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      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/scrollbar/base_scroll_bar.h"
      6 
      7 #include "base/bind.h"
      8 #include "base/bind_helpers.h"
      9 #include "base/callback.h"
     10 #include "base/compiler_specific.h"
     11 #include "base/message_loop/message_loop.h"
     12 #include "base/strings/string16.h"
     13 #include "base/strings/utf_string_conversions.h"
     14 #include "build/build_config.h"
     15 #include "grit/ui_strings.h"
     16 #include "ui/base/l10n/l10n_util.h"
     17 #include "ui/events/event.h"
     18 #include "ui/events/keycodes/keyboard_codes.h"
     19 #include "ui/gfx/canvas.h"
     20 #include "ui/gfx/geometry/safe_integer_conversions.h"
     21 #include "ui/views/controls/menu/menu_item_view.h"
     22 #include "ui/views/controls/menu/menu_runner.h"
     23 #include "ui/views/controls/scroll_view.h"
     24 #include "ui/views/controls/scrollbar/base_scroll_bar_thumb.h"
     25 #include "ui/views/widget/widget.h"
     26 
     27 #if defined(OS_LINUX)
     28 #include "ui/gfx/screen.h"
     29 #endif
     30 
     31 #undef min
     32 #undef max
     33 
     34 namespace views {
     35 
     36 ///////////////////////////////////////////////////////////////////////////////
     37 // BaseScrollBar, public:
     38 
     39 BaseScrollBar::BaseScrollBar(bool horizontal, BaseScrollBarThumb* thumb)
     40     : ScrollBar(horizontal),
     41       thumb_(thumb),
     42       contents_size_(0),
     43       contents_scroll_offset_(0),
     44       viewport_size_(0),
     45       thumb_track_state_(CustomButton::STATE_NORMAL),
     46       last_scroll_amount_(SCROLL_NONE),
     47       repeater_(base::Bind(&BaseScrollBar::TrackClicked,
     48                            base::Unretained(this))),
     49       context_menu_mouse_position_(0) {
     50   AddChildView(thumb_);
     51 
     52   set_context_menu_controller(this);
     53   thumb_->set_context_menu_controller(this);
     54 }
     55 
     56 void BaseScrollBar::ScrollByAmount(ScrollAmount amount) {
     57   int offset = contents_scroll_offset_;
     58   switch (amount) {
     59     case SCROLL_START:
     60       offset = GetMinPosition();
     61       break;
     62     case SCROLL_END:
     63       offset = GetMaxPosition();
     64       break;
     65     case SCROLL_PREV_LINE:
     66       offset -= GetScrollIncrement(false, false);
     67       offset = std::max(GetMinPosition(), offset);
     68       break;
     69     case SCROLL_NEXT_LINE:
     70       offset += GetScrollIncrement(false, true);
     71       offset = std::min(GetMaxPosition(), offset);
     72       break;
     73     case SCROLL_PREV_PAGE:
     74       offset -= GetScrollIncrement(true, false);
     75       offset = std::max(GetMinPosition(), offset);
     76       break;
     77     case SCROLL_NEXT_PAGE:
     78       offset += GetScrollIncrement(true, true);
     79       offset = std::min(GetMaxPosition(), offset);
     80       break;
     81     default:
     82       break;
     83   }
     84   contents_scroll_offset_ = offset;
     85   ScrollContentsToOffset();
     86 }
     87 
     88 BaseScrollBar::~BaseScrollBar() {
     89 }
     90 
     91 void BaseScrollBar::ScrollToThumbPosition(int thumb_position,
     92                                           bool scroll_to_middle) {
     93   contents_scroll_offset_ =
     94       CalculateContentsOffset(thumb_position, scroll_to_middle);
     95   if (contents_scroll_offset_ < GetMinPosition()) {
     96     contents_scroll_offset_ = GetMinPosition();
     97   } else if (contents_scroll_offset_ > GetMaxPosition()) {
     98     contents_scroll_offset_ = GetMaxPosition();
     99   }
    100   ScrollContentsToOffset();
    101   SchedulePaint();
    102 }
    103 
    104 bool BaseScrollBar::ScrollByContentsOffset(int contents_offset) {
    105   int old_offset = contents_scroll_offset_;
    106   contents_scroll_offset_ -= contents_offset;
    107   if (contents_scroll_offset_ < GetMinPosition()) {
    108     contents_scroll_offset_ = GetMinPosition();
    109   } else if (contents_scroll_offset_ > GetMaxPosition()) {
    110     contents_scroll_offset_ = GetMaxPosition();
    111   }
    112   if (old_offset == contents_scroll_offset_)
    113     return false;
    114 
    115   ScrollContentsToOffset();
    116   return true;
    117 }
    118 
    119 void BaseScrollBar::OnThumbStateChanged(CustomButton::ButtonState old_state,
    120                                         CustomButton::ButtonState new_state) {
    121   if (old_state == CustomButton::STATE_PRESSED &&
    122       new_state == CustomButton::STATE_NORMAL &&
    123       GetThumbTrackState() == CustomButton::STATE_HOVERED) {
    124     SetThumbTrackState(CustomButton::STATE_NORMAL);
    125   }
    126 }
    127 
    128 ///////////////////////////////////////////////////////////////////////////////
    129 // BaseScrollBar, View implementation:
    130 
    131 bool BaseScrollBar::OnMousePressed(const ui::MouseEvent& event) {
    132   if (event.IsOnlyLeftMouseButton())
    133     ProcessPressEvent(event);
    134   return true;
