Bug 613659 - Implement box-decoration-break layout for border/box-shadow and paddding/margin for inlines. r=cam

layout/base/nsCSSRendering.cpp

@@ -61,6 +61,19 @@ using mozilla::CSSSizeOrRatio;
 
 static int gFrameTreeLockCount = 0;
 
+static void
+ApplySkipSides(int aSkipSides, nsMargin* aMargin)
+{
+  if (aSkipSides & SIDE_BIT_LEFT)
+    aMargin->left = 0;
+  if (aSkipSides & SIDE_BIT_TOP)
+    aMargin->top = 0;
+  if (aSkipSides & SIDE_BIT_RIGHT)
+    aMargin->right = 0;
+  if (aSkipSides & SIDE_BIT_BOTTOM)
+    aMargin->bottom = 0;
+}
+
 // To avoid storing this data on nsInlineFrame (bloat) and to avoid
 // recalculating this for each frame in a continuation (perf), hold
 // a cache of various coordinate information that we need in order
@@ -81,10 +94,18 @@ struct InlineBackgroundData
     mBoundingBox.SetRect(0,0,0,0);
     mContinuationPoint = mLineContinuationPoint = mUnbrokenWidth = 0;
     mFrame = mBlockFrame = nullptr;
+    mLeftBorderData.Reset();
   }
 
+  /**
+   * Return a continuous rect for (an inline) aFrame relative to the
+   * continuation that draws the left-most part of the background.
+   * This is used when painting backgrounds.
+   */
   nsRect GetContinuousRect(nsIFrame* aFrame)
   {
+    MOZ_ASSERT(aFrame->GetType() == nsGkAtoms::inlineFrame);
+
     SetFrame(aFrame);
 
     nscoord x;
@@ -98,12 +119,9 @@ struct InlineBackgroundData
                            NS_STYLE_DIRECTION_RTL);
       nscoord curOffset = aFrame->GetOffsetTo(mBlockFrame).x;
 
-      // No need to use our GetPrevContinuation/GetNextContinuation methods
-      // here, since ib-split siblings are certainly not on the same line.
-
-      nsIFrame* inlineFrame = aFrame->GetPrevContinuation();
       // If the continuation is fluid we know inlineFrame is not on the same line.
       // If it's not fluid, we need to test further to be sure.
+      nsIFrame* inlineFrame = aFrame->GetPrevContinuation();
       while (inlineFrame && !inlineFrame->GetNextInFlow() &&
              AreOnSameLine(aFrame, inlineFrame)) {
         nscoord frameXOffset = inlineFrame->GetOffsetTo(mBlockFrame).x;
@@ -140,6 +158,39 @@ struct InlineBackgroundData
     return nsRect(-x, 0, mUnbrokenWidth, mFrame->GetSize().height);
   }
 
+  /**
+   * Return a continuous rect for (an inline) aFrame relative to the
+   * continuation that should draw the left-border.  This is used when painting
+   * borders and clipping backgrounds.  This may NOT be the same continuous rect
+   * as for drawing backgrounds; the continuation with the left-border might be
+   * somewhere in the middle of that rect (e.g. BIDI), in those cases we need
+   * the reverse background order starting at the left-border continuation.
+   */
+  nsRect GetBorderContinuousRect(nsIFrame* aFrame, nsRect aBorderArea)
+  {
+    // Calling GetContinuousRect(aFrame) here may lead to Reset/Init which
+    // resets our mLeftBorderData so we save it ...
+    LeftBorderData saved(mLeftBorderData);
+    nsRect joinedBorderArea = GetContinuousRect(aFrame);
+    if (!saved.mIsValid || saved.mFrame != mLeftBorderData.mFrame) {
+      if (aFrame == mLeftBorderData.mFrame) {
+        mLeftBorderData.SetX(joinedBorderArea.x);
+      } else if (mLeftBorderData.mFrame) {
+        mLeftBorderData.SetX(GetContinuousRect(mLeftBorderData.mFrame).x);
+      }
+    } else {
+      // ... and restore it when possible.
+      mLeftBorderData.mX = saved.mX;
+    }
+    if (joinedBorderArea.x > mLeftBorderData.mX) {
+      joinedBorderArea.x =
+        -(mUnbrokenWidth + joinedBorderArea.x - aBorderArea.width);
+    } else {
+      joinedBorderArea.x -= mLeftBorderData.mX;
+    }
+    return joinedBorderArea;
+  }
+
   nsRect GetBoundingRect(nsIFrame* aFrame)
   {
     SetFrame(aFrame);
@@ -157,13 +208,22 @@ struct InlineBackgroundData
   }
 
 protected:
-  nsIFrame*     mFrame;
+  struct LeftBorderData {
-  nsBlockFrame* mBlockFrame;
+    nsIFrame* mFrame;   // the continuation that may have a left-border
-  nsRect        mBoundingBox;
+    nscoord   mX;       // cached GetContinuousRect(mFrame).x
-  nscoord       mContinuationPoint;
+    bool      mIsValid; // true if mX is valid
-  nscoord       mUnbrokenWidth;
+    void Reset() { mFrame = nullptr; mIsValid = false; }
-  nscoord       mLineContinuationPoint;
+    void SetX(nscoord aX) { mX = aX; mIsValid = true; }
-  bool          mBidiEnabled;
+  };
+
+  nsIFrame*      mFrame;
+  nsBlockFrame*  mBlockFrame;
+  nsRect         mBoundingBox;
+  nscoord        mContinuationPoint;
+  nscoord        mUnbrokenWidth;
+  nscoord        mLineContinuationPoint;
+  LeftBorderData mLeftBorderData;
+  bool           mBidiEnabled;
 
