ui/views/controls/scrollbar/base_scroll_bar_thumb.cc

   1 // Copyright (c) 2011 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/base_scroll_bar_thumb.h"
   6
   7 #include "ui/gfx/canvas.h"
   8 #include "ui/gfx/geometry/rect.h"
   9 #include "ui/views/controls/scrollbar/base_scroll_bar.h"
  10
  11 namespace {
  12 // The distance the mouse can be dragged outside the bounds of the thumb during
  13 // dragging before the scrollbar will snap back to its regular position.
  14 static const int kScrollThumbDragOutSnap = 100;
  15 }
  16
  17 namespace views {
  18
  19 BaseScrollBarThumb::BaseScrollBarThumb(BaseScrollBar* scroll_bar)
  20     : scroll_bar_(scroll_bar),
  21       drag_start_position_(-1),
  22       mouse_offset_(-1),
  23       state_(CustomButton::STATE_NORMAL) {
  24 }
  25
  26 BaseScrollBarThumb::~BaseScrollBarThumb() {
  27 }
  28
  29 void BaseScrollBarThumb::SetSize(int size) {
  30   // Make sure the thumb is never sized smaller than its minimum possible
  31   // display size.
  32   gfx::Size prefsize = GetPreferredSize();
  33   size = std::max(size, scroll_bar_->IsHorizontal() ? prefsize.width() :
  34                                                       prefsize.height());
  35   gfx::Rect thumb_bounds = bounds();
  36   if (scroll_bar_->IsHorizontal()) {
  37     thumb_bounds.set_width(size);
  38   } else {
  39     thumb_bounds.set_height(size);
  40   }
  41   SetBoundsRect(thumb_bounds);
  42 }
  43
  44 int BaseScrollBarThumb::GetSize() const {
  45   if (scroll_bar_->IsHorizontal())
  46     return width();
  47   return height();
  48 }
  49
  50 void BaseScrollBarThumb::SetPosition(int position) {
  51   gfx::Rect thumb_bounds = bounds();
  52   gfx::Rect track_bounds = scroll_bar_->GetTrackBounds();
  53   if (scroll_bar_->IsHorizontal()) {
  54     thumb_bounds.set_x(track_bounds.x() + position);
  55   } else {
  56     thumb_bounds.set_y(track_bounds.y() + position);
  57   }
  58   SetBoundsRect(thumb_bounds);
  59 }
  60
  61 int BaseScrollBarThumb::GetPosition() const {
  62   gfx::Rect track_bounds = scroll_bar_->GetTrackBounds();
  63   if (scroll_bar_->IsHorizontal())
  64     return x() - track_bounds.x();
  65   return y() - track_bounds.y();
  66 }
  67
  68 void BaseScrollBarThumb::OnMouseEntered(const ui::MouseEvent& event) {
  69   SetState(CustomButton::STATE_HOVERED);
  70 }
  71
  72 void BaseScrollBarThumb::OnMouseExited(const ui::MouseEvent& event) {
  73   SetState(CustomButton::STATE_NORMAL);
  74 }
  75
  76 bool BaseScrollBarThumb::OnMousePressed(const ui::MouseEvent& event) {
  77   mouse_offset_ = scroll_bar_->IsHorizontal() ? event.x() : event.y();
  78   drag_start_position_ = GetPosition();
  79   SetState(CustomButton::STATE_PRESSED);
  80   return true;
  81 }
  82
  83 bool BaseScrollBarThumb::OnMouseDragged(const ui::MouseEvent& event) {
  84   // If the user moves the mouse more than |kScrollThumbDragOutSnap| outside
  85   // the bounds of the thumb, the scrollbar will snap the scroll back to the
  86   // point it was at before the drag began.
  87   if (scroll_bar_->IsHorizontal()) {
  88     if ((event.y() < y() - kScrollThumbDragOutSnap) ||
  89         (event.y() > (y() + height() + kScrollThumbDragOutSnap))) {
  90       scroll_bar_->ScrollToThumbPosition(drag_start_position_, false);
  91       return true;
  92     }
  93   } else {
  94     if ((event.x() < x() - kScrollThumbDragOutSnap) ||
  95         (event.x() > (x() + width() + kScrollThumbDragOutSnap))) {
  96       scroll_bar_->ScrollToThumbPosition(drag_start_position_, false);
  97       return true;
  98     }
  99   }
 100   if (scroll_bar_->IsHorizontal()) {
 101     int thumb_x = event.x() - mouse_offset_;
 102     if (base::i18n::IsRTL())
 103       thumb_x *= -1;
 104     scroll_bar_->ScrollToThumbPosition(GetPosition() + thumb_x, false);
 105   } else {
 106     int thumb_y = event.y() - mouse_offset_;
 107     scroll_bar_->ScrollToThumbPosition(GetPosition() + thumb_y, false);
 108   }
 109   return true;
 110 }
 111
 112 void BaseScrollBarThumb::OnMouseReleased(const ui::MouseEvent& event) {
 113   SetState(HitTestPoint(event.location()) ?
 114            CustomButton::STATE_HOVERED : CustomButton::STATE_NORMAL);
 115 }
 116
 117 void BaseScrollBarThumb::OnMouseCaptureLost() {
 118   SetState(CustomButton::STATE_HOVERED);
 119 }
 120
 121 CustomButton::ButtonState BaseScrollBarThumb::GetState() const {
 122   return state_;
 123 }
 124
 125 void BaseScrollBarThumb::SetState(CustomButton::ButtonState state) {
 126   if (state_ == state)
 127     return;
 128
 129   CustomButton::ButtonState old_state = state_;
 130   state_ = state;
 131   scroll_bar_->OnThumbStateChanged(old_state, state);
 132   SchedulePaint();
 133 }
 134
 135 }  // namespace views