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#![no_std]
//! Paint — the first GUI app: a freehand pen on a raster canvas.
use rsnix::ps2::{KeyEvent, MouseKind};
use rsnix::{sched, wm};
const W: usize = 640;
const H: usize = 480;
/// 8-colour palette selected by keys 1–8.
const PALETTE: [(u8, u8, u8); 8] = [
(255, 255, 255), // 1 white
(0, 0, 0), // 2 black
(170, 0, 0), // 3 red
(0, 170, 0), // 4 green
(0, 0, 170), // 5 blue
(170, 170, 0), // 6 yellow
(0, 170, 170), // 7 cyan
(170, 0, 170), // 8 magenta
];
/// Run the paint program as a spawned task: create a window, then loop on
/// events (pen strokes from the mouse, colour/clear from keys) until `Close`.
pub fn run() {
let Some(id) = wm::create_window("paint", W, H) else {
return;
};
let Some((buf, _, _)) = wm::buffer(id) else {
return;
};
let mut color: usize = 0; // white
let mut last: Option<(i32, i32)> = None;
loop {
match sched::recv_blocking() {
sched::TaskMsg::Close => break,
sched::TaskMsg::AppMouse(m) => match m.kind {
MouseKind::Press => {
plot(buf, m.x, m.y, color);
last = Some((m.x, m.y));
wm::flush(id);
}
MouseKind::Move => {
if m.buttons & 1 != 0 {
if let Some((lx, ly)) = last {
line(buf, lx, ly, m.x, m.y, color);
wm::flush(id);
}
}
last = Some((m.x, m.y));
}
MouseKind::Release => {
last = None;
}
},
sched::TaskMsg::Key(k) => {
if let KeyEvent::Char(c) = k {
match c {
'1'..='8' => color = (c as u8 - b'1') as usize,
'c' => {
fill(buf, 1); // clear to black
wm::flush(id);
}
_ => {}
}
}
}
_ => {}
}
}
wm::destroy(id);
}
fn pack(idx: usize) -> u32 {
let (r, g, b) = PALETTE[idx.min(PALETTE.len() - 1)];
rsnix::gop::rgb(r, g, b)
}
fn plot(buf: *mut u32, x: i32, y: i32, color: usize) {
if x < 0 || y < 0 || x >= W as i32 || y >= H as i32 {
return;
}
unsafe {
*buf.add(y as usize * W + x as usize) = pack(color);
}
}
/// Bresenham line between two points.
fn line(buf: *mut u32, x0: i32, y0: i32, x1: i32, y1: i32, color: usize) {
let mut x = x0;
let mut y = y0;
let dx = (x1 - x0).abs();
let sx = if x0 < x1 { 1 } else { -1 };
let dy = -(y1 - y0).abs();
let sy = if y0 < y1 { 1 } else { -1 };
let mut err = dx + dy;
loop {
plot(buf, x, y, color);
if x == x1 && y == y1 {
break;
}
let e2 = 2 * err;
if e2 >= dy {
err += dy;
x += sx;
}
if e2 <= dx {
err += dx;
y += sy;
}
}
}
fn fill(buf: *mut u32, color: usize) {
unsafe {
for i in 0..(W * H) {
*buf.add(i) = pack(color);
}
}
}
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