Hello Michael,
2009/2/15 Michael B. Trausch <[email protected]>
> I am trying to create a small Xlib binding for Vala, with a little bit
> of difficulty. I think I just don't understand what it is that I am
> doing fully.
>
> Starting with what Frederik gave as an initial set of code, I have so
> far come up with:
>
> [CCode(cprefix = "X", cheader_filename = "X11/Xlib.h")]
> namespace XLib {
> [Compact]
> [CCode(cname = "Display", free_function = "XCloseDisplay")]
> public class Display {
> [CCode(cname = "XOpenDisplay")]
> public Display(string? display_name = null);
>
> [CCode(cname = "XDefaultScreen")]
> public int get_default_screen();
>
> [CCode(cname = "XBlackPixel")]
> public long get_black_pixel(int screen_number);
>
> [CCode(cname = "XWhitePixel")]
> public long get_white_pixel(int screen_number);
>
> [CCode(cname = "XConnectionNumber")]
> public int get_connection_number();
>
> [CCode(cname = "XDefaultColormap")]
> public ColorMap get_default_colormap(int screen_number);
>
> [CCode(cname = "XAllPlanes")]
> public static long get_all_planes();
> }
> }
>
> Now, the problem is the return value for XDefaultColormap. This is
> really a typedef to XID, which itself is a typedef to CARD32, which is
> in turn a typedef to "unsigned long". I could just declare it to be an
> ulong, but it'd seem that there should be some way to do this in a
> type-safe manner. Is there something simple that I am just not getting?
>
You can define the ColorMap like this:
[CCode (cname="ColorMap")]
public struct ColorMap { }
if is a typedef of XID->CARD32->unsigned long you can also do this:
[CCode (cname="CARD32")]
public struct CARD32 : ulong {}
[CCode (cname="XID")]
public struct XID : CARD32 {}
[CCode (cname="ColorMap")]
public struct ColorMap: XID {}
Try both ways and see what C code valac generates. If the parameter is
passed by value add [SimpleType].
See gl.vapi in http://live.gnome.org/Vala/ExternalBindings there's some
definition that I use for GLboolean, GLint, etc
Matias
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