Alternate rgba implementation

[Susurrus]

That takes into account all the conversation over in #139 and implements RGBA as a custom struct. The end-use usability between this and #139 is vastly improved. Basically every function supported by RGBA corresponds to an existing trait in Rust.

I've done some testing of some of the various code here as I have GTK working with these changes and my own application using both. I don't fully understand the memory management done by GTK for the GdkRGBA struct behind the scenes but I haven't run into crashes here.

Do note that there is one outstanding issue here and that's the error type to use for the FromStr trait. Since the GTK interface just uses an Option type but this trait uses Result I had to make up an error type. It looks like Glib has some error types but none of them looked appropriate. I think it's good to implement this trait but I don't think this is the best way to do the error type. Anyone have any ideas?

[Susurrus]

I just realized that I didn't implement copy or free like the GTK interface has. I don't know if they're necessary, as like I said above I don't really get the memory management strategy used by GTK and how gtk-rs interfaces with it. But I'll leave it for now until I get some feedback from you guys.

[EPashkin]

move this after PartialEq

[Susurrus]

I had just arranged everything alphabetically, but I'll move this if you like.

[EPashkin]

Actually, better move FromStr, Hash, PartiallyEq here. This way all xGlibPtrx will go to one place

[EPashkin]

At minimum better not separate Eq and Partial Eq

[EPashkin]

with this Gtks ColorChooserExt.addPalette again looks like

ffi::gtk_color_chooser_add_palette(self.to_glib_none().0, orientation.to_glib(),
    colors_per_line, colors.len() as c_int, colors.as_ptr() as *mut gdk_ffi::GdkRGBA)

and both function of StyleContext need minor change to use
let mut rgba = gdk::RGBA::uninitialized(); that don't needed from_glib_xx conversion

[EPashkin]

About usage copy, free: IMHO copy better just ignored
and maybe need add FromGlibPtrFull just in case.
It need call gdk_rgba_free after get local copy of RGBA

[EPashkin]

also cc @GuillaumeGomez
Seems I found way to build all gtk generated code when enabling RGBA.
Currently don't see way to move it to glib due conflicting implementation errors,
so gtk need additional dependence gobject-sys

impl glib::StaticType for RGBA {
    fn static_type() -> glib::types::Type {
        unsafe { from_glib(ffi::gdk_rgba_get_type()) }
    }
}

impl glib::value::FromValueOptional for RGBA {
    unsafe fn from_value_optional(value: &glib::Value) -> Option<Self> {
        from_glib_full(gobject_ffi::g_value_dup_boxed(value.to_glib_none().0) as *mut ffi::GdkRGBA)
    }
}

impl glib::value::SetValue for RGBA {
    unsafe fn set_value(value: &mut glib::Value, this: &Self)  {
        gobject_ffi::g_value_set_boxed(value.to_glib_none_mut().0, this.to_glib_none().0 as gconstpointer)
    }
}

impl glib::value::SetValueOptional for RGBA {
    unsafe fn set_value_optional(value: &mut glib::Value, this: Option<&Self>) {
        gobject_ffi::g_value_set_boxed(value.to_glib_none_mut().0, this.to_glib_none().0 as gconstpointer)
    }
}

[GuillaumeGomez]

unsafe fn set_value(value: &mut glib::Value, this: &Self)  {

Shouldn't Self be first?

[EPashkin]

This as defined in glib:

/// Sets a value.
pub trait SetValue: StaticType {
    unsafe fn set_value(&mut Value, &Self);
}

may to be same as

pub trait SetValueOptional: SetValue {
    unsafe fn set_value_optional(&mut Value, Option<&Self>);
}

[GuillaumeGomez]

Hum ok, too bad...

[Susurrus]

So what needs to be done to wrap up this PR? From your comments it looks like:

1. Reorder trait implementations
2. Implement FromGlibPtrFull
3. Add glib trait impl shown in Alternate rgba implementation #140 (comment)

Is that it?

[EPashkin]

For me it seems complete list.

[Susurrus]

Alright, that should all be implemented. Local code that I have is still working correctly. I also updated gtk-rs/gtk#462 so that it's now dependent on this PR.

[EPashkin]

@Susurrus, Thanks
I have minor worry about FromStr trait error, but prefer skip it now.

@GuillaumeGomez, what you think: this PR or #139 ?

[GuillaumeGomez]

Code seems ok to me but CIs errors seem legit.

[EPashkin]

Whose?

[GuillaumeGomez]

check_init

[EPashkin]

@GuillaumeGomez you right.
@Susurrus, all these functions need skip_assert_initialized!();

$ ./check_init_asserts
src/rgba.rs:black() -> RGBA 
src/rgba.rs:blue() -> RGBA 
src/rgba.rs:green() -> RGBA 
src/rgba.rs:red() -> RGBA 
src/rgba.rs:white() -> RGBA 
src/rgba.rs:static_type() -> glib::types::Type

[Susurrus]

Whoops, forgot I left those out and meant to ask about what functions actually needed them. Good catch!

So I've pushed a new version with fixes.

[Susurrus]

I pushed another version that fixes a minor style issue and also exports the RgbaParseError type.

[EPashkin]

Ping

[GuillaumeGomez]

Oups, forgot about it... Thanks!