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       1             : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* This Source Code Form is subject to the terms of the Mozilla Public
       3             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       4             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       5             : 
       6             : #ifndef nsIScrollbarMediator_h___
       7             : #define nsIScrollbarMediator_h___
       8             : 
       9             : #include "nsQueryFrame.h"
      10             : #include "nsCoord.h"
      11             : 
      12             : class nsScrollbarFrame;
      13             : class nsIFrame;
      14             : 
      15          43 : class nsIScrollbarMediator : public nsQueryFrame
      16             : {
      17             : public:
      18             :   NS_DECL_QUERYFRAME_TARGET(nsIScrollbarMediator)
      19             : 
      20             :   /**
      21             :    * The aScrollbar argument denotes the scrollbar that's firing the notification.
      22             :    * aScrollbar is never null.
      23             :    * 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             :    */
      32             :   enum ScrollSnapMode { DISABLE_SNAP, ENABLE_SNAP };
      33             : 
      34             :   /**
      35             :    * One of the following three methods is called when the scrollbar's button is
      36             :    * clicked.
      37             :    * @note These methods might destroy the frame, pres shell, and other objects.
      38             :    */
      39             :   virtual void ScrollByPage(nsScrollbarFrame* aScrollbar, int32_t aDirection,
      40             :                             ScrollSnapMode aSnap = DISABLE_SNAP) = 0;
      41             :   virtual void ScrollByWhole(nsScrollbarFrame* aScrollbar, int32_t aDirection,
      42             :                             ScrollSnapMode aSnap = DISABLE_SNAP) = 0;
      43             :   virtual void ScrollByLine(nsScrollbarFrame* aScrollbar, int32_t aDirection,
      44             :                             ScrollSnapMode aSnap = DISABLE_SNAP) = 0;
      45             :   /**
      46             :    * RepeatButtonScroll is called when the scrollbar's button is held down. When the
      47             :    * button is first clicked the increment is set; RepeatButtonScroll adds this
      48             :    * increment to the current position.
      49             :    * @note This method might destroy the frame, pres shell, and other objects.
      50             :    */
      51             :   virtual void RepeatButtonScroll(nsScrollbarFrame* aScrollbar) = 0;
      52             :   /**
      53             :    * aOldPos and aNewPos are scroll positions.
      54             :    * The scroll positions start with zero at the left edge; implementors that want
      55             :    * zero at the right edge for RTL content will need to adjust accordingly.
      56             :    * (See ScrollFrameHelper::ThumbMoved in nsGfxScrollFrame.cpp.)
      57             :    * @note This method might destroy the frame, pres shell, and other objects.
      58             :    */
      59             :   virtual void ThumbMoved(nsScrollbarFrame* aScrollbar,
      60             :                           nscoord aOldPos,
      61             :                           nscoord aNewPos) = 0;
      62             :   /**
      63             :    * Called when the scroll bar thumb, slider, or any other component is
      64             :    * released.
      65             :    */
      66             :   virtual void ScrollbarReleased(nsScrollbarFrame* aScrollbar) = 0;
      67             :   virtual void VisibilityChanged(bool aVisible) = 0;
      68             : 
      69             :   /**
      70             :    * Obtain the frame for the horizontal or vertical scrollbar, or null
      71             :    * if there is no such box.
      72             :    */
      73             :   virtual nsIFrame* GetScrollbarBox(bool aVertical) = 0;
      74             :   /**
      75             :    * Show or hide scrollbars on 2 fingers touch.
      76             :    * Subclasses should call their ScrollbarActivity's corresponding methods.
      77             :    */
      78             :   virtual void ScrollbarActivityStarted() const = 0;
      79             :   virtual void ScrollbarActivityStopped() const = 0;
      80             : 
      81             :   virtual bool IsScrollbarOnRight() const = 0;
      82             : 
      83             :   /**
      84             :    * Returns true if the mediator is asking the scrollbar to suppress
      85             :    * repainting itself on changes.
      86             :    */
      87             :   virtual bool ShouldSuppressScrollbarRepaints() const = 0;
      88             : };
      89             : 
      90             : #endif
      91             :