Add hex constructors for Color

[BillyDM]

It would be nice to add a feature to create colors from a single hexadecimal number like this:

let color1 = Color::from_hex_rgb(0x3280c8);
let color2 = Color::from_hex_rgba(0x3280c86f);

The code could be something like this:

pub fn from_hex_rgb(hex: u32) -> Color {
    let r = (hex & 0xff0000) >> 16;
    let g = (hex & 0xff00) >> 8;
    let b = (hex & 0xff);

    Color {
        r: f32::from(r) / 255.0,
        g: f32::from(g) / 255.0,
        b: f32::from(b) / 255.0,
        a: 1.0f32,
    }
}

pub fn from_hex_rgba(hex: u32) -> Color {
    let r = (hex & 0xff000000) >> 24;
    let g = (hex & 0xff0000) >> 16;
    let b = (hex & 0xff00) >> 8;
    let a = (hex & 0xff);

    Color {
        r: f32::from(r) / 255.0,
        g: f32::from(g) / 255.0,
        b: f32::from(b) / 255.0,
        a: f32::from(a) / 255.0,
    }
}

[hecrj]

You can currently write:

let color1 = Color::from_rgb8(0x32, 0x80, 0xC8);
let color2 = Color::from_rgba8(0x32, 0x80, 0xC8, 0.44);

A constructor like from_hex_rgb doesn't exist because it feels wrong to ask for a u32 and discard part of it.

However, I think we could add from_hex_rgba. But maybe we should name it from_rgba8_u32 for consistency (i.e. the hexadecimal representation of the value isn't relevant).

[BillyDM]

Well, I'm usually copying and pasting the hex values straight from an external program like Inkscape. It is cumbersome to have to constantly reformat it every time I want to check how it looks in the app.

[BillyDM]

Actually, yeah, from_rgba8_u32 could work. Inkscape uses that format anyway, even if the alpha is ff. I feel like that name's not that clear that it's an option for using hex values, but perhaps that could be explained in a comment / documentation.

[hecrj]

Well, I'm usually copying and pasting the hex values straight from an external program like Inkscape. It is cumbersome to have to constantly reformat it every time I want to check how it looks in the app.

You could create your own helper function:

fn inkscape_color(value: u32) -> iced::Color { /* ... */ }

I feel like that name's not that clear that it's an option for using hex values, but perhaps that could be explained in a comment / documentation.

Yes. It feels wrong to mention hex when the argument can be any u32.

[BillyDM]

Oh yeah, I could write my own helper function. It would be nice just to have this in iced at some point though. Other people using iced may want the same thing but not know how to write that specific helper function.