when drawing a replicated source image with a clipr with
clipr.min > Pt(0, 0), drawclip() would translate the
src->clipr on the dstr but then clamp the source rectangle
back on src->r.
this causes problems in libmemlayer when it drawclips() at each iteration
when traversing down the layers. the clamping of sr back to src->r (which is 1x1
in the example below) it will shift the destination rectangle to the right
as it is reapplied at each loop iteration.
#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);
}
}
in 9front, i added drawclipnorepl() function that is like drawclip() but does
not clamp
the source and mask rectangles to be in src->r and mask->r and use it in
libmemlayer.
http://code.google.com/p/plan9front/source/detail?r=c18ae5b7ea0ee138080824c4f164628f899b7770
--
cinap