   void SetFrame(nsIFrame* aFrame)
   {
@@ -236,6 +296,7 @@ protected:
 
   void Init(nsIFrame* aFrame)
   {
+    mLeftBorderData.Reset();
     mBidiEnabled = aFrame->PresContext()->BidiEnabled();
     if (mBidiEnabled) {
       // Find the containing block frame
@@ -252,8 +313,11 @@ protected:
     // Start with the previous flow frame as our continuation point
     // is the total of the widths of the previous frames.
     nsIFrame* inlineFrame = GetPrevContinuation(aFrame);
-
     while (inlineFrame) {
+      if (!mLeftBorderData.mFrame &&
+          !(inlineFrame->GetSkipSides() & SIDE_BIT_LEFT)) {
+        mLeftBorderData.mFrame = inlineFrame;
+      }
       nsRect rect = inlineFrame->GetRect();
       mContinuationPoint += rect.width;
       if (mBidiEnabled && !AreOnSameLine(aFrame, inlineFrame)) {
@@ -268,6 +332,10 @@ protected:
     // unbroken width.
     inlineFrame = aFrame;
     while (inlineFrame) {
+      if (!mLeftBorderData.mFrame &&
+          !(inlineFrame->GetSkipSides() & SIDE_BIT_LEFT)) {
+        mLeftBorderData.mFrame = inlineFrame;
+      }
       nsRect rect = inlineFrame->GetRect();
       mUnbrokenWidth += rect.width;
       mBoundingBox.UnionRect(mBoundingBox, rect);
@@ -371,6 +439,94 @@ MakeBevelColor(mozilla::css::Side whichSide, uint8_t style,
   return theColor;
 }
 
+static bool
+GetRadii(nsIFrame* aForFrame, const nsStyleBorder& aBorder,
+         const nsRect& aOrigBorderArea, const nsRect& aBorderArea,
+         gfxCornerSizes* aBgRadii)
+{
+  nscoord radii[8];
+  bool haveRoundedCorners;
+  nsSize sz = aBorderArea.Size();
+  nsSize frameSize = aForFrame->GetSize();
+  if (&aBorder == aForFrame->StyleBorder() &&
+      frameSize == aOrigBorderArea.Size()) {
+    haveRoundedCorners = aForFrame->GetBorderRadii(sz, sz, 0, radii);
+   } else {
+    haveRoundedCorners =
+      nsIFrame::ComputeBorderRadii(aBorder.mBorderRadius, frameSize, sz, 0, radii);
+  }
+  if (haveRoundedCorners) {
+    auto d2a = aForFrame->PresContext()->AppUnitsPerDevPixel();
+    nsCSSRendering::ComputePixelRadii(radii, d2a, aBgRadii);
+  }
+  return haveRoundedCorners;
+}
+
+static nsRect
+JoinBoxesForVerticalSlice(nsIFrame* aFrame, const nsRect& aBorderArea)
+{
+  // Inflate vertically as if our continuations were laid out vertically
+  // adjacent. Note that we don't touch the width.
+  nsRect borderArea = aBorderArea;
+  nscoord h = 0;
+  nsIFrame* f = aFrame->GetNextContinuation();
+  for (; f; f = f->GetNextContinuation()) {
+    MOZ_ASSERT(!(f->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT),
+               "anonymous ib-split block shouldn't have border/background");
+    h += f->GetRect().height;
+  }
+  borderArea.height += h;
+  h = 0;
+  f = aFrame->GetPrevContinuation();
+  for (; f; f = f->GetPrevContinuation()) {
+    MOZ_ASSERT(!(f->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT),
+               "anonymous ib-split block shouldn't have border/background");
+    h += f->GetRect().height;
+  }
+  borderArea.y -= h;
+  borderArea.height += h;
+  return borderArea;
+}
+
+/**
+ * Inflate aBorderArea which is relative to aFrame's origin to calculate
+ * a hypothetical non-split frame area for all the continuations.
+ * See "Joining Boxes for 'slice'" in
+ * http://dev.w3.org/csswg/css-break/#break-decoration
+ */
+enum InlineBoxOrder { eForBorder, eForBackground };
+static nsRect
+JoinBoxesForSlice(nsIFrame* aFrame, const nsRect& aBorderArea,
+                  InlineBoxOrder aOrder)
+{
+  if (aFrame->GetType() == nsGkAtoms::inlineFrame) {
+    return (aOrder == eForBorder
+            ? gInlineBGData->GetBorderContinuousRect(aFrame, aBorderArea)
+            : gInlineBGData->GetContinuousRect(aFrame)) +
+      aBorderArea.TopLeft();
+  }
+  return JoinBoxesForVerticalSlice(aFrame, aBorderArea);
+}
+
+static bool
+IsBoxDecorationSlice(const nsStyleBorder& aStyleBorder)
+{
+  return aStyleBorder.mBoxDecorationBreak ==
+           NS_STYLE_BOX_DECORATION_BREAK_SLICE;
+}
+
+static nsRect
+BoxDecorationRectForBorder(nsIFrame* aFrame, const nsRect& aBorderArea,
+                           const nsStyleBorder* aStyleBorder = nullptr)
+{
+  if (!aStyleBorder) {
+    aStyleBorder = aFrame->StyleBorder();
+  }
+  return ::IsBoxDecorationSlice(*aStyleBorder)
+           ? ::JoinBoxesForSlice(aFrame, aBorderArea, eForBorder)
+           : aBorderArea;
+}
+
 //----------------------------------------------------------------------
 // Thebes Border Rendering Code Start
 
