gecko-dev/layout/generic/nsHTMLReflowCommand.h

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#ifndef nsHTMLReflowCommand_h___
#define nsHTMLReflowCommand_h___
#include "nsReflowType.h"
#include "nsVoidArray.h"
#include <stdio.h>

class  nsIAtom;
class  nsIFrame;
class  nsIPresContext;
class  nsIRenderingContext;
struct nsHTMLReflowMetrics;
struct nsSize;

// Reflow command flags
#define NS_RC_CREATED_DURING_DOCUMENT_LOAD 0x0001


/**
 * A reflow command is an object that is generated in response to a content
 * model change notification. The reflow command is given to a presentation
 * shell where it is queued and then dispatched by invoking the reflow
 * commands's Dispatch() member function.
 *
 * Reflow command processing follows a path from the root frame down to the
 * target frame (the frame for which the reflow command is destined). Reflow
 * commands are processed by invoking the frame's Reflow() member function.
 *
 * The typical flow of control for a given reflow command starts with a content
 * change notification. The content notifications are sent to document observers.
 * The presentation shell forwards the notifications to the style set. The style
 * system responds to the notifications by creating new frame (or destroying
 * existing frames) as appropriate, and then generating a reflow command.
 *
 * @see nsIDocumentObserver
 * @see nsIStyleSet
 * @see nsIFrameReflow#Reflow()
 * @see nsIPresShell#AppendReflowCommand()
 * @see nsIPresShell#ProcessReflowCommands()
 */
class nsHTMLReflowCommand {
public:
  /**
   * Construct an HTML reflow command of type aReflowType and with target
   * frame aTargetFrame. You can also specify an optional child frame, e.g.
   * to indicate the inserted child frame
   */
  nsHTMLReflowCommand(nsIFrame*    aTargetFrame,
                      nsReflowType aReflowType,
                      nsIFrame*    aChildFrame = nsnull,
                      nsIAtom*     aAttribute = nsnull);

  ~nsHTMLReflowCommand();

  /**
   * Get the target of the reflow command.
   */
  nsresult GetTarget(nsIFrame*& aTargetFrame) const;

  /**
   * Change the target of the reflow command.
   */
  nsresult SetTarget(nsIFrame* aTargetFrame);

  /**
   * Get the type of reflow command.
   */
  nsresult GetType(nsReflowType& aReflowType) const;

  /**
   * Can return nsnull.  If nsnull is not returned, the caller must NS_RELEASE aAttribute
   */
  nsresult GetAttribute(nsIAtom *& aAttribute) const;

  /**
   * Get the child frame associated with the reflow command.
   */
  nsresult GetChildFrame(nsIFrame*& aChildFrame) const;

  /**
   * Returns the name of the child list to which the child frame belongs.
   * Only used for reflow command types FrameAppended, FrameInserted, and
   * FrameRemoved
   *
   * Returns nsnull if the child frame is associated with the unnamed
   * principal child list
   */
  nsresult GetChildListName(nsIAtom*& aListName) const;

  /**
   * Sets the name of the child list to which the child frame belongs.
   * Only used for reflow command types FrameAppended, FrameInserted, and
   * FrameRemoved
   */
  nsresult SetChildListName(nsIAtom* aListName);

  /**
   * Dump out the reflow-command to out
   */
  nsresult List(FILE* out) const;

  /**
   * Get/set reflow command flags
   */
  nsresult GetFlags(PRInt32* aFlags);
  nsresult SetFlags(PRInt32 aFlags);

private:
  nsReflowType    mType;
  nsIFrame*       mTargetFrame;
  nsIFrame*       mChildFrame;
  nsIAtom*        mAttribute;
  nsIAtom*        mListName;
  PRInt32         mFlags;
};

#endif /* nsHTMLReflowCommand_h___ */