Add logging for bezier-rs web demos (#1286)

website/other/bezier-rs-demos/wasm/src/lib.rs

@@ -2,3 +2,50 @@ pub mod bezier;
 pub mod subpath;
 mod svg_drawing;
 mod utils;
+
+use wasm_bindgen::prelude::*;
+pub static LOGGER: WasmLog = WasmLog;
+
+/// Initialize the backend
+#[wasm_bindgen(start)]
+pub fn init_graphite() {
+	// Set up the logger with a default level of debug
+	log::set_logger(&LOGGER).expect("Failed to set logger");
+	log::set_max_level(log::LevelFilter::Trace);
+}
+
+/// Logging to the JS console
+#[wasm_bindgen]
+extern "C" {
+	#[wasm_bindgen(js_namespace = console)]
+	fn log(msg: &str, format: &str);
+	#[wasm_bindgen(js_namespace = console)]
+	fn info(msg: &str, format: &str);
+	#[wasm_bindgen(js_namespace = console)]
+	fn warn(msg: &str, format: &str);
+	#[wasm_bindgen(js_namespace = console)]
+	fn error(msg: &str, format: &str);
+}
+
+#[derive(Default)]
+pub struct WasmLog;
+
+impl log::Log for WasmLog {
+	fn enabled(&self, metadata: &log::Metadata) -> bool {
+		metadata.level() <= log::Level::Info
+	}
+
+	fn log(&self, record: &log::Record) {
+		let (log, name, color): (fn(&str, &str), &str, &str) = match record.level() {
+			log::Level::Trace => (log, "trace", "color:plum"),
+			log::Level::Debug => (log, "debug", "color:cyan"),
+			log::Level::Warn => (warn, "warn", "color:goldenrod"),
+			log::Level::Info => (info, "info", "color:mediumseagreen"),
+			log::Level::Error => (error, "error", "color:red"),
+		};
+		let msg = &format!("%c{}\t{}", name, record.args());
+		log(msg, color)
+	}
+
+	fn flush(&self) {}
+}