Implement text-shadow rendering (bug 10713). r+sr=roc. Relanding with fixes to make tests pass on Mac

layout/base/nsCSSRendering.cpp

@@ -25,6 +25,7 @@
  *   Takeshi Ichimaru <ayakawa.m@gmail.com>
  *   Masayuki Nakano <masayuki@d-toybox.com>
  *   L. David Baron <dbaron@dbaron.org>, Mozilla Corporation
+ *   Michael Ventnor <m.ventnor@gmail.com>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either of the GNU General Public License Version 2 or later (the "GPL"),
@@ -4707,3 +4708,155 @@ nsCSSRendering::GetTextDecorationRectInternal(const gfxPoint& aPt,
   r.pos.y = baseline - NS_floor(offset + 0.5);
   return r;
 }
+
+// -----
+// nsContextBoxBlur
+// -----
+void
+nsContextBoxBlur::BoxBlurHorizontal(unsigned char* aInput,
+                                    unsigned char* aOutput,
+                                    PRUint32 aLeftLobe,
+                                    PRUint32 aRightLobe)
+{
+  // Box blur involves looking at one pixel, and setting its value to the average of
+  // its neighbouring pixels. leftLobe is how many pixels to the left to include
+  // in the average, rightLobe is to the right.
+  // boxSize is how many pixels total will be averaged when looking at each pixel.
+  PRUint32 boxSize = aLeftLobe + aRightLobe + 1;
+
+  long stride = mImageSurface->Stride();
+  PRUint32 rows = mRect.Height();
+
+  for (PRUint32 y = 0; y < rows; y++) {
+    PRUint32 alphaSum = 0;
+    for (PRUint32 i = 0; i < boxSize; i++) {
+      PRInt32 pos = i - aLeftLobe;
+      pos = PR_MAX(pos, 0);
+      pos = PR_MIN(pos, stride - 1);
+      alphaSum += aInput[stride * y + pos];
+    }
+    for (PRInt32 x = 0; x < stride; x++) {
+      PRInt32 tmp = x - aLeftLobe;
+      PRInt32 last = PR_MAX(tmp, 0);
+      PRInt32 next = PR_MIN(tmp + boxSize, stride - 1);
+
+      aOutput[stride * y + x] = alphaSum/boxSize;
+
+      alphaSum += aInput[stride * y + next] -
+                  aInput[stride * y + last];
+    }
+  }
+}
+
+void
+nsContextBoxBlur::BoxBlurVertical(unsigned char* aInput,
+                                  unsigned char* aOutput,
+                                  PRUint32 aTopLobe,
+                                  PRUint32 aBottomLobe)
+{
+  PRUint32 boxSize = aTopLobe + aBottomLobe + 1;
+
+  long stride = mImageSurface->Stride();
+  PRUint32 rows = mRect.Height();
+
+  for (PRInt32 x = 0; x < stride; x++) {
+    PRUint32 alphaSum = 0;
+    for (PRUint32 i = 0; i < boxSize; i++) {
+      PRInt32 pos = i - aTopLobe;
+      pos = PR_MAX(pos, 0);
+      pos = PR_MIN(pos, stride - 1);
+      alphaSum += aInput[stride * pos + x];
+    }
+    for (PRUint32 y = 0; y < rows; y++) {
+      PRInt32 tmp = y - aTopLobe;
+      PRInt32 last = PR_MAX(tmp, 0);
+      PRInt32 next = PR_MIN(tmp + boxSize, rows - 1);
+
+      aOutput[stride * y + x] = alphaSum/boxSize;
+
+      alphaSum += aInput[stride * next + x] -
+                  aInput[stride * last + x];
+    }
+  }
+}
+
+gfxContext*
+nsContextBoxBlur::Init(const gfxRect& aRect, nscoord aBlurRadius,
+                       PRInt32 aAppUnitsPerDevPixel,
+                       gfxContext* aDestinationCtx)
+{
+  mBlurRadius = aBlurRadius / aAppUnitsPerDevPixel;
+
+  if (mBlurRadius <= 0) {
+    mContext = aDestinationCtx;
+    return mContext;
+  }
+
+  mDestinationCtx = aDestinationCtx;
+
+  // Convert from app units to device pixels
+  mRect = aRect;
+  mRect.Outset(aBlurRadius);
+  mRect.ScaleInverse(aAppUnitsPerDevPixel);
+  mRect.RoundOut();
+
+  // Make an alpha-only surface to draw on. We will play with the data after everything is drawn
+  // to create a blur effect.
+  mImageSurface = new gfxImageSurface(gfxIntSize(mRect.Width(), mRect.Height()),
+                                      gfxASurface::ImageFormatA8);
+  if (!mImageSurface)
+    return nsnull;
+
+  // Use a device offset so callers don't need to worry about translating coordinates,
+  // they can draw as if this was part of the destination context at the coordinates
+  // of mRect.
+  mImageSurface->SetDeviceOffset(-mRect.TopLeft());
+
+  mContext = new gfxContext(mImageSurface);
+  return mContext;
+}
+
+void
+nsContextBoxBlur::DoPaint()
+{
+  if (mBlurRadius <= 0)
+    return;
+
+  unsigned char* boxData = mImageSurface->Data();
+
+  // A blur radius of 1 achieves nothing (1/2 = 0 in int terms),
+  // but we still want a blur!
+  mBlurRadius = PR_MAX(mBlurRadius, 2);
+
+  nsTArray<unsigned char> tempAlphaDataBuf;
+  if (!tempAlphaDataBuf.SetLength(mImageSurface->GetDataSize()))
+    return; // OOM
+
+  // Here we do like what the SVG gaussian blur filter does in calculating
+  // the lobes.
+  if (mBlurRadius & 1) {
+    // blur radius is odd
+    BoxBlurHorizontal(boxData, tempAlphaDataBuf.Elements(), mBlurRadius/2, mBlurRadius/2);
+    BoxBlurHorizontal(tempAlphaDataBuf.Elements(), boxData, mBlurRadius/2, mBlurRadius/2);
+    BoxBlurHorizontal(boxData, tempAlphaDataBuf.Elements(), mBlurRadius/2, mBlurRadius/2);
+    BoxBlurVertical(tempAlphaDataBuf.Elements(), boxData, mBlurRadius/2, mBlurRadius/2);
+    BoxBlurVertical(boxData, tempAlphaDataBuf.Elements(), mBlurRadius/2, mBlurRadius/2);
+    BoxBlurVertical(tempAlphaDataBuf.Elements(), boxData, mBlurRadius/2, mBlurRadius/2);
+  } else {
+    // blur radius is even
+    BoxBlurHorizontal(boxData, tempAlphaDataBuf.Elements(), mBlurRadius/2, mBlurRadius/2 - 1);
+    BoxBlurHorizontal(tempAlphaDataBuf.Elements(), boxData, mBlurRadius/2 - 1, mBlurRadius/2);
+    BoxBlurHorizontal(boxData, tempAlphaDataBuf.Elements(), mBlurRadius/2, mBlurRadius/2);
+    BoxBlurVertical(tempAlphaDataBuf.Elements(), boxData, mBlurRadius/2, mBlurRadius/2 - 1);
+    BoxBlurVertical(boxData, tempAlphaDataBuf.Elements(), mBlurRadius/2 - 1, mBlurRadius/2);
+    BoxBlurVertical(tempAlphaDataBuf.Elements(), boxData, mBlurRadius/2, mBlurRadius/2);
+  }
+
+  mDestinationCtx->Mask(mImageSurface);
+}
+
+gfxContext*
+nsContextBoxBlur::GetContext()
+{
+  return mContext;
+}

