ui/views/controls/scroll_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_SCROLL_VIEW_H_
   6 #define UI_VIEWS_CONTROLS_SCROLL_VIEW_H_
   7
   8 #include <string>
   9
  10 #include "base/compiler_specific.h"
  11 #include "ui/views/controls/scrollbar/scroll_bar.h"
  12
  13 namespace views {
  14
  15 /////////////////////////////////////////////////////////////////////////////
  16 //
  17 // ScrollView class
  18 //
  19 // A ScrollView is used to make any View scrollable. The view is added to
  20 // a viewport which takes care of clipping.
  21 //
  22 // In this current implementation both horizontal and vertical scrollbars are
  23 // added as needed.
  24 //
  25 // The scrollview supports keyboard UI and mousewheel.
  26 //
  27 /////////////////////////////////////////////////////////////////////////////
  28
  29 class VIEWS_EXPORT ScrollView : public View, public ScrollBarController {
  30  public:
  31   static const char kViewClassName[];
  32
  33   ScrollView();
  34
  35   virtual ~ScrollView();
  36
  37   // Creates a ScrollView with a theme specific border.
  38   static ScrollView* CreateScrollViewWithBorder();
  39
  40   // Set the contents. Any previous contents will be deleted. The contents
  41   // is the view that needs to scroll.
  42   void SetContents(View* a_view);
  43   const View* contents() const { return contents_; }
  44   View* contents() { return contents_; }
  45
  46   // Sets the header, deleting the previous header.
  47   void SetHeader(View* header);
  48
  49   // Returns the visible region of the content View.
  50   gfx::Rect GetVisibleRect() const;
  51
  52   void set_hide_horizontal_scrollbar(bool visible) {
  53     hide_horizontal_scrollbar_ = visible;
  54   }
  55
  56   // Turns this scroll view into a bounded scroll view, with a fixed height.
  57   // By default, a ScrollView will stretch to fill its outer container.
  58   void ClipHeightTo(int min_height, int max_height);
  59
  60   // Returns whether or not the ScrollView is bounded (as set by ClipHeightTo).
  61   bool is_bounded() const { return max_height_ >= 0 && min_height_ >= 0; }
  62
  63   // Retrieves the width/height of scrollbars. These return 0 if the scrollbar
  64   // has not yet been created.
  65   int GetScrollBarWidth() const;
  66   int GetScrollBarHeight() const;
  67
  68   // Returns the horizontal/vertical scrollbar. This may return NULL.
  69   const ScrollBar* horizontal_scroll_bar() const { return horiz_sb_; }
  70   const ScrollBar* vertical_scroll_bar() const { return vert_sb_; }
  71
  72   // Customize the scrollbar design. ScrollView takes the ownership of the
  73   // specified ScrollBar. |horiz_sb| and |vert_sb| cannot be NULL.
  74   void SetHorizontalScrollBar(ScrollBar* horiz_sb);
  75   void SetVerticalScrollBar(ScrollBar* vert_sb);
  76
  77   // View overrides:
  78   virtual gfx::Size GetPreferredSize() const OVERRIDE;
  79   virtual int GetHeightForWidth(int width) const OVERRIDE;
  80   virtual void Layout() OVERRIDE;
  81   virtual bool OnKeyPressed(const ui::KeyEvent& event) OVERRIDE;
  82   virtual bool OnMouseWheel(const ui::MouseWheelEvent& e) OVERRIDE;
  83   virtual void OnMouseEntered(const ui::MouseEvent& event) OVERRIDE;
  84   virtual void OnMouseExited(const ui::MouseEvent& event) OVERRIDE;
  85   virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
  86   virtual const char* GetClassName() const OVERRIDE;
  87
  88   // ScrollBarController overrides:
  89   virtual void ScrollToPosition(ScrollBar* source, int position) OVERRIDE;
  90   virtual int GetScrollIncrement(ScrollBar* source,
  91                                  bool is_page,
  92                                  bool is_positive) OVERRIDE;
  93
  94  private:
  95   class Viewport;
  96
  97   // Used internally by SetHeader() and SetContents() to reset the view.  Sets
  98   // |member| to |new_view|. If |new_view| is non-null it is added to |parent|.
  99   void SetHeaderOrContents(View* parent, View* new_view, View** member);
 100
 101   // Scrolls the minimum amount necessary to make the specified rectangle
 102   // visible, in the coordinates of the contents view. The specified rectangle
 103   // is constrained by the bounds of the contents view. This has no effect if
 104   // the contents have not been set.
 105   void ScrollContentsRegionToBeVisible(const gfx::Rect& rect);
 106
 107   // Computes the visibility of both scrollbars, taking in account the view port
 108   // and content sizes.