    135 }
    136 
    137 void BaseScrollBar::OnMouseReleased(const ui::MouseEvent& event) {
    138   SetState(HitTestPoint(event.location()) ?
    139            CustomButton::STATE_HOVERED : CustomButton::STATE_NORMAL);
    140 }
    141 
    142 void BaseScrollBar::OnMouseCaptureLost() {
    143   SetState(CustomButton::STATE_NORMAL);
    144 }
    145 
    146 void BaseScrollBar::OnMouseEntered(const ui::MouseEvent& event) {
    147   SetThumbTrackState(CustomButton::STATE_HOVERED);
    148 }
    149 
    150 void BaseScrollBar::OnMouseExited(const ui::MouseEvent& event) {
    151   if (GetThumbTrackState() == CustomButton::STATE_HOVERED)
    152     SetState(CustomButton::STATE_NORMAL);
    153 }
    154 
    155 bool BaseScrollBar::OnKeyPressed(const ui::KeyEvent& event) {
    156   ScrollAmount amount = SCROLL_NONE;
    157   switch (event.key_code()) {
    158     case ui::VKEY_UP:
    159       if (!IsHorizontal())
    160         amount = SCROLL_PREV_LINE;
    161       break;
    162     case ui::VKEY_DOWN:
    163       if (!IsHorizontal())
    164         amount = SCROLL_NEXT_LINE;
    165       break;
    166     case ui::VKEY_LEFT:
    167       if (IsHorizontal())
    168         amount = SCROLL_PREV_LINE;
    169       break;
    170     case ui::VKEY_RIGHT:
    171       if (IsHorizontal())
    172         amount = SCROLL_NEXT_LINE;
    173       break;
    174     case ui::VKEY_PRIOR:
    175       amount = SCROLL_PREV_PAGE;
    176       break;
    177     case ui::VKEY_NEXT:
    178       amount = SCROLL_NEXT_PAGE;
    179       break;
    180     case ui::VKEY_HOME:
    181       amount = SCROLL_START;
    182       break;
    183     case ui::VKEY_END:
    184       amount = SCROLL_END;
    185       break;
    186     default:
    187       break;
    188   }
    189   if (amount != SCROLL_NONE) {
    190     ScrollByAmount(amount);
    191     return true;
    192   }
    193   return false;
    194 }
    195 
    196 bool BaseScrollBar::OnMouseWheel(const ui::MouseWheelEvent& event) {
    197   ScrollByContentsOffset(event.y_offset());
    198   return true;
    199 }
    200 
    201 void BaseScrollBar::OnGestureEvent(ui::GestureEvent* event) {
    202   // If a fling is in progress, then stop the fling for any incoming gesture
    203   // event (except for the GESTURE_END event that is generated at the end of the
    204   // fling).
    205   if (scroll_animator_.get() && scroll_animator_->is_scrolling() &&
    206       (event->type() != ui::ET_GESTURE_END ||
    207        event->details().touch_points() > 1)) {
    208     scroll_animator_->Stop();
    209   }
    210 
    211   if (event->type() == ui::ET_GESTURE_TAP_DOWN) {
    212     ProcessPressEvent(*event);
    213     event->SetHandled();
    214     return;
    215   }
    216 
    217   if (event->type() == ui::ET_GESTURE_LONG_PRESS) {
    218     // For a long-press, the repeater started in tap-down should continue. So
    219     // return early.
    220     return;
    221   }
    222 
    223   SetState(CustomButton::STATE_NORMAL);
    224 
    225   if (event->type() == ui::ET_GESTURE_TAP) {
    226     // TAP_DOWN would have already scrolled some amount. So scrolling again on
    227     // TAP is not necessary.
