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);
  }

  /**
   * Both GetMinWidth and GetPrefWidth will return whatever GetIntrinsicWidth
   * returns.
   */
  virtual nscoord GetMinWidth(nsIRenderingContext *aRenderingContext);
  virtual nscoord GetPrefWidth(nsIRenderingContext *aRenderingContext);

  /**
   * Reflow our frame.  This will use the computed width plus borderpadding for
   * the desired width, and use the return value of GetIntrinsicHeight plus
   * borderpadding for the desired height.  Ascent will be set to the height,
   * and descent will be set to 0.
   */
  NS_IMETHOD Reflow(nsPresContext*      aPresContext,
                    nsHTMLReflowMetrics& aDesiredSize,
                    const nsHTMLReflowState& aReflowState,
                    nsReflowStatus&      aStatus);

  virtual PRBool IsFrameOfType(PRUint32 aFlags) const
  {
    // We don't actually contain a block, but we do always want a
    // computed width, so tell a little white lie here.
    return nsFrame::IsFrameOfType(aFlags & ~(nsIFrame::eReplacedContainsBlock));
  }

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

  /**
   * Return the intrinsic width of the frame's content area. Note that this
   * should not include borders or padding and should not depend on the applied
   * styles.
   */
  virtual nscoord GetIntrinsicWidth() = 0;

  /**
   * Return the intrinsic height of the frame's content area.  This should not
   * include border or padding.  This will only be called if there is no
   * computed height.  Note that subclasses must either implement this or
   * override Reflow; the default Reflow impl calls this method.
   */
  virtual nscoord GetIntrinsicHeight();

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

  /**
   * Set aDesiredSize to be the available size
   */
  void SizeToAvailSize(const nsHTMLReflowState& aReflowState,
                       nsHTMLReflowMetrics& aDesiredSize);
};

#endif /* nsLeafFrame_h___ */