Bug 1917763 - Do not override MeasureForWidth/Reflow for mroot. r=emilio

fred-wang · fred-wang · commit fac124e3b173 · 2024-09-13T08:03:56.000Z
This patch reimplements layout of the mroot element by overridding the Place() method, which is used by nsMathMLContainerFrame for the implementation of Reflow and MeasureForWidth. These two latter methods then don't need to be overridden anymore in nsMathMLmrootFrame. Differential Revision: https://phabricator.services.mozilla.com/D221629
diff --git a/layout/mathml/nsMathMLmrootFrame.cpp b/layout/mathml/nsMathMLmrootFrame.cpp
@@ -129,64 +129,26 @@ void nsMathMLmrootFrame::GetRadicalXOffsets(nscoord aIndexWidth,
   if (aSqrOffset) *aSqrOffset = dxSqr;
 }
 
-void nsMathMLmrootFrame::Reflow(nsPresContext* aPresContext,
-                                ReflowOutput& aDesiredSize,
-                                const ReflowInput& aReflowInput,
-                                nsReflowStatus& aStatus) {
+nsresult nsMathMLmrootFrame::Place(DrawTarget* aDrawTarget,
+                                   const PlaceFlags& aFlags,
+                                   ReflowOutput& aDesiredSize) {
   if (ShouldUseRowFallback()) {
-    ReportChildCountError();
-    nsMathMLContainerFrame::Reflow(aPresContext, aDesiredSize, aReflowInput,
-                                   aStatus);
-    return;
+    // report an error, encourage people to get their markups in order
+    if (!aFlags.contains(PlaceFlag::MeasureOnly)) {
+      ReportChildCountError();
+    }
+    return PlaceAsMrow(aDrawTarget, aFlags, aDesiredSize);
   }
 
-  MarkInReflow();
-  MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!");
-
-  nsReflowStatus childStatus;
-  aDesiredSize.ClearSize();
-  aDesiredSize.SetBlockStartAscent(0);
-
   nsBoundingMetrics bmSqr, bmBase, bmIndex;
-  nsMargin baseMargin, indexMargin;
-  DrawTarget* drawTarget = aReflowInput.mRenderingContext->GetDrawTarget();
-
-  //////////////////
-  // Reflow Children
-
-  int32_t count = 0;
-  nsIFrame* baseFrame = nullptr;
-  nsIFrame* indexFrame = nullptr;
-  ReflowOutput baseSize(aReflowInput);
-  ReflowOutput indexSize(aReflowInput);
-  nsIFrame* childFrame = mFrames.FirstChild();
-  while (childFrame) {
-    // ask our children to compute their bounding metrics
-    ReflowOutput childDesiredSize(aReflowInput);
-    WritingMode wm = childFrame->GetWritingMode();
-    LogicalSize availSize = aReflowInput.ComputedSize(wm);
-    availSize.BSize(wm) = NS_UNCONSTRAINEDSIZE;
-    ReflowInput childReflowInput(aPresContext, aReflowInput, childFrame,
-                                 availSize);
-    ReflowChild(childFrame, aPresContext, childDesiredSize, childReflowInput,
-                childStatus);
-    // NS_ASSERTION(childStatus.IsComplete(), "bad status");
-    if (0 == count) {
-      // base
-      baseFrame = childFrame;
-      baseSize = childDesiredSize;
-      bmBase = childDesiredSize.mBoundingMetrics;
-      baseMargin = baseFrame->GetUsedMargin();
-    } else if (1 == count) {
-      // index
-      indexFrame = childFrame;
-      indexSize = childDesiredSize;
-      bmIndex = childDesiredSize.mBoundingMetrics;
-      indexMargin = indexFrame->GetUsedMargin();
-    }
-    count++;
-    childFrame = childFrame->GetNextSibling();
-  }
+  nsIFrame* baseFrame = mFrames.FirstChild();
+  nsIFrame* indexFrame = baseFrame->GetNextSibling();
+  nsMargin baseMargin = GetMarginForPlace(aFlags, baseFrame),
+           indexMargin = GetMarginForPlace(aFlags, indexFrame);
+  ReflowOutput baseSize(aDesiredSize.GetWritingMode());
+  ReflowOutput indexSize(aDesiredSize.GetWritingMode());
+  GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
+  GetReflowAndBoundingMetricsFor(indexFrame, indexSize, bmIndex);
 