@@ -449,10 +605,6 @@ nsCSSRendering::PaintBorderWithStyleBorder(nsPresContext* aPresContext,
                                            nsStyleContext* aStyleContext,
                                            int aSkipSides)
 {
-  nsMargin            border;
-  nscoord             twipsRadii[8];
-  nsCompatibility     compatMode = aPresContext->CompatibilityMode();
-
   SN("++ PaintBorder");
 
   // Check to see if we have an appearance defined.  If so, we let the theme
@@ -474,59 +626,67 @@ nsCSSRendering::PaintBorderWithStyleBorder(nsPresContext* aPresContext,
   // Get our style context's color struct.
   const nsStyleColor* ourColor = aStyleContext->StyleColor();
 
-  // in NavQuirks mode we want to use the parent's context as a starting point
+  // In NavQuirks mode we want to use the parent's context as a starting point
-  // for determining the background color
+  // for determining the background color.
-  nsIFrame* bgFrame = nsCSSRendering::FindNonTransparentBackgroundFrame
+  bool quirks = aPresContext->CompatibilityMode() == eCompatibility_NavQuirks;
-    (aForFrame, compatMode == eCompatibility_NavQuirks ? true : false);
+  nsIFrame* bgFrame = FindNonTransparentBackgroundFrame(aForFrame, quirks);
   nsStyleContext* bgContext = bgFrame->StyleContext();
   nscolor bgColor =
     bgContext->GetVisitedDependentColor(eCSSProperty_background_color);
 
-  border = aStyleBorder.GetComputedBorder();
+  nsMargin border = aStyleBorder.GetComputedBorder();
   if ((0 == border.left) && (0 == border.right) &&
       (0 == border.top) && (0 == border.bottom)) {
     // Empty border area
     return;
   }
 
-  nsSize frameSize = aForFrame->GetSize();
+  // Compute the outermost boundary of the area that might be painted.
-  if (&aStyleBorder == aForFrame->StyleBorder() &&
+  // Same coordinate space as aBorderArea & aBGClipRect.
-      frameSize == aBorderArea.Size()) {
+  nsRect joinedBorderArea =
-    aForFrame->GetBorderRadii(twipsRadii);
+    ::BoxDecorationRectForBorder(aForFrame, aBorderArea, &aStyleBorder);
+  gfxCornerSizes bgRadii;
+  ::GetRadii(aForFrame, aStyleBorder, aBorderArea, joinedBorderArea, &bgRadii);
+
+
+  SF(" joinedBorderArea: %d %d %d %d\n", joinedBorderArea.x, joinedBorderArea.y,
+     joinedBorderArea.width, joinedBorderArea.height);
+
+  // start drawing
+  gfxContext* ctx = aRenderingContext.ThebesContext();
+  ctx->Save();
+
+  if (::IsBoxDecorationSlice(aStyleBorder)) {
+    if (aSkipSides == 0) {
+      // No continuations most likely, or ::first-letter that wants all border-
+      // sides on the first continuation.
+      joinedBorderArea = aBorderArea;
+    } else if (joinedBorderArea.IsEqualEdges(aBorderArea)) {
+      // No need for a clip, just skip the sides we don't want.
+      ::ApplySkipSides(aSkipSides, &border);
+    } else {
+      // We're drawing borders around the joined continuation boxes so we need
+      // to clip that to the slice that we want for this frame.
+      aRenderingContext.IntersectClip(aBorderArea);
+    }
   } else {
-    nsIFrame::ComputeBorderRadii(aStyleBorder.mBorderRadius, frameSize,
+    MOZ_ASSERT(joinedBorderArea.IsEqualEdges(aBorderArea),
-                                 aBorderArea.Size(), aSkipSides, twipsRadii);
+               "Should use aBorderArea for box-decoration-break:clone");
+    MOZ_ASSERT(aForFrame->GetSkipSides() == 0,
+               "Should not skip sides for box-decoration-break:clone except "
+               "::first-letter/line continuations or other frame types that "
+               "don't have borders but those shouldn't reach this point.");
   }
 
-  // Turn off rendering for all of the zero sized sides
+  // Convert to dev pixels.
-  if (aSkipSides & SIDE_BIT_TOP) border.top = 0;
-  if (aSkipSides & SIDE_BIT_RIGHT) border.right = 0;
-  if (aSkipSides & SIDE_BIT_BOTTOM) border.bottom = 0;
-  if (aSkipSides & SIDE_BIT_LEFT) border.left = 0;
-
-  // get the inside and outside parts of the border
-  nsRect outerRect(aBorderArea);
-
-  SF(" outerRect: %d %d %d %d\n", outerRect.x, outerRect.y, outerRect.width, outerRect.height);
-
-  // we can assume that we're already clipped to aDirtyRect -- I think? (!?)
-
-  // Get our conversion values
   nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);
-
+  gfxRect joinedBorderAreaPx =
-  // convert outer and inner rects
+    nsLayoutUtils::RectToGfxRect(joinedBorderArea, twipsPerPixel);
-  gfxRect oRect(nsLayoutUtils::RectToGfxRect(outerRect, twipsPerPixel));
-
-  // convert the border widths
   gfxFloat borderWidths[4] = { gfxFloat(border.top / twipsPerPixel),
                                gfxFloat(border.right / twipsPerPixel),
                                gfxFloat(border.bottom / twipsPerPixel),
                                gfxFloat(border.left / twipsPerPixel) };
 
