gecko/layout/base/nsCSSRendering.h

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/* utility functions for drawing borders and backgrounds */

#ifndef nsCSSRendering_h___
#define nsCSSRendering_h___

#include "nsIRenderingContext.h"
#include "nsStyleConsts.h"
#include "gfxContext.h"
#include "gfxImageSurface.h"
struct nsPoint;
class nsStyleContext;
class nsPresContext;

class nsCSSRendering {
public:
  /**
   * Initialize any static variables used by nsCSSRendering.
   */
  static nsresult Init();
  
  /**
   * Clean up any static variables used by nsCSSRendering.
   */
  static void Shutdown();
  
  static void PaintBoxShadow(nsPresContext* aPresContext,
                             nsIRenderingContext& aRenderingContext,
                             nsIFrame* aForFrame,
                             const nsPoint& aForFramePt);

  /**
   * Render the border for an element using css rendering rules
   * for borders. aSkipSides is a bitmask of the sides to skip
   * when rendering. If 0 then no sides are skipped.
   *
   * Both aDirtyRect and aBorderArea are in the local coordinate space
   * of aForFrame
   */
  static void PaintBorder(nsPresContext* aPresContext,
                          nsIRenderingContext& aRenderingContext,
                          nsIFrame* aForFrame,
                          const nsRect& aDirtyRect,
                          const nsRect& aBorderArea,
                          const nsStyleBorder& aBorderStyle,
                          nsStyleContext* aStyleContext,
                          PRIntn aSkipSides = 0);

  /**
   * Render the outline for an element using css rendering rules
   * for borders. aSkipSides is a bitmask of the sides to skip
   * when rendering. If 0 then no sides are skipped.
   *
   * Both aDirtyRect and aBorderArea are in the local coordinate space
   * of aForFrame
   */
  static void PaintOutline(nsPresContext* aPresContext,
                          nsIRenderingContext& aRenderingContext,
                          nsIFrame* aForFrame,
                          const nsRect& aDirtyRect,
                          const nsRect& aBorderArea,
                          const nsStyleBorder& aBorderStyle,
                          const nsStyleOutline& aOutlineStyle,
                          nsStyleContext* aStyleContext);

  /**
   * Render keyboard focus on an element.
   * |aFocusRect| is the outer rectangle of the focused element.
   * Uses a fixed style equivalent to "1px dotted |aColor|".
   * Not used for controls, because the native theme may differ.
   */
  static void PaintFocus(nsPresContext* aPresContext,
                         nsIRenderingContext& aRenderingContext,
                         const nsRect& aFocusRect,
                         nscolor aColor);

  /**
   * Fill in an nsStyleBackground to be used to paint the background for
   * an element.  The nsStyleBackground should first be initialized
   * using the pres context.  This applies the rules for propagating
   * backgrounds between BODY, the root element, and the canvas.
   * @return PR_TRUE if there is some meaningful background.
   */
  static PRBool FindBackground(nsPresContext* aPresContext,
                               nsIFrame* aForFrame,
                               const nsStyleBackground** aBackground,
                               PRBool* aIsCanvas);
                               
  /**
   * Find a non-transparent background, for various table-related and
   * HR-related backwards-compatibility hacks.  Be very hesitant if
   * you're considering calling this function -- it's usually not what
   * you want.
   */
  static const nsStyleBackground*
  FindNonTransparentBackground(nsStyleContext* aContext,
                               PRBool aStartAtParent = PR_FALSE);

  /**
   * Render the background for an element using css rendering rules
   * for backgrounds.
   *
   * Both aDirtyRect and aBorderArea are in the local coordinate space
   * of aForFrame
   */
  static void PaintBackground(nsPresContext* aPresContext,
                              nsIRenderingContext& aRenderingContext,
                              nsIFrame* aForFrame,
                              const nsRect& aDirtyRect,
                              const nsRect& aBorderArea,
                              const nsStyleBorder& aBorder,
                              const nsStylePadding& aPadding,
                              PRBool aUsePrintSettings,
                              nsRect* aBGClipRect = nsnull);

  /**
   * Same as |PaintBackground|, except using the provided style context
   * (which short-circuits the code that ensures that the root element's
   * background is drawn on the canvas.
   */
  static void PaintBackgroundWithSC(nsPresContext* aPresContext,
                                    nsIRenderingContext& aRenderingContext,
                                    nsIFrame* aForFrame,
                                    const nsRect& aDirtyRect,
                                    const nsRect& aBorderArea,
                                    const nsStyleBackground& aColor,
                                    const nsStyleBorder& aBorder,
                                    const nsStylePadding& aPadding,
                                    PRBool aUsePrintSettings = PR_FALSE,
                                    nsRect* aBGClipRect = nsnull);

  /**
   * Called by the presShell when painting is finished, so we can clear our
   * inline background data cache.
   */
  static void DidPaint();

