wasm: support rendering to multiple canvases

Qt (via the the qtloader.js API) now supports rendering
to multiple canvases. The application sees each canvas
as a QScreen.

Make qtloader.js support multiple canvases:

  var qtloader = QtLoader({
    canvasElements : [array-of-canvas],
    showCanvas: function() {
      // make canvas(es) visible
    },
 });

The canvases were previously created/returned by showCanvas(),
however this function is called after the Qt app has
been started and adding screens that that point is
too late. (This worked before since there was only one
screen, and no need to connect each screen instance
to specific canvas.)

Remove QWasmScreen, QWasmCompositor, and QWasmEventTranslator
singletons from QWasmIntegration. These are are now
crated per-screen and are owned by the QWasmScreen.

Task-number: QTBUG-64079
Change-Id: I24689929fd5bfb7ff0ba076f66937728fa4bc4e4
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

1 files changed, 9 insertions, 7 deletions

diff --git a/src/plugins/platforms/wasm/qwasmcursor.cpp b/src/plugins/platforms/wasm/qwasmcursor.cpp
index 744b160dd1..2b3f37300d 100644
--- a/src/plugins/platforms/wasm/qwasmcursor.cpp
+++ b/src/plugins/platforms/wasm/qwasmcursor.cpp
@@ -28,20 +28,21 @@
 ****************************************************************************/
 
 #include "qwasmcursor.h"
+#include "qwasmscreen.h"
 
 #include <QtCore/qdebug.h>
+#include <QtGui/qwindow.h>
 
 #include <emscripten/emscripten.h>
 #include <emscripten/bind.h>
 
 void QWasmCursor::changeCursor(QCursor *windowCursor, QWindow *window)
 {
-    if (windowCursor == nullptr)
+    if (!windowCursor || !window)
+        return;
+    QScreen *screen = window->screen();
+    if (!screen)
         return;
-
-    // FIXME: The HTML5 plugin sets the cursor on the native canvas; when using multiple windows
-    // multiple cursors need to be managed taking mouse postion and stacking into account.
-    Q_UNUSED(window);
 
     // Bitmap and custom cursors are not implemented (will fall back to "auto")
     if (windowCursor->shape() == Qt::BitmapCursor || windowCursor->shape() >= Qt::CustomCursor)
@@ -52,8 +53,9 @@ void QWasmCursor::changeCursor(QCursor *windowCursor, QWindow *window)
     if (htmlCursorName.isEmpty())
         htmlCursorName = "auto";
 
-    // Set cursor on the main canvas
-    emscripten::val canvasStyle = emscripten::val::module_property("canvas")["style"];
+    // Set cursor on the canvas
+    QString canvasId = QWasmScreen::get(screen)->canvasId();
+    emscripten::val canvasStyle = emscripten::val::global(canvasId.toUtf8().constData())["style"];
     canvasStyle.set("cursor", emscripten::val(htmlCursorName.constData()));
 }