layout/base/nsCSSRendering.h

@@ -43,6 +43,7 @@
 #include "nsIRenderingContext.h"
 #include "nsStyleConsts.h"
 #include "gfxContext.h"
+#include "gfxImageSurface.h"
 struct nsPoint;
 class nsStyleContext;
 class nsPresContext;
@@ -306,5 +307,85 @@ protected:
                                                const PRUint8 aStyle);
 };
 
+/*
+ * 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, because no blurring is required.
+   */
+  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___ */

layout/base/nsLayoutUtils.cpp

@@ -1286,6 +1286,30 @@ nsLayoutUtils::GetAllInFlowRectsUnion(nsIFrame* aFrame, nsIFrame* aRelativeTo) {
           : accumulator.mResultRect;
 }
 
+nsRect
+nsLayoutUtils::GetTextShadowRectsUnion(const nsRect& aTextAndDecorationsRect,
+                                       nsIFrame* aFrame)
+{
+  const nsStyleText* textStyle = aFrame->GetStyleText();
+  if (!textStyle->mShadowArray)
+    return aTextAndDecorationsRect;
+
+  nsRect resultRect = aTextAndDecorationsRect;
+  for (PRUint32 i = 0; i < textStyle->mShadowArray->Length(); ++i) {
+    nsRect tmpRect(aTextAndDecorationsRect);
+    nsTextShadowItem* shadow = textStyle->mShadowArray->ShadowAt(i);
+    nscoord xOffset = shadow->mXOffset.GetCoordValue();
+    nscoord yOffset = shadow->mYOffset.GetCoordValue();
+    nscoord blurRadius = shadow->mRadius.GetCoordValue();
+
+    tmpRect.MoveBy(nsPoint(xOffset, yOffset));
+    tmpRect.Inflate(blurRadius, blurRadius);
+
+    resultRect.UnionRect(resultRect, tmpRect);
+  }
+  return resultRect;
+}
+
 nsresult
 nsLayoutUtils::GetFontMetricsForFrame(nsIFrame* aFrame,
                                       nsIFontMetrics** aFontMetrics)

layout/base/nsLayoutUtils.h

@@ -502,6 +502,14 @@ public:
    */
   static nsRect GetAllInFlowRectsUnion(nsIFrame* aFrame, nsIFrame* aRelativeTo);
 
+  /**
+   * Takes a text-shadow array from the style properties of a given nsIFrame and
+   * computes the union of those shadows along with the given initial rect.
+   * If there are no shadows, the initial rect is returned.
+   */
+  static nsRect GetTextShadowRectsUnion(const nsRect& aTextAndDecorationsRect,
+                                        nsIFrame* aFrame);
+
   /**
    * Get the font metrics corresponding to the frame's style data.
    * @param aFrame the frame

layout/generic/nsBlockFrame.cpp

@@ -1439,10 +1439,20 @@ nsBlockFrame::ComputeCombinedArea(const nsHTMLReflowState& aReflowState,
   // XXX_perf: This can be done incrementally.  It is currently one of
   // the things that makes incremental reflow O(N^2).
   nsRect area(0, 0, aMetrics.width, aMetrics.height);
+
   if (NS_STYLE_OVERFLOW_CLIP != aReflowState.mStyleDisplay->mOverflowX) {
+    PRBool inQuirks = (PresContext()->CompatibilityMode() == eCompatibility_NavQuirks);
     for (line_iterator line = begin_lines(), line_end = end_lines();
          line != line_end;
          ++line) {
+
+      // Text-shadow overflows
+      if (!inQuirks && line->IsInline()) {
+        nsRect shadowRect = nsLayoutUtils::GetTextShadowRectsUnion(line->GetCombinedArea(),
+                                                                   this);
+        area.UnionRect(area, shadowRect);
+      }
+
       area.UnionRect(area, line->GetCombinedArea());
     }
 
