Add bindings to save* functions about gtk3-rs

[EPashkin]

I mean that gdk_pixbuf_save have at minimum 5 parameters.
gdk_pixbuf_save(pb, save_path.as_ptr(), format.as_ptr(), err_[or]_, ptr::null_mut());

[gkoz]

The difficulty with varargs is why they provide the _savev and other ...v functions. I believe there are translation implementations for &[&str] to char** so this should be doable.

[occamz]

Second that! I've been trying to capture a screenshot using the functions through gdk_pixbuf_sys:

let save_path = CString::new("--full-path-to-file--").unwrap();
let format = CString::new("png").unwrap();

gdk::init();

let desktop = gdk::Window::get_default_root_window();

//Init "empty" GError object
let msg = ptr::null_mut::<i8>();
let b = Box::new(GError { domain: 0, code: 0, message: msg });
let error: *mut *mut GError = &mut Box::into_raw(b);
//Result: (gdk_testing:5953): GdkPixbuf-CRITICAL **: gdk_pixbuf_save: assertion 'error == NULL || *error == NULL' failed

//GError *err = NULL;
let err = &mut ptr::null_mut::<GError>();
//Result: Process didn't exit successfully: target/debug/gdk_testing (signal: 11, SIGSEGV: invalid memory reference)

unsafe {
    let pb = gdk_pixbuf_get_from_window(gdk_get_default_root_window(), 0, 0, desktop.get_width(), desktop.get_height());
    println!("Channels: {}", gdk_pixbuf_get_n_channels(pb));
    gdk_pixbuf_save(pb, save_path.as_ptr(), format.as_ptr(), err_[or]_);

    println!("{}x{}", desktop.get_width(), desktop.get_height());
}

When I use the error variable as input to the save function I get

Result: (gdk_testing:5953): GdkPixbuf-CRITICAL **: gdk_pixbuf_save: assertion 'error == NULL || *error == NULL' failed

and for the err variable

Result: Process didn't exit successfully: target/debug/gdk_testing (signal: 11, SIGSEGV: invalid memory reference)

Probably my usage of GError, got any tips?

[EPashkin]

You need error argument be null or pointer to null. We have rust class Error as wrapper.

    pub fn load_from_path(&self, path: &str) -> Result<(), Error> {
        unsafe {
            let mut error = ptr::null_mut();
            let _ = ffi::gtk_css_provider_load_from_path(self.to_glib_none().0, path.to_glib_none().0, &mut error);
            if error.is_null() { Ok(()) } else { Err(from_glib_full(error)) }
        }
    }

[EPashkin]

Missed that you tried both cases :(
May be problem with last parameter, you tried pass ptr::null_mut() after error?

[occamz]

I saw the Error struct when I searched through all sources for any reference or abstraction of GError, but I wasn't able to use it with the lower level _sys functions. Is there some way I could create an Error and convert it to GError and pass it to the _sys functions?

I tried using ptr::null_mut() instead of &mut ptr::null_mut::<GError>()which compiled but resulted in the same segfault.

Thanks for a response :)

[occamz]

Thank you! I can't believe I didn't understand that the "..." ment options until NULL. I went with let null: *const i32 = ptr::null(); and it worked!

Awesome :D

[EPashkin]

"..." is main problem why no save_* currently, almost only gdk_pixbuf_savev can be added 😢

[occamz]

Yeah, it's a really weird way to specify parameters :/ so it isn't technically possible to do that through Rust in a reliable way? I'm really new to it...

[sdroege]

There are various save functions now.