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, 23 insertions, 15 deletions

diff --git a/src/plugins/platforms/wasm/qwasmeventtranslator.cpp b/src/plugins/platforms/wasm/qwasmeventtranslator.cpp
index 23bf9a7de6..14222da807 100644
--- a/src/plugins/platforms/wasm/qwasmeventtranslator.cpp
+++ b/src/plugins/platforms/wasm/qwasmeventtranslator.cpp
@@ -320,8 +320,8 @@ EMSCRIPTEN_BINDINGS(mouse_module) {
     function("mouseWheelEvent", &mouseWheelEvent);
 }
 
-QWasmEventTranslator::QWasmEventTranslator(QObject *parent)
-    : QObject(parent)
+QWasmEventTranslator::QWasmEventTranslator(QWasmScreen *screen)
+    : QObject(screen)
     , draggedWindow(nullptr)
     , lastWindow(nullptr)
     , pressedButtons(Qt::NoButton)
@@ -332,13 +332,16 @@ QWasmEventTranslator::QWasmEventTranslator(QObject *parent)
     touchDevice->setCapabilities(QTouchDevice::Position | QTouchDevice::Area | QTouchDevice::NormalizedPosition);
     QWindowSystemInterface::registerTouchDevice(touchDevice);
 
-    QWasmScreen *wasmScreen = QWasmIntegration::get()->screen();
-    initEventHandlers(wasmScreen->m_canvasId);
+    initEventHandlers();
 }
 
-void QWasmEventTranslator::initEventHandlers(const QString &canvas)
+void QWasmEventTranslator::initEventHandlers()
 {
-    const char *canvasId = canvas.toLocal8Bit().constData();
+    qDebug() << "QWasmEventTranslator::initEventHandlers";
+
+    QByteArray _canvasId = screen()->canvasId().toUtf8();
+    const char *canvasId = _canvasId.constData();
+
     // The Platform Detect: expand coverage and move as needed
     enum Platform {
         GenericPlatform,
@@ -375,7 +378,7 @@ void QWasmEventTranslator::initEventHandlers(const QString &canvas)
     emscripten_set_touchmove_callback(canvasId, (void *)this, 1, &touchCallback);
     emscripten_set_touchcancel_callback(canvasId, (void *)this, 1, &touchCallback);
 
-    emscripten_set_resize_callback(canvasId, (void *)this, 1, uiEvent_cb);
+    emscripten_set_resize_callback(nullptr, (void *)this, 1, uiEvent_cb); // Note: handles browser window resize
 
 }
 
@@ -425,6 +428,11 @@ int QWasmEventTranslator::keyboard_cb(int eventType, const EmscriptenKeyboardEve
     return accepted ? 1 : 0;
 }
 
+QWasmScreen *QWasmEventTranslator::screen()
+{
+    return static_cast<QWasmScreen *>(parent());
+}
+
 Qt::Key QWasmEventTranslator::translateEmscriptKey(const EmscriptenKeyboardEvent *emscriptKey)
 {
     Qt::Key qtKey = Qt::Key_unknown;
@@ -541,14 +549,14 @@ void resizeWindow(QWindow *window, QWasmWindow::ResizeMode mode,
 void QWasmEventTranslator::processMouse(int eventType, const EmscriptenMouseEvent *mouseEvent)
 {
     auto timestamp = mouseEvent->timestamp;
-    QPoint point(mouseEvent->canvasX, mouseEvent->canvasY);
+    QPoint point(mouseEvent->targetX, mouseEvent->targetY);
 
     QEvent::Type buttonEventType = QEvent::None;
 
     Qt::MouseButton button = translateMouseButton(mouseEvent->button);
     Qt::KeyboardModifiers modifiers = translateMouseEventModifier(mouseEvent);
 
-    QWindow *window2 = QWasmIntegration::get()->compositor()->windowAt(point, 5);
+    QWindow *window2 = screen()->compositor()->windowAt(point, 5);
     if (window2 != nullptr)
         lastWindow = window2;
 
@@ -645,6 +653,7 @@ int QWasmEventTranslator::wheel_cb(int eventType, const EmscriptenWheelEvent *wh
 {
     Q_UNUSED(eventType)
 
+    QWasmEventTranslator *eventTranslator = static_cast<QWasmEventTranslator *>(userData);
     EmscriptenMouseEvent mouseEvent = wheelEvent->mouse;
 
     int scrollFactor = 0;
@@ -668,7 +677,7 @@ int QWasmEventTranslator::wheel_cb(int eventType, const EmscriptenWheelEvent *wh
     auto timestamp = mouseEvent.timestamp;
     QPoint globalPoint(mouseEvent.canvasX, mouseEvent.canvasY);
 
-    QWindow *window2 = QWasmIntegration::get()->compositor()->windowAt(globalPoint, 5);
+    QWindow *window2 = eventTranslator->screen()->compositor()->windowAt(globalPoint, 5);
 
     QPoint localPoint(globalPoint.x() - window2->geometry().x(), globalPoint.y() - window2->geometry().y());
 
@@ -686,6 +695,7 @@ int QWasmEventTranslator::wheel_cb(int eventType, const EmscriptenWheelEvent *wh
 
 int QWasmEventTranslator::touchCallback(int eventType, const EmscriptenTouchEvent *touchEvent, void *userData)
 {
+    QWasmEventTranslator *eventTranslator = static_cast<QWasmEventTranslator *>(userData);
     QList<QWindowSystemInterface::TouchPoint> touchPointList;
     touchPointList.reserve(touchEvent->numTouches);
     QWindow *window2;
@@ -695,7 +705,7 @@ int QWasmEventTranslator::touchCallback(int eventType, const EmscriptenTouchEven
         const EmscriptenTouchPoint *touches = &touchEvent->touches[i];
 
         QPoint point(touches->canvasX, touches->canvasY);
-        window2 = QWasmIntegration::get()->compositor()->windowAt(point, 5);
+        window2 = eventTranslator->screen()->compositor()->windowAt(point, 5);
 
         QWindowSystemInterface::TouchPoint touchPoint;
 
@@ -878,15 +888,13 @@ bool QWasmEventTranslator::processKeyboard(int eventType, const EmscriptenKeyboa
 int QWasmEventTranslator::uiEvent_cb(int eventType, const EmscriptenUiEvent *e, void *userData)
 {
     Q_UNUSED(e)
-    Q_UNUSED(userData)
+    QWasmEventTranslator *eventTranslator = static_cast<QWasmEventTranslator *>(userData);
 
     if (eventType == EMSCRIPTEN_EVENT_RESIZE) {
         // This resize event is called when the HTML window is resized. Depending
         // on the page layout the the canvas might also have been resized, so we
         // update the Qt screen size (and canvas render size).
-        QWasmScreen *wasmScreen = QWasmIntegration::get()->screen();
-
-        wasmScreen->updateQScreenAndCanvasRenderSize(wasmScreen->m_canvasId.toLocal8Bit().constData());
+        eventTranslator->screen()->updateQScreenAndCanvasRenderSize();
     }
 
     return 0;