RetroZilla/view/public/nsIViewObserver.h

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 * The Original Code is mozilla.org code.
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#ifndef nsIViewObserver_h___
#define nsIViewObserver_h___

#include "nsISupports.h"
#include "nsEvent.h"

class nsIRenderingContext;
struct nsRect;
class nsGUIEvent;

#define NS_IVIEWOBSERVER_IID   \
{ 0x0f4bc34a, 0xc93b, 0x4699, \
{ 0xb6, 0xc2, 0xb3, 0xca, 0x9e, 0xe4, 0x6c, 0x95 } }

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

  /* called when the observer needs to paint
   * @param aRenderingContext - rendering context to paint to
   * @param aDirtyRect - rectangle of dirty area
   * @return error status
   */
  NS_IMETHOD Paint(nsIView *            aView,
                   nsIRenderingContext& aRenderingContext,
                   const nsRect&        aDirtyRect) = 0;

  /* called when the observer needs to handle an event
   * @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,
                         PRBool          aForceHandle,
                         PRBool&         aHandled) = 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;

  /**
   * 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() = 0;
};

#endif