@@ -5904,7 +5914,7 @@ nsBlockFrame::IsVisibleInSelection(nsISelection* aSelection)
 }
 
 /* virtual */ void
-nsBlockFrame::PaintTextDecorationLine(nsIRenderingContext& aRenderingContext, 
+nsBlockFrame::PaintTextDecorationLine(gfxContext* aCtx, 
                                       const nsPoint& aPt,
                                       nsLineBox* aLine,
                                       nscolor aColor, 
@@ -5945,12 +5955,11 @@ nsBlockFrame::PaintTextDecorationLine(nsIRenderingContext& aRenderingContext,
       
   // Only paint if we have a positive width
   if (width > 0) {
-    gfxContext *ctx = aRenderingContext.ThebesContext();
     gfxPoint pt(PresContext()->AppUnitsToGfxUnits(start + aPt.x),
                 PresContext()->AppUnitsToGfxUnits(aLine->mBounds.y + aPt.y));
     gfxSize size(PresContext()->AppUnitsToGfxUnits(width), aSize);
     nsCSSRendering::PaintDecorationLine(
-      ctx, aColor, pt, size,
+      aCtx, aColor, pt, size,
       PresContext()->AppUnitsToGfxUnits(aLine->GetAscent()),
       aOffset, aDecoration, NS_STYLE_BORDER_STYLE_SOLID);
   }

layout/generic/nsBlockFrame.h

@@ -341,7 +341,7 @@ protected:
    * Overides member function of nsHTMLContainerFrame. Needed to handle the 
    * lines in a nsBlockFrame properly.
    */
-  virtual void PaintTextDecorationLine(nsIRenderingContext& aRenderingContext,
+  virtual void PaintTextDecorationLine(gfxContext* aCtx,
                                        const nsPoint& aPt,
                                        nsLineBox* aLine,
                                        nscolor aColor,

layout/generic/nsHTMLContainerFrame.cpp

@@ -20,6 +20,7 @@
  * the Initial Developer. All Rights Reserved.
  *
  * Contributor(s):
+ *   Michael Ventnor <m.ventnor@gmail.com>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either of the GNU General Public License Version 2 or later (the "GPL"),
@@ -131,15 +132,15 @@ nsDisplayTextDecoration::Paint(nsDisplayListBuilder* aBuilder,
   nsHTMLContainerFrame* f = static_cast<nsHTMLContainerFrame*>(mFrame);
   if (mDecoration == NS_STYLE_TEXT_DECORATION_UNDERLINE) {
     gfxFloat underlineOffset = fontGroup->GetUnderlineOffset();
-    f->PaintTextDecorationLine(*aCtx, pt, mLine, mColor,
+    f->PaintTextDecorationLine(aCtx->ThebesContext(), pt, mLine, mColor,
                                underlineOffset, ascent,
                                metrics.underlineSize, mDecoration);
   } else if (mDecoration == NS_STYLE_TEXT_DECORATION_OVERLINE) {
-    f->PaintTextDecorationLine(*aCtx, pt, mLine, mColor,
+    f->PaintTextDecorationLine(aCtx->ThebesContext(), pt, mLine, mColor,
                                metrics.maxAscent, ascent,
                                metrics.underlineSize, mDecoration);
   } else {
-    f->PaintTextDecorationLine(*aCtx, pt, mLine, mColor,
+    f->PaintTextDecorationLine(aCtx->ThebesContext(), pt, mLine, mColor,
                                metrics.strikeoutOffset, ascent,
                                metrics.strikeoutSize, mDecoration);
   }
@@ -151,6 +152,95 @@ nsDisplayTextDecoration::GetBounds(nsDisplayListBuilder* aBuilder)
   return mFrame->GetOverflowRect() + aBuilder->ToReferenceFrame(mFrame);
 }
 
