Re: goocanvas vs crcanvas,which better?

[Dov Grobgeld <dov grobgeld gmail com>]

The following does it:

  int img_width = gdk_pixbuf_get_width(pixbuf);
  int img_height = gdk_pixbuf_get_height(pixbuf);
  cairo_surface_t *surface
    = cairo_image_surface_create_for_data(gdk_pixbuf_get_pixels(pixbuf),
                                          CAIRO_FORMAT_ARGB32,
                                          img_width,
                                          img_height,
                                          gdk_pixbuf_get_rowstride(pixbuf));


You will have to swap R and B in calls to:

  cairo_set_source_rgba (cr, 0,0,1.0,0.5);


when drawing though, as cairo and gdk_pixbuf have different ideas about
their order.

(These examples are copied from the GtkImageViewer tutorial.)

Regards,
Dov

2009/3/26 Alexander <b3nder yandex ru>

> Hi, Dov.
>
> On Thursday 26 March 2009, Dov Grobgeld wrote:
>
> >    - If the annotation is static, it certainly faster to prepare a
> >    transparent pixbuf and draw the annotation on the pixbuf and then
> simply
> >    merge the data from the frame grabber with the overlay mostly
> transparent
> >    pixbuf, and then ship the result of to display.
>
> Is there standard facility for creating cairo context for pixbuf? Like
> gdk_cairo_create() for drawables.
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