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ftgrays: Speed up rendering of small cubic splines. 

* src/smooth/ftgrays.c (gray_render_cubic): Implement new,
simplified algorithm to find out whether the spline can be replaced
with two straight lines.  See this thread for more:

  http://lists.gnu.org/archive/html/freetype-devel/2010-06/msg00000.html
This commit is contained in:
Graham Asher 2010-06-10 08:10:57 +02:00 committed by Werner Lemberg
parent ad61f178e2
commit 7fb3ef64a2
2 changed files with 29 additions and 22 deletions
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10
ChangeLog
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@ -1,3 +1,13 @@
2010-06-10 Graham Asher <graham.asher@btinternet.com>
ftgrays: Speed up rendering of small cubic splines.
* src/smooth/ftgrays.c (gray_render_cubic): Implement new,
simplified algorithm to find out whether the spline can be replaced
with two straight lines. See this thread for more:
http://lists.gnu.org/archive/html/freetype-devel/2010-06/msg00000.html
2010-06-09 Werner Lemberg <wl@gnu.org>
Fix Savannah bug #30082.

41
src/smooth/ftgrays.c
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@ -4,7 +4,7 @@
/* */
/* A new `perfect' anti-aliasing renderer (body). */
/* */
/* Copyright 2000-2001, 2002, 2003, 2005, 2006, 2007, 2008, 2009 by */
/* Copyright 2000-2001, 2002, 2003, 2005, 2006, 2007, 2008, 2009, 2010 by */
/* David Turner, Robert Wilhelm, and Werner Lemberg. */
/* */
/* This file is part of the FreeType project, and may only be used, */
@ -1007,56 +1007,53 @@
const FT_Vector* control2,
const FT_Vector* to )
{
TPos dx, dy, da, db;
int top, level;
int* levels;
FT_Vector* arc;
int mid_x = ( DOWNSCALE( ras.x ) + to->x +
3 * (control1->x + control2->x ) ) / 8;
int mid_y = ( DOWNSCALE( ras.y ) + to->y +
3 * (control1->y + control2->y ) ) / 8;
TPos dx = DOWNSCALE( ras.x ) + to->x - ( mid_x << 1 );
TPos dy = DOWNSCALE( ras.y ) + to->y - ( mid_y << 1 );
dx = DOWNSCALE( ras.x ) + to->x - ( control1->x << 1 );
if ( dx < 0 )
dx = -dx;
dy = DOWNSCALE( ras.y ) + to->y - ( control1->y << 1 );
if ( dy < 0 )
dy = -dy;
if ( dx < dy )
dx = dy;
da = dx;
dx = DOWNSCALE( ras.x ) + to->x - 3 * ( control1->x + control2->x );
if ( dx < 0 )
dx = -dx;
dy = DOWNSCALE( ras.y ) + to->y - 3 * ( control1->x + control2->y );
if ( dy < 0 )
dy = -dy;
if ( dx < dy )
dx = dy;
db = dx;
level = 1;
da = da / ras.cubic_level;
db = db / ras.conic_level;
while ( da > 0 || db > 0 )
dx /= ras.cubic_level;
while ( dx > 0 )
{
da >>= 2;
db >>= 3;
dx >>= 3;
level++;
}
if ( level <= 1 )
{
TPos to_x, to_y, mid_x, mid_y;
TPos to_x, to_y;
to_x = UPSCALE( to->x );
to_y = UPSCALE( to->y );
/* Recalculation of midpoint is needed only if */
/* UPSCALE and DOWNSCALE have any effect. */
#if ( PIXEL_BITS != 6 )
mid_x = ( ras.x + to_x +
3 * UPSCALE( control1->x + control2->x ) ) / 8;
mid_y = ( ras.y + to_y +
3 * UPSCALE( control1->y + control2->y ) ) / 8;
#endif
gray_render_line( RAS_VAR_ mid_x, mid_y );
gray_render_line( RAS_VAR_ to_x, to_y );
return;
}
@ -1104,7 +1101,7 @@
Draw:
{
TPos to_x, to_y, mid_x, mid_y;
TPos to_x, to_y;
to_x = arc[0].x;