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[raster] Remove the jitter exception.

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The jitter exception used to be applied when two neighboring pixels
were barely inside the outline. One the left one was turned on then,
which contradicts the OpenType specifications.  Intended to remove
glitches, it caused disappearing lines and was softened by adding an
exception to the exception (#54589).

* src/raster/ftraster.c (Vertical_Sweep_Span): Drop the jitter exception.
This commit is contained in:
Alexei Podtelezhnikov (Алексей Подтележников) 2023-11-02 22:08:04 -04:00 committed by Alexei Podtelezhnikov
parent dc519d06ea
commit f2e76e8356
1 changed files with 6 additions and 31 deletions
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37
src/raster/ftraster.c
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@ -448,7 +448,6 @@
Int precision_half;
Int precision_scale;
Int precision_step;
Int precision_jitter;
PLong buff; /* The profiles buffer */
PLong sizeBuff; /* Render pool size */
@ -549,27 +548,17 @@
*
* 256 / (1 << 12) = 0.0625 pixels.
*
* `precision_jitter' is an epsilon threshold used in
* `Vertical_Sweep_Span' to deal with small imperfections in the Bezier
* decomposition (after all, we are working with approximations only);
* it avoids switching on additional pixels which would cause artifacts
* otherwise.
*
* The value of `precision_jitter' has been determined heuristically.
*
*/
if ( High )
{
ras.precision_bits = 12;
ras.precision_step = 256;
ras.precision_jitter = 30;
}
else
{
ras.precision_bits = 6;
ras.precision_step = 32;
ras.precision_jitter = 2;
}
ras.precision = 1 << ras.precision_bits;
@ -2139,9 +2128,7 @@
PProfile left,
PProfile right )
{
Long e1, e2;
Int dropOutControl = left->flags & 7;
Int e1, e2;
FT_UNUSED( y );
FT_UNUSED( left );
@ -2153,20 +2140,8 @@
ras.precision_bits, (double)x1 / (double)ras.precision,
ras.precision_bits, (double)x2 / (double)ras.precision ));
/* Drop-out control */
e1 = CEILING( x1 );
e2 = FLOOR( x2 );
/* take care of the special case where both the left */
/* and right contour lie exactly on pixel centers */
if ( dropOutControl != 2 &&
x2 - x1 - ras.precision <= ras.precision_jitter &&
e1 != x1 && e2 != x2 )
e2 = e1;
e1 = TRUNC( e1 );
e2 = TRUNC( e2 );
e1 = (Int)TRUNC( CEILING( x1 ) );
e2 = (Int)TRUNC( FLOOR( x2 ) );
if ( e2 >= 0 && e1 < ras.bWidth )
{
@ -2180,10 +2155,10 @@
if ( e2 >= ras.bWidth )
e2 = ras.bWidth - 1;
FT_TRACE7(( " -> x=[%ld;%ld]", e1, e2 ));
FT_TRACE7(( " -> x=[%d;%d]", e1, e2 ));
c1 = (Int)( e1 >> 3 );
c2 = (Int)( e2 >> 3 );
c1 = e1 >> 3;
c2 = e2 >> 3;
f1 = 0xFF >> ( e1 & 7 );
f2 = ~0x7F >> ( e2 & 7 );