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 *
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 * for the specific language governing rights and limitations under the
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 *
 * The Original Code is mozilla.org code.
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 * The Initial Developer of the Original Code is
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 * Portions created by the Initial Developer are Copyright (C) 1998
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 *
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#ifndef nsIViewObserver_h___
#define nsIViewObserver_h___

#include "nsISupports.h"
#include "nsEvent.h"
#include "nsColor.h"
#include "nsRect.h"

class nsIRenderingContext;
class nsGUIEvent;

#define NS_IVIEWOBSERVER_IID  \
  { 0xc5dfb460, 0x50fb, 0x483e, \
    { 0xb4, 0x22, 0x19, 0xb7, 0x20, 0x4f, 0xe2, 0xdc } } //xxx

class nsIViewObserver : public nsISupports
{
public:
  
  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IVIEWOBSERVER_IID)

  /* called when the observer needs to paint. This paints the entire
   * frame subtree rooted at aViewToPaint, including frame subtrees from
   * subdocuments.
   * @param aViewToPaint the view for the widget that is being painted
   * @param aWidgetToPaint the widget that is being painted, the widget of
   * aViewToPaint
   * @param aDirtyRegion the region to be painted, in appunits of aDisplayRoot
   * and relative to aDisplayRoot
   * @param aIntDirtyRegion the region to be painted, in dev pixels, in the
   * coordinates of aWidgetToPaint. This conveys the same information as
   * aDirtyRegion but in a different format.
   * @param aPaintDefaultBackground just paint the default background,
   * don't try to paint any content. This is set when the observer
   * needs to paint something, but the view tree is unstable, so it
   * must *not* paint, or even examine, the frame subtree rooted at the
   * view.  (It is, however, safe to inspect the state of the view itself,
   * and any associated widget.) The name illustrates the expected behavior,
   * which is to paint some default background color over the dirty region.
   * @return error status
   */
  NS_IMETHOD Paint(nsIView*           aDisplayRoot,
                   nsIView*           aViewToPaint,
                   nsIWidget*         aWidgetToPaint,
                   const nsRegion&    aDirtyRegion,
                   const nsIntRegion& aIntDirtyRegion,
                   PRBool             aPaintDefaultBackground,
                   PRBool             aWillSendDidPaint) = 0;

  /* called when the observer needs to handle an event
   * @param aView  - where to start processing the event; the root view,
   * or the view that's currently capturing this sort of event; must be a view
   * for this presshell
   * @param aEvent - event notification
   * @param aEventStatus - out parameter for event handling
   *                       status
   * @param aHandled - whether the correct frame was found to
   *                   handle the event
   * @return error status
   */
  NS_IMETHOD HandleEvent(nsIView*       aView,
                         nsGUIEvent*    aEvent,
                         nsEventStatus* aEventStatus) = 0;

  /* called when the view has been resized and the
   * content within the view needs to be reflowed.
   * @param aWidth - new width of view
   * @param aHeight - new height of view
   * @return error status
   */
  NS_IMETHOD ResizeReflow(nsIView * aView, nscoord aWidth, nscoord aHeight) = 0;

  /**
   * Hack to find out if the view observer is itself visible, in lieu
   * of having the view trees linked.
   */
  NS_IMETHOD_(PRBool) IsVisible() = 0;

  /**
   * Returns true if the view observer wants to drop all invalidation right now
   * because painting is suppressed. It will invalidate everything when it
   * unsuppresses.
   */
  NS_IMETHOD_(PRBool) ShouldIgnoreInvalidation() = 0;

  /**
   * Notify the observer that we're about to start painting.  This
   * gives the observer a chance to make some last-minute invalidates
   * and geometry changes if it wants to.
   */
  NS_IMETHOD_(void) WillPaint(PRBool aWillSendDidPaint) = 0;

  /**
   * Notify the observer that we finished painting.  This
   * gives the observer a chance to make some last-minute invalidates
   * and geometry changes if it wants to.
   */
  NS_IMETHOD_(void) DidPaint() = 0;

  /**
   * Dispatch the given synthesized mouse move event, and if
   * aFlushOnHoverChange is true, flush layout if :hover changes cause
   * any restyles.
   */
  NS_IMETHOD_(void) DispatchSynthMouseMove(nsGUIEvent *aEvent,
                                           PRBool aFlushOnHoverChange) = 0;

  /**
   * If something within aView is capturing the mouse, clear the capture.
   * if aView is null, clear the mouse capture no matter what is capturing it.
   */
  NS_IMETHOD_(void) ClearMouseCapture(nsIView* aView) = 0;

};

NS_DEFINE_STATIC_IID_ACCESSOR(nsIViewObserver, NS_IVIEWOBSERVER_IID)

#endif