 109   void ComputeScrollBarsVisibility(const gfx::Size& viewport_size,
 110                                    const gfx::Size& content_size,
 111                                    bool* horiz_is_shown,
 112                                    bool* vert_is_shown) const;
 113
 114   // Shows or hides the scrollbar/resize_corner based on the value of
 115   // |should_show|.
 116   void SetControlVisibility(View* control, bool should_show);
 117
 118   // Update the scrollbars positions given viewport and content sizes.
 119   void UpdateScrollBarPositions();
 120
 121   // The current contents and its viewport. |contents_| is contained in
 122   // |contents_viewport_|.
 123   View* contents_;
 124   View* contents_viewport_;
 125
 126   // The current header and its viewport. |header_| is contained in
 127   // |header_viewport_|.
 128   View* header_;
 129   View* header_viewport_;
 130
 131   // Horizontal scrollbar.
 132   ScrollBar* horiz_sb_;
 133
 134   // Vertical scrollbar.
 135   ScrollBar* vert_sb_;
 136
 137   // Resize corner.
 138   View* resize_corner_;
 139
 140   // The min and max height for the bounded scroll view. These are negative
 141   // values if the view is not bounded.
 142   int min_height_;
 143   int max_height_;
 144
 145   // If true, never show the horizontal scrollbar (even if the contents is wider
 146   // than the viewport).
 147   bool hide_horizontal_scrollbar_;
 148
 149   DISALLOW_COPY_AND_ASSIGN(ScrollView);
 150 };
 151
 152 // VariableRowHeightScrollHelper is intended for views that contain rows of
 153 // varying height. To use a VariableRowHeightScrollHelper create one supplying
 154 // a Controller and delegate GetPageScrollIncrement and GetLineScrollIncrement
 155 // to the helper. VariableRowHeightScrollHelper calls back to the
 156 // Controller to determine row boundaries.
 157 class VariableRowHeightScrollHelper {
 158  public:
 159   // The origin and height of a row.
 160   struct RowInfo {
 161     RowInfo(int origin, int height) : origin(origin), height(height) {}
 162
 163     // Origin of the row.
 164     int origin;
 165
 166     // Height of the row.
 167     int height;
 168   };
 169
 170   // Used to determine row boundaries.
 171   class Controller {
 172    public:
 173     // Returns the origin and size of the row at the specified location.
 174     virtual VariableRowHeightScrollHelper::RowInfo GetRowInfo(int y) = 0;
 175   };
 176
 177   // Creates a new VariableRowHeightScrollHelper. Controller is
 178   // NOT deleted by this VariableRowHeightScrollHelper.
 179   explicit VariableRowHeightScrollHelper(Controller* controller);
 180   virtual ~VariableRowHeightScrollHelper();
 181
 182   // Delegate the View methods of the same name to these. The scroll amount is
 183   // determined by querying the Controller for the appropriate row to scroll
 184   // to.
 185   int GetPageScrollIncrement(ScrollView* scroll_view,
 186                              bool is_horizontal, bool is_positive);
 187   int GetLineScrollIncrement(ScrollView* scroll_view,
 188                              bool is_horizontal, bool is_positive);
 189
 190  protected:
 191   // Returns the row information for the row at the specified location. This
 192   // calls through to the method of the same name on the controller.
 193   virtual RowInfo GetRowInfo(int y);
 194
 195  private:
 196   Controller* controller_;
 197
 198   DISALLOW_COPY_AND_ASSIGN(VariableRowHeightScrollHelper);
 199 };
 200
 201 // FixedRowHeightScrollHelper is intended for views that contain fixed height
 202 // height rows. To use a FixedRowHeightScrollHelper delegate
 203 // GetPageScrollIncrement and GetLineScrollIncrement to it.
 204 class FixedRowHeightScrollHelper : public VariableRowHeightScrollHelper {
 205  public:
 206   // Creates a FixedRowHeightScrollHelper. top_margin gives the distance from
 207   // the top of the view to the first row, and may be 0. row_height gives the
 208   // height of each row.
 209   FixedRowHeightScrollHelper(int top_margin, int row_height);
 210
 211  protected:
 212   // Calculates the bounds of the row from the top margin and row height.
 213   virtual RowInfo GetRowInfo(int y) OVERRIDE;
 214
 215  private:
 216   int top_margin_;
 217   int row_height_;
 218
 219   DISALLOW_COPY_AND_ASSIGN(FixedRowHeightScrollHelper);
 220 };
 221
 222 }  // namespace views
 223
 224 #endif  // UI_VIEWS_CONTROLS_SCROLL_VIEW_H_