[raster] Improve the second pass (#58373).
Besides dropout control the second horizontal sweep is supposed to
clean up straight horizontal edges that are mishandled by the first
vertical sweep when a line passes through pixel centers. This line
would present as perfectly aligned span edges in the second sweep.
* src/raster/ftraster.c (Horizontal_Sweep_Span): Replace the old
implementation with a better one focusing on aligned span edges only.
diff --git a/ChangeLog b/ChangeLog
index 05033bd..9731f04 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2020-09-11 Alexei Podtelezhnikov <apodtele@gmail.com>
+
+ [raster] Improve the second pass (#58373).
+
+ Besides dropout control the second horizontal sweep is supposed to
+ clean up straight horizontal edges that are mishandled by the first
+ vertical sweep when a line passes through pixel centers. This line
+ would present as perfectly aligned span edges in the second sweep.
+
+ * src/raster/ftraster.c (Horizontal_Sweep_Span): Replace the old
+ implementation with a better one focusing on aligned span edges only.
+
2020-09-08 Alexei Podtelezhnikov <apodtele@gmail.com>
[raster] Tune SMART macro (#58352).
diff --git a/src/raster/ftraster.c b/src/raster/ftraster.c
index 71fac3f..1408e51 100644
--- a/src/raster/ftraster.c
+++ b/src/raster/ftraster.c
@@ -2495,45 +2495,68 @@
PProfile left,
PProfile right )
{
+ Long e1, e2;
+
FT_UNUSED( left );
FT_UNUSED( right );
- if ( x2 - x1 < ras.precision )
+ FT_TRACE7(( " x=%d y=[% .12f;% .12f]",
+ y,
+ x1 / (double)ras.precision,
+ x2 / (double)ras.precision ));
+
+ /* We should not need this procedure but the vertical sweep */
+ /* mishandles horizontal lines through pixel centers. So we */
+ /* have to check perfectly aligned span edges here. */
+ /* */
+ /* XXX: Can we handle horizontal lines better and drop this? */
+
+ e1 = CEILING( x1 );
+
+ if ( x1 == e1 )
{
- Long e1, e2;
+ e1 = TRUNC( e1 );
-
- FT_TRACE7(( " x=%d y=[% .12f;% .12f]",
- y,
- x1 / (double)ras.precision,
- x2 / (double)ras.precision ));
-
- e1 = CEILING( x1 );
- e2 = FLOOR ( x2 );
-
- if ( e1 == e2 )
+ if ( e1 >= 0 && (ULong)e1 < ras.target.rows )
{
- e1 = TRUNC( e1 );
-
- if ( e1 >= 0 && (ULong)e1 < ras.target.rows )
- {
- Byte f1;
- PByte bits;
+ Byte f1;
+ PByte bits;
- bits = ras.bOrigin + ( y >> 3 ) - e1 * ras.target.pitch;
- f1 = (Byte)( 0x80 >> ( y & 7 ) );
+ bits = ras.bOrigin + ( y >> 3 ) - e1 * ras.target.pitch;
+ f1 = (Byte)( 0x80 >> ( y & 7 ) );
- FT_TRACE7(( bits[0] & f1 ? " redundant"
- : " -> y=%ld", e1 ));
+ FT_TRACE7(( bits[0] & f1 ? " redundant"
+ : " -> y=%ld edge", e1 ));
- bits[0] |= f1;
- }
+ bits[0] |= f1;
}
-
- FT_TRACE7(( "\n" ));
}
+
+ e2 = FLOOR ( x2 );
+
+ if ( x2 == e2 )
+ {
+ e2 = TRUNC( e2 );
+
+ if ( e2 >= 0 && (ULong)e2 < ras.target.rows )
+ {
+ Byte f1;
+ PByte bits;
+
+
+ bits = ras.bOrigin + ( y >> 3 ) - e2 * ras.target.pitch;
+ f1 = (Byte)( 0x80 >> ( y & 7 ) );
+
+ FT_TRACE7(( bits[0] & f1 ? " redundant"
+ : " -> y=%ld edge", e2 ));
+
+ bits[0] |= f1;
+ }
+ }
+
+ FT_TRACE7(( "\n" ));
}
