commit 64b08a1026851a84031713f0e12a3e59d55ce808
author commit-bot@chromium.org <commit-bot@chromium.org@2bbb7eff-a529-9590-31e7-b0007b416f81> Tue Apr 15 17:53:21 2014 +0000
committer commit-bot@chromium.org <commit-bot@chromium.org@2bbb7eff-a529-9590-31e7-b0007b416f81> Tue Apr 15 17:53:21 2014 +0000
tree df26732c34ec830af5e9260ab712c7d2982ee319
parent 51b0d0bc5c82f257dca244c864702c66d84100a2

Fix artifacts in distance field rendering due to bilerp

Because we were using the full distance field glyph rect, there were cases
when a neighboring texel might be set to full value (e.g. we might copy the
glyph over old data after a purge). This was giving artifacts, and insetting
the rect by 1 solves the problem. In doing this, I discovered that removing the
extra 1 texel pad around the glyph meant to handle bilerp, and insetting by 2,
works just as well and saves space in the glyph atlas.

R=bsalomon@google.com

Author: jvanverth@google.com

Review URL: https://codereview.chromium.org/239333002

git-svn-id: http://skia.googlecode.com/svn/trunk@14203 2bbb7eff-a529-9590-31e7-b0007b416f81

src/gpu/GrDistanceFieldTextContext.cpp

diff --git a/src/gpu/GrDistanceFieldTextContext.cpp b/src/gpu/GrDistanceFieldTextContext.cpp
index 448e709..238bcca 100755
--- a/src/gpu/GrDistanceFieldTextContext.cpp
+++ b/src/gpu/GrDistanceFieldTextContext.cpp
@@ -14,6 +14,7 @@
 #include "GrIndexBuffer.h"
 #include "GrTextStrike.h"
 #include "GrTextStrike_impl.h"
+#include "SkDistanceFieldGen.h"
 #include "SkDraw.h"
 #include "SkGpuDevice.h"
 #include "SkPath.h"
@@ -295,10 +296,10 @@
         SkASSERT(2*sizeof(SkPoint) == fDrawTarget->getDrawState().getVertexSize());
     }
 
-    SkScalar dx = SkIntToScalar(glyph->fBounds.fLeft);
-    SkScalar dy = SkIntToScalar(glyph->fBounds.fTop);
-    SkScalar width = SkIntToScalar(glyph->fBounds.width());
-    SkScalar height = SkIntToScalar(glyph->fBounds.height());
+    SkScalar dx = SkIntToScalar(glyph->fBounds.fLeft + SK_DistanceFieldInset);
+    SkScalar dy = SkIntToScalar(glyph->fBounds.fTop + SK_DistanceFieldInset);
+    SkScalar width = SkIntToScalar(glyph->fBounds.width() - 2*SK_DistanceFieldInset);
+    SkScalar height = SkIntToScalar(glyph->fBounds.height() - 2*SK_DistanceFieldInset);
 
     SkScalar scale = fTextRatio;
     dx *= scale;
@@ -308,10 +309,10 @@
     width *= scale;
     height *= scale;
 
-    SkFixed tx = SkIntToFixed(glyph->fAtlasLocation.fX);
-    SkFixed ty = SkIntToFixed(glyph->fAtlasLocation.fY);
-    SkFixed tw = SkIntToFixed(glyph->fBounds.width());
-    SkFixed th = SkIntToFixed(glyph->fBounds.height());
+    SkFixed tx = SkIntToFixed(glyph->fAtlasLocation.fX + SK_DistanceFieldInset);
+    SkFixed ty = SkIntToFixed(glyph->fAtlasLocation.fY + SK_DistanceFieldInset);
+    SkFixed tw = SkIntToFixed(glyph->fBounds.width() - 2*SK_DistanceFieldInset);
+    SkFixed th = SkIntToFixed(glyph->fBounds.height() - 2*SK_DistanceFieldInset);
 
     static const size_t kVertexSize = 2 * sizeof(SkPoint);
     fVertices[2*fCurrVertex].setRectFan(sx,