+class nsDisplayTextShadow : public nsDisplayItem {
+public:
+  nsDisplayTextShadow(nsHTMLContainerFrame* aFrame, const PRUint8 aDecoration,
+                      const nscolor& aColor, nsLineBox* aLine,
+                      const nscoord& aBlurRadius, const gfxPoint& aOffset)
+    : nsDisplayItem(aFrame), mLine(aLine), mColor(aColor),
+      mDecorationFlags(aDecoration),
+      mBlurRadius(aBlurRadius), mOffset(aOffset) {
+    MOZ_COUNT_CTOR(nsDisplayTextShadow);
+  }
+  virtual ~nsDisplayTextShadow() {
+    MOZ_COUNT_DTOR(nsDisplayTextShadow);
+  }
+
+  virtual void Paint(nsDisplayListBuilder* aBuilder, nsIRenderingContext* aCtx,
+     const nsRect& aDirtyRect);
+  virtual nsRect GetBounds(nsDisplayListBuilder* aBuilder);
+  NS_DISPLAY_DECL_NAME("TextShadow")
+private:
+  nsLineBox*    mLine;
+  nscolor       mColor;
+  PRUint8       mDecorationFlags;
+  nscoord       mBlurRadius; // App units
+  gfxPoint      mOffset;     // App units
+};
+
+void
+nsDisplayTextShadow::Paint(nsDisplayListBuilder* aBuilder,
+                           nsIRenderingContext* aCtx,
+                           const nsRect& aDirtyRect)
+{
+  mBlurRadius = PR_MAX(mBlurRadius, 0);
+
+  nsCOMPtr<nsIFontMetrics> fm;
+  nsLayoutUtils::GetFontMetricsForFrame(mFrame, getter_AddRefs(fm));
+  nsIThebesFontMetrics* tfm = static_cast<nsIThebesFontMetrics*>(fm.get());
+  gfxFontGroup* fontGroup = tfm->GetThebesFontGroup();
+  gfxFont* firstFont = fontGroup->GetFontAt(0);
+  if (!firstFont)
+    return; // OOM
+  const gfxFont::Metrics& metrics = firstFont->GetMetrics();
+  nsPoint pt = aBuilder->ToReferenceFrame(mFrame) + nsPoint(mOffset.x, mOffset.y);
+
+  nsHTMLContainerFrame* f = static_cast<nsHTMLContainerFrame*>(mFrame);
+  nsMargin bp = f->GetUsedBorderAndPadding();
+  nscoord innerWidthInAppUnits = (mFrame->GetSize().width - bp.LeftRight());
+
+  gfxRect shadowRect = gfxRect(pt.x, pt.y, innerWidthInAppUnits, mFrame->GetSize().height);
+  gfxContext* thebesCtx = aCtx->ThebesContext();
+
+  nsContextBoxBlur contextBoxBlur;
+  gfxContext* shadowCtx = contextBoxBlur.Init(shadowRect, mBlurRadius,
+                                              mFrame->PresContext()->AppUnitsPerDevPixel(),
+                                              thebesCtx);
+  if (!shadowCtx)
+    return;
+
+  thebesCtx->Save();
+  thebesCtx->NewPath();
+  thebesCtx->SetColor(gfxRGBA(mColor));
+
+  if (mDecorationFlags & NS_STYLE_TEXT_DECORATION_UNDERLINE) {
+    gfxFloat underlineOffset = fontGroup->GetUnderlineOffset();
+    f->PaintTextDecorationLine(shadowCtx, pt, mLine, mColor,
+                               underlineOffset, metrics.maxAscent,
+                               metrics.underlineSize, NS_STYLE_TEXT_DECORATION_UNDERLINE);
+  }
+  if (mDecorationFlags & NS_STYLE_TEXT_DECORATION_OVERLINE) {
+    f->PaintTextDecorationLine(shadowCtx, pt, mLine, mColor,
+                               metrics.maxAscent, metrics.maxAscent,
+                               metrics.underlineSize, NS_STYLE_TEXT_DECORATION_OVERLINE);
+  }
+  if (mDecorationFlags & NS_STYLE_TEXT_DECORATION_LINE_THROUGH) {
+    f->PaintTextDecorationLine(shadowCtx, pt, mLine, mColor,
+                               metrics.strikeoutOffset, metrics.maxAscent,
+                               metrics.strikeoutSize, NS_STYLE_TEXT_DECORATION_LINE_THROUGH);
+  }
+
+  contextBoxBlur.DoPaint();
+  thebesCtx->Restore();
+}
+
+nsRect
+nsDisplayTextShadow::GetBounds(nsDisplayListBuilder* aBuilder)
+{
+  // Shadows are always painted in the overflow rect
+  return mFrame->GetOverflowRect() + aBuilder->ToReferenceFrame(mFrame);
+}
+
 nsresult
 nsHTMLContainerFrame::DisplayTextDecorations(nsDisplayListBuilder* aBuilder,
                                              nsDisplayList* aBelowTextDecorations,
@@ -170,6 +260,34 @@ nsHTMLContainerFrame::DisplayTextDecorations(nsDisplayListBuilder* aBuilder,
   GetTextDecorations(PresContext(), aLine != nsnull, decorations, underColor, 
                      overColor, strikeColor);
 
+  if (decorations == NS_STYLE_TEXT_DECORATION_NONE)
+    return NS_OK;
+
+  // The text-shadow spec says that any text decorations must also have a shadow applied to
+  // it. So draw the shadows as part of the display list.
+  const nsStyleText* textStyle = GetStyleText();
+
+  if (textStyle->mShadowArray) {
+    for (PRUint32 i = textStyle->mShadowArray->Length(); i > 0; --i) {
+      nsTextShadowItem* shadow = textStyle->mShadowArray->ShadowAt(i - 1);
+      nscoord blurRadius = shadow->mRadius.GetCoordValue();
+      nscolor shadowColor;
+
+      if (shadow->mHasColor)
+        shadowColor = shadow->mColor;
+      else
+        shadowColor = GetStyleColor()->mColor;
+
+      gfxPoint offset = gfxPoint(shadow->mXOffset.GetCoordValue(),
+                                 shadow->mYOffset.GetCoordValue());
+
+      // Add it to the display list so it is painted underneath the text and all decorations
+      nsresult rv = aBelowTextDecorations->AppendNewToTop(new (aBuilder)
+        nsDisplayTextShadow(this, decorations, shadowColor, aLine, blurRadius, offset));
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+  }
+
   if (decorations & NS_STYLE_TEXT_DECORATION_UNDERLINE) {
     nsresult rv = aBelowTextDecorations->AppendNewToTop(new (aBuilder)
       nsDisplayTextDecoration(this, NS_STYLE_TEXT_DECORATION_UNDERLINE, underColor, aLine));
@@ -221,7 +339,7 @@ HasTextFrameDescendantOrInFlow(nsIFrame* aFrame);
 
