send 2d image data from worker only from canvas context that is the screen

1 files changed, 3 insertions, 1 deletions

diff --git a/src/proxyWorker.js b/src/proxyWorker.js
index 76fb942c..4b700b61 100644
--- a/src/proxyWorker.js
+++ b/src/proxyWorker.js
@@ -73,7 +73,9 @@ document.createElement = function document_createElement(what) {
               canvas.ensureData();
               assert(x == 0 && y == 0 && image.width == canvas.width && image.height == canvas.height);
               canvas.data.data.set(image.data); // TODO: can we avoid this copy?
-              postMessage({ target: 'canvas', op: 'render', image: canvas.data });
+              if (this === Module['ctx']) {
+                postMessage({ target: 'canvas', op: 'render', image: canvas.data });
+              }
             }
           };
         } else {