[cairo] Zero matrix transformation
d at domob.eu
Wed Mar 19 05:22:10 PDT 2008
I just set-up git cairo and pixman and was playing around a bit with it.
On the GSoC ideas page there's one item:
Fix cairo so that a degenerate matrix draws nothing rather than
triggering an error state. That is: cairo_scale (cr, 0, 0); should not
cause an error, (though maybe it shouldn't actually draw nothing for
painting an infinite source pattern---compute the average color for a
surface-based source pattern perhaps?).
I tried to reproduce this, but for me (using the hello-program from the
FAQ with this scale-statement added) this seems to work. Using numbers
between 0 and 1, the writing becomes smaller as I would expect; for
using 0, nothing is drawn, as the item states as desired behaviour.
Did I understand something wrong, did my test not trigger the error for
some reason, is this already done...? I'd like to start working on
cairo a bit to make experiences, and this looked not too hard. If you
have any other suggestions, I'd be happy to hear from you!
My test program:
main (int argc, char *argv)
surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 240,
cr = cairo_create (surface);
cairo_select_font_face (cr, "serif", CAIRO_FONT_SLANT_NORMAL,
cairo_set_font_size (cr, 32.0);
cairo_set_source_rgb (cr, 0.0, 0.0, 1.0);
cairo_move_to (cr, 10.0, 50.0);
cairo_scale(cr, 0., 0.);
cairo_show_text (cr, "Hello, world");
cairo_surface_write_to_png (surface, "hello.png");
Done: Bar-Sam-Val-Wiz, Dwa-Elf-Hum-Orc, Cha-Law, Fem-Mal
To go: Arc-Cav-Hea-Kni-Mon-Pri-Rog-Tou
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