 /*virtual*/ void
 nsHTMLContainerFrame::PaintTextDecorationLine(
-                   nsIRenderingContext& aRenderingContext, 
+                   gfxContext* aCtx, 
                    const nsPoint& aPt,
                    nsLineBox* aLine,
                    nscolor aColor, 
@@ -239,11 +357,10 @@ nsHTMLContainerFrame::PaintTextDecorationLine(
     }
   }
   nscoord innerWidth = mRect.width - bp.left - bp.right;
-  gfxContext *ctx = aRenderingContext.ThebesContext();
   gfxPoint pt(PresContext()->AppUnitsToGfxUnits(bp.left + aPt.x),
               PresContext()->AppUnitsToGfxUnits(bp.top + aPt.y));
   gfxSize size(PresContext()->AppUnitsToGfxUnits(innerWidth), aSize);
-  nsCSSRendering::PaintDecorationLine(ctx, aColor, pt, size, aAscent, aOffset,
+  nsCSSRendering::PaintDecorationLine(aCtx, aColor, pt, size, aAscent, aOffset,
                                       aDecoration, NS_STYLE_BORDER_STYLE_SOLID);
 }
 

layout/generic/nsHTMLContainerFrame.h

@@ -161,7 +161,7 @@ protected:
   /** 
    * Function that does the actual drawing of the textdecoration. 
    *   input:
-   *    @param aRenderingContext
+   *    @param aCtx               the Thebes graphics context to draw on
    *    @param aLine              the line, or nsnull if this is an inline frame
    *    @param aColor             the color of the text-decoration
    *    @param aAscent            ascent of the font from which the
@@ -176,7 +176,7 @@ protected:
    *                                      NS_STYLE_TEXT_DECORATION_OVERLINE or
    *                                      NS_STYLE_TEXT_DECORATION_LINE_THROUGH.
    */
-  virtual void PaintTextDecorationLine(nsIRenderingContext& aRenderingContext,
+  virtual void PaintTextDecorationLine(gfxContext* aCtx,
                                        const nsPoint& aPt,
                                        nsLineBox* aLine,
                                        nscolor aColor,
@@ -186,6 +186,7 @@ protected:
                                        const PRUint8 aDecoration);
 
   friend class nsDisplayTextDecoration;
+  friend class nsDisplayTextShadow;
 };
 
 #endif /* nsHTMLContainerFrame_h___ */

layout/generic/nsLineLayout.cpp

@@ -2556,6 +2556,14 @@ nsLineLayout::RelativePositionFrames(PerSpanData* psd, nsRect& aCombinedArea)
     // bidi reordering can move and resize the frames. So use the frame's
     // rect instead of mBounds.
     nsRect adjustedBounds(nsPoint(0, 0), psd->mFrame->mFrame->GetSize());
+
+    // Text-shadow overflow
+    if (mPresContext->CompatibilityMode() != eCompatibility_NavQuirks) {
+      nsRect shadowRect = nsLayoutUtils::GetTextShadowRectsUnion(adjustedBounds,
+                                                                 psd->mFrame->mFrame);
+      adjustedBounds.UnionRect(adjustedBounds, shadowRect);
+    }
+
     combinedAreaResult.UnionRect(psd->mFrame->mCombinedArea, adjustedBounds);
   }
   else {

layout/generic/nsTextFrame.h

@@ -54,6 +54,7 @@
 #include "nsLineBox.h"
 #include "gfxFont.h"
 #include "gfxSkipChars.h"
+#include "gfxContext.h"
 
 class nsTextPaintStyle;
 class PropertyProvider;
@@ -253,6 +254,7 @@ public:
   gfxFloat GetSnappedBaselineY(gfxContext* aContext, gfxFloat aY);
 
   // primary frame paint method called from nsDisplayText
+  // The private DrawText() is what applies the text to a graphics context
   void PaintText(nsIRenderingContext* aRenderingContext, nsPoint aPt,
                  const nsRect& aDirtyRect);
   // helper: paint quirks-mode CSS text decorations
@@ -260,7 +262,8 @@ public:
                             const gfxPoint& aFramePt,
                             const gfxPoint& aTextBaselinePt,
                             nsTextPaintStyle& aTextStyle,
-                            PropertyProvider& aProvider);
+                            PropertyProvider& aProvider,
+                            const nscolor& aOverrideColor = 0);
   // helper: paint text frame when we're impacted by at least one selection.
   // Return PR_FALSE if the text was not painted and we should continue with
   // the fast path.
@@ -382,6 +385,25 @@ protected:
                                    PropertyProvider& aProvider,
                                    nsRect* aOverflowRect);
 
+  void DrawText(gfxContext* aCtx,
+                const gfxPoint& aTextBaselinePt,
+                PRUint32 aOffset,
+                PRUint32 aLength,
+                const gfxRect* aDirtyRect,
+                PropertyProvider* aProvider,
+                gfxFloat& aAdvanceWidth,
+                PRBool aDrawSoftHyphen);
+
+  void PaintOneShadow(PRUint32 aOffset,
+                      PRUint32 aLength,
+                      nsTextShadowItem* aShadowDetails,
+                      PropertyProvider* aProvider,
+                      const gfxRect& aDirtyRect,
+                      const gfxPoint& aFramePt,
+                      const gfxPoint& aTextBaselinePt,
+                      gfxContext* aCtx,
+                      const nscolor& aForegroundColor);
+
   struct TextDecorations {
     PRUint8 mDecorations;
     nscolor mOverColor;

layout/generic/nsTextFrameThebes.cpp

@@ -32,6 +32,7 @@
  *   Mats Palmgren <mats.palmgren@bredband.net>
  *   Uri Bernstein <uriber@gmail.com>
  *   Stephen Blackheath <entangled.mooched.stephen@blacksapphire.com>
+ *   Michael Ventnor <m.ventnor@gmail.com>
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either of the GNU General Public License Version 2 or later (the "GPL"),
@@ -115,6 +116,7 @@
 #include "gfxFont.h"
 #include "gfxContext.h"
 #include "gfxTextRunWordCache.h"
+#include "gfxImageSurface.h"
 