-  // convert the radii
-  gfxCornerSizes borderRadii;
-  ComputePixelRadii(twipsRadii, twipsPerPixel, &borderRadii);
-
   uint8_t borderStyles[4];
   nscolor borderColors[4];
   nsBorderColors *compositeColors[4];
@@ -543,32 +703,25 @@ nsCSSRendering::PaintBorderWithStyleBorder(nsPresContext* aPresContext,
   }
 
   SF(" borderStyles: %d %d %d %d\n", borderStyles[0], borderStyles[1], borderStyles[2], borderStyles[3]);
-
+  //SF ("bgRadii: %f %f %f %f\n", bgRadii[0], bgRadii[1], bgRadii[2], bgRadii[3]);
-  // start drawing
-  gfxContext *ctx = aRenderingContext.ThebesContext();
-
-  ctx->Save();
 
 #if 0
-  // this will draw a transparent red backround underneath the oRect area
+  // this will draw a transparent red backround underneath the border area
   ctx->Save();
-  ctx->Rectangle(oRect);
+  ctx->Rectangle(joinedBorderAreaPx);
   ctx->SetColor(gfxRGBA(1.0, 0.0, 0.0, 0.5));
   ctx->Fill();
   ctx->Restore();
 #endif
 
-  //SF ("borderRadii: %f %f %f %f\n", borderRadii[0], borderRadii[1], borderRadii[2], borderRadii[3]);
-
   nsCSSBorderRenderer br(twipsPerPixel,
                          ctx,
-                         oRect,
+                         joinedBorderAreaPx,
                          borderStyles,
                          borderWidths,
-                         borderRadii,
+                         bgRadii,
                          borderColors,
                          compositeColors,
-                         aSkipSides,
                          bgColor);
   br.DrawBorders();
 
@@ -688,7 +841,7 @@ nsCSSRendering::PaintOutline(nsPresContext* aPresContext,
                          outlineWidths,
                          outlineRadii,
                          outlineColors,
-                         nullptr, 0,
+                         nullptr,
                          bgColor);
   br.DrawBorders();
 
@@ -741,7 +894,7 @@ nsCSSRendering::PaintFocus(nsPresContext* aPresContext,
                          focusWidths,
                          focusRadii,
                          focusColors,
-                         nullptr, 0,
+                         nullptr,
                          NS_RGB(255, 0, 0));
   br.DrawBorders();
 
@@ -996,13 +1149,10 @@ nsCSSRendering::PaintBoxShadowOuter(nsPresContext* aPresContext,
   nsCSSShadowArray* shadows = styleBorder->mBoxShadow;
   if (!shadows)
     return;
-  nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);
 
+  gfxContextAutoSaveRestore gfxStateRestorer;
   bool hasBorderRadius;
   bool nativeTheme; // mutually exclusive with hasBorderRadius
-  gfxCornerSizes borderRadii;
-
-  // Get any border radius, since box-shadow must also have rounded corners if the frame does
   const nsStyleDisplay* styleDisplay = aForFrame->StyleDisplay();
   nsITheme::Transparency transparency;
   if (aForFrame->IsThemed(styleDisplay, &transparency)) {
@@ -1013,17 +1163,29 @@ nsCSSRendering::PaintBoxShadowOuter(nsPresContext* aPresContext,
     nativeTheme = transparency != nsITheme::eOpaque;
   } else {
     nativeTheme = false;
+    hasBorderRadius = true; // we'll update this below
+  }
+
+  nsRect frameRect = nativeTheme ?
+    aForFrame->GetVisualOverflowRectRelativeToSelf() + aFrameArea.TopLeft() :
+    aFrameArea;
+  frameRect = ::BoxDecorationRectForBorder(aForFrame, frameRect);
+
+  // Get any border radius, since box-shadow must also have rounded corners if
+  // the frame does.
+  gfxCornerSizes borderRadii;
+  const nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);
+  if (hasBorderRadius) {
     nscoord twipsRadii[8];
     NS_ASSERTION(aFrameArea.Size() == aForFrame->VisualBorderRectRelativeToSelf().Size(),
                  "unexpected size");
-    hasBorderRadius = aForFrame->GetBorderRadii(twipsRadii);
+    nsSize sz = frameRect.Size();
+    hasBorderRadius = aForFrame->GetBorderRadii(sz, sz, 0, twipsRadii);
     if (hasBorderRadius) {
       ComputePixelRadii(twipsRadii, twipsPerPixel, &borderRadii);
     }
   }
 
-  nsRect frameRect =
-    nativeTheme ? aForFrame->GetVisualOverflowRectRelativeToSelf() + aFrameArea.TopLeft() : aFrameArea;
   gfxRect frameGfxRect(nsLayoutUtils::RectToGfxRect(frameRect, twipsPerPixel));
   frameGfxRect.Round();
 
@@ -1047,6 +1209,7 @@ nsCSSRendering::PaintBoxShadowOuter(nsPresContext* aPresContext,
         std::max(borderRadii[C_BL].height, borderRadii[C_BR].height), 0));
   }
 
