veloren/voxygen/src/ui/img_ids.rs

use super::Graphic;
use dot_vox::DotVoxData;
use image::DynamicImage;
use common::assets::{Error, load};

pub struct BlankGraphic;
pub struct ImageGraphic;
pub struct VoxelGraphic;

pub trait GraphicCreator<'a> {
    type Specifier;
    fn new_graphic(specifier: Self::Specifier) -> Result<Graphic, Error>;
}
impl<'a> GraphicCreator<'a> for BlankGraphic {
    type Specifier = ();
    fn new_graphic(_: ()) -> Result<Graphic, Error> {
        Ok(Graphic::Blank)
    }
}
impl<'a> GraphicCreator<'a> for ImageGraphic {
    type Specifier = &'a str;
    fn new_graphic(specifier: Self::Specifier) -> Result<Graphic, Error> {
       Ok(Graphic::Image(load::<DynamicImage>(specifier)?))
    }
}
impl<'a> GraphicCreator<'a> for VoxelGraphic {
    type Specifier = &'a str;
    fn new_graphic(specifier: Self::Specifier) -> Result<Graphic, Error> {
       Ok(Graphic::Voxel(load::<DotVoxData>(specifier)?))
    }
}

/// This macro will automatically load all specified assets, get the corresponding ImgIds and
/// create a struct with all of them
///
/// Example usage:
/// ```
/// image_ids! {
///     pub struct Imgs {
///         <VoxelGraphic>
///         button1: "filename1.vox",
///         button2: "filename2.vox",
///
///         <ImageGraphic>
///         background: "background.png",
/// 
///         <BlankGraphic>
///         blank: (),
///     }
/// }
/// ```
// TODO: will this work with shorter name paths? eg not rate::ui::Graphic::
#[macro_export]
macro_rules! image_ids {
    ($($v:vis struct $Ids:ident { $( <$T:ty> $( $name:ident: $specifier:expr ),* $(,)? )* })*) => {
        $(
            $v struct $Ids {
                    $($( $v $name: conrod_core::image::Id, )*)*
            }

            impl $Ids {
                pub fn load(ui: &mut crate::ui::Ui) -> Result<Self, common::assets::Error> {
                    use crate::ui::GraphicCreator;
                    Ok(Self {
                        $($( $name: ui.add_graphic(<$T>::new_graphic($specifier)?), )*)*
                    })
                }
            }
        )*
    };
}