Galactica/src/sprite.rs

use image::io::Reader as ImageReader;
use sdl2::{
	rect::{Point, Rect},
	render::{Canvas, Texture, TextureCreator},
	video::{Window, WindowContext},
};

use std::collections::HashMap;

use crate::physics::Cartesian;

/// A handle for a sprite inside a SpriteAtlas
pub struct Sprite<'a> {
	texture: &'a Texture<'a>,
	rect: Rect,
	scale: f64,
}

impl<'a> Sprite<'a> {
	/// Draw this sprite on the screen.
	///
	/// Position represents the center of the sprite
	/// on-screen position, NOT in the world.
	pub fn draw(
		&self,
		canvas: &mut Canvas<Window>,
		position: Cartesian,
		angle: f64,
		scale: f64,
	) -> Result<(), String> {
		let win_size = Cartesian::from(canvas.window().size());
		let scale = scale * self.scale;

		// Post-scale dimensions on the screen
		let width = self.rect.width() as f64 * scale;
		let height = self.rect.height() as f64 * scale;

		// Don't draw if we're not on the screen.
		// An offset is included to ensure we're completely
		// off the screen. We add the whole width intentionally.
		if position.x < -1.0 * (width as f64)
			|| position.x > win_size.x + width as f64
			|| position.y < -1.0 * (height as f64)
			|| position.y > win_size.y + height as f64
		{
			return Ok(());
		}

		let mut dest = Rect::new(0, 0, width as u32, height as u32);
		dest.center_on(Point::new((position.x) as i32, (position.y) as i32));

		// copy the frame to the canvas
		canvas.copy_ex(
			&self.texture,
			Some(self.rect),
			Some(dest),
			angle,                                                   // angle
			Point::new((width / 2.0) as i32, (height / 2.0) as i32), // Rotation center
			false,
			false,
		)?;

		/*
		canvas.set_draw_color(Color::RGB(255, 0, 0));
		canvas.aa_circle(
			position.x as i16,
			position.y as i16,
			5,
			Color::RGB(255, 0, 0),
		)?;
		canvas.set_draw_color(Color::RGB(0, 0, 0));
		*/

		return Ok(());
	}
}

/// A cache of textures we use when drawing the screen.
///
/// This is implemented very carefully, since SDL2 textures have tricky lifetimes.
pub struct SpriteAtlas<'a> {
	data: HashMap<String, (Texture<'a>, Rect, f64)>,
}

impl<'a> SpriteAtlas<'a> {
	pub fn new(texture_creator: &'a TextureCreator<WindowContext>) -> Result<Self, String> {
		let mut b = Self {
			data: HashMap::new(),
		};

		b.load_one(texture_creator, "gypsum.png", 0.75)?;
		b.load_one(texture_creator, "a0.png", 1.0)?;
		b.load_one(texture_creator, "small.png", 1.0)?;
		b.load_one(texture_creator, "earth.png", 1.0)?;

		return Ok(b);
	}

	pub fn get(&'a self, name: &str) -> Sprite<'a> {
		let (texture, rect, scale) = self.data.get(name).unwrap();
		return Sprite {
			texture,
			scale: scale.clone(),
			rect: rect.clone(),
		};
	}

	fn load_one(
		&mut self,
		texture_creator: &'a TextureCreator<WindowContext>,
		s: &str,
		scale: f64,
	) -> Result<(), String> {
		let im = ImageReader::open(format!("assets/{s}"))
			.unwrap()
			.decode()
			.unwrap();
		let width = im.width();
		let height = im.height();
		let mut im = im.as_bytes().to_vec();

		let surface = sdl2::surface::Surface::from_data(
			&mut im,
			width,
			height,
			width * 4,
			sdl2::pixels::PixelFormatEnum::RGBA32,
		)?;

		let texture = texture_creator
			.create_texture_from_surface(&surface)
			.map_err(|e| e.to_string())?;

		self.data.insert(
			s.to_owned(),
			(texture, Rect::new(0, 0, width, height), scale),
		);

		return Ok(());
	}
}