   ////////////
   // Prepare the radical symbol and the overline bar
@@ -203,7 +165,7 @@ void nsMathMLmrootFrame::Reflow(nsPresContext* aPresContext,
   // p.131)
   char16_t one = '1';
   nsBoundingMetrics bmOne =
-      nsLayoutUtils::AppUnitBoundsOfString(&one, 1, *fm, drawTarget);
+      nsLayoutUtils::AppUnitBoundsOfString(&one, 1, *fm, aDrawTarget);
   if (bmOne.ascent > bmBase.ascent + baseMargin.top) {
     psi += bmOne.ascent - bmBase.ascent - baseMargin.top;
   }
@@ -228,13 +190,22 @@ void nsMathMLmrootFrame::Reflow(nsPresContext* aPresContext,
 
   // height(radical) should be >= height(base) + psi + ruleThickness
   nsBoundingMetrics radicalSize;
-  mSqrChar.Stretch(this, drawTarget, fontSizeInflation,
-                   NS_STRETCH_DIRECTION_VERTICAL, contSize, radicalSize,
-                   NS_STRETCH_LARGER,
-                   StyleVisibility()->mDirection == StyleDirection::Rtl);
-  // radicalSize have changed at this point, and should match with
-  // the bounding metrics of the char
-  mSqrChar.GetBoundingMetrics(bmSqr);
+  if (aFlags.contains(PlaceFlag::IntrinsicSize)) {
+    nscoord radical_width =
+        mSqrChar.GetMaxWidth(this, aDrawTarget, fontSizeInflation);
+    bmSqr.leftBearing = 0;
+    bmSqr.rightBearing = radical_width;
+    bmSqr.width = radical_width;
+    bmSqr.ascent = bmSqr.descent = 0;
+  } else {
+    mSqrChar.Stretch(this, aDrawTarget, fontSizeInflation,
+                     NS_STRETCH_DIRECTION_VERTICAL, contSize, radicalSize,
+                     NS_STRETCH_LARGER,
+                     StyleVisibility()->mDirection == StyleDirection::Rtl);
+    // radicalSize have changed at this point, and should match with
+    // the bounding metrics of the char
+    mSqrChar.GetBoundingMetrics(bmSqr);
+  }
 
   // Update the desired size for the container (like msqrt, index is not yet
   // included) the baseline will be that of the base.
@@ -305,92 +276,46 @@ void nsMathMLmrootFrame::Reflow(nsPresContext* aPresContext,
   aDesiredSize.mBoundingMetrics = mBoundingMetrics;
 
   // Add padding+border around the final layout.
-  auto borderPadding = GetUsedBorderAndPadding();
+  auto borderPadding = GetBorderPaddingForPlace(aFlags);
   InflateReflowAndBoundingMetrics(borderPadding, aDesiredSize,
                                   mBoundingMetrics);
 
