Add texture scale mode

[jagprog5]

otherwise texture copy to a smaller destination can look quite bad

[jagprog5]

@Cobrand

[Cobrand]

Huge no-no, it will crash badly if n is not a safe value, even though the function is a try_from, which should simply output a Err on invalid value.

Read the implications of transmute with enums and fix this PR, this is not the only time you're using it, and I don't think you should be using it even once.

[jagprog5]

I'm happy to make this change. Quick question first, should these existing instances be changed as well? My intent was to follow the existing style.

• TextureAccess
• BlendMode
• PixelFormatEnum
• EventType

Thanks

[Cobrand]

I just checked on the playground, they are all big mistakes and should be fixed ASAP:

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=1f798ba39aef506228d8ecfeeda9b759

Try in debug and release modes, it's wildly different behaviors, and never what's expected

[jagprog5]

Addressed in: aa858db

[jagprog5]

@Cobrand friendly ping!

[jagprog5]

@Cobrand I have addressed cf7d253 one of the job failures.

But the other one is more involved and related to this. Please consider applying the fix listed there to a different PR - I can't run the CI manually to check it.

[jagprog5]

@Cobrand hello! I noticed that there is some subtle differences between sdl2-sys and sdl3-sys. sdl2-sys causes the casts to be required in this MR. that being said, I'd prefer the scope of this one not to expand too much. Is there anything I can do on my end? I'd love to get this merged in.

[jagprog5]

@AngryLawyer

[jagprog5]

Relates #1388

[jagprog5]

I did not include this test, as it requires creating a texture creator, which I doubt would work with the CI.

Of note, the default is Nearest for SDL2, but Linear for SDL3.

use sdl2::{render::ScaleMode, surface::Surface};

extern crate sdl2;
extern crate sdl2_sys;

#[test]
fn test_scale_mode() {
    let sdl_context = sdl2::init().unwrap();
    let sdl_video_subsystem = sdl_context.video().unwrap();
    let window = sdl_video_subsystem
    .window(
        "tester",
        100,
        100,
    )
    .build()
    .unwrap();

    let canvas = window.into_canvas().build().unwrap();
    let texture_creator = canvas.texture_creator();
    let surface = Surface::new(1, 1, sdl2::pixels::PixelFormatEnum::ARGB8888).unwrap();

    let mut texture = texture_creator.create_texture_from_surface(surface).unwrap();

    // checking the default scale mode
    assert_eq!(texture.scale_mode(), ScaleMode::Nearest);
    // check set get
    texture.set_scale_mode(ScaleMode::Nearest);
    assert_eq!(texture.scale_mode(), ScaleMode::Nearest);
}

[Cobrand]

I feel like there is probably a prettier way to match everything to their sdl2-sys counterparts without doing x if x == CONST as u32 but I can't find it. In the meantime it's at least sound, so I'll wait for the workflow to finish and merge.

[antonilol]

I feel like there is probably a prettier way to match everything to their sdl2-sys counterparts without doing x if x == CONST as u32 but I can't find it. In the meantime it's at least sound, so I'll wait for the workflow to finish and merge.

I don't know, because the constants are enum variants the as casting is needed. A macro can always make it look nicer (and still result in the same compiled code).

[jagprog5]

@Cobrand @antonilol for comparison the equivalent change working with sdl3-rs: https://github.com/vhspace/sdl3-rs/pull/92/files

that being said, I don't want this MR to get out of scope - this can be a follow up issue

[jagprog5]

the difference is:

sdl3-sys

Auto generated bindings gave a struct: here:

pub struct SDL_EventType(pub Uint32);
impl SDL_EventType {
    /// Unused (do not remove)
    pub const FIRST: Self = Self(0);
    ...

sdl2-sys

Auto generated bindings gave an enum:

pub enum SDL_EventType {
    #[doc = "< Unused (do not remove)"]
    SDL_FIRSTEVENT = 0,
    ...

[antonilol]

UB is gone but I don't like x if x == <constant> as u32 => ... match arms, a macro can be used to fix this. (I don't think there is a better way without a macro)

I checked with compiler explorer and Rust seems to have no issue compiling this compared to what it was before.