[cairo] Cairo crash with a simple stroke (win32)

[Fred bca21]

Hi,

I have just tested with the latest cairo release (1.12.6), and it
appears that the issue is still here (crash at the exact same
location). Has anyone an idea of how to fix it? Should I maybe post
this to the bugs mailing list?

Regards,

Fred.


2012/10/19 Fred bca21 <fredbca21 at gmail.com>:
> Hi,
>
> I am new to this list but I have been using cairo and monitoring posts
> for a couple of months now. I have a strange issue on windows when the
> intersection between the clipping region and the drawing is very
> small, so I am posting here with the hope that someone can help (I am
> a bit too new to cairo's internals to debug this problem).
>
> Typically, the simple code below crashes (I am using a DDB bitmap for
> the example, but it also crashes with any DC).
>
> #include "cairo.h"
> #include "cairo-win32.h"
> #include <windows.h>
> {
> // build a bitmap (same issue with DIB, whatever the bit depth)
> HDC dc=::CreateCompatibleDC(NULL);
> HBITMAP hBmp=::CreateCompatibleBitmap(dc,100,200);
> ::SelectObject(dc,hBmp);
>
> // set clip region for the DC to one single line in the middle of the bitmap
> HRGN hrgn = CreateRectRgn(0,100,100, 101);
> SelectClipRgn(dc, hrgn);
> ::DeleteObject(hrgn);
>
> // create cairo context
> cairo_surface_t* surface=cairo_win32_surface_create(dc);
> if(surface)
> {
> cairo_t* context=cairo_create(surface);
> if(context)
> {
> // draw one line
> cairo_move_to(context,1, 1);
> cairo_line_to(context,10,120);
> cairo_set_source_rgb(context,1,1,1);
>
> // CRASHES HERE (see below):
> cairo_stroke(context);
>
> // cleanup
> cairo_destroy(context);
> }
> cairo_surface_destroy(surface);
> }
> }
>
> The crash occurs in cairo-image-compositor.c, on line 2197, in
> _fill_xrgb32_lerp_opaque_spans():
>
>                 } else while (len--) {
>                     // On this line below, d has an invalid address
>                     *d = lerp8x4 (r->u.fill.pixel, a, *d);
>                     d++;
>                 }
>
> If it may help, am using the static lib version of the latest release
> (1.12.4 - pixman 26.2), and it crashes in debug or release mode, 32 or
> 64-bit windows. It's too bad because this crash occurs all the time in
> my code that extensively uses clipping regions!
>
> This crash also occurs with the previous version of cairo (1.12.2) and
> pixman 26.0, but at a different stage (in pixman if I remember well),