gecko-dev/accessible/src/base/nsEventShell.h

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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.
 *
 * The Initial Developer of the Original Code is
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 * Portions created by the Initial Developer are Copyright (C) 2010
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 * Contributor(s):
 *   Alexander Surkov <surkov.alexander@gmail.com> (original author)
 *
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#ifndef _nsEventShell_H_
#define _nsEventShell_H_

#include "nsAccEvent.h"

#include "a11yGeneric.h"

#include "nsAutoPtr.h"

#include "nsRefreshDriver.h"

class nsIPersistentProperties;

/**
 * Used for everything about events.
 */
class nsEventShell
{
public:

  /**
   * Fire the accessible event.
   */
  static void FireEvent(nsAccEvent *aEvent);

  /**
   * Fire accessible event of the given type for the given accessible.
   *
   * @param  aEventType   [in] the event type
   * @param  aAccessible  [in] the event target
   * @param  aIsAsync     [in, optional] specifies whether the origin change
   *                        this event is fired owing to is async.
   */
  static void FireEvent(PRUint32 aEventType, nsAccessible *aAccessible,
                        PRBool aIsAsynch = PR_FALSE,
                        EIsFromUserInput aIsFromUserInput = eAutoDetect);

  /**
   * Append 'event-from-input' object attribute if the accessible event has
   * been fired just now for the given node.
   *
   * @param  aNode        [in] the DOM node
   * @param  aAttributes  [in, out] the attributes
   */
  static void GetEventAttributes(nsINode *aNode,
                                 nsIPersistentProperties *aAttributes);

private:
  static nsCOMPtr<nsINode> sEventTargetNode;
  static PRBool sEventFromUserInput;
};


/**
 * Event queue.
 */
class nsAccEventQueue : public nsISupports,
                        public nsARefreshObserver
{
public:
  nsAccEventQueue(nsDocAccessible *aDocument);
  ~nsAccEventQueue();

  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_CLASS(nsAccEventQueue)

  /**
   * Push event to queue, coalesce it if necessary. Start pending processing.
   */
  void Push(nsAccEvent *aEvent);

  /**
   * Shutdown the queue.
   */
  void Shutdown();

private:

  /**
   * Start pending events processing asynchronously.
   */
  void PrepareFlush();
  
  /**
   * Process pending events. It calls nsDocAccessible::ProcessPendingEvent()
   * where the real event processing is happen.
   */
  virtual void WillRefresh(mozilla::TimeStamp aTime);

  /**
   * Coalesce redundant events from the queue.
   */
  void CoalesceEvents();

  /**
   * Apply aEventRule to same type event that from sibling nodes of aDOMNode.
   * @param aEventsToFire    array of pending events
   * @param aStart           start index of pending events to be scanned
   * @param aEnd             end index to be scanned (not included)
   * @param aEventType       target event type
   * @param aDOMNode         target are siblings of this node
   * @param aEventRule       the event rule to be applied
   *                         (should be eDoNotEmit or eAllowDupes)
   */
  void ApplyToSiblings(PRUint32 aStart, PRUint32 aEnd,
                       PRUint32 aEventType, nsINode* aNode,
                       nsAccEvent::EEventRule aEventRule);

  /**
   * Do not emit one of two given reorder events fired for the same DOM node.
   */
  void CoalesceReorderEventsFromSameSource(nsAccEvent *aAccEvent1,
                                           nsAccEvent *aAccEvent2);

  /**
   * Do not emit one of two given reorder events fired for DOM nodes in the case
   * when one DOM node is in parent chain of second one.
   */
  void CoalesceReorderEventsFromSameTree(nsAccEvent *aAccEvent,
                                         nsAccEvent *aDescendantAccEvent);

  /**
   * Coalesce text change events caused by sibling hide events.
   */
  void CoalesceTextChangeEventsFor(AccHideEvent* aTailEvent,
                                   AccHideEvent* aThisEvent);

  /**
   * Create text change event caused by hide event. When a node is hidden or
   * removed, the text in an ancestor hyper text will lose characters. Create
   * text change event unless the node is being removed or frame is being
   * destroyed.
   */
  void CreateTextChangeEventFor(AccHideEvent* aEvent);

  /**
   * Indicates whether we're waiting on a refresh notification from our
   * presshell to flush events
   */
  PRBool mObservingRefresh;

  /**
   * The document accessible reference owning this queue.
   */
  nsRefPtr<nsDocAccessible> mDocument;

  /**
   * Pending events array.  Don't make this an nsAutoTArray; we use
   * SwapElements() on it.
   */
  nsTArray<nsRefPtr<nsAccEvent> > mEvents;
};

#endif