feat: bg colour option

src/main.rs

@@ -134,6 +134,27 @@ fn main() {
                 None => {}
             }
 
+            let mut background = Color::TRANSPARENT;
+            match req.url.query.get("background") {
+                Some(background_str) => {
+                    match u32::from_str_radix(&background_str, 16) {
+                        Ok(background_val) => {
+                            if background_val > 0xFFFFFF {
+                                return Response::new(req, 400, Body::Static("Invalid background value. Background value must be a valid hex color 000000 - FFFFFF"));
+                            }
+                            let red = ((background_val >> 16) & 0xFF) as u8;
+                            let green = ((background_val >> 8) & 0xFF) as u8;
+                            let blue = (background_val & 0xFF) as u8;
+                            background = Color::from_rgba8(red, green, blue, 255);
+                        }
+                        Err(_) => {
+                            return Response::new(req, 400, Body::Static("Invalid background value. Background value must be a valid hex color"));
+                        }
+                    }
+                }
+                None => {}
+            }
+
             let length = 24 * scale + padding;
 
             let mut pixmap = match Pixmap::new(length, length) {
@@ -142,6 +163,7 @@ fn main() {
             };
 
             let mut pixmap_mut = pixmap.as_mut();
+            pixmap_mut.fill(background);
 
             resvg::render(
                 &tree,