add canvas_image builtin for PNG rendering with alpha blending

Registers canvas_image(path, x, y, w, h) in the type system and
implements it in the interpreter using the image crate — scales to
exact dimensions via Lanczos3 and alpha-composites onto the pixmap.

Cargo.lock

@@ -272,6 +272,12 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "byteorder-lite"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f1fe948ff07f4bd06c30984e69f5b4899c516a3ef74f34df92a2df2ab535495"
+
 [[package]]
 name = "bytes"
 version = "1.11.1"
@@ -672,6 +678,7 @@ dependencies = [
  "fontdue",
  "hex",
  "hmac",
+ "image",
  "reqwest",
  "serde_json",
  "sha2",
@@ -1421,6 +1428,19 @@ dependencies = [
  "icu_properties",
 ]
 
+[[package]]
+name = "image"
+version = "0.25.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85ab80394333c02fe689eaf900ab500fbd0c2213da414687ebf995a65d5a6104"
+dependencies = [
+ "bytemuck",
+ "byteorder-lite",
+ "moxcms",
+ "num-traits",
+ "png 0.18.1",
+]
+
 [[package]]
 name = "indexmap"
 version = "2.14.0"
@@ -1676,6 +1696,16 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "moxcms"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bb85c154ba489f01b25c0d36ae69a87e4a1c73a72631fc6c0eb6dde34a73e44b"
+dependencies = [
+ "num-traits",
+ "pxfm",
+]
+
 [[package]]
 name = "native-tls"
 version = "0.2.18"
@@ -1735,6 +1765,15 @@ dependencies = [
  "memoffset",
 ]
 
+[[package]]
+name = "num-traits"
+version = "0.2.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "num_enum"
 version = "0.7.6"
@@ -1897,6 +1936,19 @@ dependencies = [
  "miniz_oxide",
 ]
 
+[[package]]
+name = "png"
+version = "0.18.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60769b8b31b2a9f263dae2776c37b1b28ae246943cf719eb6946a1db05128a61"
+dependencies = [
+ "bitflags 2.11.1",
+ "crc32fast",
+ "fdeflate",
+ "flate2",
+ "miniz_oxide",
+]
+
 [[package]]
 name = "polling"
 version = "3.11.0"
@@ -1969,6 +2021,12 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "pxfm"
+version = "0.1.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e0c5ccf5294c6ccd63a74f1565028353830a9c2f5eb0c682c355c471726a6e3f"
+
 [[package]]
 name = "quick-xml"
 version = "0.39.2"
@@ -2641,7 +2699,7 @@ dependencies = [
  "bytemuck",
  "cfg-if",
  "log",
- "png",
+ "png 0.17.16",
  "tiny-skia-path",
 ]
 

Cargo.toml

@@ -62,3 +62,4 @@ winit       = { version = "0.29", default-features = false, features = ["rwh_05"
 softbuffer  = "0.3"
 tiny-skia   = "0.11"
 fontdue     = "0.8"
+image       = { version = "0.25", default-features = false, features = ["png"] }

bin/el/Cargo.toml

@@ -38,3 +38,4 @@ winit       = { version = "0.29", default-features = false, features = ["rwh_05"
 softbuffer  = "0.3"
 tiny-skia   = "0.11"
 fontdue     = "0.8"
+image       = { workspace = true }

bin/el/src/main.rs

@@ -4724,6 +4724,50 @@ fn dispatch_builtin(
             unreachable!()
         }
 
+        "canvas_image" => {
+            // canvas_image(path: String, x: Int, y: Int, w: Int, h: Int) -> Void
+            // Draws a PNG image scaled to w×h at (x, y) with alpha blending.
+            let draw_h = match stack.pop().unwrap_or(Value::Nil) { Value::Int(n) => n as i32, _ => 0 };
+            let draw_w = match stack.pop().unwrap_or(Value::Nil) { Value::Int(n) => n as i32, _ => 0 };
+            let dy     = match stack.pop().unwrap_or(Value::Nil) { Value::Int(n) => n as i32, _ => 0 };
+            let dx     = match stack.pop().unwrap_or(Value::Nil) { Value::Int(n) => n as i32, _ => 0 };
+            let path   = match stack.pop().unwrap_or(Value::Nil) { Value::Str(s) => s, _ => { stack.push(Value::Nil); return BuiltinResult::Handled; } };
+
+            if draw_w <= 0 || draw_h <= 0 { stack.push(Value::Nil); return BuiltinResult::Handled; }
+
+            use image::GenericImageView;
+            if let Ok(img) = image::open(&path) {
+                let img = img.resize_exact(draw_w as u32, draw_h as u32, image::imageops::FilterType::Lanczos3);
+                let rgba = img.to_rgba8();
+                CANVAS.with(|cv| {
+                    let mut cv = cv.borrow_mut();
+                    if let Some(px) = cv.pixmap.as_mut() {
+                        let pw = px.width() as i32;
+                        let ph = px.height() as i32;
+                        let data = px.data_mut();
+                        for row in 0..draw_h {
+                            for col in 0..draw_w {
+                                let ix = dx + col;
+                                let iy = dy + row;
+                                if ix < 0 || iy < 0 || ix >= pw || iy >= ph { continue; }
+                                let p = rgba.get_pixel(col as u32, row as u32);
+                                let sa = p[3] as u32;
+                                if sa == 0 { continue; }
+                                let ia = 255 - sa;
+                                let idx = (iy as usize * pw as usize + ix as usize) * 4;
+                                data[idx]     = ((ia * data[idx]   as u32 + sa * p[0] as u32) / 255) as u8;
+                                data[idx + 1] = ((ia * data[idx+1] as u32 + sa * p[1] as u32) / 255) as u8;
+                                data[idx + 2] = ((ia * data[idx+2] as u32 + sa * p[2] as u32) / 255) as u8;
+                                data[idx + 3] = ((ia * data[idx+3] as u32 + sa * sa) / 255) as u8;
+                            }
+                        }
+                    }
+                });
+            }
+            stack.push(Value::Nil);
+            BuiltinResult::Handled
+        }
+
         _ => BuiltinResult::NotBuiltin,
     }
 }

crates/el-types/src/types.rs

@@ -278,6 +278,7 @@ impl TypeEnv {
         env.functions.insert("canvas_events".into(),      str_fn(vec![], s.clone()));
         env.functions.insert("canvas_swap".into(),        str_fn(vec![], Type::Void));
         env.functions.insert("canvas_run_loop".into(),    str_fn(vec![s.clone()], Type::Void));
+        env.functions.insert("canvas_image".into(),       str_fn(vec![s.clone(), i.clone(), i.clone(), i.clone(), i.clone()], Type::Void));
         env.functions.insert("state_set".into(),          str_fn(vec![s.clone(), s.clone()], Type::Void));
         env.functions.insert("state_get".into(),          str_fn(vec![s.clone()], s.clone()));