From 18e06c37e10943f4b4f6d57b7044b9bce3a23202 Mon Sep 17 00:00:00 2001
From: Alexandra Cherdantseva <neluhus.vagus@gmail.com>
Date: Mon, 30 Dec 2019 14:40:03 +0300
Subject: 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>
---
 src/plugins/platforms/wasm/qwasmscreen.cpp | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

(limited to 'src/plugins/platforms/wasm/qwasmscreen.cpp')

diff --git a/src/plugins/platforms/wasm/qwasmscreen.cpp b/src/plugins/platforms/wasm/qwasmscreen.cpp
index 37f1ea832a..fe44fdb096 100644
--- a/src/plugins/platforms/wasm/qwasmscreen.cpp
+++ b/src/plugins/platforms/wasm/qwasmscreen.cpp
@@ -44,6 +44,7 @@
 #include <QtGui/qguiapplication.h>
 #include <private/qhighdpiscaling_p.h>
 
+using namespace emscripten;
 
 QT_BEGIN_NAMESPACE
 
@@ -182,13 +183,15 @@ void QWasmScreen::updateQScreenAndCanvasRenderSize()
     QSizeF cssSize(css_width, css_height);
 
     QSizeF canvasSize = cssSize * devicePixelRatio();
-    emscripten::val canvas = emscripten::val::global(canvasId.constData());
+    val document = val::global("document");
+    val canvas = document.call<val>("getElementById", val(canvasId.constData()));
+
     canvas.set("width", canvasSize.width());
     canvas.set("height", canvasSize.height());
 
     QPoint offset;
-    offset.setX(emscripten::val::global(canvasId.constData())["offsetTop"].as<int>());
-    offset.setY(emscripten::val::global(canvasId.constData())["offsetLeft"].as<int>());
+    offset.setX(canvas["offsetTop"].as<int>());
+    offset.setY(canvas["offsetLeft"].as<int>());
 
     emscripten::val rect = canvas.call<emscripten::val>("getBoundingClientRect");
     QPoint position(rect["left"].as<int>() - offset.x(), rect["top"].as<int>() - offset.y());
-- 
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