+  int skipSides = aForFrame->GetSkipSides();
   for (uint32_t i = shadows->Length(); i > 0; --i) {
     nsCSSShadowItem* shadowItem = shadows->ShadowAt(i - 1);
     if (shadowItem->mInset)
@@ -1127,7 +1290,7 @@ nsCSSRendering::PaintBoxShadowOuter(nsPresContext* aPresContext,
     } else {
       renderContext->Save();
       // Clip out the area of the actual frame so the shadow is not shown within
-      // the frame
+      // the frame.
       renderContext->NewPath();
       renderContext->Rectangle(shadowGfxRectPlusBlur);
       if (hasBorderRadius) {
@@ -1139,6 +1302,36 @@ nsCSSRendering::PaintBoxShadowOuter(nsPresContext* aPresContext,
       renderContext->SetFillRule(gfxContext::FILL_RULE_EVEN_ODD);
       renderContext->Clip();
 
+      // Clip the shadow so that we only get the part that applies to aForFrame.
+      nsRect fragmentClip = shadowRectPlusBlur;
+      if (skipSides) {
+        if (skipSides & SIDE_BIT_LEFT) {
+          nscoord xmost = fragmentClip.XMost();
+          fragmentClip.x = aFrameArea.x;
+          fragmentClip.width = xmost - fragmentClip.x;
+        }
+        if (skipSides & SIDE_BIT_RIGHT) {
+          nscoord xmost = fragmentClip.XMost();
+          nscoord overflow = xmost - aFrameArea.XMost();
+          if (overflow > 0) {
+            fragmentClip.width -= overflow;
+          }
+        }
+        if (skipSides & SIDE_BIT_TOP) {
+          nscoord ymost = fragmentClip.YMost();
+          fragmentClip.y = aFrameArea.y;
+          fragmentClip.height = ymost - fragmentClip.y;
+        }
+        if (skipSides & SIDE_BIT_BOTTOM) {
+          nscoord ymost = fragmentClip.YMost();
+          nscoord overflow = ymost - aFrameArea.YMost();
+          if (overflow > 0) {
+            fragmentClip.height -= overflow;
+          }
+        }
+      }
+      aRenderingContext.IntersectClip(fragmentClip);
+
       gfxCornerSizes clipRectRadii;
       if (hasBorderRadius) {
         gfxFloat spreadDistance = shadowItem->mSpread / twipsPerPixel;
@@ -1188,18 +1381,20 @@ nsCSSRendering::PaintBoxShadowInner(nsPresContext* aPresContext,
     return;
   }
 
+  NS_ASSERTION(aForFrame->GetType() == nsGkAtoms::fieldSetFrame ||
+               aFrameArea.Size() == aForFrame->GetSize(), "unexpected size");
+
+  nsRect frameRect = ::BoxDecorationRectForBorder(aForFrame, aFrameArea);
+  nsRect paddingRect = frameRect;
+  nsMargin border = aForFrame->GetUsedBorder();
+  paddingRect.Deflate(border);
+
   // Get any border radius, since box-shadow must also have rounded corners
   // if the frame does.
   nscoord twipsRadii[8];
-  NS_ASSERTION(aForFrame->GetType() == nsGkAtoms::fieldSetFrame ||
+  nsSize sz = frameRect.Size();
-               aFrameArea.Size() == aForFrame->GetSize(), "unexpected size");
+  bool hasBorderRadius = aForFrame->GetBorderRadii(sz, sz, 0, twipsRadii);
-  bool hasBorderRadius = aForFrame->GetBorderRadii(twipsRadii);
+  const nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);
-  nscoord twipsPerPixel = aPresContext->DevPixelsToAppUnits(1);
-
-  nsRect paddingRect = aFrameArea;
-  nsMargin border = aForFrame->GetUsedBorder();
-  aForFrame->ApplySkipSides(border);
-  paddingRect.Deflate(border);
 
   gfxCornerSizes innerRadii;
   if (hasBorderRadius) {
@@ -1221,13 +1416,9 @@ nsCSSRendering::PaintBoxShadowInner(nsPresContext* aPresContext,
     if (!shadowItem->mInset)
       continue;
 
-    /*
+    // shadowPaintRect: the area to paint on the temp surface
-     * shadowRect: the frame's padding rect
+    // shadowClipRect: the area on the temporary surface within shadowPaintRect
-     * shadowPaintRect: the area to paint on the temp surface, larger than shadowRect
+    //                 that we will NOT paint in
-     *                  so that blurs still happen properly near the edges
-     * shadowClipRect: the area on the temporary surface within shadowPaintRect
-     *                 that we will NOT paint in
-     */
     nscoord blurRadius = shadowItem->mRadius;
     nsMargin blurMargin =
       nsContextBoxBlur::GetBlurRadiusMargin(blurRadius, twipsPerPixel);
@@ -4935,10 +5126,8 @@ nsContextBoxBlur::GetBlurRadiusMargin(nscoord aBlurRadius,
   gfxIntSize blurRadius = ComputeBlurRadius(aBlurRadius, aAppUnitsPerDevPixel);
 
   nsMargin result;
-  result.top    = blurRadius.height * aAppUnitsPerDevPixel;
+  result.top = result.bottom = blurRadius.height * aAppUnitsPerDevPixel;
-  result.right  = blurRadius.width  * aAppUnitsPerDevPixel;
+  result.left = result.right = blurRadius.width  * aAppUnitsPerDevPixel;
-  result.bottom = blurRadius.height * aAppUnitsPerDevPixel;
-  result.left   = blurRadius.width  * aAppUnitsPerDevPixel;
   return result;
 }
 

