wasm: fix redundant string conversions between wasm and JavaScript

Avoid redundant conversions from UTF16 to UTF8 to UTF16 with
help of new class QWasmString static methods:
+ QWasmString::fromQString to convert QString to js string
using js Module.UTF16ToString
+ QWasmString::toQString to convert js string to QString
using js Module.stringToUTF16

Fixed document.getElementById calls for cavasId with unicode characters.

Change-Id: I3fc55bfeb6aeda75fa3acd85d22cea667b542f38
Reviewed-by: Morten Johan Sørvig <[email protected]>
Reviewed-by: Lorn Potter <[email protected]>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/plugins/platforms/wasm/qwasmscreen.cpp b/src/plugins/platforms/wasm/qwasmscreen.cpp
index fe44fdb0963..d407111c2f9 100644
--- a/src/plugins/platforms/wasm/qwasmscreen.cpp
+++ b/src/plugins/platforms/wasm/qwasmscreen.cpp
@@ -32,6 +32,8 @@
 #include "qwasmeventtranslator.h"
 #include "qwasmcompositor.h"
 #include "qwasmintegration.h"
+#include "qwasmstring.h"
+
 #include <emscripten/bind.h>
 #include <emscripten/val.h>
 
@@ -184,7 +186,7 @@ void QWasmScreen::updateQScreenAndCanvasRenderSize()
 
     QSizeF canvasSize = cssSize * devicePixelRatio();
     val document = val::global("document");
-    val canvas = document.call<val>("getElementById", val(canvasId.constData()));
+    val canvas = document.call<val>("getElementById", QWasmString::fromQString(m_canvasId));
 
     canvas.set("width", canvasSize.width());
     canvas.set("height", canvasSize.height());