Adding a Views scrollbar implementation.

views/controls/scrollbar/base_scroll_bar.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.

[Ben Goodger (Google), 2011/08/23 16:05:15]

Is this code identical to BitmapScrollBar with the bitmap bits removed? It would
be helpful for reviewing this if you had made this file using svn cp so I could
see the differences.

+
+#include "views/controls/scrollbar/base_scroll_bar.h"
+
+#if defined(OS_LINUX)
+#include "ui/gfx/screen.h"
+#endif
+
+#include "base/callback.h"
+#include "base/compiler_specific.h"
+#include "base/message_loop.h"
+#include "base/string16.h"
+#include "base/utf_string_conversions.h"
+#include "grit/ui_strings.h"
+#include "ui/base/keycodes/keyboard_codes.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/gfx/canvas.h"
+#include "views/controls/menu/menu.h"
+#include "views/controls/scrollbar/base_scroll_bar_thumb.h"
+#include "views/controls/scroll_view.h"
+#include "views/widget/widget.h"
+
+#undef min
+#undef max
+
+namespace views {
+
+///////////////////////////////////////////////////////////////////////////////
+// BaseScrollBar, public:
+
+BaseScrollBar::BaseScrollBar(bool horizontal, BaseScrollBarThumb* thumb)
+    : ScrollBar(horizontal),
+      thumb_(thumb),
+      contents_size_(0),
+      contents_scroll_offset_(0),
+      thumb_track_state_(CustomButton::BS_NORMAL),
+      last_scroll_amount_(SCROLL_NONE),
+      ALLOW_THIS_IN_INITIALIZER_LIST(repeater_(
+          NewCallback<BaseScrollBar>(this,
+                                       &BaseScrollBar::TrackClicked))),
+      context_menu_mouse_position_(0) {
+
+  AddChildView(thumb_);
+
+  set_context_menu_controller(this);
+  thumb_->set_context_menu_controller(this);
+}
+
+void BaseScrollBar::ScrollByAmount(ScrollAmount amount) {
+  int offset = contents_scroll_offset_;
+  switch (amount) {
+    case SCROLL_START:
+      offset = GetMinPosition();
+      break;
+    case SCROLL_END:
+      offset = GetMaxPosition();
+      break;
+    case SCROLL_PREV_LINE:
+      offset -= GetScrollIncrement(false, false);
+      offset = std::max(GetMinPosition(), offset);
+      break;
+    case SCROLL_NEXT_LINE:
+      offset += GetScrollIncrement(false, true);
+      offset = std::min(GetMaxPosition(), offset);
+      break;
+    case SCROLL_PREV_PAGE:
+      offset -= GetScrollIncrement(true, false);
+      offset = std::max(GetMinPosition(), offset);
+      break;
+    case SCROLL_NEXT_PAGE:
+      offset += GetScrollIncrement(true, true);
+      offset = std::min(GetMaxPosition(), offset);
+      break;
+    default:
+      break;
+  }
+  contents_scroll_offset_ = offset;
+  ScrollContentsToOffset();
+}
+
+void BaseScrollBar::ScrollToThumbPosition(int thumb_position,
+                                          bool scroll_to_middle) {
+  contents_scroll_offset_ =
+      CalculateContentsOffset(thumb_position, scroll_to_middle);
+  if (contents_scroll_offset_ < GetMinPosition()) {
+    contents_scroll_offset_ = GetMinPosition();
+  } else if (contents_scroll_offset_ > GetMaxPosition()) {
+    contents_scroll_offset_ = GetMaxPosition();
+  }
+  ScrollContentsToOffset();
+  SchedulePaint();
+}
+
+void BaseScrollBar::ScrollByContentsOffset(int contents_offset) {
+  contents_scroll_offset_ -= contents_offset;
+  if (contents_scroll_offset_ < GetMinPosition()) {
+    contents_scroll_offset_ = GetMinPosition();
+  } else if (contents_scroll_offset_ > GetMaxPosition()) {
+    contents_scroll_offset_ = GetMaxPosition();
+  }
+  ScrollContentsToOffset();
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// BaseScrollBar, View implementation:
+
+bool BaseScrollBar::OnMousePressed(const MouseEvent& event) {
+  if (event.IsOnlyLeftMouseButton()) {
+    SetThumbTrackState(CustomButton::BS_PUSHED);
+    gfx::Rect thumb_bounds = thumb_->bounds();
+    if (IsHorizontal()) {
+      if (event.x() < thumb_bounds.x()) {
+        last_scroll_amount_ = SCROLL_PREV_PAGE;
+      } else if (event.x() > thumb_bounds.right()) {
+        last_scroll_amount_ = SCROLL_NEXT_PAGE;
+      }
+    } else {
+      if (event.y() < thumb_bounds.y()) {
+        last_scroll_amount_ = SCROLL_PREV_PAGE;
+      } else if (event.y() > thumb_bounds.bottom()) {
+        last_scroll_amount_ = SCROLL_NEXT_PAGE;
