gnustep/libs-back
0
0
Fork 0
mirror of https://github.com/gnustep/libs-back.git synced 2025-04-23 08:07:07 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

Use integer arithmatic

Browse source 
git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/back/branches/freeze-0_8_0@14207 72102866-910b-0410-8b05-ffd578937521
This commit is contained in:
Adam Fedor 2002-07-29 02:05:26 +00:00
parent ef81d41060
commit abdb40c9eb
2 changed files with 56 additions and 43 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
ChangeLog
View file

@ -1,3 +1,8 @@
2002-07-28 Adam Fedor <fedor@gnu.org>
* Source/xlib/XGBitmap.m (_pixmap_combine_alpha): Use
interger arithmatic. (Patch from Jeff Teunissen)
2002-07-19 Adam Fedor <fedor@gnu.org>
* Source/xlib/XGGeometry.m (clipXRectsForCopying): Shift rect
@ -18,7 +23,7 @@
* Source/xlib/XGBitmap.m (_pixmap_combine_alpha): Fix and
cleanup alpha blending (Rescale by alpha)
(_bitmap_combine_alpha): Idem. (Patch from deek@d2dc.net).
(_bitmap_combine_alpha): Idem. (Patch from Jeff Teunissen).
2002-06-28 Adam Fedor <fedor@gnu.org>

92
Source/xlib/XGBitmap.m
View file

@ -150,18 +150,18 @@ _pixmap_combine_alpha(RContext *context,
for (col = 0; col < srect.width; col++)
{
unsigned sr, sg, sb, sa; // source
unsigned dr, dg, db, da; // dest
double alpha, ialpha;
unsigned sr, sg, sb, sa; // source
unsigned dr, dg, db, da; // dest
unsigned ialpha;
// Get the source pixel information
pixel = XGetPixel (source_im->image, srect.x+col, srect.y+row);
PixelToRGB (pixel, sr, sg, sb);
pixel = XGetPixel(source_im->image, srect.x+col, srect.y+row);
PixelToRGB(pixel, sr, sg, sb);
if (source_alpha)
{
pixel = XGetPixel(source_alpha->image,
srect.x+col, srect.y+row);
pixel = XGetPixel(source_alpha->image,
srect.x + col, srect.y + row);
sa = (pixel >> _ashift) & _amask;
}
else
@ -173,30 +173,37 @@ _pixmap_combine_alpha(RContext *context,
if (fraction < 1.0)
sa *= fraction;
alpha = ((double) sa) / _amask;
sr *= sa;
sg *= sa;
sb *= sa;
ialpha = (_amask - sa);
// Now get dest pixel
pixel = XGetPixel(dest_im->image, col, row);
PixelToRGB (pixel, dr, dg, db);
pixel = XGetPixel(dest_im->image, col, row);
PixelToRGB(pixel, dr, dg, db);
dr *= ialpha;
dg *= ialpha;
db *= ialpha;
if (dest_alpha)
{
{
pixel = XGetPixel(dest_alpha->image, col, row);
da = (pixel >> _ashift) & _amask;
}
}
else // no alpha channel, background is opaque
da = _amask;
ialpha = (1.0 - alpha);
dr = (sr * alpha) + (dr * ialpha);
dg = (sg * alpha) + (dg * ialpha);
db = (sb * alpha) + (db * ialpha);
dr = (sr + dr) / _amask;
dg = (sg + dg) / _amask;
db = (sb + db) / _amask;
// calc final alpha
if (sa == _amask || da == _amask)
da = _amask;
else
da = sa + (da * ialpha);
da = sa + ((da * ialpha) / _amask);
CLAMP(dr);
CLAMP(dg);
@ -857,7 +864,7 @@ _bitmap_combine_alpha(RContext *context,
img.a = malloc(img.screen_w);
{
unsigned long pixel;
unsigned long pixel;
/* Two cases, the *_FAST* method, which
is covered in the first a part of the if
@ -911,24 +918,21 @@ _bitmap_combine_alpha(RContext *context,
unsigned short sg = (*gptr++ >> (8 - _gwidth));
unsigned short sb = (*bptr++ >> (8 - _bwidth));
unsigned short sa = (*aptr++ >> (8 - _awidth));
unsigned dr, dg, db, da;
double alpha = (double) sa / ((1 << _rwidth) - 1);
unsigned dr, dg, db, da; // dest
if (sa == 0) // dest wouldn't be changed
continue;
/*
* Unscale alpha value in each color component
*/
if (sa < _amask)
if (sa == _amask) // source only, don't bother with the rest
{
double multiplier = (double) _amask / sa;
sr *= multiplier;
sg *= multiplier;
sb *= multiplier;
// Yes, this is duplicated code -- but it's worth it.
RGBToPixel(sr, sg, sb, pixel);
XPutPixel(dest_im->image, col, row, pixel);
if (dest_alpha)
XPutPixel(dest_alpha->image, col, row, sa << _ashift);
continue;
}
// get the destination pixel
pixel = XGetPixel(dest_im->image, col, row);
PixelToRGB(pixel, dr, dg, db);
@ -940,24 +944,28 @@ _bitmap_combine_alpha(RContext *context,
}
else // no alpha channel, background is opaque
da = _amask;
if (sa == _amask || da == 0) // source only
{
dr = sr;
dg = sg;
db = sb;
if (da == 0)
{
/*
* Unscale the colors
*/
dr = (sr * _amask) / sa;
dg = (sg * _amask) / sa;
db = (sb * _amask) / sa;
da = sa;
}
else
{
double ialpha = (1.0 - alpha);
dr = (sr * alpha) + (dr * ialpha);
dg = (sg * alpha) + (dg * ialpha);
db = (sb * alpha) + (db * ialpha);
unsigned ialpha = _amask - sa;
dr = (sr * sa + (dr * ialpha)) / _amask;
dg = (sg * sa + (dg * ialpha)) / _amask;
db = (sb * sa + (db * ialpha)) / _amask;
if (da == _amask || da == _amask)
da = _amask;
else
da = sa + (da * ialpha);
da = sa + ((da * ialpha) / _amask);
}
CLAMP(dr);