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[raster] Tune SMART macro (#58352).

Windows seems to perform smart dropout control at 26.6 precision.
To mimick Windows independent of increased precision, we need to tweak
the macro so that some close calls break down rather than up.

* src/raster/ftraster.c (SMART): Tweak the macro.

git/fs: mount .git/fs: mount/attach disallowed

--- a/ChangeLog

+++ b/ChangeLog

@@ -1,5 +1,15 @@

 2020-09-08  Alexei Podtelezhnikov  <[email protected]>

+	[raster] Tune SMART macro (#58352).

+

+	Windows seems to perform smart dropout control at 26.6 precision.

+	To mimick Windows independent of increased precision, we need to tweak

+	the macro so that some close calls break down rather than up.

+

+	* src/raster/ftraster.c (SMART): Tweak the macro.

+

+2020-09-08  Alexei Podtelezhnikov  <[email protected]>

+

 	[raster] Introduce SMART macro.

 	* src/raster/ftraster.c (SMART): New macro for smart dropout rounding.

--- a/src/raster/ftraster.c

+++ b/src/raster/ftraster.c

@@ -459,8 +459,9 @@

 #define IS_TOP_OVERSHOOT( x )    \

           (Bool)( x - FLOOR( x ) >= ras.precision_half )

-  /* smart dropout rounding */

-#define SMART( x1, x2 )  FLOOR( ( (x1) + (x2) - 1 ) / 2 + ras.precision_half )

+  /* smart dropout rounding to find which pixel is closer to span ends;    */

+  /* to mimick Windows, symmetric cases break down indepenent of precision */

+#define SMART( p, q )  FLOOR( ( (p) + (q) + ras.precision * 63 / 64 ) >> 1 )

 #if FT_RENDER_POOL_SIZE > 2048

 #define FT_MAX_BLACK_POOL  ( FT_RENDER_POOL_SIZE / sizeof ( Long ) )