  // Draw a border segment in the table collapsing border model without beveling corners
  static void DrawTableBorderSegment(nsIRenderingContext&     aContext,
                                     PRUint8                  aBorderStyle,  
                                     nscolor                  aBorderColor,
                                     const nsStyleBackground* aBGColor,
                                     const nsRect&            aBorderRect,
                                     PRInt32                  aAppUnitsPerCSSPixel,
                                     PRUint8                  aStartBevelSide = 0,
                                     nscoord                  aStartBevelOffset = 0,
                                     PRUint8                  aEndBevelSide = 0,
                                     nscoord                  aEndBevelOffset = 0);
  /**
   * transform a color to a color that will show up on a printer if needed
   * aMapColor - color to evaluate
   * aIsPrinter - Is this a printing device
   * return - the transformed color
   */
  static nscolor TransformColor(nscolor  aMapColor,PRBool aNoBackGround);

  /**
   * Function for painting the decoration lines for the text.
   * NOTE: aPt, aLineSize, aAscent and aOffset are non-rounded device pixels,
   *       not app units.
   *   input:
   *     @param aGfxContext
   *     @param aColor            the color of the decoration line
   *     @param aPt               the top/left edge of the text
   *     @param aLineSize         the width and the height of the decoration
   *                              line
   *     @param aAscent           the ascent of the text
   *     @param aOffset           the offset of the decoration line from
   *                              the baseline of the text (if the value is
   *                              positive, the line is lifted up)
   *     @param aDecoration       which line will be painted. The value can be
   *                              NS_STYLE_TEXT_DECORATION_UNDERLINE or
   *                              NS_STYLE_TEXT_DECORATION_OVERLINE or
   *                              NS_STYLE_TEXT_DECORATION_LINE_THROUGH.
   *     @param aStyle            the style of the decoration line. The value
   *                              can be NS_STYLE_BORDER_STYLE_SOLID or
   *                              NS_STYLE_BORDER_STYLE_DOTTED or
   *                              NS_STYLE_BORDER_STYLE_DASHED or
   *                              NS_STYLE_BORDER_STYLE_DOUBLE.
   */
  static void PaintDecorationLine(gfxContext* aGfxContext,
                                  const nscolor aColor,
                                  const gfxPoint& aPt,
                                  const gfxSize& aLineSize,
                                  const gfxFloat aAscent,
                                  const gfxFloat aOffset,
                                  const PRUint8 aDecoration,
                                  const PRUint8 aStyle);

  /**
   * Function for getting the decoration line rect for the text.
   * NOTE: aLineSize, aAscent and aOffset are non-rounded device pixels,
   *       not app units.
   *   input:
   *     @param aPresContext
   *     @param aLineSize         the width and the height of the decoration
   *                              line
   *     @param aAscent           the ascent of the text
   *     @param aOffset           the offset of the decoration line from
   *                              the baseline of the text (if the value is
   *                              positive, the line is lifted up)
   *     @param aDecoration       which line will be painted. The value can be
   *                              NS_STYLE_TEXT_DECORATION_UNDERLINE or
   *                              NS_STYLE_TEXT_DECORATION_OVERLINE or
   *                              NS_STYLE_TEXT_DECORATION_LINE_THROUGH.
   *     @param aStyle            the style of the decoration line. The value
   *                              can be NS_STYLE_BORDER_STYLE_SOLID or
   *                              NS_STYLE_BORDER_STYLE_DOTTED or
   *                              NS_STYLE_BORDER_STYLE_DASHED or
   *                              NS_STYLE_BORDER_STYLE_DOUBLE.
   *   output:
   *     @return                  the decoration line rect for the input,
   *                              the each values are app units.
   */
  static nsRect GetTextDecorationRect(nsPresContext* aPresContext,
                                      const gfxSize& aLineSize,
                                      const gfxFloat aAscent,
                                      const gfxFloat aOffset,
                                      const PRUint8 aDecoration,
                                      const PRUint8 aStyle);

protected:

  static void DrawBorderImage(nsPresContext* aPresContext,
                              nsIRenderingContext& aRenderingContext,
                              nsIFrame* aForFrame,
                              const nsRect& aBorderArea,
                              const nsStyleBorder& aBorderStyle);

  static void DrawBorderImageSide(gfxContext *aThebesContext,
                                  nsIDeviceContext* aDeviceContext,
                                  imgIContainer* aImage,
                                  gfxRect& aDestRect,
                                  gfxSize& aInterSize,
                                  gfxRect& aSourceRect,
                                  PRUint8 aHFillType,
                                  PRUint8 aVFillType);

  static void PaintBackgroundColor(nsPresContext* aPresContext,
                                   nsIRenderingContext& aRenderingContext,
                                   nsIFrame* aForFrame,
                                   const nsRect& aBgClipArea,
                                   const nsStyleBackground& aColor,
                                   const nsStyleBorder& aBorder,
                                   const nsStylePadding& aPadding,
                                   PRBool aCanPaintNonWhite);

