[cairo] cairo-1.10 regression?

Uli Schlachter psychon at znc.in
Sat Nov 27 02:26:08 PST 2010

Am 26.11.2010 16:11, Julien Bramary wrote:
> Hey guys,
> I tried 1.10 today and found some odd glitches in my application. I narrowed it down to a vertical and horizontal line crossing showing strange artefacts.
> The concerned lines either have a non-integer width or non-integer starting and end points.
> Here is the code snippet I used to test this (the code before that paints the background to white):
> layer_0 = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 600, 600);cairo_t *cr = cairo_create (layer_0);
> cairo_set_source_rgb (cr, 1, 1, 1);cairo_paint (cr);
> double x = 50.323;double y = 50.768;
> cairo_set_operator (cr, CAIRO_OPERATOR_OVER);cairo_set_source_rgb (cr, 0.1f, 0.1f, 0.1f);cairo_set_line_width (cr, 6);
> cairo_move_to (cr, x, 0);cairo_line_to (cr, x, 600);cairo_move_to (cr, 0, y);cairo_line_to (cr, 600, y);cairo_stroke (cr);
> The screenshots attached clearly show that 1.8.10 is doing the right thing with the semi-transparent bits whereas 1.10.0 is not.Anyone seen this with 1.10? I couldn't find related bugs in the tracker. I just tried with latest Git version and it still happens.
> ThanksJulien

git bisect poinrts fingers at

commit b9407af6a4bc792c1bcb52c90aa8a618627bb618
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Fri Jan 22 17:57:41 2010 +0000

    image: Implement high level interface.

    Write a dedicated compositor for pixman so that we avoid the
    middle-layer syndrome of surface-fallback. The major upshot of this
    rewrite is that the image surface is now several times quicker for glyph
    compositing, which dramatically improves performance for text rendering
    by firefox and friends. It also uses a couple of the new scan
    convertors, such as the rectangular scan converter for rectilinear

So this doesn't help at all... :(

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