color_pixels.rs

extern crate ggez;
use ggez::*;
use ggez::graphics::{DrawMode, Point};
use std::time::Duration;

struct MainState {
    imagebuffer: Vec<u8>, // represents an image, groupings of 4 values (R,G,B,A) representing one pixel.
    width: usize,
    height: usize,
    i: u8,
}

impl MainState {
    fn new(_ctx: &mut Context) -> GameResult<MainState> {
        // an 800x600 image, times 4 for each component
        let mut v = Vec::with_capacity(800*600*4); 
        v.resize(800*600*4, 0);
        let state = MainState { 
            imagebuffer: v,
            width: 800,
            height: 600,
            i: 0,
        };
        Ok(state)
    }
}

impl event::EventHandler for MainState {
    fn update(&mut self, _ctx: &mut Context, _dt: Duration) -> GameResult<()> {
        for i in 0..(self.framebuffer.len() / 4) {
            // white or pink checkerboard, obviously you can do whatever here
            if i % 2 == 0 {
                self.framebuffer[i * 4] = 255;
                self.framebuffer[i * 4 + 1] = 255;
                self.framebuffer[i * 4 + 2] = 255;
                self.framebuffer[i * 4 + 3] = 255;
            } else {
                self.framebuffer[i * 4] = 255;
                self.framebuffer[i * 4 + 1] = 135;
                self.framebuffer[i * 4 + 2] = 220;
                self.framebuffer[i * 4 + 3] = 255;
            }
        }
        Ok(())
    }

    fn draw(&mut self, ctx: &mut Context) -> GameResult<()> {
        graphics::clear(ctx);
        // creates an image from the raw buffer
        let img = graphics::Image::from_rgba8(ctx, self.width as u16, self.height as u16, &self.framebuffer)?;
        // draws the image with a center at 400, 300
        graphics::draw(ctx, &img, Point::new(400.0, 300.0), 0.0)?;
        // actually presents draws to the screen
        graphics::present(ctx);
        Ok(())
    }
}

pub fn main() {
    let c = conf::Conf::new();
    let ctx = &mut Context::load_from_conf("super_simple", "ggez", c).unwrap();
    let state = &mut MainState::new(ctx).unwrap();
    event::run(ctx, state).unwrap();
}