    228     event->SetHandled();
    229     return;
    230   }
    231 
    232   if (event->type() == ui::ET_GESTURE_SCROLL_BEGIN ||
    233       event->type() == ui::ET_GESTURE_SCROLL_END) {
    234     event->SetHandled();
    235     return;
    236   }
    237 
    238   if (event->type() == ui::ET_GESTURE_SCROLL_UPDATE) {
    239     float scroll_amount_f;
    240     int scroll_amount;
    241     if (IsHorizontal()) {
    242       scroll_amount_f = event->details().scroll_x() - roundoff_error_.x();
    243       scroll_amount = gfx::ToRoundedInt(scroll_amount_f);
    244       roundoff_error_.set_x(scroll_amount - scroll_amount_f);
    245     } else {
    246       scroll_amount_f = event->details().scroll_y() - roundoff_error_.y();
    247       scroll_amount = gfx::ToRoundedInt(scroll_amount_f);
    248       roundoff_error_.set_y(scroll_amount - scroll_amount_f);
    249     }
    250     if (ScrollByContentsOffset(scroll_amount))
    251       event->SetHandled();
    252     return;
    253   }
    254 
    255   if (event->type() == ui::ET_SCROLL_FLING_START) {
    256     if (!scroll_animator_.get())
    257       scroll_animator_.reset(new ScrollAnimator(this));
    258     scroll_animator_->Start(
    259         IsHorizontal() ?  event->details().velocity_x() : 0.f,
    260         IsHorizontal() ? 0.f : event->details().velocity_y());
    261     event->SetHandled();
    262   }
    263 }
    264 
    265 ///////////////////////////////////////////////////////////////////////////////
    266 // BaseScrollBar, ScrollDelegate implementation:
    267 
    268 bool BaseScrollBar::OnScroll(float dx, float dy) {
    269   return IsHorizontal() ? ScrollByContentsOffset(dx) :
    270                           ScrollByContentsOffset(dy);
    271 }
    272 
    273 ///////////////////////////////////////////////////////////////////////////////
    274 // BaseScrollBar, ContextMenuController implementation:
    275 
    276 enum ScrollBarContextMenuCommands {
    277   ScrollBarContextMenuCommand_ScrollHere = 1,
    278   ScrollBarContextMenuCommand_ScrollStart,
    279   ScrollBarContextMenuCommand_ScrollEnd,
    280   ScrollBarContextMenuCommand_ScrollPageUp,
    281   ScrollBarContextMenuCommand_ScrollPageDown,
    282   ScrollBarContextMenuCommand_ScrollPrev,
    283   ScrollBarContextMenuCommand_ScrollNext
    284 };
    285 
    286 void BaseScrollBar::ShowContextMenuForView(View* source,
    287                                            const gfx::Point& p,
    288                                            ui::MenuSourceType source_type) {
    289   Widget* widget = GetWidget();
    290   gfx::Rect widget_bounds = widget->GetWindowBoundsInScreen();
    291   gfx::Point temp_pt(p.x() - widget_bounds.x(), p.y() - widget_bounds.y());
    292   View::ConvertPointFromWidget(this, &temp_pt);
    293   context_menu_mouse_position_ = IsHorizontal() ? temp_pt.x() : temp_pt.y();
    294 
    295   views::MenuItemView* menu = new views::MenuItemView(this);
    296   // MenuRunner takes ownership of |menu|.
