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      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/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
    136