layout/base/nsCSSRenderingBorders.cpp

@@ -120,7 +120,6 @@ nsCSSBorderRenderer::nsCSSBorderRenderer(int32_t aAppUnitsPerPixel,
                                          gfxCornerSizes& aBorderRadii,
                                          const nscolor* aBorderColors,
                                          nsBorderColors* const* aCompositeColors,
-                                         int aSkipSides,
                                          nscolor aBackgroundColor)
   : mContext(aDestContext),
     mOuterRect(aOuterRect),
@@ -130,7 +129,6 @@ nsCSSBorderRenderer::nsCSSBorderRenderer(int32_t aAppUnitsPerPixel,
     mBorderColors(aBorderColors),
     mCompositeColors(aCompositeColors),
     mAUPP(aAppUnitsPerPixel),
-    mSkipSides(aSkipSides),
     mBackgroundColor(aBackgroundColor)
 {
   if (!mCompositeColors) {

layout/base/nsCSSRenderingBorders.h

@@ -79,7 +79,6 @@ struct nsCSSBorderRenderer {
                       gfxCornerSizes& aBorderRadii,
                       const nscolor* aBorderColors,
                       nsBorderColors* const* aCompositeColors,
-                      int aSkipSides,
                       nscolor aBackgroundColor);
 
   gfxCornerSizes mBorderCornerDimensions;
@@ -105,8 +104,7 @@ struct nsCSSBorderRenderer {
   // core app units per pixel
   int32_t mAUPP;
 
-  // misc -- which sides to skip, the background color
+  // the background color
-  int mSkipSides;
   nscolor mBackgroundColor;
 
   // calculated values

layout/base/nsDisplayList.cpp

@@ -2839,11 +2839,8 @@ nsDisplayBoxShadowOuter::Paint(nsDisplayListBuilder* aBuilder,
 
   PROFILER_LABEL("nsDisplayBoxShadowOuter", "Paint");
   for (uint32_t i = 0; i < rects.Length(); ++i) {
-    aCtx->PushState();
-    aCtx->IntersectClip(rects[i]);
     nsCSSRendering::PaintBoxShadowOuter(presContext, *aCtx, mFrame,
                                         borderRect, rects[i], mOpacity);
-    aCtx->PopState();
   }
 }
 

layout/generic/nsContainerFrame.cpp

@@ -849,12 +849,31 @@ nsContainerFrame::DoInlineIntrinsicWidth(nsRenderingContext *aRenderingContext,
   // This frame is a first-in-flow, but it might have a previous bidi
   // continuation, in which case that continuation should handle the startSide
   // border.
+  // For box-decoration-break:clone we setup clonePBM = startPBM + endPBM and
+  // add that to each line.  For box-decoration-break:slice clonePBM is zero.
+  nscoord clonePBM = 0; // PBM = PaddingBorderMargin
+  const bool sliceBreak =
+    styleBorder->mBoxDecorationBreak == NS_STYLE_BOX_DECORATION_BREAK_SLICE;
   if (!GetPrevContinuation()) {
-    aData->currentLine +=
+    nscoord startPBM =
       // clamp negative calc() to 0
       std::max(GetCoord(stylePadding->mPadding.Get(startSide), 0), 0) +
       styleBorder->GetComputedBorderWidth(startSide) +
       GetCoord(styleMargin->mMargin.Get(startSide), 0);
+    if (MOZ_LIKELY(sliceBreak)) {
+      aData->currentLine += startPBM;
+    } else {
+      clonePBM = startPBM;
+    }
+  }
+
+  nscoord endPBM =
+    // clamp negative calc() to 0
+    std::max(GetCoord(stylePadding->mPadding.Get(endSide), 0), 0) +
+    styleBorder->GetComputedBorderWidth(endSide) +
+    GetCoord(styleMargin->mMargin.Get(endSide), 0);
+  if (MOZ_UNLIKELY(!sliceBreak)) {
+    clonePBM += endPBM;
   }
 
   const nsLineList_iterator* savedLine = aData->line;
@@ -863,6 +882,9 @@ nsContainerFrame::DoInlineIntrinsicWidth(nsRenderingContext *aRenderingContext,
   nsContainerFrame *lastInFlow;
   for (nsContainerFrame *nif = this; nif;
        nif = static_cast<nsContainerFrame*>(nif->GetNextInFlow())) {
+    if (aData->currentLine == 0) {
+      aData->currentLine = clonePBM;
+    }
     for (nsIFrame *kid = nif->mFrames.FirstChild(); kid;
          kid = kid->GetNextSibling()) {
       if (aType == nsLayoutUtils::MIN_WIDTH)
@@ -891,12 +913,8 @@ nsContainerFrame::DoInlineIntrinsicWidth(nsRenderingContext *aRenderingContext,
   // We reached the last-in-flow, but it might have a next bidi
   // continuation, in which case that continuation should handle
   // the endSide border.
-  if (!lastInFlow->GetNextContinuation()) {
+  if (MOZ_LIKELY(!lastInFlow->GetNextContinuation() && sliceBreak)) {
-    aData->currentLine +=
+    aData->currentLine += endPBM;
-      // clamp negative calc() to 0
-      std::max(GetCoord(stylePadding->mPadding.Get(endSide), 0), 0) +
-      styleBorder->GetComputedBorderWidth(endSide) +
-      GetCoord(styleMargin->mMargin.Get(endSide), 0);
   }
 }
 

