Moved screen update code into Go thanks to tip

Author: djhworld

static/gomeboycolor/index.html

@@ -470,8 +470,7 @@ <h5 class="modal-title" id="controlsModalLabel">Controls</h5>
 			}
 
 			function updateCanvas(screenData) {
-				var decodedData = new Uint8ClampedArray(screenData);
-				var imageData = new ImageData(decodedData, 160, 144);
+				var imageData = new ImageData(screenData, 160, 144);
 				context.putImageData(imageData, canvas.width / 4, 4);
 			}
 

static/gomeboycolor/js/worker.js

@@ -6,15 +6,7 @@ if (!WebAssembly.instantiateStreaming) { // polyfill
 }
 
 importScripts('wasm_exec.js');
-importScripts('base64js.min.js');
 const GOMEBOY_COLOR_WASM = "../wasm/gbc.wasm";
-const SCREEN_UPDATE = "screen-update";
-
-// uses transferable on post message
-function sendScreenUpdate(bs64) {
-    var buf =  new Uint8ClampedArray(base64js.toByteArray(bs64)).buffer;
-    postMessage([SCREEN_UPDATE, buf], [buf]);
-}
 
 const go = new Go();
 let mod, inst;

static/gomeboycolor/wasm/gbc.wasm

@@ -3,7 +3,6 @@
 package main
 
 import (
-	"encoding/base64"
 	"log"
 
 	"syscall/js"
@@ -128,6 +127,6 @@ func (s *html5CanvasDisplay) DrawFrame(screenData *types.Screen) {
 
 	// TODO this is probably a performance bottleneck
 	if !s.headless {
-		webworker.SendScreenUpdate(base64.StdEncoding.EncodeToString(s.imageData))
+		webworker.SendScreenUpdate(s.imageData)
 	}
 }

web_io.go

@@ -35,8 +35,13 @@ func SendSaveState(gameId, state string) {
 	postMessage("save-state", []interface{}{gameId, state})
 }
 
-func SendScreenUpdate(screenData string) {
-	js.Global().Call("sendScreenUpdate", screenData)
+func SendScreenUpdate(screenData []uint8) {
+	typedArray := js.TypedArrayOf(screenData)
+	defer typedArray.Release()
+
+	clamped := js.Global().Get("Uint8ClampedArray").New(typedArray)
+	transferable := js.Global().Get("Array").New(clamped).Get("buffer")
+	js.Global().Call("postMessage", []interface{}{"screen-update", clamped}, transferable)
 }
 
 func SendFrameRate(rate float32) {