Use correct gradient calculation for rotated distance fields.

For all uniform scaled matrices, we were using the y coordinate of the
y-direction gradient of the v texel space coordinate to scale the
distance values. The problem is, if you rotate by 90 degrees this value
becomes 0. The correct answer is to take the length of the y-direction
gradient.

BUG=skia:4864
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1776383002

Review URL: https://codereview.chromium.org/1776383002

2 files changed, 4 insertions, 2 deletions

diff --git a/src/gpu/batches/GrAADistanceFieldPathRenderer.cpp b/src/gpu/batches/GrAADistanceFieldPathRenderer.cpp
index 8525eb2fde..b585de963a 100644
--- a/src/gpu/batches/GrAADistanceFieldPathRenderer.cpp
+++ b/src/gpu/batches/GrAADistanceFieldPathRenderer.cpp
@@ -190,8 +190,10 @@ private:
             return;
         }
 
+        const SkMatrix& ctm = this->viewMatrix();
         uint32_t flags = 0;
-        flags |= this->viewMatrix().isSimilarity() ? kSimilarity_DistanceFieldEffectFlag : 0;
+        flags |= ctm.isScaleTranslate() ? kScaleOnly_DistanceFieldEffectFlag : 0;
+        flags |= ctm.isSimilarity() ? kSimilarity_DistanceFieldEffectFlag : 0;
 
         GrTextureParams params(SkShader::kRepeat_TileMode, GrTextureParams::kBilerp_FilterMode);
 
diff --git a/src/gpu/batches/GrAtlasTextBatch.cpp b/src/gpu/batches/GrAtlasTextBatch.cpp
index 432322ff7a..1d8d7fe143 100644
--- a/src/gpu/batches/GrAtlasTextBatch.cpp
+++ b/src/gpu/batches/GrAtlasTextBatch.cpp
@@ -261,11 +261,11 @@ GrGeometryProcessor* GrAtlasTextBatch::setupDfProcessor(const SkMatrix& viewMatr
     bool isLCD = this->isLCD();
     // set up any flags
     uint32_t flags = viewMatrix.isSimilarity() ? kSimilarity_DistanceFieldEffectFlag : 0;
+    flags |= viewMatrix.isScaleTranslate() ? kScaleOnly_DistanceFieldEffectFlag : 0;
 
     // see if we need to create a new effect
     if (isLCD) {
         flags |= kUseLCD_DistanceFieldEffectFlag;
-        flags |= viewMatrix.rectStaysRect() ? kRectToRect_DistanceFieldEffectFlag : 0;
         flags |= fUseBGR ? kBGR_DistanceFieldEffectFlag : 0;
 
         GrColor colorNoPreMul = skcolor_to_grcolor_nopremultiply(filteredColor);