gecko-dev/layout/generic/nsLeafFrame.h

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/* base class for rendering objects that do not have child lists */

#ifndef nsLeafFrame_h___
#define nsLeafFrame_h___

#include "nsFrame.h"
#include "nsDisplayList.h"

/**
 * Abstract class that provides simple fixed-size layout for leaf objects
 * (e.g. images, form elements, etc.). Deriviations provide the implementation
 * of the GetDesiredSize method. The rendering method knows how to render
 * borders and backgrounds.
 */
class nsLeafFrame : public nsFrame {
public:

  // nsIFrame replacements
  NS_IMETHOD BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                              const nsRect&           aDirtyRect,
                              const nsDisplayListSet& aLists) {
    DO_GLOBAL_REFLOW_COUNT_DSP("nsLeafFrame");
    return DisplayBorderBackgroundOutline(aBuilder, aLists);
  }
  NS_IMETHOD Reflow(nsPresContext*      aPresContext,
                    nsHTMLReflowMetrics& aDesiredSize,
                    const nsHTMLReflowState& aReflowState,
                    nsReflowStatus&      aStatus);

protected:
  nsLeafFrame(nsStyleContext* aContext) : nsFrame(aContext) {}
  virtual ~nsLeafFrame();

  /**
   * Return the desired size of the frame's content area. Note that this
   * method doesn't need to deal with padding or borders (the caller will
   * deal with it). In addition, the ascent will be set to the height
   * and the descent will be set to zero.
   */
  virtual void GetDesiredSize(nsPresContext* aPresContext,
                              const nsHTMLReflowState& aReflowState,
                              nsHTMLReflowMetrics& aDesiredSize) = 0;

  /**
   * Subroutine to add in borders and padding
   */
  void AddBordersAndPadding(nsPresContext* aPresContext,
                            const nsHTMLReflowState& aReflowState,
                            nsHTMLReflowMetrics& aDesiredSize,
                            nsMargin& aBorderPadding);
};

#endif /* nsLeafFrame_h___ */