wasm: do not get canvas as property of js global object

You cannot be sure that property with specified key in
a global object is really a canvas.
Should use `document.getElementById`.

Change-Id: Ife55adaad5517aed64122b0c9bff32489cf19a2f
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

1 files changed, 7 insertions, 5 deletions

diff --git a/src/plugins/platforms/wasm/qwasmeventtranslator.cpp b/src/plugins/platforms/wasm/qwasmeventtranslator.cpp
index ad94ba9c77..8b7d00082f 100644
--- a/src/plugins/platforms/wasm/qwasmeventtranslator.cpp
+++ b/src/plugins/platforms/wasm/qwasmeventtranslator.cpp
@@ -47,9 +47,10 @@
 
 #include <iostream>
 
-QT_BEGIN_NAMESPACE
 using namespace emscripten;
 
+QT_BEGIN_NAMESPACE
+
 typedef struct emkb2qt {
     const char *em;
     unsigned int qt;
@@ -353,10 +354,11 @@ void QWasmEventTranslator::initEventHandlers()
         g_useNaturalScrolling = false; // make this !default on macOS
 
         if (emscripten::val::global("window")["safari"].isUndefined()) {
-
-            emscripten::val::global(canvasId).call<void>("addEventListener",
-                                                         std::string("wheel"),
-                                                         val::module_property("qtMouseWheelEvent"));
+            val document = val::global("document");
+            val canvas = document.call<val>("getElementById", val(canvasId));
+            canvas.call<void>("addEventListener",
+                              std::string("wheel"),
+                              val::module_property("qtMouseWheelEvent"));
         }
     }