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Code Issues 4 Releases Wiki Activity

[smooth] More efficient accounting of conic splits and draws. 

A single decrement counter of segments to draw, instead of an array,
contains all the information necessary to decide when to split and
when to draw a conic segment. The number of splits before each draw is
equal to the number of trailing zeros in the counter.

* src/smooth/ftgrays.c (gray_TWorker): Remove `lev_stack'.
(gray_render_conic): Updated to use decrement counter of segments.
This commit is contained in:
Alexei Podtelezhnikov 2016-05-05 23:41:03 -04:00
parent 0b3cb8a8af
commit 6e88087d69
2 changed files with 26 additions and 21 deletions
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12
ChangeLog
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@ -1,3 +1,15 @@
2016-05-05 Alexei Podtelezhnikov <apodtele@gmail.com>
[smooth] More efficient accounting of conic splits and draws.
A single decrement counter of segments to draw, instead of an array,
contains all the information necessary to decide when to split and
when to draw a conic segment. The number of splits before each draw is
equal to the number of trailing zeros in the counter.
* src/smooth/ftgrays.c (gray_TWorker): Remove `lev_stack'.
(gray_render_conic): Updated to use decrement counter of segments.
2016-05-05 Werner Lemberg <wl@gnu.org>
[cff, truetype] Fix logic for `FT_Property_Set'.

35
src/smooth/ftgrays.c
View File

@ -369,7 +369,7 @@ typedef ptrdiff_t FT_PtrDist;
/* These macros speed up repetitive divisions by replacing them */
/* with multiplications and right shifts. */
/* with multiplications and right shifts. */
#define FT_UDIVPREP( b ) \
long b ## _r = (long)( FT_ULONG_MAX >> PIXEL_BITS ) / ( b )
#define FT_UDIV( a, b ) \
@ -435,7 +435,6 @@ typedef ptrdiff_t FT_PtrDist;
TPos x, y;
FT_Vector bez_stack[32 * 3 + 1];
int lev_stack[32];
FT_Outline outline;
FT_Bitmap target;
@ -1068,50 +1067,44 @@ typedef ptrdiff_t FT_PtrDist;
gray_render_conic( RAS_ARG )
{
TPos dx, dy;
int top, level;
int* levels = ras.lev_stack;
int draw, split, level;
FT_Vector* arc = ras.bez_stack;
top = 0;
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 );
if ( dx < dy )
dx = dy;
if ( dx < ONE_PIXEL / 4 )
goto Draw;
/* We can calculate the number of necessary bisections because */
/* each bisection predictably reduces deviation exactly 4-fold. */
/* we can calculate the number of necessary bisections because */
/* each bisection predictably reduces deviation at least 4-fold */
level = 0;
do
while ( dx > ONE_PIXEL / 4 )
{
dx >>= 2;
level++;
} while ( dx > ONE_PIXEL / 4 );
}
levels[0] = level;
/* 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
{
level = levels[top];
if ( level > 0 )
split = 1;
while ( ( draw & split ) == 0 )
{
gray_split_conic( arc );
arc += 2;
top++;
levels[top] = levels[top - 1] = level - 1;
continue;
split <<= 1;
}
Draw:
gray_render_line( RAS_VAR_ arc[0].x, arc[0].y );
top--;
arc -= 2;
} while ( top >= 0 );
} while ( --draw );
}