  static void PaintRoundedBackground(nsPresContext* aPresContext,
                                     nsIRenderingContext& aRenderingContext,
                                     nsIFrame* aForFrame,
                                     const nsRect& aBorderArea,
                                     const nsStyleBackground& aColor,
                                     const nsStyleBorder& aBorder,
                                     nscoord aTheRadius[4],
                                     PRBool aCanPaintNonWhite);

  static nscolor MakeBevelColor(PRIntn whichSide, PRUint8 style,
                                nscolor aBackgroundColor,
                                nscolor aBorderColor);

  static void DrawLine (nsIRenderingContext& aContext, 
                        nscoord aX1, nscoord aY1, nscoord aX2, nscoord aY2,
                        nsRect* aGap);

  static void FillPolygon (nsIRenderingContext& aContext, 
                           const nsPoint aPoints[],
                           PRInt32 aNumPoints,
                           nsRect* aGap);

  static gfxRect GetTextDecorationRectInternal(const gfxPoint& aPt,
                                               const gfxSize& aLineSize,
                                               const gfxFloat aAscent,
                                               const gfxFloat aOffset,
                                               const PRUint8 aDecoration,
                                               const PRUint8 aStyle);

  /* Returns FALSE iff all returned aTwipsRadii == 0, TRUE otherwise */
  static PRBool GetBorderRadiusTwips(const nsStyleSides& aBorderRadius,
                                     const nscoord& aFrameWidth,
                                     PRInt32 aTwipsRadii[4]);
};

/*
 * nsContextBoxBlur
 * Creates an 8-bit alpha channel context for callers to draw in, blurs the
 * contents of that context and applies it as a 1-color mask on a
 * different existing context.
 *
 * You must call Init() first to create a suitable temporary surface to draw on.
 * You must then draw any desired content onto the given context, then call DoPaint()
 * to apply the blurred content as a single-color mask. You can only call Init() once,
 * so objects cannot be reused.
 *
 * This is very useful for creating drop shadows or silhouettes.
 */
class nsContextBoxBlur {
public:
  /**
   * Prepares a gfxContext to draw on. Do not call this twice; if you want to
   * get the gfxContext again use GetContext().
   *
   * @param aRect                The coordinates of the surface to create.
   *                             All coordinates must be in app units.
   *                             This must not include the blur radius, pass it as the
   *                             second parameter and everything is taken care of.
   *
   * @param aBlurRadius          The blur radius in app units.
   *
   * @param aAppUnitsPerDevPixel The number of app units in a device pixel, for conversion.
   *                             Most of the time you'll pass this from the current
   *                             PresContext if available.
   *
   * @param aDestinationCtx      The graphics context to apply the blurred mask to
   *                             when you call DoPaint(). Make sure it is not destroyed
   *                             before you call DoPaint(). To set the color of the resulting
   *                             blurred graphic mask, you must set the color on this
   *                             context before calling Init().
   *
   * @return            A blank 8-bit alpha-channel-only graphics context to draw on, or null on
   *                    error. Must not be freed. The context has a device offset applied to it given
   *                    by aRect. This means you can use coordinates as if it were at the desired position
   *                    at aRect and you don't need to worry about translating any coordinates to draw
   *                    on this temporary surface.
   *
   * If aBlurRadius is 0, the returned context is aDestinationCtx and DoPaint() does nothing,
   * because no blurring is required. Therefore, you should prepare the destination context as
   * if you were going to draw directly on it instead of any temporary surface created in this class.
   */
  gfxContext* Init(const gfxRect& aRect, nscoord aBlurRadius, PRInt32 aAppUnitsPerDevPixel,
                   gfxContext* aDestinationCtx);

  /**
   * Does the actual blurring and mask applying. Users of this object *must*
   * have called Init() first, then have drawn whatever they want to be
   * blurred onto the internal gfxContext before calling this.
   */
  void DoPaint();

  /**
   * Gets the internal gfxContext at any time. Must not be freed. Avoid calling
   * this before calling Init() since the context would not be constructed at that
   * point.
   */
  gfxContext* GetContext();

protected:
  void BoxBlurHorizontal(unsigned char* aInput,
                         unsigned char* aOutput,
                         PRUint32 aLeftLobe,
                         PRUint32 aRightLobe);
  void BoxBlurVertical(unsigned char* aInput,
                       unsigned char* aOutput,
                       PRUint32 aTopLobe,
                       PRUint32 aBottomLobe);

  nsRefPtr<gfxContext> mContext;
  nsRefPtr<gfxImageSurface> mImageSurface;
  gfxContext* mDestinationCtx;

  // Contrary to what is passed as parameters, these are in device pixels
  gfxRect mRect;
  PRInt32 mBlurRadius;
  
};

#endif /* nsCSSRendering_h___ */