollDelegate* delegate,
 135                                   int preferred_width,
 136                                   int preferred_height) {
 137   views::View* view = new DragHandleView(
 138       scroll_direction, delegate, preferred_width, preferred_height);
 139   return view;
 140 }
 141
 142 }  // namespace athena