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[smooth] Shrink bisection stack.

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The convergence of Bézier flatteners is fast with the deviation
from straight line being assymptotically cut 4-fold on each bisection.
This justifies smaller bisection stack size.

* src/smooth/ftgrays.c (gray_TWorker): Remove common `bez_stack'.
(gray_render_conic): Create and use conic `bez_stack'. Move back the
band analysis from...
(gray_conic_to): ... here.
(gray_render_cubic): Create and use cubic `bez_stack'. Move back the
band analysis from...
(gray_cubic_to): ... here.
(gray_move_to): Updated.
2.6.5
Alexei Podtelezhnikov 9 years ago
parent e97918c57b
commit e9f950938f
2 changed files with 80 additions and 62 deletions
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  1. 17
      ChangeLog
  2. 125
      src/smooth/ftgrays.c

17
ChangeLog
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@ -1,3 +1,20 @@
2016-05-26 Alexei Podtelezhnikov <apodtele@gmail.com>
[smooth] Shrink bisection stack.
The convergence of Bézier flatteners is fast with the deviation
from straight line being assymptotically cut 4-fold on each bisection.
This justifies smaller bisection stack size.
* src/smooth/ftgrays.c (gray_TWorker): Remove common `bez_stack'.
(gray_render_conic): Create and use conic `bez_stack'. Move back the
band analysis from...
(gray_conic_to): ... here.
(gray_render_cubic): Create and use cubic `bez_stack'. Move back the
band analysis from...
(gray_cubic_to): ... here.
(gray_move_to): Updated.
2016-05-25 Werner Lemberg <wl@gnu.org>
[autofit] Fixes for Armenian and Gujarati ranges.

