Bug 1824025 - transformed patterns may be blurry r=jfkthame a=reland

Differential Revision: https://phabricator.services.mozilla.com/D173545

layout/reftests/svg/pattern-transformed-02-ref.svg

@@ -0,0 +1,20 @@
+<svg width="800" height="500" xmlns="http://www.w3.org/2000/svg">
+
+  <text x="25" y="25">Both patterns should render without blurriness</text>
+
+  <pattern id="pattern1" viewBox="0 0 100 20" width="100" height="20"
+           patternUnits="userSpaceOnUse">
+    <circle r="2" cx="10" cy="10" fill="green"/>
+    <circle r="4" cx="30" cy="10" fill="green"/>
+    <circle r="6" cx="50" cy="10" fill="green"/>
+    <circle r="8" cx="70" cy="10" fill="green"/>
+    <circle r="10" cx="90" cy="10" fill="green"/>
+  </pattern>
+
+  <circle r="150" cx="200" cy="200" stroke="gray" fill="none"/>
+  <circle r="150" cx="200" cy="200" fill="url(#pattern1)"/>
+
+  <circle r="150" cx="600" cy="200" stroke="gray" fill="none"/>
+  <circle r="150" cx="600" cy="200" fill="url(#pattern1)"/>
+
+</svg>

layout/reftests/svg/pattern-transformed-02.svg

@@ -0,0 +1,29 @@
+<svg width="800" height="500" xmlns="http://www.w3.org/2000/svg">
+
+  <text x="25" y="25">Both patterns should render without blurriness</text>
+
+  <pattern id="pattern1" viewBox="0 0 100 20" width="100" height="20"
+           patternUnits="userSpaceOnUse">
+    <circle r="2" cx="10" cy="10" fill="green"/>
+    <circle r="4" cx="30" cy="10" fill="green"/>
+    <circle r="6" cx="50" cy="10" fill="green"/>
+    <circle r="8" cx="70" cy="10" fill="green"/>
+    <circle r="10" cx="90" cy="10" fill="green"/>
+  </pattern>
+
+  <circle r="150" cx="200" cy="200" stroke="gray" fill="none"/>
+  <circle r="150" cx="200" cy="200" fill="url(#pattern1)"/>
+
+  <pattern id="pattern2" viewBox="0 0 20 100" width="20" height="100"
+           patternUnits="userSpaceOnUse" patternTransform="rotate(270)">
+    <circle r="2" cx="10" cy="10" fill="green"/>
+    <circle r="4" cx="10" cy="30" fill="green"/>
+    <circle r="6" cx="10" cy="50" fill="green"/>
+    <circle r="8" cx="10" cy="70" fill="green"/>
+    <circle r="10" cx="10" cy="90" fill="green"/>
+  </pattern>
+
+  <circle r="150" cx="600" cy="200" stroke="gray" fill="none"/>
+  <circle r="150" cx="600" cy="200" fill="url(#pattern2)"/>
+
+</svg>

layout/reftests/svg/reftest.list

@@ -394,11 +394,12 @@ fuzzy(0-128,0-100) == pattern-big-image.html pattern-big-image-ref.html
 fuzzy(0-1,0-5) == pattern-live-01a.svg pattern-live-01-ref.svg
 fuzzy(0-1,0-5) == pattern-live-01b.svg pattern-live-01-ref.svg
 fuzzy(0-1,0-5) == pattern-live-01c.svg pattern-live-01-ref.svg
-fuzzy(0-1,0-5) == pattern-scale-01a.svg pattern-scale-01-ref.svg
+== pattern-scale-01a.svg pattern-scale-01-ref.svg
 == pattern-scale-01b.svg pattern-scale-01-ref.svg
-fuzzy(0-3,0-5) == pattern-scale-01c.svg pattern-scale-01-ref.svg
-fuzzy(0-2,0-227) == pattern-transform-presence-01.svg pattern-transform-presence-01-ref.svg
-fuzzy(0-72,0-1255) == pattern-transformed-01.svg pattern-transformed-01-ref.svg
+== pattern-scale-01c.svg pattern-scale-01-ref.svg
+== pattern-transform-presence-01.svg pattern-transform-presence-01-ref.svg
+fuzzy(0-67,0-805) == pattern-transformed-01.svg pattern-transformed-01-ref.svg
+fuzzy(0-17,0-2375) == pattern-transformed-02.svg pattern-transformed-02-ref.svg
 
 == polygon-01.svg polygon-01-ref.svg
 == polygon-marker-01.svg pass.svg

layout/svg/SVGPatternFrame.cpp

@@ -304,12 +304,11 @@ already_AddRefed<SourceSurface> SVGPatternFrame::PaintPattern(
 
   // Now that we have all of the necessary geometries, we can
   // create our surface.
-  gfxRect transformedBBox =
-      ThebesRect(patternTransform.TransformBounds(ToRect(bbox)));
+  gfxSize scaledSize = bbox.Size() * MaxExpansion(patternTransform);
 
   bool resultOverflows;
   IntSize surfaceSize =
-      SVGUtils::ConvertToSurfaceSize(transformedBBox.Size(), &resultOverflows);
+      SVGUtils::ConvertToSurfaceSize(scaledSize, &resultOverflows);
 
   // 0 disables rendering, < 0 is an error
   if (surfaceSize.width <= 0 || surfaceSize.height <= 0) {
@@ -322,9 +321,8 @@ already_AddRefed<SourceSurface> SVGPatternFrame::PaintPattern(
   if (resultOverflows || patternWidth != surfaceSize.width ||
       patternHeight != surfaceSize.height) {
     // scale drawing to pattern surface size
-    gfxMatrix tempTM = gfxMatrix(surfaceSize.width / patternWidth, 0.0, 0.0,
-                                 surfaceSize.height / patternHeight, 0.0, 0.0);
-    patternWithChildren->mCTM->PreMultiply(tempTM);
+    patternWithChildren->mCTM->PreScale(surfaceSize.width / patternWidth,
+                                        surfaceSize.height / patternHeight);
 
     // and rescale pattern to compensate
     patternMatrix->PreScale(patternWidth / surfaceSize.width,