Re: Raster operations

[Asela Leelaratne <leelaratne asela meta co jp>]

Hi Ivan and Iago,
Thanx for the tips and the explanations. I will study Cairo and try to
draw with Cairo.
---
Asela.


On Tue, 18 Jul 2006 19:04:38 +0200
Iago Rubio <iago iagorubio com> wrote:

> Hi Asela,
>
> On Tue, 2006-07-11 at 11:45 +0900, Asela Leelaratne wrote:
> > Hello List members,
> [snip]
> > The problem is I need to do some raster operations like ROP2, ROP3,
> > Porter and Duff etc... Are there any api's in Gtk(or Gdk) to achive it?
> > If not is there a library or something that I can use(C language)?
> > If both the above is not possible is there a standard method to do the
> > above operations(C language, GDK and Gtk widgets)?
>
> There is support for Porter/Duff operations in cairo. Check the cairo
> documentation on cairo_operator_t .
>
> It supports all 12 Porter/Duff operations plus 'add' and 'saturate'.
>
> typedef enum _cairo_operator {
>     CAIRO_OPERATOR_CLEAR,
>     CAIRO_OPERATOR_SOURCE,
>     CAIRO_OPERATOR_OVER,
>     CAIRO_OPERATOR_IN,
>     CAIRO_OPERATOR_OUT,
>     CAIRO_OPERATOR_ATOP,
>     CAIRO_OPERATOR_DEST,
>     CAIRO_OPERATOR_DEST_OVER,
>     CAIRO_OPERATOR_DEST_IN,
>     CAIRO_OPERATOR_DEST_OUT,
>     CAIRO_OPERATOR_DEST_ATOP,
>     CAIRO_OPERATOR_XOR,
>
>     CAIRO_OPERATOR_ADD,
>     CAIRO_OPERATOR_SATURATE
> } cairo_operator_t;
>
> You just need to set the operator with cairo_set_operator(cairo_t,
> cairo_operator_t) and it will be used on subsequent drawing operators.
>
> To pick the cairo context from a GdkDrawable you may use 
> cairo_t*  gdk_cairo_create (GdkDrawable *drawable);
>
> Once you aquired the cairo context, you can start to use the cairo API
> on it.
>
> // ...
> cairo_t ct;
> GtkWidget* widget;
>
> widget = gtk_drawing_area_new();
> ct = gdk_cairo_create (widget->window);
> cairo_set_operator(ct, CAIRO_OPERATOR_DEST_OVER);
> // ...
>
> This is available as for GTK+2.8.
> -- 
> Iago Rubio
>
> _______________________________________________
> gtk-app-devel-list mailing list
> gtk-app-devel-list gnome org
> http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list

以上、よろしくお願いいたします。

-------------------------------
Asela Leelaratne