 #ifdef NS_DEBUG
 #undef NOISY_BLINK
@@ -3675,6 +3677,10 @@ nsTextFrame::UnionTextDecorationOverflow(nsPresContext* aPresContext,
                                          PropertyProvider& aProvider,
                                          nsRect* aOverflowRect)
 {
+  // Text-shadow overflows
+  nsRect shadowRect = nsLayoutUtils::GetTextShadowRectsUnion(*aOverflowRect, this);
+  aOverflowRect->UnionRect(*aOverflowRect, shadowRect);
+
   if (IsFloatingFirstLetterChild()) {
     // The underline/overline drawable area must be contained in the overflow
     // rect when this is in floating first letter frame at *both* modes.
@@ -3704,7 +3710,8 @@ nsTextFrame::PaintTextDecorations(gfxContext* aCtx, const gfxRect& aDirtyRect,
                                   const gfxPoint& aFramePt,
                                   const gfxPoint& aTextBaselinePt,
                                   nsTextPaintStyle& aTextPaintStyle,
-                                  PropertyProvider& aProvider)
+                                  PropertyProvider& aProvider,
+                                  const nscolor& aOverrideColor)
 {
   TextDecorations decorations =
     GetTextDecorations(aTextPaintStyle.PresContext());
@@ -3722,24 +3729,28 @@ nsTextFrame::PaintTextDecorations(gfxContext* aCtx, const gfxRect& aDirtyRect,
   gfxSize size(GetRect().width / app, 0);
   gfxFloat ascent = gfxFloat(mAscent) / app;
 
+  nscolor lineColor;
   if (decorations.HasOverline()) {
+    lineColor = aOverrideColor ? aOverrideColor : decorations.mOverColor;
     size.height = fontMetrics.underlineSize;
     nsCSSRendering::PaintDecorationLine(
-      aCtx, decorations.mOverColor, pt, size, ascent, fontMetrics.maxAscent,
+      aCtx, lineColor, pt, size, ascent, fontMetrics.maxAscent,
       NS_STYLE_TEXT_DECORATION_OVERLINE, NS_STYLE_BORDER_STYLE_SOLID);
   }
   if (decorations.HasUnderline()) {
+    lineColor = aOverrideColor ? aOverrideColor : decorations.mUnderColor;
     size.height = fontMetrics.underlineSize;
     gfxFloat offset = aProvider.GetFontGroup()->GetUnderlineOffset();
     nsCSSRendering::PaintDecorationLine(
-      aCtx, decorations.mUnderColor, pt, size, ascent, offset,
+      aCtx, lineColor, pt, size, ascent, offset,
       NS_STYLE_TEXT_DECORATION_UNDERLINE, NS_STYLE_BORDER_STYLE_SOLID);
   }
   if (decorations.HasStrikeout()) {
+    lineColor = aOverrideColor ? aOverrideColor : decorations.mStrikeColor;
     size.height = fontMetrics.strikeoutSize;
     gfxFloat offset = fontMetrics.strikeoutOffset;
     nsCSSRendering::PaintDecorationLine(
-      aCtx, decorations.mStrikeColor, pt, size, ascent, offset,
+      aCtx, lineColor, pt, size, ascent, offset,
       NS_STYLE_TEXT_DECORATION_LINE_THROUGH, NS_STYLE_BORDER_STYLE_SOLID);
   }
 }
@@ -3948,6 +3959,72 @@ PRBool SelectionIterator::GetNextSegment(gfxFloat* aXOffset,
   return PR_TRUE;
 }
 
