Commit e9f950938f4862b21cb74c71595b79bfe9a76e5f
2016-05-26T23:46:38
[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.
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diff --git a/ChangeLog b/ChangeLog
index abd36ed..f6c4b0a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -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.
diff --git a/src/smooth/ftgrays.c b/src/smooth/ftgrays.c
index c69a184..bee4043 100644
--- a/src/smooth/ftgrays.c
+++ b/src/smooth/ftgrays.c
@@ -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;
}