> Hi,
[Freenect C init sample ]
> Trying to implement that in Vala, I took the approach below.
> It seems however, that the init_async does not work. Looking at the
> generated C-Code it looks like the g_async_initable_init_finish method
> is called right after init_async an not with in the callback as expected.
> As a result the code is crashing in the underlying libusb due to
> incorrect initialization.
>
> What am I missing here? Any idea how to solve the issue.
>
> thanks and sorry for the lengthy post,
>
> --tomw
>
> ---------------------------------------------------------
>
> using GLib;
> using GFreenect;
>
> public class Main : Object
> {
>
> public GFreenect.Device device;
> public Cancellable cancellable;
>
> public Main () {
> Cancellable cancellable = new Cancellable ();
>
> }
>
> public async void run (out Device dev) {
> debug ("Starting");
> Device device = (Device) GLib.Object.@new (
> typeof (Device),
> "index", 0,
> "subdevices", Subdevice.CAMERA
> );
> debug ("Device created");
> Idle.add (run.callback);
^^ No need for this since you're using yield in the function. Might
actually be harmful, causing a race between the init_async you call and
the one Vala calls implicitly.
> try {
> debug ("Trying to run init_async");
> bool re = yield device.init_async (Priority.DEFAULT,
> cancellable);
^^ this yield returns to main loop and once init_async calls its
call-back will call init_finish for you. So after this line the device
is initialized.
> if (re) {
> debug ("Result = OK");
> } else {
> debug ("Result = FAILED");
> }
> } catch (Error e) {
> debug ("Error initalizing device : %s", e.message);
> }
> }
>
> public void callback (Main? source, GLib.AsyncResult? res, void*
> user_data) {
> debug ("Entering Callback");
> Device dev;
> if (res != null) {
> source.run.end (res, out dev);
> debug ("Callback called - Device created");
> try {
> Device kinect = new dev.finish(res);
^^ And here you're basically trying to create another device.
> } catch (Error e) {
> debug ("Error finalizing device : %s", e.message);
> }
> } else {
> debug ("No result delivered");
> }
> }
I would do it like this:
using GLib;
using GFreenect;
public class Main : Object
{
public GFreenect.Device device;
public Cancellable cancellable;
public Main () {
Cancellable cancellable = new Cancellable ();
}
public async void run () {
debug ("Starting");
Device device = (Device) GLib.Object.@new (
typeof (Device),
"index", 0,
"subdevices", Subdevice.CAMERA
);
debug ("Device created");
try {
debug ("Trying to run init_async");
bool re = yield device.init_async (Priority.DEFAULT,
cancellable);
// start using the device
} catch (Error e) {
// re will always be true in the try block if you always get an
error
// when it's false, because you end up here anyway.
debug ("Error initalizing device : %s", e.message);
}
}
static int main (string[] args) {
var loop = new MainLoop ();
var app = new Main ();
app.run.begin ();
loop.run ();
return 0;
}
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