commit 9564ce60a657acce89fb956deb8645b324eaad1e
author jvanverth <jvanverth@google.com> Tue Sep 16 05:45:19 2014 -0700
committer Commit bot <commit-bot@chromium.org> Tue Sep 16 05:45:19 2014 -0700
tree 0fbe408f717124b40ef6c0822828c6d5371fcf0e
parent 49005bf8929dd8ca86431e13414d683b509cd538

Fix scaling issue with distance field text.

Picks the correct distance field size based on both the text size and
the max matrix scale. Adjusts the matrix scale if non-unity. Also adds
GM for verifying proper distance field scaling.

BUG=skia:2928
R=bsalomon@google.com, joshualitt@google.com

Author: jvanverth@google.com

Review URL: https://codereview.chromium.org/568843002

src/gpu/GrDistanceFieldTextContext.cpp

diff --git a/src/gpu/GrDistanceFieldTextContext.cpp b/src/gpu/GrDistanceFieldTextContext.cpp
index d32dcb9..18058be 100755
--- a/src/gpu/GrDistanceFieldTextContext.cpp
+++ b/src/gpu/GrDistanceFieldTextContext.cpp
@@ -127,9 +127,9 @@
     
     // set up any flags
     uint32_t flags = 0;
-    flags |= fContext->getMatrix().isSimilarity() ? kSimilarity_DistanceFieldEffectFlag : 0;
+    flags |= fTextMatrix.isSimilarity() ? kSimilarity_DistanceFieldEffectFlag : 0;
     flags |= fUseLCDText ? kUseLCD_DistanceFieldEffectFlag : 0;
-    flags |= fUseLCDText && fContext->getMatrix().rectStaysRect() ?
+    flags |= fUseLCDText && fTextMatrix.rectStaysRect() ?
     kRectToRect_DistanceFieldEffectFlag : 0;
     bool useBGR = SkDeviceProperties::Geometry::kBGR_Layout ==
     fDeviceProperties.fGeometry.getLayout();
@@ -176,7 +176,8 @@
 
     GrDrawState* drawState = fDrawTarget->drawState();
     GrDrawState::AutoRestoreEffects are(drawState);
-    drawState->setFromPaint(fPaint, fContext->getMatrix(), fContext->getRenderTarget());
+
+    drawState->setFromPaint(fPaint, fTextMatrix, fContext->getRenderTarget());
 
     if (fCurrVertex > 0) {
         // setup our sampler state for our text texture/atlas
@@ -443,18 +444,32 @@
 
     fStrike = NULL;
 
+    fTextMatrix = fContext->getMatrix();
+
+    // getMaxScale doesn't support perspective, so neither do we at the moment
+    SkASSERT(!fTextMatrix.hasPerspective());
+    SkScalar maxScale = fTextMatrix.getMaxScale();
+    SkScalar textSize = fSkPaint.getTextSize();
+    // if we have non-unity scale, we need to adjust our text size accordingly
+    // to avoid aliasing, and prescale the matrix by the inverse to end up with the same size
+    // TODO: do we need to do this if we're scaling down (i.e. maxScale < 1)?
+    if (maxScale > 0 && !SkScalarNearlyEqual(maxScale, SK_Scalar1)) {
+        textSize *= maxScale;
+        fTextMatrix.preScale(SK_Scalar1 / maxScale, SK_Scalar1 / maxScale);
+    }
+
     fCurrVertex = 0;
 
     fVertices = NULL;
 
-    if (fSkPaint.getTextSize() <= kSmallDFFontLimit) {
-        fTextRatio = fSkPaint.getTextSize()/kSmallDFFontSize;
+    if (textSize <= kSmallDFFontLimit) {
+        fTextRatio = textSize / kSmallDFFontSize;
         fSkPaint.setTextSize(SkIntToScalar(kSmallDFFontSize));
-    } else if (fSkPaint.getTextSize() <= kMediumDFFontLimit) {
-        fTextRatio = fSkPaint.getTextSize()/kMediumDFFontSize;
+    } else if (textSize <= kMediumDFFontLimit) {
+        fTextRatio = textSize / kMediumDFFontSize;
         fSkPaint.setTextSize(SkIntToScalar(kMediumDFFontSize));
     } else {
-        fTextRatio = fSkPaint.getTextSize()/kLargeDFFontSize;
+        fTextRatio = textSize / kLargeDFFontSize;
         fSkPaint.setTextSize(SkIntToScalar(kLargeDFFontSize));
     }