the boolcopy optimization doesnt doesnt use Buffer.alpha, tho
the debug function dumpbuf() still can dereference it. to keep
it simple, always have Buffer.alpha point to the channel or
&ones when not used.
memfillcolor() used to write longs in host byte
order which is wrong. have to always use little
endian.
to simplify, moved little endian conversion into
memsetl() and memsets() avoiding code duplication.
remove unused memsetb() routine.
replace foo ? 1 : 0 with foo != 0
avoid double calculation of rgb components in readbyte()
handle byte aligned color components in writebyte()
which lets us avoid the read-modify-write and the shifting.
surprisingly, the branches in the loop are way less important
than avoiding the memory access.
this change makes ganes/snes playable at -3 scaling.
when a replicated source image with a clipr with clipr.min > Pt(0, 0),
drawclip() would properly translate the src->clipr on the dstr
but then clamp the source rectangle back on src->r.
while traversing down multiple layers, this would cause the translation to
be applied multiple times to the dst rectangle giving the wrong image result.
this change adds a new drawclipnorepl() function that avoids the clamping
of source and mask rectangles to src->r and mask->r. this is then used in
libmemlayer.
the final memimagedraw() call will call drawclip() which will do the final
claming.
a testcase is provided:
#include <u.h>
#include <libc.h>
#include <draw.h>
Image *blue;
Image *red;
void
main(int, char *argv[])
{
Image *i;
if(initdraw(nil, nil, argv[0]) < 0)
sysfatal("initdraw: %r");
i = allocimage(display, screen->r, screen->chan, 1, DWhite);
red = allocimage(display, Rect(0,0,1,1), screen->chan, 1, DRed);
blue = allocimage(display, Rect(0,0,1,1), screen->chan, 1, DPaleblue);
replclipr(red, 1, Rect(10, 10, 110, 110));
replclipr(blue, 1, Rect(11, 11, 111, 111));
/* draw on non-layer, works correctly */
draw(i, i->r, red, nil, ZP);
draw(i, i->r, blue, nil, ZP);
draw(screen, screen->r, i, nil, i->r.min);
flushimage(display, 1);
/* draw on (screen) layer is too far to the right */
draw(screen, screen->r, red, nil, ZP);
draw(screen, screen->r, blue, nil, ZP);
flushimage(display, 1);
for(;;){
sleep(1000);
}
}