-  GatherAndStoreOverflow(&aDesiredSize);
-
-  // place the index
-  const bool isRTL = StyleVisibility()->mDirection == StyleDirection::Rtl;
-  nscoord borderPaddingInlineStart =
-      isRTL ? borderPadding.right : borderPadding.left;
-  nscoord dx = borderPaddingInlineStart + dxIndex +
-               indexMargin.Side(isRTL ? eSideRight : eSideLeft);
-  nscoord dy =
-      aDesiredSize.BlockStartAscent() -
-      (indexRaisedAscent + indexSize.BlockStartAscent() - bmIndex.ascent);
-  FinishReflowChild(indexFrame, aPresContext, indexSize, nullptr,
-                    MirrorIfRTL(aDesiredSize.Width(), indexSize.Width(), dx),
-                    dy + indexMargin.top, ReflowChildFlags::Default);
-
-  // place the radical symbol and the radical bar
-  dx = borderPaddingInlineStart + dxSqr;
-  dy = borderPadding.top + indexClearance +
-       leading;  // leave a leading at the top
-  mSqrChar.SetRect(nsRect(MirrorIfRTL(aDesiredSize.Width(), bmSqr.width, dx),
-                          dy, bmSqr.width, bmSqr.ascent + bmSqr.descent));
-  dx += bmSqr.width;
-  mBarRect.SetRect(MirrorIfRTL(aDesiredSize.Width(),
-                               bmBase.width + baseMargin.LeftRight(), dx),
-                   dy, bmBase.width + baseMargin.LeftRight(), ruleThickness);
-
-  // place the base
-  dx += isRTL ? baseMargin.right : baseMargin.left;
-  dy = aDesiredSize.BlockStartAscent() - baseSize.BlockStartAscent();
-  FinishReflowChild(baseFrame, aPresContext, baseSize, nullptr,
-                    MirrorIfRTL(aDesiredSize.Width(), baseSize.Width(), dx), dy,
-                    ReflowChildFlags::Default);
+  if (!aFlags.contains(PlaceFlag::MeasureOnly)) {
+    nsPresContext* presContext = PresContext();
+    // place the index
+    const bool isRTL = StyleVisibility()->mDirection == StyleDirection::Rtl;
+    nscoord borderPaddingInlineStart =
+        isRTL ? borderPadding.right : borderPadding.left;
+    nscoord dx = borderPaddingInlineStart + dxIndex +
+                 indexMargin.Side(isRTL ? eSideRight : eSideLeft);
+    nscoord dy =
+        aDesiredSize.BlockStartAscent() -
+        (indexRaisedAscent + indexSize.BlockStartAscent() - bmIndex.ascent);
+    FinishReflowChild(indexFrame, presContext, indexSize, nullptr,
+                      MirrorIfRTL(aDesiredSize.Width(), indexSize.Width(), dx),
+                      dy + indexMargin.top, ReflowChildFlags::Default);
+
+    // place the radical symbol and the radical bar
+    dx = borderPaddingInlineStart + dxSqr;
+    dy = borderPadding.top + indexClearance +
+         leading;  // leave a leading at the top
+    mSqrChar.SetRect(nsRect(MirrorIfRTL(aDesiredSize.Width(), bmSqr.width, dx),
+                            dy, bmSqr.width, bmSqr.ascent + bmSqr.descent));
+    dx += bmSqr.width;
+    mBarRect.SetRect(MirrorIfRTL(aDesiredSize.Width(),
+                                 bmBase.width + baseMargin.LeftRight(), dx),
+                     dy, bmBase.width + baseMargin.LeftRight(), ruleThickness);
+
+    // place the base
+    dx += isRTL ? baseMargin.right : baseMargin.left;
+    dy = aDesiredSize.BlockStartAscent() - baseSize.BlockStartAscent();
+    FinishReflowChild(baseFrame, presContext, baseSize, nullptr,
+                      MirrorIfRTL(aDesiredSize.Width(), baseSize.Width(), dx),
+                      dy, ReflowChildFlags::Default);
+  }
 
