ui/views/controls/menu/submenu_view.h

   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 #ifndef UI_VIEWS_CONTROLS_MENU_SUBMENU_VIEW_H_
   6 #define UI_VIEWS_CONTROLS_MENU_SUBMENU_VIEW_H_
   7
   8 #include <string>
   9
  10 #include "base/compiler_specific.h"
  11 #include "ui/views/animation/scroll_animator.h"
  12 #include "ui/views/controls/menu/menu_delegate.h"
  13 #include "ui/views/controls/prefix_delegate.h"
  14 #include "ui/views/controls/prefix_selector.h"
  15 #include "ui/views/view.h"
  16
  17 namespace views {
  18
  19 class MenuHost;
  20 class MenuItemView;
  21 class MenuScrollViewContainer;
  22
  23 // SubmenuView is the parent of all menu items.
  24 //
  25 // SubmenuView has the following responsibilities:
  26 // . It positions and sizes all child views (any type of View may be added,
  27 //   not just MenuItemViews).
  28 // . Forwards the appropriate events to the MenuController. This allows the
  29 //   MenuController to update the selection as the user moves the mouse around.
  30 // . Renders the drop indicator during a drop operation.
  31 // . Shows and hides the window (a NativeWidget) when the menu is shown on
  32 //   screen.
  33 //
  34 // SubmenuView is itself contained in a MenuScrollViewContainer.
  35 // MenuScrollViewContainer handles showing as much of the SubmenuView as the
  36 // screen allows. If the SubmenuView is taller than the screen, scroll buttons
  37 // are provided that allow the user to see all the menu items.
  38 class VIEWS_EXPORT SubmenuView : public PrefixDelegate,
  39                                  public ScrollDelegate {
  40  public:
  41   // The submenu's class name.
  42   static const char kViewClassName[];
  43
  44   // Creates a SubmenuView for the specified menu item.
  45   explicit SubmenuView(MenuItemView* parent);
  46   ~SubmenuView() override;
  47
  48   // Returns the number of child views that are MenuItemViews.
  49   // MenuItemViews are identified by ID.
  50   int GetMenuItemCount();
  51
  52   // Returns the MenuItemView at the specified index.
  53   MenuItemView* GetMenuItemAt(int index);
  54
  55   PrefixSelector* GetPrefixSelector();
  56
  57   // Positions and sizes the child views. This tiles the views vertically,
  58   // giving each child the available width.
  59   void Layout() override;
  60   gfx::Size GetPreferredSize() const override;
  61
  62   // Override from View.
  63   void GetAccessibleState(ui::AXViewState* state) override;
  64
  65   // Painting.
  66   void PaintChildren(const ui::PaintContext& context) override;
  67
  68   // Drag and drop methods. These are forwarded to the MenuController.
  69   bool GetDropFormats(
  70       int* formats,
  71       std::set<OSExchangeData::CustomFormat>* custom_formats) override;
  72   bool AreDropTypesRequired() override;
  73   bool CanDrop(const OSExchangeData& data) override;
  74   void OnDragEntered(const ui::DropTargetEvent& event) override;
  75   int OnDragUpdated(const ui::DropTargetEvent& event) override;
  76   void OnDragExited() override;
  77   int OnPerformDrop(const ui::DropTargetEvent& event) override;
  78
  79   // Scrolls on menu item boundaries.
  80   bool OnMouseWheel(const ui::MouseWheelEvent& e) override;
  81
  82   // Overridden from ui::EventHandler.
  83   // Scrolls on menu item boundaries.
  84   void OnGestureEvent(ui::GestureEvent* event) override;
  85
  86   // Overridden from PrefixDelegate.
  87   int GetRowCount() override;
  88   int GetSelectedRow() override;
  89   void SetSelectedRow(int row) override;
  90   base::string16 GetTextForRow(int row) override;
  91
  92   // Returns true if the menu is showing.
  93   virtual bool IsShowing();
  94
  95   // Shows the menu at the specified location. Coordinates are in screen
  96   // coordinates. max_width gives the max width the view should be.
  97   void ShowAt(Widget* parent, const gfx::Rect& bounds, bool do_capture);
  98
  99   // Resets the bounds of the submenu to |bounds|.
 100   void Reposition(const gfx::Rect& bounds);
 101
 102   // Closes the menu, destroying the host.
 103   void Close();
 104
 105   // Hides the hosting window.
 106   //
 107   // The hosting window is hidden first, then deleted (Close) when the menu is
 108   // done running. This is done to avoid deletion ordering dependencies. In
 109   // particular, during drag and drop (and when a modal dialog is shown as
 110   // a result of choosing a context menu) it is possible that an event is
 111   // being processed by the host, so that host is on the stack when we need to
 112   // close the window. If we closed the window immediately (and deleted it),
 113   // when control returned back to host we would crash as host was deleted.