+void
+nsTextFrame::PaintOneShadow(PRUint32 aOffset, PRUint32 aLength,
+                            nsTextShadowItem* aShadowDetails,
+                            PropertyProvider* aProvider, const gfxRect& aDirtyRect,
+                            const gfxPoint& aFramePt, const gfxPoint& aTextBaselinePt,
+                            gfxContext* aCtx, const nscolor& aForegroundColor)
+{
+  nscoord xOffset = aShadowDetails->mXOffset.GetCoordValue();
+  nscoord yOffset = aShadowDetails->mYOffset.GetCoordValue();
+  nscoord blurRadius = PR_MAX(aShadowDetails->mRadius.GetCoordValue(), 0);
+
+  nsTextPaintStyle textPaintStyle(this);
+  gfxFloat advanceWidth;
+
+  gfxTextRun::Metrics shadowMetrics =
+    mTextRun->MeasureText(aOffset, aLength, PR_FALSE,
+                          nsnull, aProvider);
+
+  // This rect is the box which is equivalent to where the shadow will be painted.
+  // X and Y are significant because they can affect the rounding.
+  // The origin of mBoundingBox is the text baseline point, so we must translate it by
+  // that much in order to make the origin the top-left corner of the text bounding box.
+  gfxRect shadowRect = shadowMetrics.mBoundingBox + aTextBaselinePt;
+  shadowRect.MoveBy(gfxPoint(xOffset, yOffset));
+
+  if (GetStateBits() & TEXT_HYPHEN_BREAK) {
+    // Add the width of the soft hyphen so it isn't cut off
+    shadowRect.size.width += aProvider->GetHyphenWidth();
+  }
+
+  nsContextBoxBlur contextBoxBlur;
+  gfxContext* shadowContext = contextBoxBlur.Init(shadowRect, blurRadius,
+                                                  PresContext()->AppUnitsPerDevPixel(),
+                                                  aCtx);
+  if (!shadowContext)
+    return;
+
+  nscolor shadowColor;
+  if (aShadowDetails->mHasColor)
+    shadowColor = aShadowDetails->mColor;
+  else
+    shadowColor = aForegroundColor;
+
+  aCtx->Save();
+  aCtx->NewPath();
+  aCtx->SetColor(gfxRGBA(shadowColor));
+
+  // Draw the text onto our alpha-only surface to capture the alpha values.
+  // Remember that the box blur context has a device offset on it, so we don't need to
+  // translate any coordinates to fit on the surface.
+  DrawText(shadowContext,
+           aTextBaselinePt + gfxPoint(xOffset, yOffset),
+           aOffset, aLength, &aDirtyRect, aProvider, advanceWidth,
+           (GetStateBits() & TEXT_HYPHEN_BREAK) != 0);
+
+  // This will only have an effect in quirks mode. Standards mode text-decoration shadow painting
+  // is handled in nsHTMLContainerFrame.cpp, so you must remember to consider that if you change
+  // any code behaviour here.
+  PaintTextDecorations(shadowContext, aDirtyRect, aFramePt + gfxPoint(xOffset, yOffset),
+                       aTextBaselinePt + gfxPoint(xOffset, yOffset),
+                       textPaintStyle, *aProvider, shadowColor);
+
+  contextBoxBlur.DoPaint();
+  aCtx->Restore();
+}
+
 // Paints selection backgrounds and text in the correct colors. Also computes
 // aAllTypes, the union of all selection types that are applying to this text.
 void
@@ -4031,18 +4108,11 @@ nsTextFrame::PaintTextWithSelectionColors(gfxContext* aCtx,
     // Draw text segment
     aCtx->SetColor(gfxRGBA(foreground));
     gfxFloat advance;
-    mTextRun->Draw(aCtx, gfxPoint(aFramePt.x + xOffset, aTextBaselinePt.y), offset, length,
-                   &aDirtyRect, &aProvider, &advance);
+
+    DrawText(aCtx, gfxPoint(aFramePt.x + xOffset, aTextBaselinePt.y),
+             offset, length, &aDirtyRect, &aProvider,
+             advance, hyphenWidth > 0);
     if (hyphenWidth) {
-      // Draw the hyphen
-      gfxFloat hyphenBaselineX = aFramePt.x + xOffset + mTextRun->GetDirection()*advance;
-      // Get a reference rendering context because aCtx might not have the
-      // reference matrix currently set
-      gfxTextRunCache::AutoTextRun hyphenTextRun(GetHyphenTextRun(mTextRun, nsnull, this));
-      if (hyphenTextRun.get()) {
-        hyphenTextRun->Draw(aCtx, gfxPoint(hyphenBaselineX, aTextBaselinePt.y),
-                            0, hyphenTextRun->GetLength(), &aDirtyRect, nsnull, nsnull);
-      }
       advance += hyphenWidth;
     }
     iterator.UpdateWithAdvance(advance);
@@ -4193,6 +4263,23 @@ nsTextFrame::PaintText(nsIRenderingContext* aRenderingContext, nsPoint aPt,
   gfxRect dirtyRect(aDirtyRect.x, aDirtyRect.y,
                     aDirtyRect.width, aDirtyRect.height);
 
+  gfxFloat advanceWidth;
+  gfxRGBA foregroundColor = gfxRGBA(textPaintStyle.GetTextColor());
+
+  // Paint the text shadow before doing any foreground stuff
+  const nsStyleText* textStyle = GetStyleText();
+  if (textStyle->mShadowArray) {
+    // Text shadow happens with the last value being painted at the back,
+    // ie. it is painted first.
+    for (PRUint32 i = textStyle->mShadowArray->Length(); i > 0; --i) {
+      PaintOneShadow(provider.GetStart().GetSkippedOffset(),
+                     ComputeTransformedLength(provider),
+                     textStyle->mShadowArray->ShadowAt(i - 1), &provider,
+                     dirtyRect, framePt, textBaselinePt, ctx,
+                     textPaintStyle.GetTextColor());
+    }
+  }
+
   // Fork off to the (slower) paint-with-selection path if necessary.
   if (GetNonGeneratedAncestor(this)->GetStateBits() & NS_FRAME_SELECTED_CONTENT) {
     if (PaintTextWithSelection(ctx, framePt, textBaselinePt,
@@ -4200,27 +4287,36 @@ nsTextFrame::PaintText(nsIRenderingContext* aRenderingContext, nsPoint aPt,
       return;
   }
 
-  gfxFloat advanceWidth;
-  gfxFloat* needAdvanceWidth =
-    (GetStateBits() & TEXT_HYPHEN_BREAK) ? &advanceWidth : nsnull;
-  ctx->SetColor(gfxRGBA(textPaintStyle.GetTextColor()));
-  
-  mTextRun->Draw(ctx, textBaselinePt,
-                 provider.GetStart().GetSkippedOffset(),
-                 ComputeTransformedLength(provider),
-                 &dirtyRect, &provider, needAdvanceWidth);
-  if (GetStateBits() & TEXT_HYPHEN_BREAK) {
-    gfxFloat hyphenBaselineX = textBaselinePt.x + mTextRun->GetDirection()*advanceWidth;
+  ctx->SetColor(foregroundColor);
+
+  DrawText(ctx, textBaselinePt, provider.GetStart().GetSkippedOffset(),
+           ComputeTransformedLength(provider), &dirtyRect,
+           &provider, advanceWidth,
+           (GetStateBits() & TEXT_HYPHEN_BREAK) != 0);
+  PaintTextDecorations(ctx, dirtyRect, framePt, textBaselinePt,
+                       textPaintStyle, provider);
+}
+
+void
+nsTextFrame::DrawText(gfxContext* aCtx, const gfxPoint& aTextBaselinePt,
+                      PRUint32 aOffset, PRUint32 aLength,
+                      const gfxRect* aDirtyRect, PropertyProvider* aProvider,
+                      gfxFloat& aAdvanceWidth, PRBool aDrawSoftHyphen)
+{
+  // Paint the text and soft-hyphen (if any) onto the given graphics context
+  mTextRun->Draw(aCtx, aTextBaselinePt, aOffset, aLength,
+                 aDirtyRect, aProvider, &aAdvanceWidth);
+
+  if (aDrawSoftHyphen) {
+    gfxFloat hyphenBaselineX = aTextBaselinePt.x + mTextRun->GetDirection() * aAdvanceWidth;
     // Don't use ctx as the context, because we need a reference context here,
     // ctx may be transformed.
     gfxTextRunCache::AutoTextRun hyphenTextRun(GetHyphenTextRun(mTextRun, nsnull, this));
     if (hyphenTextRun.get()) {
-      hyphenTextRun->Draw(ctx, gfxPoint(hyphenBaselineX, textBaselinePt.y),
-                          0, hyphenTextRun->GetLength(), &dirtyRect, nsnull, nsnull);
+      hyphenTextRun->Draw(aCtx, gfxPoint(hyphenBaselineX, aTextBaselinePt.y),
+                          0, hyphenTextRun->GetLength(), aDirtyRect, nsnull, nsnull);
     }
   }
-  PaintTextDecorations(ctx, dirtyRect, framePt, textBaselinePt,
-                       textPaintStyle, provider);
 }
 
