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, 1 insertions, 4 deletions

diff --git a/src/plugins/platforms/wasm/qwasmclipboard.cpp b/src/plugins/platforms/wasm/qwasmclipboard.cpp
index f02c2c6ccb..890b01fa3c 100644
--- a/src/plugins/platforms/wasm/qwasmclipboard.cpp
+++ b/src/plugins/platforms/wasm/qwasmclipboard.cpp
@@ -192,15 +192,12 @@ void QWasmClipboard::initClipboardEvents()
     permissions.call<val>("query", writePermissionsMap);
 }
 
-void QWasmClipboard::installEventHandlers(const QString &canvasId)
+void QWasmClipboard::installEventHandlers(const emscripten::val &canvas)
 {
     if (hasClipboardApi)
         return;
 
     // Fallback path for browsers which do not support direct clipboard access
-    val document = val::global("document");
-    val canvas = document.call<val>("getElementById", QWasmString::fromQString(canvasId));
-
     canvas.call<void>("addEventListener", val("cut"),
                       val::module_property("qtClipboardCutTo"));
     canvas.call<void>("addEventListener", val("copy"),