layout/xul/nsIScrollbarMediator.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef nsIScrollbarMediator_h___
   8 #define nsIScrollbarMediator_h___
   9
  10 #include "mozilla/ScrollTypes.h"
  11 #include "nsQueryFrame.h"
  12 #include "nsCoord.h"
  13
  14 class nsScrollbarFrame;
  15 class nsIFrame;
  16
  17 class nsIScrollbarMediator : public nsQueryFrame {
  18  public:
  19   NS_DECL_QUERYFRAME_TARGET(nsIScrollbarMediator)
  20
  21   /**
  22    * The aScrollbar argument denotes the scrollbar that's firing the
  23    * notification. aScrollbar is never null. aDirection is either -1, 0, or 1.
  24    */
  25
  26   /**
  27    * When set to ENABLE_SNAP, additional scrolling will be performed after the
  28    * scroll operation to maintain the constraints set by CSS Scroll snapping.
  29    * The additional scrolling may include asynchronous smooth scrolls that
  30    * continue to animate after the initial scroll position has been set.
  31    * In case of DEFAULT, it means ENABLE_SNAP for CSS scroll snap v1,
  32    * DISABLE_SNAP for the old scroll snap.
  33    */
  34
  35   /**
  36    * One of the following three methods is called when the scrollbar's button is
  37    * clicked.
  38    * @note These methods might destroy the frame, pres shell, and other objects.
  39    */
  40   virtual void ScrollByPage(nsScrollbarFrame* aScrollbar, int32_t aDirection,
  41                             mozilla::ScrollSnapFlags aSnapFlags =
  42                                 mozilla::ScrollSnapFlags::Disabled) = 0;
  43   virtual void ScrollByWhole(nsScrollbarFrame* aScrollbar, int32_t aDirection,
  44                              mozilla::ScrollSnapFlags aSnapFlags =
  45                                  mozilla::ScrollSnapFlags::Disabled) = 0;
  46   virtual void ScrollByLine(nsScrollbarFrame* aScrollbar, int32_t aDirection,
  47                             mozilla::ScrollSnapFlags aSnapFlags =
  48                                 mozilla::ScrollSnapFlags::Disabled) = 0;
  49
  50   // Only implemented for nsGfxScrollFrame, not nsTreeBodyFrame.
  51   virtual void ScrollByUnit(nsScrollbarFrame* aScrollbar,
  52                             mozilla::ScrollMode aMode, int32_t aDirection,
  53                             mozilla::ScrollUnit aUnit,
  54                             mozilla::ScrollSnapFlags aSnapFlags =
  55                                 mozilla::ScrollSnapFlags::Disabled) = 0;
  56
  57   /**
  58    * RepeatButtonScroll is called when the scrollbar's button is held down. When
  59    * the button is first clicked the increment is set; RepeatButtonScroll adds
  60    * this increment to the current position.
  61    * @note This method might destroy the frame, pres shell, and other objects.
  62    */
  63   virtual void RepeatButtonScroll(nsScrollbarFrame* aScrollbar) = 0;
  64   /**
  65    * aOldPos and aNewPos are scroll positions.
  66    * The scroll positions start with zero at the left edge; implementors that
  67    * want zero at the right edge for RTL content will need to adjust
  68    * accordingly. (See nsHTMLScrollFrame::ThumbMoved in nsGfxScrollFrame.cpp.)
  69    * @note This method might destroy the frame, pres shell, and other objects.
  70    */
  71   virtual void ThumbMoved(nsScrollbarFrame* aScrollbar, nscoord aOldPos,
  72                           nscoord aNewPos) = 0;
  73   /**
  74    * Called when the scroll bar thumb, slider, or any other component is
  75    * released.
  76    */
  77   virtual void ScrollbarReleased(nsScrollbarFrame* aScrollbar) = 0;
  78   virtual void VisibilityChanged(bool aVisible) = 0;
  79
  80   /**
  81    * Obtain the frame for the horizontal or vertical scrollbar, or null
  82    * if there is no such box.
  83    */
  84   virtual nsScrollbarFrame* GetScrollbarBox(bool aVertical) = 0;
  85   /**
  86    * Show or hide scrollbars on 2 fingers touch.
  87    * Subclasses should call their ScrollbarActivity's corresponding methods.
  88    */
  89   virtual void ScrollbarActivityStarted() const = 0;
  90   virtual void ScrollbarActivityStopped() const = 0;
  91
  92   virtual bool IsScrollbarOnRight() const = 0;
  93
  94   /**
  95    * Returns true if the mediator is asking the scrollbar to suppress
  96    * repainting itself on changes.
  97    */
  98   virtual bool ShouldSuppressScrollbarRepaints() const = 0;
  99 };
 100
 101 #endif