    297   menu_runner_.reset(new MenuRunner(menu));
    298   menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollHere);
    299   menu->AppendSeparator();
    300   menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollStart);
    301   menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollEnd);
    302   menu->AppendSeparator();
    303   menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollPageUp);
    304   menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollPageDown);
    305   menu->AppendSeparator();
    306   menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollPrev);
    307   menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollNext);
    308   if (menu_runner_->RunMenuAt(
    309           GetWidget(),
    310           NULL,
    311           gfx::Rect(p, gfx::Size()),
    312           MENU_ANCHOR_TOPLEFT,
    313           source_type,
    314           MenuRunner::HAS_MNEMONICS | views::MenuRunner::CONTEXT_MENU) ==
    315       MenuRunner::MENU_DELETED) {
    316     return;
    317   }
    318 }
    319 
    320 ///////////////////////////////////////////////////////////////////////////////
    321 // BaseScrollBar, Menu::Delegate implementation:
    322 
    323 base::string16 BaseScrollBar::GetLabel(int id) const {
    324   int ids_value = 0;
    325   switch (id) {
    326     case ScrollBarContextMenuCommand_ScrollHere:
    327       ids_value = IDS_APP_SCROLLBAR_CXMENU_SCROLLHERE;
    328       break;
    329     case ScrollBarContextMenuCommand_ScrollStart:
    330       ids_value = IsHorizontal() ? IDS_APP_SCROLLBAR_CXMENU_SCROLLLEFTEDGE
    331                                  : IDS_APP_SCROLLBAR_CXMENU_SCROLLHOME;
    332       break;
    333     case ScrollBarContextMenuCommand_ScrollEnd:
    334       ids_value = IsHorizontal() ? IDS_APP_SCROLLBAR_CXMENU_SCROLLRIGHTEDGE
    335                                  : IDS_APP_SCROLLBAR_CXMENU_SCROLLEND;
    336       break;
    337     case ScrollBarContextMenuCommand_ScrollPageUp:
    338       ids_value = IDS_APP_SCROLLBAR_CXMENU_SCROLLPAGEUP;
    339       break;
    340     case ScrollBarContextMenuCommand_ScrollPageDown:
    341       ids_value = IDS_APP_SCROLLBAR_CXMENU_SCROLLPAGEDOWN;
    342       break;
    343     case ScrollBarContextMenuCommand_ScrollPrev:
    344       ids_value = IsHorizontal() ? IDS_APP_SCROLLBAR_CXMENU_SCROLLLEFT
    345                                  : IDS_APP_SCROLLBAR_CXMENU_SCROLLUP;
    346       break;
    347     case ScrollBarContextMenuCommand_ScrollNext:
    348       ids_value = IsHorizontal() ? IDS_APP_SCROLLBAR_CXMENU_SCROLLRIGHT
    349                                  : IDS_APP_SCROLLBAR_CXMENU_SCROLLDOWN;
    350       break;
    351     default:
    352       NOTREACHED() << "Invalid BaseScrollBar Context Menu command!";
    353   }
    354 
    355   return ids_value ? l10n_util::GetStringUTF16(ids_value) : base::string16();
    356 }
    357 
    358 bool BaseScrollBar::IsCommandEnabled(int id) const {
    359   switch (id) {
    360     case ScrollBarContextMenuCommand_ScrollPageUp:
    361     case ScrollBarContextMenuCommand_ScrollPageDown:
    362       return !IsHorizontal();
    363   }
    364   return true;
    365 }
    366 
    367 void BaseScrollBar::ExecuteCommand(int id) {
    368   switch (id) {
    369     case ScrollBarContextMenuCommand_ScrollHere:
    370       ScrollToThumbPosition(context_menu_mouse_position_, true);
    371       break;
    372     case ScrollBarContextMenuCommand_ScrollStart:
    373       ScrollByAmount(SCROLL_START);
    374       break;
    375     case ScrollBarContextMenuCommand_ScrollEnd:
    376       ScrollByAmount(SCROLL_END);
    377       break;
    378     case ScrollBarContextMenuCommand_ScrollPageUp:
    379       ScrollByAmount(SCROLL_PREV_PAGE);
    380       break;
    381     case ScrollBarContextMenuCommand_ScrollPageDown:
    382       ScrollByAmount(SCROLL_NEXT_PAGE);
    383       break;
    384     case ScrollBarContextMenuCommand_ScrollPrev:
    385       ScrollByAmount(SCROLL_PREV_LINE);
    386       break;
    387     case ScrollBarContextMenuCommand_ScrollNext:
    388       ScrollByAmount(SCROLL_NEXT_LINE);
    389       break;
    390   }
    391 }
    392 
    393 ///////////////////////////////////////////////////////////////////////////////
    394 // BaseScrollBar, ScrollBar implementation:
    395 
    396 void BaseScrollBar::Update(int viewport_size,
    397                            int content_size,
    398                            int contents_scroll_offset) {
    399   ScrollBar::Update(viewport_size, content_size, contents_scroll_offset);
    400 
    401   // Make sure contents_size is always > 0 to avoid divide by zero errors in
    402   // calculations throughout this code.
    403   contents_size_ = std::max(1, content_size);
    404 
    405   viewport_size_ = std::max(1, viewport_size);
    406 
    407   if (content_size < 0)
    408     content_size = 0;
    409   if (contents_scroll_offset < 0)
    410     contents_scroll_offset = 0;
    411   if (contents_scroll_offset > content_size)
    412     contents_scroll_offset = content_size;
    413   contents_scroll_offset_ = contents_scroll_offset;
    414 
    415   // Thumb Height and Thumb Pos.