layout/generic/nsFrame.cpp

@@ -953,6 +953,11 @@ nsIFrame::GetUsedPadding() const
 int
 nsIFrame::GetSkipSides(const nsHTMLReflowState* aReflowState) const
 {
+  if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
+                     NS_STYLE_BOX_DECORATION_BREAK_CLONE)) {
+    return 0;
+  }
+
   // Convert the logical skip sides to physical sides using the frame's
   // writing mode
   WritingMode writingMode = GetWritingMode();

layout/generic/nsImageFrame.cpp

@@ -1782,6 +1782,10 @@ nsImageFrame::List(FILE* out, const char* aPrefix, uint32_t aFlags) const
 int
 nsImageFrame::GetLogicalSkipSides(const nsHTMLReflowState* aReflowState) const
 {
+  if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
+                     NS_STYLE_BOX_DECORATION_BREAK_CLONE)) {
+    return 0;
+  }
   int skip = 0;
   if (nullptr != GetPrevInFlow()) {
     skip |= LOGICAL_SIDE_B_START;

layout/generic/nsInlineFrame.cpp

@@ -115,7 +115,11 @@ nsInlineFrame::IsSelfEmpty()
     !nsLayoutUtils::IsPaddingZero(padding->mPadding.GetLeft()) ||
     !IsMarginZero(margin->mMargin.GetLeft());
   if (haveLeft || haveRight) {
-    if (GetStateBits() & NS_FRAME_PART_OF_IBSPLIT) {
+    // We skip this block and return false for box-decoration-break:clone since
+    // in that case all the continuations will have the border/padding/margin.
+    if ((GetStateBits() & NS_FRAME_PART_OF_IBSPLIT) &&
+        StyleBorder()->mBoxDecorationBreak ==
+          NS_STYLE_BOX_DECORATION_BREAK_SLICE) {
       bool haveStart, haveEnd;
       if (NS_STYLE_DIRECTION_LTR == StyleVisibility()->mDirection) {
         haveStart = haveLeft;
@@ -491,9 +495,15 @@ nsInlineFrame::ReflowFrames(nsPresContext* aPresContext,
   RestyleManager* restyleManager = aPresContext->RestyleManager();
   WritingMode wm = aReflowState.GetWritingMode();
   nscoord startEdge = 0;
+  const bool boxDecorationBreakClone =
+    MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
+                   NS_STYLE_BOX_DECORATION_BREAK_CLONE);
   // Don't offset by our start borderpadding if we have a prev continuation or
-  // if we're in a part of an {ib} split other than the first one.
+  // if we're in a part of an {ib} split other than the first one. For
-  if (!GetPrevContinuation() && !FrameIsNonFirstInIBSplit()) {
+  // box-decoration-break:clone we always offset our start since all
+  // continuations have border/padding.
+  if ((!GetPrevContinuation() && !FrameIsNonFirstInIBSplit()) ||
+      boxDecorationBreakClone) {
     startEdge = aReflowState.ComputedLogicalBorderPadding().IStart(wm);
   }
   nscoord availableISize = aReflowState.AvailableISize();
@@ -654,8 +664,10 @@ nsInlineFrame::ReflowFrames(nsPresContext* aPresContext,
 
   // Make sure to not include our start border and padding if we have a prev
   // continuation or if we're in a part of an {ib} split other than the first
-  // one.
+  // one.  For box-decoration-break:clone we always include our start border
-  if (!GetPrevContinuation() && !FrameIsNonFirstInIBSplit()) {
+  // and padding since all continuations have them.
+  if ((!GetPrevContinuation() && !FrameIsNonFirstInIBSplit()) ||
+      boxDecorationBreakClone) {
     aMetrics.ISize() += aReflowState.ComputedLogicalBorderPadding().IStart(wm);
   }
 
@@ -664,11 +676,13 @@ nsInlineFrame::ReflowFrames(nsPresContext* aPresContext,
    * continuation and either not in an {ib} split or the last part of it.  To
    * be the last continuation we have to be complete (so that we won't get a
    * next-in-flow) and have no non-fluid continuations on our continuation
-   * chain.
+   * chain.  For box-decoration-break:clone we always apply the end border and
+   * padding since all continuations have them.
    */
-  if (NS_FRAME_IS_COMPLETE(aStatus) &&
+  if ((NS_FRAME_IS_COMPLETE(aStatus) &&
-      !LastInFlow()->GetNextContinuation() &&
+       !LastInFlow()->GetNextContinuation() &&
-      !FrameIsNonLastInIBSplit()) {
+       !FrameIsNonLastInIBSplit()) ||
+      boxDecorationBreakClone) {
     aMetrics.Width() += aReflowState.ComputedLogicalBorderPadding().IEnd(wm);
   }
 