125
src/smooth/ftgrays.c
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@ -434,8 +434,6 @@ typedef ptrdiff_t FT_PtrDist;
TPos x, y;
FT_Vector bez_stack[32 * 3 + 1];
FT_Outline outline;
FT_Bitmap target;
FT_BBox clip_box;
@ -1064,12 +1062,34 @@ typedef ptrdiff_t FT_PtrDist;
static void
gray_render_conic( RAS_ARG )
gray_render_conic( RAS_ARG_ const FT_Vector* control,
const FT_Vector* to )
{
FT_Vector bez_stack[16 * 2 + 1]; /* enough to accommodate bisections */
FT_Vector* arc = bez_stack;
TPos dx, dy;
int draw, split, level;
FT_Vector* arc = ras.bez_stack;
int draw, split;
arc[0].x = UPSCALE( to->x );
arc[0].y = UPSCALE( to->y );
arc[1].x = UPSCALE( control->x );
arc[1].y = UPSCALE( control->y );
arc[2].x = ras.x;
arc[2].y = ras.y;
/* short-cut the arc that crosses the current band */
if ( ( TRUNC( arc[0].y ) >= ras.max_ey &&
TRUNC( arc[1].y ) >= ras.max_ey &&
TRUNC( arc[2].y ) >= ras.max_ey ) ||
( TRUNC( arc[0].y ) < ras.min_ey &&
TRUNC( arc[1].y ) < ras.min_ey &&
TRUNC( arc[2].y ) < ras.min_ey ) )
{
ras.x = arc[0].x;
ras.y = arc[0].y;
return;
}
dx = FT_ABS( arc[2].x + arc[0].x - 2 * arc[1].x );
dy = FT_ABS( arc[2].y + arc[0].y - 2 * arc[1].y );
@ -1078,19 +1098,17 @@ typedef ptrdiff_t FT_PtrDist;
/* We can calculate the number of necessary bisections because */
/* each bisection predictably reduces deviation exactly 4-fold. */
level = 0;
/* Even 32-bit deviation would vanish after 16 bisections. */
draw = 1;
while ( dx > ONE_PIXEL / 4 )
{
dx >>= 2;
level++;
dx >>= 2;
draw <<= 1;
}
/* We use decrement counter to count the total number of segments */
/* to draw starting from 2^level. Before each draw we split as */
/* many times as there are trailing zeros in the counter. */
draw = 1 << level;
do
{
split = 1;
@ -1137,14 +1155,41 @@ typedef ptrdiff_t FT_PtrDist;
static void
gray_render_cubic( RAS_ARG )
gray_render_cubic( RAS_ARG_ const FT_Vector* control1,
const FT_Vector* control2,
const FT_Vector* to )
{
FT_Vector* arc = ras.bez_stack;
FT_Vector bez_stack[16 * 3 + 1]; /* enough to accommodate bisections */
FT_Vector* arc = bez_stack;
TPos dx, dy, dx_, dy_;
TPos dx1, dy1, dx2, dy2;
TPos L, s, s_limit;
arc[0].x = UPSCALE( to->x );
arc[0].y = UPSCALE( to->y );
arc[1].x = UPSCALE( control2->x );
arc[1].y = UPSCALE( control2->y );
arc[2].x = UPSCALE( control1->x );
arc[2].y = UPSCALE( control1->y );
arc[3].x = ras.x;
arc[3].y = ras.y;
/* short-cut the arc that crosses the current band */
if ( ( TRUNC( arc[0].y ) >= ras.max_ey &&
TRUNC( arc[1].y ) >= ras.max_ey &&
TRUNC( arc[2].y ) >= ras.max_ey &&
TRUNC( arc[3].y ) >= ras.max_ey ) ||
( TRUNC( arc[0].y ) < ras.min_ey &&
TRUNC( arc[1].y ) < ras.min_ey &&
TRUNC( arc[2].y ) < ras.min_ey &&
TRUNC( arc[3].y ) < ras.min_ey ) )
{
ras.x = arc[0].x;
ras.y = arc[0].y;
return;
}
for (;;)
{
/* Decide whether to split or draw. See `Rapid Termination */
@ -1190,7 +1235,7 @@ typedef ptrdiff_t FT_PtrDist;
gray_render_line( RAS_VAR_ arc[0].x, arc[0].y );
if ( arc == ras.bez_stack )
if ( arc == bez_stack )
return;
arc -= 3;
@ -1220,8 +1265,8 @@ typedef ptrdiff_t FT_PtrDist;
gray_start_cell( RAS_VAR_ TRUNC( x ), TRUNC( y ) );
worker->x = x;
worker->y = y;
ras.x = x;
ras.y = y;
return 0;
}
@ -1240,27 +1285,7 @@ typedef ptrdiff_t FT_PtrDist;
const FT_Vector* to,
gray_PWorker worker )
{
FT_Vector* arc = ras.bez_stack;
arc[0].x = UPSCALE( to->x );
arc[0].y = UPSCALE( to->y );
arc[1].x = UPSCALE( control->x );
arc[1].y = UPSCALE( control->y );
arc[2].x = ras.x;
arc[2].y = ras.y;
/* short-cut the arc that crosses the current band */
if ( ( TRUNC( arc[0].y ) >= ras.max_ey &&
TRUNC( arc[1].y ) >= ras.max_ey &&
TRUNC( arc[2].y ) >= ras.max_ey ) ||
( TRUNC( arc[0].y ) < ras.min_ey &&
TRUNC( arc[1].y ) < ras.min_ey &&
TRUNC( arc[2].y ) < ras.min_ey ) )
gray_render_line( RAS_VAR_ arc[0].x, arc[0].y );
else
gray_render_conic( RAS_VAR );
gray_render_conic( RAS_VAR_ control, to );
return 0;
}
@ -1271,31 +1296,7 @@ typedef ptrdiff_t FT_PtrDist;
const FT_Vector* to,
gray_PWorker worker )
{
FT_Vector* arc = ras.bez_stack;
arc[0].x = UPSCALE( to->x );
arc[0].y = UPSCALE( to->y );
arc[1].x = UPSCALE( control2->x );
arc[1].y = UPSCALE( control2->y );
arc[2].x = UPSCALE( control1->x );
arc[2].y = UPSCALE( control1->y );
arc[3].x = ras.x;
arc[3].y = ras.y;
/* short-cut the arc that crosses the current band */
if ( ( TRUNC( arc[0].y ) >= ras.max_ey &&
TRUNC( arc[1].y ) >= ras.max_ey &&
TRUNC( arc[2].y ) >= ras.max_ey &&
TRUNC( arc[3].y ) >= ras.max_ey ) ||
( TRUNC( arc[0].y ) < ras.min_ey &&
TRUNC( arc[1].y ) < ras.min_ey &&
TRUNC( arc[2].y ) < ras.min_ey &&
TRUNC( arc[3].y ) < ras.min_ey ) )
gray_render_line( RAS_VAR_ arc[0].x, arc[0].y );
else
gray_render_cubic( RAS_VAR );
gray_render_cubic( RAS_VAR_ control1, control2, to );
return 0;
}

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