Add graphics crate

Cargo.lock

@@ -2,6 +2,65 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "autocfg"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"
+
+[[package]]
+name = "az"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7b7e4c2464d97fe331d41de9d5db0def0a96f4d823b8b32a2efd503578988973"
+
+[[package]]
+name = "byteorder"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fd0f2584146f6f2ef48085050886acf353beff7305ebd1ae69500e27c67f64b"
+
+[[package]]
+name = "embedded-graphics"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0649998afacf6d575d126d83e68b78c0ab0e00ca2ac7e9b3db11b4cbe8274ef0"
+dependencies = [
+ "az",
+ "byteorder",
+ "embedded-graphics-core",
+ "float-cmp",
+ "micromath",
+]
+
+[[package]]
+name = "embedded-graphics-core"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ba9ecd261f991856250d2207f6d8376946cd9f412a2165d3b75bc87a0bc7a044"
+dependencies = [
+ "az",
+ "byteorder",
+]
+
+[[package]]
+name = "float-cmp"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "98de4bbd547a563b716d8dfa9aad1cb19bfab00f4fa09a6a4ed21dbcf44ce9c4"
+dependencies = [
+ "num-traits",
+]
+
+[[package]]
+name = "graphics"
+version = "0.1.0"
+dependencies = [
+ "embedded-graphics",
+ "embedded-graphics-core",
+ "memmap2",
+]
+
 [[package]]
 name = "itoa"
 version = "1.0.15"
@@ -14,6 +73,21 @@ version = "0.2.177"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2874a2af47a2325c2001a6e6fad9b16a53b802102b528163885171cf92b15976"
 
+[[package]]
+name = "memmap2"
+version = "0.9.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "744133e4a0e0a658e1374cf3bf8e415c4052a15a111acd372764c55b4177d490"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "micromath"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3c8dda44ff03a2f238717214da50f65d5a53b45cd213a7370424ffdb6fae815"
+
 [[package]]
 name = "minapk"
 version = "0.1.0"
@@ -51,6 +125,15 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "num-traits"
+version = "0.2.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "oc2r-core"
 version = "0.1.0"

crates/graphics/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "graphics"
+version = "0.1.0"
+authors.workspace = true
+edition.workspace = true
+repository.workspace = true
+license.workspace = true
+keywords.workspace = true
+categories.workspace = true
+
+[lints]
+workspace = true
+
+[dependencies]
+memmap2 = "0.9"
+embedded-graphics = "0.8"
+embedded-graphics-core = "0.4"
+

crates/graphics/src/main.rs

@@ -0,0 +1,119 @@
+#![allow(
+    clippy::cast_possible_truncation,
+    clippy::cast_sign_loss,
+    clippy::cast_possible_wrap
+)]
+use std::{convert::Infallible, fs::OpenOptions, io, thread, time::Duration};
+
+use embedded_graphics::{
+    geometry::Size,
+    mono_font::{MonoTextStyle, ascii::FONT_6X10},
+    pixelcolor::Rgb565,
+    prelude::*,
+    text::{Baseline, Text},
+};
+use memmap2::{MmapMut, MmapOptions};
+
+const FB_PATH: &str = "/dev/fb0";
+const WIDTH: u32 = 640;
+const HEIGHT: u32 = 480;
+const BYTES_PER_PIXEL: usize = 2;
+
+struct FbDisplay {
+    fb: MmapMut,
+}
+
+impl FbDisplay {
+    fn new() -> io::Result<Self> {
+        println!("Opening framebuffer device at {FB_PATH}");
+        let file = OpenOptions::new().read(true).write(true).open(FB_PATH)?;
+        let fb_size = (WIDTH as usize) * (HEIGHT as usize) * BYTES_PER_PIXEL;
+        // Safety: map /dev/fb0 as writable memory
+        let fb = unsafe { MmapOptions::new().len(fb_size).map_mut(&file)? };
+        println!(
+            "Mapped framebuffer: {}x{} at {} bytes ({} bytes per pixel)",
+            WIDTH,
+            HEIGHT,
+            fb.len(),
+            BYTES_PER_PIXEL
+        );
+        Ok(Self { fb })
+    }
+
+    fn clear(&mut self) {
+        println!("Clearing framebuffer to black");
+        for chunk in self.fb.chunks_exact_mut(BYTES_PER_PIXEL) {
+            chunk.copy_from_slice(&[0x00, 0x00]); // RGB565 black
+        }
+    }
+
+    fn put_pixel(&mut self, x: u32, y: u32, color: Rgb565) {
+        if x >= WIDTH || y >= HEIGHT {
+            return;
+        }
+
+        let idx = ((y * WIDTH + x) as usize) * BYTES_PER_PIXEL;
+        if idx + 1 >= self.fb.len() {
+            return;
+        }
+
+        // Rgb565 stores 16-bit value; little endian in memory.
+        let raw: u16 = color.into_storage();
+        let bytes = raw.to_le_bytes();
+        self.fb[idx] = bytes[0];
+        self.fb[idx + 1] = bytes[1];
+    }
+}
+
+impl DrawTarget for FbDisplay {
+    type Color = Rgb565;
+    type Error = Infallible;
+
+    fn draw_iter<I>(&mut self, pixels: I) -> Result<(), Self::Error>
+    where
+        I: IntoIterator<Item = Pixel<Self::Color>>,
+    {
+        for Pixel(coord, color) in pixels {
+            let x = coord.x;
+            let y = coord.y;
+            if x >= 0 && y >= 0 {
+                self.put_pixel(x as u32, y as u32, color);
+            }
+        }
+        Ok(())
+    }
+}
+
+impl OriginDimensions for FbDisplay {
+    fn size(&self) -> Size {
+        Size::new(WIDTH, HEIGHT)
+    }
+}
+
+pub fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let mut fb = FbDisplay::new()?;
+    fb.clear();
+
+    let style = MonoTextStyle::new(&FONT_6X10, Rgb565::WHITE);
+
+    let text = "Hello embedded-graphics on RGB565";
+
+    let text_width = (text.len() as u32) * 6;
+    let text_height = 10;
+
+    let x = (WIDTH - text_width) / 2;
+    let y = (HEIGHT / 2) + (text_height / 2);
+
+    Text::with_baseline(
+        text,
+        Point::new(x as i32, y as i32),
+        style,
+        Baseline::Bottom,
+    )
+    .draw(&mut fb)?;
+
+    // Keep the framebuffer content visible
+    loop {
+        thread::sleep(Duration::from_secs(1));
+    }
+}