+      }
+    }
+    TrackClicked();
+    repeater_.Start();
+  }
+  return true;
+}
+
+void BaseScrollBar::OnMouseReleased(const MouseEvent& event) {
+  OnMouseCaptureLost();
+}
+
+void BaseScrollBar::OnMouseCaptureLost() {
+  SetThumbTrackState(CustomButton::BS_NORMAL);
+  repeater_.Stop();
+}
+
+bool BaseScrollBar::OnKeyPressed(const KeyEvent& event) {
+  ScrollAmount amount = SCROLL_NONE;
+  switch (event.key_code()) {
+    case ui::VKEY_UP:
+      if (!IsHorizontal())
+        amount = SCROLL_PREV_LINE;
+      break;
+    case ui::VKEY_DOWN:
+      if (!IsHorizontal())
+        amount = SCROLL_NEXT_LINE;
+      break;
+    case ui::VKEY_LEFT:
+      if (IsHorizontal())
+        amount = SCROLL_PREV_LINE;
+      break;
+    case ui::VKEY_RIGHT:
+      if (IsHorizontal())
+        amount = SCROLL_NEXT_LINE;
+      break;
+    case ui::VKEY_PRIOR:
+      amount = SCROLL_PREV_PAGE;
+      break;
+    case ui::VKEY_NEXT:
+      amount = SCROLL_NEXT_PAGE;
+      break;
+    case ui::VKEY_HOME:
+      amount = SCROLL_START;
+      break;
+    case ui::VKEY_END:
+      amount = SCROLL_END;
+      break;
+    default:
+      break;
+  }
+  if (amount != SCROLL_NONE) {
+    ScrollByAmount(amount);
+    return true;
+  }
+  return false;
+}
+
+bool BaseScrollBar::OnMouseWheel(const MouseWheelEvent& event) {
+  ScrollByContentsOffset(event.offset());
+  return true;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// BaseScrollBar, ContextMenuController implementation:
+
+enum ScrollBarContextMenuCommands {
+  ScrollBarContextMenuCommand_ScrollHere = 1,
+  ScrollBarContextMenuCommand_ScrollStart,
+  ScrollBarContextMenuCommand_ScrollEnd,
+  ScrollBarContextMenuCommand_ScrollPageUp,
+  ScrollBarContextMenuCommand_ScrollPageDown,
+  ScrollBarContextMenuCommand_ScrollPrev,
+  ScrollBarContextMenuCommand_ScrollNext
+};
+
+void BaseScrollBar::ShowContextMenuForView(View* source,
+                                             const gfx::Point& p,
+                                             bool is_mouse_gesture) {
+  Widget* widget = GetWidget();
+  gfx::Rect widget_bounds = widget->GetWindowScreenBounds();
+  gfx::Point temp_pt(p.x() - widget_bounds.x(), p.y() - widget_bounds.y());
+  View::ConvertPointFromWidget(this, &temp_pt);
+  context_menu_mouse_position_ = IsHorizontal() ? temp_pt.x() : temp_pt.y();
+
+  scoped_ptr<Menu> menu(
+      Menu::Create(this, Menu::TOPLEFT, GetWidget()->GetNativeView()));
+  menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollHere);
+  menu->AppendSeparator();
+  menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollStart);
+  menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollEnd);
+  menu->AppendSeparator();
+  menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollPageUp);
+  menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollPageDown);
+  menu->AppendSeparator();
+  menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollPrev);
+  menu->AppendDelegateMenuItem(ScrollBarContextMenuCommand_ScrollNext);
+  menu->RunMenuAt(p.x(), p.y());
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// BaseScrollBar, Menu::Delegate implementation:
+
+std::wstring BaseScrollBar::GetLabel(int id) const {
+  int ids_value = 0;
+  switch (id) {
+    case ScrollBarContextMenuCommand_ScrollHere:
+      ids_value = IDS_APP_SCROLLBAR_CXMENU_SCROLLHERE;
+      break;
+    case ScrollBarContextMenuCommand_ScrollStart:
+      ids_value = IsHorizontal() ? IDS_APP_SCROLLBAR_CXMENU_SCROLLLEFTEDGE
+                                 : IDS_APP_SCROLLBAR_CXMENU_SCROLLHOME;
+      break;
+    case ScrollBarContextMenuCommand_ScrollEnd:
+      ids_value = IsHorizontal() ? IDS_APP_SCROLLBAR_CXMENU_SCROLLRIGHTEDGE
+                                 : IDS_APP_SCROLLBAR_CXMENU_SCROLLEND;
+      break;
+    case ScrollBarContextMenuCommand_ScrollPageUp:
+      ids_value = IDS_APP_SCROLLBAR_CXMENU_SCROLLPAGEUP;
+      break;
+    case ScrollBarContextMenuCommand_ScrollPageDown:
+      ids_value = IDS_APP_SCROLLBAR_CXMENU_SCROLLPAGEDOWN;
+      break;
+    case ScrollBarContextMenuCommand_ScrollPrev:
+      ids_value = IsHorizontal() ? IDS_APP_SCROLLBAR_CXMENU_SCROLLLEFT
+                                 : IDS_APP_SCROLLBAR_CXMENU_SCROLLUP;
