wasm: store and pass canvases as emscripten::val

Store and pass canvases as emscripten::val instead of
a QString containing the element id.

This simplifies code which interacts with the canvas
using the emscripten::val API, by removing the need to
look up with getElementById.

The Emscripten C event API does not accept emscripten::val,
and using the element id is still needed here.

emscripten::val does not provide a hash key suitable
for use with QHash, but does provide an equality-compare
in the form of val::equals(). Change the canvas->screen
mapping code to use a QVector instead of a QHash.

Change-Id: I1dbdbbc8fb06bb869031f1500e83ae2d64780a7f
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/src/plugins/platforms/wasm/qwasmscreen.h b/src/plugins/platforms/wasm/qwasmscreen.h
index fcf693681c..ea7ffc4193 100644
--- a/src/plugins/platforms/wasm/qwasmscreen.h
+++ b/src/plugins/platforms/wasm/qwasmscreen.h
@@ -37,6 +37,8 @@
 #include <QtCore/qscopedpointer.h>
 #include <QtCore/qtextstream.h>
 
+#include <emscripten/val.h>
+
 QT_BEGIN_NAMESPACE
 
 class QPlatformOpenGLContext;
@@ -50,12 +52,13 @@ class QWasmScreen : public QObject, public QPlatformScreen
 {
     Q_OBJECT
 public:
-    QWasmScreen(const QString &canvasId);
+    QWasmScreen(const emscripten::val &canvas);
     ~QWasmScreen();
     void destroy();
 
     static QWasmScreen *get(QPlatformScreen *screen);
     static QWasmScreen *get(QScreen *screen);
+    emscripten::val canvas() const;
     QString canvasId() const;
 
     QWasmCompositor *compositor();
@@ -80,7 +83,7 @@ public slots:
     void setGeometry(const QRect &rect);
 
 private:
-    QString m_canvasId;
+    emscripten::val m_canvas;
     QWasmCompositor *m_compositor = nullptr;
     QWasmEventTranslator *m_eventTranslator = nullptr;
     QRect m_geometry = QRect(0, 0, 100, 100);