Merge pull request 'feat (canvas): OffscreenCanvas fallback' (#12) from dev into master

Reviewed-on: #12

src/components/CanvasBoard.vue

@@ -81,10 +81,19 @@
     store.renderer.ctx = store.renderer.canvas.getContext("2d", {
       willReadFrequently: true,
     });
-    store.renderer.workCanvas = new OffscreenCanvas(
+    if (typeof OffscreenCanvas != "undefined") {
-      canvas.parentElement.clientWidth,
+      store.renderer.workCanvas = new OffscreenCanvas(
-      canvas.parentElement.clientHeight
+        canvas.parentElement.clientWidth,
-    );
+        canvas.parentElement.clientHeight
+      );
+    }
+    // https://developer.mozilla.org/en-US/docs/Web/API/OffscreenCanvas/OffscreenCanvas#Browser_compatibility
+    // Fallback for when offscreenCanvas is unsupported or disabled (Firefox < 44, default for Firefox?)
+    else {
+      store.renderer.workCanvas = document.createElement("canvas");
+      store.renderer.workCanvas.width = canvas.parentElement.clientWidth;
+      store.renderer.workCanvas.height = canvas.parentElement.clientHeight;
+    }
     store.renderer.workCtx = store.renderer.workCanvas.getContext("2d", {
       willReadFrequently: true,
     });