+      break;
+    case ScrollBarContextMenuCommand_ScrollNext:
+      ids_value = IsHorizontal() ? IDS_APP_SCROLLBAR_CXMENU_SCROLLRIGHT
+                                 : IDS_APP_SCROLLBAR_CXMENU_SCROLLDOWN;
+      break;
+    default:
+      NOTREACHED() << "Invalid BaseScrollBar Context Menu command!";
+  }
+
+  return ids_value ? UTF16ToWide(l10n_util::GetStringUTF16(ids_value)) : L"";
+}
+
+bool BaseScrollBar::IsCommandEnabled(int id) const {
+  switch (id) {
+    case ScrollBarContextMenuCommand_ScrollPageUp:
+    case ScrollBarContextMenuCommand_ScrollPageDown:
+      return !IsHorizontal();
+  }
+  return true;
+}
+
+void BaseScrollBar::ExecuteCommand(int id) {
+  switch (id) {
+    case ScrollBarContextMenuCommand_ScrollHere:
+      ScrollToThumbPosition(context_menu_mouse_position_, true);
+      break;
+    case ScrollBarContextMenuCommand_ScrollStart:
+      ScrollByAmount(SCROLL_START);
+      break;
+    case ScrollBarContextMenuCommand_ScrollEnd:
+      ScrollByAmount(SCROLL_END);
+      break;
+    case ScrollBarContextMenuCommand_ScrollPageUp:
+      ScrollByAmount(SCROLL_PREV_PAGE);
+      break;
+    case ScrollBarContextMenuCommand_ScrollPageDown:
+      ScrollByAmount(SCROLL_NEXT_PAGE);
+      break;
+    case ScrollBarContextMenuCommand_ScrollPrev:
+      ScrollByAmount(SCROLL_PREV_LINE);
+      break;
+    case ScrollBarContextMenuCommand_ScrollNext:
+      ScrollByAmount(SCROLL_NEXT_LINE);
+      break;
+  }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// BaseScrollBar, ScrollBar implementation:
+
+void BaseScrollBar::Update(int viewport_size, int content_size,
+                           int contents_scroll_offset) {
+  ScrollBar::Update(viewport_size, content_size, contents_scroll_offset);
+
+  // Make sure contents_size is always > 0 to avoid divide by zero errors in
+  // calculations throughout this code.
+  contents_size_ = std::max(1, content_size);
+
+  if (content_size < 0)
+    content_size = 0;
+  if (contents_scroll_offset < 0)
+    contents_scroll_offset = 0;
+  if (contents_scroll_offset > content_size)
+    contents_scroll_offset = content_size;
+
+  // Thumb Height and Thumb Pos.
+  // The height of the thumb is the ratio of the Viewport height to the
+  // content size multiplied by the height of the thumb track.
+  double ratio = static_cast<double>(viewport_size) / contents_size_;
+  int thumb_size = static_cast<int>(ratio * GetTrackSize());
+  thumb_->SetSize(thumb_size);
+
+  int thumb_position = CalculateThumbPosition(contents_scroll_offset);
+  thumb_->SetPosition(thumb_position);
+}
+
+int BaseScrollBar::GetPosition() const {
+  return thumb_->GetPosition();
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// BaseScrollBar, protected:
+
+BaseScrollBarThumb* BaseScrollBar::GetThumb() const {
+  return thumb_;
+}
+
+void BaseScrollBar::ScrollToPosition(int position) {
+  GetController()->ScrollToPosition(this, position);
+}
+
+int BaseScrollBar::GetScrollIncrement(bool is_page, bool is_positive) {
+  return GetController()->GetScrollIncrement(this, is_page, is_positive);
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+// BaseScrollBar, private:
+
+void BaseScrollBar::TrackClicked() {
+  if (last_scroll_amount_ != SCROLL_NONE)
+    ScrollByAmount(last_scroll_amount_);
+}
+
+void BaseScrollBar::ScrollContentsToOffset() {
+  ScrollToPosition(contents_scroll_offset_);
+  thumb_->SetPosition(CalculateThumbPosition(contents_scroll_offset_));
+}
+
+int BaseScrollBar::GetTrackSize() const {
+  gfx::Rect track_bounds = GetTrackBounds();
+  return IsHorizontal() ? track_bounds.width() : track_bounds.height();
+}
+
+int BaseScrollBar::CalculateThumbPosition(int contents_scroll_offset) const {
+  return (contents_scroll_offset * GetTrackSize()) / contents_size_;
+}
+
+int BaseScrollBar::CalculateContentsOffset(int thumb_position,
+                                             bool scroll_to_middle) const {
+  if (scroll_to_middle)
+    thumb_position = thumb_position - (thumb_->GetSize() / 2);
+  return (thumb_position * contents_size_) / GetTrackSize();
+}
+
+void BaseScrollBar::SetThumbTrackState(CustomButton::ButtonState state) {
+  thumb_track_state_ = state;
+  SchedulePaint();
+}
+
+}  // namespace views