initial commit. untested

.gitignore

+/target

Cargo.toml

+[package]
+name = "img2gcode"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+anyhow = "1.0.97"
+image = "0.25.5"

src/main.rs

+use anyhow::bail;
+use image::{GenericImageView, ImageReader};
+
+const TOAST_TIME_SECONDS: u64 = 60;
+const CENTER_X: u32 = 100;
+const CENTER_Y: u32 = 100;
+const BREAD_HEIGHT: f64 = 15.5;
+const IDLE_HEIGHT: f64 = BREAD_HEIGHT + 10.0;
+const PIXEL_SIZE_MM: f64 = 2.0;
+
+fn main() -> anyhow::Result<()> {
+    let img = ImageReader::open("/home/stephen/Downloads/qr_tiny.png")?.decode()?;
+
+    preamble();
+
+    for x in 0..img.width() {
+        for y in 0..img.height() {
+            let p = img.get_pixel(x, y);
+
+            match p.0 {
+                [0, 0, 0, 255] => {
+                    // nothing, for now
+                }
+                [255, 255, 255, 255] => {
+                    toast(x, y);
+                }
+                _ => bail!("Pixel was not entirely black nor entirely white: {:?}", p),
+            }
+        }
+    }
+
+    Ok(())
+}
+
+fn preamble() {
+    println!(
+        r#"
+G28 ; home
+M109 S220 ; heat hotend to 220C and wait
+G90 ; absolute positioning
+G0 Z{IDLE_HEIGHT}
+G0 X{CENTER_X} Y{CENTER_Y}
+"#
+    );
+}
+
+fn toast(x: u32, y: u32) {
+    println!(
+        r#"
+G0 X{:.2} Y{:.2};
+G0 Z{BREAD_HEIGHT};
+G4 S{TOAST_TIME_SECONDS} ; wait
+G0 Z{IDLE_HEIGHT};
+"#,
+        x as f64 * PIXEL_SIZE_MM,
+        y as f64 * PIXEL_SIZE_MM
+    );
+}