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 <morten.sorvig@qt.io>
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/src/plugins/platforms/wasm/qwasmcursor.cpp b/src/plugins/platforms/wasm/qwasmcursor.cpp
index c04fa6441a..616456b2fa 100644
--- a/src/plugins/platforms/wasm/qwasmcursor.cpp
+++ b/src/plugins/platforms/wasm/qwasmcursor.cpp
@@ -29,6 +29,7 @@
 
 #include "qwasmcursor.h"
 #include "qwasmscreen.h"
+#include "qwasmstring.h"
 
 #include <QtCore/qdebug.h>
 #include <QtGui/qwindow.h>
@@ -56,11 +57,11 @@ void QWasmCursor::changeCursor(QCursor *windowCursor, QWindow *window)
         htmlCursorName = "auto";
 
     // Set cursor on the canvas
-    QByteArray canvasId = QWasmScreen::get(screen)->canvasId().toUtf8();
+    val jsCanvasId = QWasmString::fromQString(QWasmScreen::get(screen)->canvasId());
     val document = val::global("document");
-    val canvas = document.call<val>("getElementById", val(canvasId.constData()));
+    val canvas = document.call<val>("getElementById", jsCanvasId);
     val canvasStyle = canvas["style"];
-    canvasStyle.set("cursor", emscripten::val(htmlCursorName.constData()));
+    canvasStyle.set("cursor", val(htmlCursorName.constData()));
 }
 
 QByteArray QWasmCursor::cursorShapeToHtml(Qt::CursorShape shape)