 PRInt16

layout/mathml/base/src/nsMathMLContainerFrame.cpp

@@ -856,6 +856,12 @@ nsMathMLContainerFrame::GatherAndStoreOverflow(nsHTMLReflowMetrics* aMetrics)
   // frame rectangle.
   nsRect frameRect(0, 0, aMetrics->width, aMetrics->height);
 
+  // Text-shadow overflows.
+  if (PresContext()->CompatibilityMode() != eCompatibility_NavQuirks) {
+    nsRect shadowRect = nsLayoutUtils::GetTextShadowRectsUnion(frameRect, this);
+    frameRect.UnionRect(frameRect, shadowRect);
+  }
+
   // All non-child-frame content such as nsMathMLChars (and most child-frame
   // content) is included in mBoundingMetrics.
   nsRect boundingBox(mBoundingMetrics.leftBearing,

layout/reftests/reftest.list

@@ -55,7 +55,7 @@ include text/reftest.list
 include text-decoration/reftest.list
 
 # text-shadow/
-# include text-shadow/reftest.list
+include text-shadow/reftest.list
 
 # text-indent/
 include text-indent/reftest.list

layout/reftests/text-shadow/decorations-multiple-zorder-ref.html

@@ -1,13 +1,25 @@
 <!DOCTYPE HTML>
 
-<!-- blue/green underline -->
-<div style="position: absolute; top: 22px; left: 22px; color: blue; text-decoration: underline;"><span style="color: rgba(0, 0, 0, 0);">testfor</span><span style="text-decoration: underline; color: green;"><span style="color: rgba(0, 0, 0, 0);">quirks</span></span></div>
-<div style="position: absolute; top: 20px; left: 20px; color: blue; text-decoration: underline;"><span style="color: rgba(0, 0, 0, 0);">testfor</span><span style="text-decoration: underline; color: green;"><span style="color: rgba(0, 0, 0, 0);">quirks</span></span></div>
+<!-- blue underline -->
+<div style="position: absolute; top: 22px; left: 22px; color: blue; text-decoration: underline;"><span style="color: rgba(0, 0, 0, 0);">testforquirks</span></div>
+<div style="position: absolute; top: 20px; left: 20px; color: blue; text-decoration: underline;"><span style="color: rgba(0, 0, 0, 0);">testforquirks</span></div>
+
+<!-- blue text -->
+<div style="position: absolute; top: 22px; left: 22px;"><span style="color: blue;">test</span></div>
+<div style="position: absolute; top: 20px; left: 20px;"><span style="color: blue;">test</span></div>
 
 <!-- red overline -->
 <div style="position: absolute; top: 22px; left: 22px; color: rgba(0, 0, 0, 0);">test<span style="text-decoration: overline; color: red;"><span style="color: rgba(0, 0, 0, 0);">forquirks</span></span></div>
 <div style="position: absolute; top: 20px; left: 20px; color: rgba(0, 0, 0, 0);">test<span style="text-decoration: overline; color: red;"><span style="color: rgba(0, 0, 0, 0);">forquirks</span></span></div>
 
-<!-- the actual text -->
-<div style="position: absolute; top: 22px; left: 22px;"><span style="color: blue;">test</span><span style="color: red;">for</span><span style="color: green;">quirks</span></div>
-<div style="position: absolute; top: 20px; left: 20px;"><span style="color: blue;">test</span><span style="color: red;">for</span><span style="color: green;">quirks</span></div>
+<!-- red text -->
+<div style="position: absolute; top: 22px; left: 22px;"><span style="color: rgba(0, 0, 0, 0);">test</span><span style="color: red;">for</span></div>
+<div style="position: absolute; top: 20px; left: 20px;"><span style="color: rgba(0, 0, 0, 0);">test</span><span style="color: red;">for</span></div>
+
+<!-- green underline -->
+<div style="position: absolute; top: 22px; left: 22px;"><span style="color: rgba(0, 0, 0, 0);">testfor</span><span style="text-decoration: underline; color: green;"><span style="color: rgba(0, 0, 0, 0);">quirks</span></span></div>
+<div style="position: absolute; top: 20px; left: 20px;"><span style="color: rgba(0, 0, 0, 0);">testfor</span><span style="text-decoration: underline; color: green;"><span style="color: rgba(0, 0, 0, 0);">quirks</span></span></div>
+
+<!-- green text -->
+<div style="position: absolute; top: 22px; left: 22px;"><span style="color: rgba(0, 0, 0, 0);">testfor</span><span style="color: green;">quirks</span></div>
+<div style="position: absolute; top: 20px; left: 20px;"><span style="color: rgba(0, 0, 0, 0);">testfor</span><span style="color: green;">quirks</span></div>