    416   // The height of the thumb is the ratio of the Viewport height to the
    417   // content size multiplied by the height of the thumb track.
    418   double ratio = static_cast<double>(viewport_size) / contents_size_;
    419   int thumb_size = static_cast<int>(ratio * GetTrackSize());
    420   thumb_->SetSize(thumb_size);
    421 
    422   int thumb_position = CalculateThumbPosition(contents_scroll_offset);
    423   thumb_->SetPosition(thumb_position);
    424 }
    425 
    426 int BaseScrollBar::GetPosition() const {
    427   return thumb_->GetPosition();
    428 }
    429 
    430 ///////////////////////////////////////////////////////////////////////////////
    431 // BaseScrollBar, protected:
    432 
    433 BaseScrollBarThumb* BaseScrollBar::GetThumb() const {
    434   return thumb_;
    435 }
    436 
    437 CustomButton::ButtonState BaseScrollBar::GetThumbTrackState() const {
    438   return thumb_track_state_;
    439 }
    440 
    441 void BaseScrollBar::ScrollToPosition(int position) {
    442   controller()->ScrollToPosition(this, position);
    443 }
    444 
    445 int BaseScrollBar::GetScrollIncrement(bool is_page, bool is_positive) {
    446   return controller()->GetScrollIncrement(this, is_page, is_positive);
    447 }
    448 
    449 ///////////////////////////////////////////////////////////////////////////////
    450 // BaseScrollBar, private:
    451 
    452 int BaseScrollBar::GetThumbSizeForTest() {
    453   return thumb_->GetSize();
    454 }
    455 
    456 void BaseScrollBar::ProcessPressEvent(const ui::LocatedEvent& event) {
    457   SetThumbTrackState(CustomButton::STATE_PRESSED);
    458   gfx::Rect thumb_bounds = thumb_->bounds();
    459   if (IsHorizontal()) {
    460     if (GetMirroredXInView(event.x()) < thumb_bounds.x()) {
    461       last_scroll_amount_ = SCROLL_PREV_PAGE;
    462     } else if (GetMirroredXInView(event.x()) > thumb_bounds.right()) {
    463       last_scroll_amount_ = SCROLL_NEXT_PAGE;
    464     }
    465   } else {
    466     if (event.y() < thumb_bounds.y()) {
    467       last_scroll_amount_ = SCROLL_PREV_PAGE;
    468     } else if (event.y() > thumb_bounds.bottom()) {
    469       last_scroll_amount_ = SCROLL_NEXT_PAGE;
    470     }
    471   }
    472   TrackClicked();
    473   repeater_.Start();
    474 }
    475 
    476 void BaseScrollBar::SetState(CustomButton::ButtonState state) {
    477   SetThumbTrackState(state);
    478   repeater_.Stop();
    479 }
    480 
    481 void BaseScrollBar::TrackClicked() {
    482   if (last_scroll_amount_ != SCROLL_NONE)
    483     ScrollByAmount(last_scroll_amount_);
    484 }
    485 
    486 void BaseScrollBar::ScrollContentsToOffset() {
    487   ScrollToPosition(contents_scroll_offset_);
    488   thumb_->SetPosition(CalculateThumbPosition(contents_scroll_offset_));
    489 }
    490 
    491 int BaseScrollBar::GetTrackSize() const {
    492   gfx::Rect track_bounds = GetTrackBounds();
    493   return IsHorizontal() ? track_bounds.width() : track_bounds.height();
    494 }
    495 
    496 int BaseScrollBar::CalculateThumbPosition(int contents_scroll_offset) const {
    497   // In some combination of viewport_size and contents_size_, the result of
    498   // simple division can be rounded and there could be 1 pixel gap even when the
    499   // contents scroll down to the bottom. See crbug.com/244671
    500   if (contents_scroll_offset + viewport_size_ == contents_size_) {
    501     int track_size = GetTrackSize();
    502     return track_size - (viewport_size_ * GetTrackSize() / contents_size_);
    503   }
    504   return (contents_scroll_offset * GetTrackSize()) / contents_size_;
    505 }
    506 
    507 int BaseScrollBar::CalculateContentsOffset(int thumb_position,
    508                                            bool scroll_to_middle) const {
    509   if (scroll_to_middle)
    510     thumb_position = thumb_position - (thumb_->GetSize() / 2);
    511   return (thumb_position * contents_size_) / GetTrackSize();
    512 }
    513 
    514 void BaseScrollBar::SetThumbTrackState(CustomButton::ButtonState state) {
    515   thumb_track_state_ = state;
    516   SchedulePaint();
    517 }
    518 
    519 }  // namespace views
    520