 114   void Hide();
 115
 116   // If mouse capture was grabbed, it is released. Does nothing if mouse was
 117   // not captured.
 118   void ReleaseCapture();
 119
 120   // Overriden from View to prevent tab from doing anything.
 121   bool SkipDefaultKeyEventProcessing(const ui::KeyEvent& e) override;
 122
 123   // Returns the parent menu item we're showing children for.
 124   MenuItemView* GetMenuItem() const;
 125
 126   // Set the drop item and position.
 127   void SetDropMenuItem(MenuItemView* item,
 128                        MenuDelegate::DropPosition position);
 129
 130   // Returns whether the selection should be shown for the specified item.
 131   // The selection is NOT shown during drag and drop when the drop is over
 132   // the menu.
 133   bool GetShowSelection(MenuItemView* item);
 134
 135   // Returns the container for the SubmenuView.
 136   MenuScrollViewContainer* GetScrollViewContainer();
 137
 138   // Invoked if the menu is prematurely destroyed. This can happen if the window
 139   // closes while the menu is shown. If invoked the SubmenuView must drop all
 140   // references to the MenuHost as the MenuHost is about to be deleted.
 141   void MenuHostDestroyed();
 142
 143   // Max width of minor text (accelerator or subtitle) in child menu items. This
 144   // doesn't include children's children, only direct children.
 145   int max_minor_text_width() const { return max_minor_text_width_; }
 146
 147   // Minimum width of menu in pixels (default 0).  This becomes the smallest
 148   // width returned by GetPreferredSize().
 149   void set_minimum_preferred_width(int minimum_preferred_width) {
 150     minimum_preferred_width_ = minimum_preferred_width;
 151   }
 152
 153   // Automatically resize menu if a subview's preferred size changes.
 154   bool resize_open_menu() const { return resize_open_menu_; }
 155   void set_resize_open_menu(bool resize_open_menu) {
 156     resize_open_menu_ = resize_open_menu;
 157   }
 158
 159  protected:
 160   // Overridden from View:
 161   const char* GetClassName() const override;
 162
 163   // View method. Overridden to schedule a paint. We do this so that when
 164   // scrolling occurs, everything is repainted correctly.
 165   void OnBoundsChanged(const gfx::Rect& previous_bounds) override;
 166
 167   void ChildPreferredSizeChanged(View* child) override;
 168
 169  private:
 170   void SchedulePaintForDropIndicator(MenuItemView* item,
 171                                      MenuDelegate::DropPosition position);
 172
 173   // Calculates the location of th edrop indicator.
 174   gfx::Rect CalculateDropIndicatorBounds(MenuItemView* item,
 175                                          MenuDelegate::DropPosition position);
 176
 177   // Implementation of ScrollDelegate
 178   bool OnScroll(float dx, float dy) override;
 179
 180   // Parent menu item.
 181   MenuItemView* parent_menu_item_;
 182
 183   // Widget subclass used to show the children. This is deleted when we invoke
 184   // |DestroyMenuHost|, or |MenuHostDestroyed| is invoked back on us.
 185   MenuHost* host_;
 186
 187   // If non-null, indicates a drop is in progress and drop_item is the item
 188   // the drop is over.
 189   MenuItemView* drop_item_;
 190
 191   // Position of the drop.
 192   MenuDelegate::DropPosition drop_position_;
 193
 194   // Ancestor of the SubmenuView, lazily created.
 195   MenuScrollViewContainer* scroll_view_container_;
 196
 197   // See description above getter.
 198   mutable int max_minor_text_width_;
 199
 200   // Minimum width returned in GetPreferredSize().
 201   int minimum_preferred_width_;
 202
 203   // Reposition open menu when contained views change size.
 204   bool resize_open_menu_;
 205
 206   // The submenu's scroll animator
 207   scoped_ptr<ScrollAnimator> scroll_animator_;
 208
 209   // Difference between current position and cumulative deltas passed to
 210   // OnScroll.
 211   // TODO(tdresser): This should be removed when raw pixel scrolling for views
 212   // is enabled. See crbug.com/329354.
 213   float roundoff_error_;
 214
 215   PrefixSelector prefix_selector_;
 216
 217   DISALLOW_COPY_AND_ASSIGN(SubmenuView);
 218 };
 219
 220 }  // namespace views
 221
 222 #endif  // UI_VIEWS_CONTROLS_MENU_SUBMENU_VIEW_H_