@@ -872,6 +886,11 @@ nsInlineFrame::PushFrames(nsPresContext* aPresContext,
 int
 nsInlineFrame::GetLogicalSkipSides(const nsHTMLReflowState* aReflowState) const
 {
+  if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
+                     NS_STYLE_BOX_DECORATION_BREAK_CLONE)) {
+    return 0;
+  }
+
   int skip = 0;
   if (!IsFirst()) {
     nsInlineFrame* prev = (nsInlineFrame*) GetPrevContinuation();

layout/generic/nsLineLayout.cpp

@@ -1076,9 +1076,12 @@ nsLineLayout::ApplyStartMargin(PerFrameData* pfd,
   // in an ib split.  Note that the ib sibling (block-in-inline
   // sibling) annotations only live on the first continuation, but we
   // don't want to apply the start margin for later continuations
-  // anyway.
+  // anyway.  For box-decoration-break:clone we apply the start-margin
-  if (pfd->mFrame->GetPrevContinuation() ||
+  // on all continuations.
-      pfd->mFrame->FrameIsNonFirstInIBSplit()) {
+  if ((pfd->mFrame->GetPrevContinuation() ||
+       pfd->mFrame->FrameIsNonFirstInIBSplit()) &&
+      aReflowState.mStyleBorder->mBoxDecorationBreak ==
+        NS_STYLE_BOX_DECORATION_BREAK_SLICE) {
     // Zero this out so that when we compute the max-element-width of
     // the frame we will properly avoid adding in the starting margin.
     pfd->mMargin.IStart(frameWM) = 0;
@@ -1160,6 +1163,9 @@ nsLineLayout::CanPlaceFrame(PerFrameData* pfd,
    * 3) The frame is in an {ib} split and is not the last part.
    *
    * However, none of that applies if this is a letter frame (XXXbz why?)
+   *
+   * For box-decoration-break:clone we apply the end margin on all
+   * continuations (that are not letter frames).
    */
   if (pfd->mFrame->GetPrevContinuation() ||
       pfd->mFrame->FrameIsNonFirstInIBSplit()) {
@@ -1167,8 +1173,10 @@ nsLineLayout::CanPlaceFrame(PerFrameData* pfd,
   }
   if ((NS_FRAME_IS_NOT_COMPLETE(aStatus) ||
        pfd->mFrame->LastInFlow()->GetNextContinuation() ||
-       pfd->mFrame->FrameIsNonLastInIBSplit())
+       pfd->mFrame->FrameIsNonLastInIBSplit()) &&
-      && !pfd->GetFlag(PFD_ISLETTERFRAME)) {
+      !pfd->GetFlag(PFD_ISLETTERFRAME) &&
+      pfd->mFrame->StyleBorder()->mBoxDecorationBreak ==
+        NS_STYLE_BOX_DECORATION_BREAK_SLICE) {
     pfd->mMargin.IEnd(frameWM) = 0;
   }
   LogicalMargin usedMargins = pfd->mMargin.ConvertTo(lineWM, frameWM);

layout/generic/nsSplittableFrame.cpp

@@ -253,8 +253,12 @@ nsSplittableFrame::GetLogicalSkipSides(const nsHTMLReflowState* aReflowState) co
     return LOGICAL_SIDES_B_BOTH;
   }
 
-  int skip = 0;
+  if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
+                     NS_STYLE_BOX_DECORATION_BREAK_CLONE)) {
+    return 0;
+  }
 
+  int skip = 0;
   if (GetPrevInFlow()) {
     skip |= LOGICAL_SIDE_B_START;
   }

layout/tables/nsTableCellFrame.cpp

@@ -550,6 +550,11 @@ nsTableCellFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 int
 nsTableCellFrame::GetLogicalSkipSides(const nsHTMLReflowState* aReflowState) const
 {
+  if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
+                     NS_STYLE_BOX_DECORATION_BREAK_CLONE)) {
+    return 0;
+  }
+
   int skip = 0;
   if (nullptr != GetPrevInFlow()) {
     skip |= LOGICAL_SIDE_B_START;

layout/tables/nsTableColGroupFrame.cpp

@@ -343,6 +343,11 @@ nsTableColGroupFrame::RemoveFrame(ChildListID     aListID,
 int
 nsTableColGroupFrame::GetLogicalSkipSides(const nsHTMLReflowState* aReflowState) const
 {
+  if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
+                     NS_STYLE_BOX_DECORATION_BREAK_CLONE)) {
+    return 0;
+  }
+
   int skip = 0;
   if (nullptr != GetPrevInFlow()) {
     skip |= 1 << LOGICAL_SIDE_B_START;

layout/tables/nsTableFrame.cpp

@@ -1409,6 +1409,11 @@ nsTableFrame::PaintTableBorderBackground(nsRenderingContext& aRenderingContext,
 int
 nsTableFrame::GetLogicalSkipSides(const nsHTMLReflowState* aReflowState) const
 {
+  if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
+                     NS_STYLE_BOX_DECORATION_BREAK_CLONE)) {
+    return 0;
+  }
+
   int skip = 0;
   // frame attribute was accounted for in nsHTMLTableElement::MapTableBorderInto
   // account for pagination

layout/tables/nsTableRowFrame.cpp

@@ -605,6 +605,11 @@ nsTableRowFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 int
 nsTableRowFrame::GetLogicalSkipSides(const nsHTMLReflowState* aReflowState) const
 {
+  if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
+                     NS_STYLE_BOX_DECORATION_BREAK_CLONE)) {
+    return 0;
+  }
+
   int skip = 0;
   if (nullptr != GetPrevInFlow()) {
     skip |= LOGICAL_SIDE_B_START;

layout/tables/nsTableRowGroupFrame.cpp

@@ -256,6 +256,11 @@ nsTableRowGroupFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 int
 nsTableRowGroupFrame::GetLogicalSkipSides(const nsHTMLReflowState* aReflowState) const
 {
+  if (MOZ_UNLIKELY(StyleBorder()->mBoxDecorationBreak ==
+                     NS_STYLE_BOX_DECORATION_BREAK_CLONE)) {
+    return 0;
+  }
+
   int skip = 0;
   if (nullptr != GetPrevInFlow()) {
     skip |= LOGICAL_SIDE_B_START;