Re: [9fans] libmemlayer bug

[Conor Williams <conor.williams@gmail.com>]

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this is what I get after compiling your code cinap




On Mon, Dec 9, 2013 at 4:09 AM, <cinap_lenrek@felloff.net> wrote:

> 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
>
>

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