   mReference.x = 0;
   mReference.y = aDesiredSize.BlockStartAscent();
-}
-
-/* virtual */
-nsresult nsMathMLmrootFrame::MeasureForWidth(DrawTarget* aDrawTarget,
-                                             ReflowOutput& aDesiredSize) {
-  const PlaceFlags flags(PlaceFlag::IntrinsicSize, PlaceFlag::MeasureOnly);
-  if (ShouldUseRowFallback()) {
-    return PlaceAsMrow(aDrawTarget, flags, aDesiredSize);
-  }
-
-  // ShouldUseRowFallback() returned false so there are exactly two children.
-  nsIFrame* baseFrame = mFrames.FirstChild();
-  MOZ_ASSERT(baseFrame);
-  nsIFrame* indexFrame = baseFrame->GetNextSibling();
-  MOZ_ASSERT(indexFrame);
-  MOZ_ASSERT(!indexFrame->GetNextSibling());
-
-  nsBoundingMetrics bmBase, bmIndex;
-  ReflowOutput baseSize(aDesiredSize.GetWritingMode());
-  ReflowOutput indexSize(aDesiredSize.GetWritingMode());
-  float fontSizeInflation = nsLayoutUtils::FontSizeInflationFor(this);
-  GetReflowAndBoundingMetricsFor(baseFrame, baseSize, bmBase);
-  GetReflowAndBoundingMetricsFor(indexFrame, indexSize, bmIndex);
-  nscoord baseMargin = baseFrame->IntrinsicISizeOffsets().margin,
-          indexMargin = indexFrame->IntrinsicISizeOffsets().margin;
-  nscoord sqrWidth = mSqrChar.GetMaxWidth(this, aDrawTarget, fontSizeInflation);
-
-  nscoord dxIndex, dxSqr;
-  RefPtr<nsFontMetrics> fm =
-      nsLayoutUtils::GetFontMetricsForFrame(this, fontSizeInflation);
-  GetRadicalXOffsets(bmIndex.width + indexMargin, sqrWidth, fm, &dxIndex,
-                     &dxSqr);
-
-  mBoundingMetrics.width = dxSqr + sqrWidth + bmBase.width + baseMargin;
-  mBoundingMetrics.leftBearing =
-      std::min(dxIndex + bmIndex.leftBearing + indexMargin, dxSqr);
-  mBoundingMetrics.rightBearing =
-      dxSqr + sqrWidth +
-      std::max(bmBase.width + baseMargin, bmBase.rightBearing + baseMargin);
-
-  aDesiredSize.Width() = mBoundingMetrics.width;
-  aDesiredSize.mBoundingMetrics = mBoundingMetrics;
-
-  // Add border+padding.
-  nsMargin borderPadding = GetBorderPaddingForPlace(flags);
-  InflateReflowAndBoundingMetrics(borderPadding, aDesiredSize,
-                                  mBoundingMetrics);
 
   return NS_OK;
 }
diff --git a/layout/mathml/nsMathMLmrootFrame.h b/layout/mathml/nsMathMLmrootFrame.h
@@ -34,17 +34,10 @@ class nsMathMLmrootFrame final : public nsMathMLContainerFrame {
   NS_IMETHOD
   TransmitAutomaticData() override;
 
-  virtual void Reflow(nsPresContext* aPresContext, ReflowOutput& aDesiredSize,
-                      const ReflowInput& aReflowInput,
-                      nsReflowStatus& aStatus) override;
-
   void GetRadicalXOffsets(nscoord aIndexWidth, nscoord aSqrWidth,
                           nsFontMetrics* aFontMetrics, nscoord* aIndexOffset,
                           nscoord* aSqrOffset);
 
-  nsresult MeasureForWidth(DrawTarget* aDrawTarget,
-                           ReflowOutput& aDesiredSize) final;
-
   virtual void BuildDisplayList(nsDisplayListBuilder* aBuilder,
                                 const nsDisplayListSet& aLists) override;
 
@@ -62,6 +55,8 @@ class nsMathMLmrootFrame final : public nsMathMLContainerFrame {
 
  private:
   bool ShouldUseRowFallback();
+  nsresult Place(DrawTarget* aDrawTarget, const PlaceFlags& aFlags,
+                 ReflowOutput& aDesiredSize) final;
 };
 
 #endif /* nsMathMLmrootFrame_h___ */
