gecko-dev/layout/generic/nsIScrollableFrame.h

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#ifndef nsIScrollFrame_h___
#define nsIScrollFrame_h___

#include "nsISupports.h"
#include "nsCoord.h"
#include "nsIViewManager.h"
#include "nsIScrollableViewProvider.h"

class nsIFrame;
class nsIBox;
class nsPresContext;
class nsBoxLayoutState;

// IID for the nsIScrollableFrame interface
#define NS_ISCROLLABLE_FRAME_IID    \
{ 0xc95f1831, 0xc372, 0x11d1, \
{ 0xb7, 0x21, 0x0, 0x64, 0x9, 0x92, 0xd8, 0xc9 } }

class nsIScrollableFrame : public nsIScrollableViewProvider {
public:

  enum nsScrollPref {
    Auto = 0,
    NeverScroll,
    AlwaysScroll,
    AlwaysScrollVertical,
    AlwaysScrollHorizontal
  };

  NS_DEFINE_STATIC_IID_ACCESSOR(NS_ISCROLLABLE_FRAME_IID)

  /**
   * Get the frame that we are scrolling within the scrollable frame.
   * @result child frame
   */
  NS_IMETHOD GetScrolledFrame(nsPresContext* aPresContext,
                              nsIFrame *&aScrolledFrame) const = 0;

  struct ScrollbarStyles {
    // one of NS_STYLE_OVERFLOW_SCROLL, NS_STYLE_OVERFLOW_HIDDEN,
    // NS_STYLE_OVERFLOW_VISIBLE, NS_STYLE_OVERFLOW_AUTO
    PRInt32 mHorizontal;
    PRInt32 mVertical;
    ScrollbarStyles(PRInt32 h, PRInt32 v) : mHorizontal(h), mVertical(v) {}
  };

  virtual ScrollbarStyles GetScrollbarStyles() const = 0;

  /**
   * Return the actual sizes of all possible scrollbars. Returns 0 for scrollbar
   * positions that don't have a scrollbar or where the scrollbar is not visible.
   */
  virtual nsMargin GetActualScrollbarSizes() const = 0;

  /**
   * Return the sizes of all scrollbars assuming that any scrollbars that could
   * be visible due to overflowing content, are.
   */
  virtual nsMargin GetDesiredScrollbarSizes(nsBoxLayoutState* aState) = 0;

  /**
   * Query whether scroll bars should be displayed all the time, never or
   * only when necessary.
   * @return current scrollbar selection
   */
  NS_IMETHOD  GetScrollPreference(nsPresContext* aPresContext, nsScrollPref* aScrollPreference) const = 0;

  /**
   * Get the position of the scrolled view.
   */
  NS_IMETHOD  GetScrollPosition(nsPresContext* aContext, nscoord &aX, nscoord& aY) const=0;

  /**
   * Scroll the view to the given x,y, update's the scrollbar's thumb
   * positions and the view's offset. Clamps the values to be
   * legal. Updates the display based on aUpdateFlags.
   * @param aX left edge to scroll to
   * @param aY top edge to scroll to
   * @param aUpdateFlags passed onto nsIViewManager->UpdateView()
   * @return error status
   */
  NS_IMETHOD ScrollTo(nsPresContext* aContext, nscoord aX, nscoord aY, PRUint32 aFlags = NS_VMREFRESH_NO_SYNC)=0;

  NS_IMETHOD GetScrollableView(nsPresContext* aContext, nsIScrollableView** aResult)=0;


  /**
   * Set information about whether the vertical and horizontal scrollbars
   * are currently visible
   */
  NS_IMETHOD SetScrollbarVisibility(nsPresContext* aPresContext,
                                    PRBool aVerticalVisible,
                                    PRBool aHorizontalVisible) = 0;

  NS_IMETHOD GetScrollbarBox(PRBool aVertical, nsIBox** aResult) = 0;

  NS_IMETHOD CurPosAttributeChanged(nsPresContext* aPresContext,
                                    nsIContent* aChild,
                                    PRInt32 aModType) = 0;

  /**
   * This tells the scroll frame to try scrolling to the scroll
   * position that was restored from the history. This must be called
   * at least once after state has been restored. It is called by the
   * scrolled frame itself during reflow, but sometimes state can be
   * restored after reflows are done...
   */
  virtual void ScrollToRestoredPosition() = 0;
};

#endif