Reduce the amount of padding needed for SDFs, take 2

SDF glyphs and paths were padded by 4 pixels, and had an inset of 2
pixels within that for rendering the shape. We should be able to
use a pad of 2, and outset the original bounds by one texel. This allows us
to increase the maximum size in the atlas.

Change-Id: I06b229c7a3bc907d75d320461320d0b588f9a77c
Reviewed-on: https://skia-review.googlesource.com/101843
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/src/core/SkDistanceFieldGen.h b/src/core/SkDistanceFieldGen.h
index 5e7af52a54..16ed00ab5a 100644
--- a/src/core/SkDistanceFieldGen.h
+++ b/src/core/SkDistanceFieldGen.h
@@ -12,11 +12,10 @@
 // the max magnitude for the distance field
 // distance values are limited to the range (-SK_DistanceFieldMagnitude, SK_DistanceFieldMagnitude]
 #define SK_DistanceFieldMagnitude   4
-// we need to pad around the original glyph to allow our maximum distance of
-// SK_DistanceFieldMagnitude texels away from any edge
-#define SK_DistanceFieldPad         4
-// the rect we render with is inset from the distance field glyph size to allow for bilerp
-#define SK_DistanceFieldInset       2
+// we need to pad around the original glyph to allow for bilerp sampling
+#define SK_DistanceFieldPad         2
+// the rect we render with is inset from the SDF size
+#define SK_DistanceFieldInset       1
 
 // For the fragment shader:
 //   The distance field is constructed as unsigned char values,