snes/snes-frontend/src/emu_ui/game.rs

use eframe::egui::{self, Pos2, Rect};
use eframe::{egui::Context, epaint::ColorImage};
use eframe::egui::{TextureOptions, Ui};
use eframe::epaint::{Vec2, TextureHandle};
use snes_core::ppu::registers::{
    MAX_TV_WIDTH,
    MAX_TV_HEIGHT,
};


pub fn build_game_window(
    ctx: &egui::Context,
    game_tv_texture: &mut Option<TextureHandle>,
    framebuffer: &[u8],
    current_res: (u16, u16),
) {
    egui::Window::new("TV")
        .collapsible(false)
        .show(ctx, |ui| {
            paint_game_texture(ui, game_tv_texture, framebuffer, current_res);
        });
}

pub fn initialize_game_texture(ctx: &Context, game_tv_texture: &mut Option<TextureHandle>) {
    if game_tv_texture.is_none() {
        println!("Initializing Game TV texture");
        let _ = game_tv_texture.insert(
            ctx.load_texture(
                "Game TV texture",
                ColorImage::default(),
                Default::default(),
            )
        );
    }
}

fn paint_game_texture(ui: &mut Ui, texture: &mut Option<TextureHandle>, framebuffer: &[u8], current_res: (u16, u16)) {
    if let Some(txt) = texture {
        txt.set(
            ColorImage::from_rgba_premultiplied([MAX_TV_WIDTH, MAX_TV_HEIGHT], framebuffer),
            TextureOptions::LINEAR,
        );
        let (whole_rect, _) =
            ui.allocate_exact_size(
                Vec2::from([(MAX_TV_WIDTH) as f32, (MAX_TV_HEIGHT) as f32]),
                egui::Sense::focusable_noninteractive(),
            );
        let current_resolution_scale = calculate_resolution_scale(current_res);
        egui::Image::new((
            txt.id(),
            txt.size_vec2(),
        ))
        .texture_options(TextureOptions::LINEAR)
        .uv(Rect::from_two_pos(
            Pos2::new(0.0,0.0),
            Pos2::new(current_resolution_scale.0, current_resolution_scale.1))
        )
        .paint_at(ui, whole_rect);
    }
}

fn calculate_resolution_scale(current_res: (u16, u16)) -> (f32, f32) {
    (
        current_res.0 as f32 / MAX_TV_WIDTH as f32,
        current_res.1 as f32 / MAX_TV_HEIGHT as f32,
    )
}