tor-browser

commit e866f02b75251ed4cc3d237cc70dc532ced8b0ec
parent a30eb75acd5d3973f671c68b91ff7bd1783caf85
Author: Jonathan Kew <jkew@mozilla.com>
Date:   Fri, 24 Oct 2025 22:15:17 +0000

Bug 1993939 followup - Do ComputeDecorationTrim()'s frame-geometry work in appUnits, before converting to device pixels for drawing. r=AlaskanEmily,layout-reviewers,emilio

Differential Revision: https://phabricator.services.mozilla.com/D269968

Diffstat:
M
layout/base/nsPresContext.h
 | 
8
++++----
M
layout/generic/nsTextFrame.cpp
 | 
26
+++++++++++++-------------

2 files changed, 17 insertions(+), 17 deletions(-)
diff --git a/layout/base/nsPresContext.h b/layout/base/nsPresContext.h
@@ -639,20 +639,20 @@ class nsPresContext : public nsISupports,
     return NSAppUnitsToIntPixels(aAppUnits, float(AppUnitsPerDevPixel()));
   }
 
-  float AppUnitsToFloatDevPixels(nscoord aAppUnits) {
+  float AppUnitsToFloatDevPixels(nscoord aAppUnits) const {
     return aAppUnits / float(AppUnitsPerDevPixel());
   }
 
-  int32_t CSSPixelsToDevPixels(int32_t aPixels) {
+  int32_t CSSPixelsToDevPixels(int32_t aPixels) const {
     return AppUnitsToDevPixels(CSSPixelsToAppUnits(aPixels));
   }
 
-  float CSSPixelsToDevPixels(float aPixels) {
+  float CSSPixelsToDevPixels(float aPixels) const {
     return NSAppUnitsToFloatPixels(CSSPixelsToAppUnits(aPixels),
                                    float(AppUnitsPerDevPixel()));
   }
 
-  int32_t DevPixelsToIntCSSPixels(int32_t aPixels) {
+  int32_t DevPixelsToIntCSSPixels(int32_t aPixels) const {
     return AppUnitsToIntCSSPixels(DevPixelsToAppUnits(aPixels));
   }
 
diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
@@ -5789,7 +5789,6 @@ static bool ComputeDecorationTrim(
     nsTextFrame* aFrame, const nsPresContext* aPresCtx,
     const nsIFrame* aDecFrame, const gfxFont::Metrics& aMetrics,
     nsCSSRendering::DecorationRectParams& aParams) {
-  const gfxFloat app = aPresCtx->AppUnitsPerDevPixel();
   const WritingMode wm = aDecFrame->GetWritingMode();
   bool verticalDec = wm.IsVertical();
 
@@ -5799,16 +5798,17 @@ static bool ComputeDecorationTrim(
   // Find the trim values for this frame.
   const StyleTextDecorationTrim& cssTrim =
       aDecFrame->StyleTextReset()->mTextDecorationTrim;
-  gfxFloat trimLeft, trimRight;
+  nscoord trimLeft, trimRight;
   if (cssTrim.IsAuto()) {
     // Use a trim factor of 1/12.5, so we get 2px of trim (resulting in a 4px
     // gap between adjacent lines) at font-size 25px.
     constexpr gfxFloat kAutoTrimFactor = 1.0 / 12.5;
     // Use the EM size multiplied by kAutoTrimFactor, with a minimum of one
     // CSS pixel to ensure that at least some separation occurs.
-    const gfxFloat scale = aPresCtx->CSSToDevPixelScale().scale;
     const nscoord autoDecorationTrim =
-        std::max(aMetrics.emHeight * kAutoTrimFactor, scale);
+        std::max(aPresCtx->DevPixelsToAppUnits(
+                     NS_round(aMetrics.emHeight * kAutoTrimFactor)),
+                 nsPresContext::CSSPixelsToAppUnits(1));
     trimLeft = autoDecorationTrim;
     trimRight = autoDecorationTrim;
   } else {
@@ -5819,8 +5819,8 @@ static bool ComputeDecorationTrim(
       // walking up and back down the frame tree, and walking continuations.
       return true;
     }
-    trimLeft = NSAppUnitsToDoublePixels(length.start.ToAppUnits(), app);
-    trimRight = NSAppUnitsToDoublePixels(length.end.ToAppUnits(), app);
+    trimLeft = length.start.ToAppUnits();
+    trimRight = length.end.ToAppUnits();
   }
 
   if (wm.IsInlineReversed()) {
@@ -5909,17 +5909,17 @@ static bool ComputeDecorationTrim(
     std::swap(applyLeft, applyRight);
   }
   if (applyLeft) {
-    trimLeft -= NSAppUnitsToDoublePixels(marginLeft, app);
+    trimLeft -= marginLeft;
   } else {
     trimLeft = 0;
   }
   if (applyRight) {
-    trimRight -= NSAppUnitsToDoublePixels(marginRight, app);
+    trimRight -= marginRight;
   } else {
     trimRight = 0;
   }
 
-  if (trimLeft >= NSAppUnitsToDoublePixels(frameSize, app) - trimRight) {
+  if (trimLeft + trimRight >= frameSize) {
     // This frame does not contain the decoration at all.
     return false;
   }
@@ -5934,11 +5934,11 @@ static bool ComputeDecorationTrim(
   // I am unsure if it's possible that the first/last frame might be inset
   // for some reason, as well, in which case we will not draw the outset
   // decorations.
-  if (trimLeft > 0.0 || marginLeft == 0) {
-    aParams.trimLeft = trimLeft;
+  if (trimLeft > 0 || marginLeft == 0) {
+    aParams.trimLeft = aPresCtx->AppUnitsToFloatDevPixels(trimLeft);
   }
-  if (trimRight > 0.0 || marginRight == 0) {
-    aParams.trimRight = trimRight;
+  if (trimRight > 0 || marginRight == 0) {
+    aParams.trimRight = aPresCtx->AppUnitsToFloatDevPixels(trimRight);
   }
   return true;
 }