wasm: make wasm platform target a specific canvas instead of default

This allows for multi canvas use

Task-number: QTBUG-64079
Change-Id: I69c998aa4c2869bb5b7f14ba65bb63284365ad70
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

src/plugins/platforms/wasm/qwasmeventtranslator.cpp

@@ -327,27 +327,18 @@ QWasmEventTranslator::QWasmEventTranslator(QObject *parent)
     , pressedButtons(Qt::NoButton)
     , resizeMode(QWasmWindow::ResizeNone)
 {
-    emscripten_set_keydown_callback(0, (void *)this, 1, &keyboard_cb);
-    emscripten_set_keyup_callback(0, (void *)this, 1, &keyboard_cb);
-
-    emscripten_set_mousedown_callback(0, (void *)this, 1, &mouse_cb);
-    emscripten_set_mouseup_callback(0, (void *)this, 1, &mouse_cb);
-    emscripten_set_mousemove_callback(0, (void *)this, 1, &mouse_cb);
-
-    emscripten_set_focus_callback(0, (void *)this, 1, &focus_cb);
-
-    emscripten_set_wheel_callback(0, (void *)this, 1, &wheel_cb);
-
     touchDevice = new QTouchDevice;
     touchDevice->setType(QTouchDevice::TouchScreen);
     touchDevice->setCapabilities(QTouchDevice::Position | QTouchDevice::Area | QTouchDevice::NormalizedPosition);
     QWindowSystemInterface::registerTouchDevice(touchDevice);
 
-    emscripten_set_touchstart_callback("#canvas", (void *)this, 1, &touchCallback);
-    emscripten_set_touchend_callback("#canvas", (void *)this, 1, &touchCallback);
-    emscripten_set_touchmove_callback("#canvas", (void *)this, 1, &touchCallback);
-    emscripten_set_touchcancel_callback("#canvas", (void *)this, 1, &touchCallback);
+    QWasmScreen *wasmScreen = QWasmIntegration::get()->screen();
+    initEventHandlers(wasmScreen->m_canvasId);
+}
 
+void QWasmEventTranslator::initEventHandlers(const QString &canvas)
+{
+    const char *canvasId = canvas.toLocal8Bit().constData();
     // The Platform Detect: expand coverage and move as needed
     enum Platform {
         GenericPlatform,
@@ -362,11 +353,30 @@ QWasmEventTranslator::QWasmEventTranslator(QObject *parent)
 
         if (emscripten::val::global("window")["safari"].isUndefined()) {
 
-            emscripten::val::global("canvas").call<void>("addEventListener",
+            emscripten::val::global(canvasId).call<void>("addEventListener",
                                                          std::string("wheel"),
                                                          val::module_property("mouseWheelEvent"));
         }
     }
+
+    emscripten_set_keydown_callback(canvasId, (void *)this, 1, &keyboard_cb);
+    emscripten_set_keyup_callback(canvasId, (void *)this, 1, &keyboard_cb);
+
+    emscripten_set_mousedown_callback(canvasId, (void *)this, 1, &mouse_cb);
+    emscripten_set_mouseup_callback(canvasId, (void *)this, 1, &mouse_cb);
+    emscripten_set_mousemove_callback(canvasId, (void *)this, 1, &mouse_cb);
+
+    emscripten_set_focus_callback(canvasId, (void *)this, 1, &focus_cb);
+
+    emscripten_set_wheel_callback(canvasId, (void *)this, 1, &wheel_cb);
+
+    emscripten_set_touchstart_callback(canvasId, (void *)this, 1, &touchCallback);
+    emscripten_set_touchend_callback(canvasId, (void *)this, 1, &touchCallback);
+    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);
+
 }
 
 template <typename Event>
@@ -865,4 +875,21 @@ bool QWasmEventTranslator::processKeyboard(int eventType, const EmscriptenKeyboa
     return accepted;
 }
 
+int QWasmEventTranslator::uiEvent_cb(int eventType, const EmscriptenUiEvent *e, void *userData)
+{
+    Q_UNUSED(e)
+    Q_UNUSED(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());
+    }
+
+    return 0;
+}
+
 QT_END_NAMESPACE

src/plugins/platforms/wasm/qwasmeventtranslator.h

@@ -57,7 +57,10 @@ public:
 
     static int touchCallback(int eventType, const EmscriptenTouchEvent *ev, void *userData);
 
+    static int uiEvent_cb(int eventType, const EmscriptenUiEvent *e, void *userData);
+
     void processEvents();
+    void initEventHandlers(const QString &);
 
 Q_SIGNALS:
     void getWindowAt(const QPoint &point, QWindow **window);

src/plugins/platforms/wasm/qwasmintegration.cpp

@@ -75,11 +75,18 @@ QWasmIntegration::QWasmIntegration()
       m_eventDispatcher(nullptr),
       m_clipboard(new QWasmClipboard)
 {
+
+    globalHtml5Integration = this;
     s_instance = this;
 
-    updateQScreenAndCanvasRenderSize();
+    emscripten::val defaultCanvasId = emscripten::val::global("canvas");
+    canvasIds.append(QString::fromStdString(defaultCanvasId["id"].as<std::string>()));
+    m_screen->setCanvas(canvasIds.at(0));
+
+    globalHtml5Integration = this;
+
+    screen()->updateQScreenAndCanvasRenderSize(m_screen->m_canvasId);
     screenAdded(m_screen);
-    emscripten_set_resize_callback(0, (void *)this, 1, uiEvent_cb);
 
     m_eventTranslator = new QWasmEventTranslator;
 
@@ -168,50 +175,6 @@ QPlatformTheme *QWasmIntegration::createPlatformTheme(const QString &name) const
     return QPlatformIntegration::createPlatformTheme(name);
 }
 
-int QWasmIntegration::uiEvent_cb(int eventType, const EmscriptenUiEvent *e, void *userData)
-{
-    Q_UNUSED(e)
-    Q_UNUSED(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).
-        updateQScreenAndCanvasRenderSize();
-    }
-
-    return 0;
-}
-
-static void set_canvas_size(double width, double height)
-{
-    emscripten::val canvas = emscripten::val::global("canvas");
-    canvas.set("width", width);
-    canvas.set("height", height);
-}
-
-void QWasmIntegration::updateQScreenAndCanvasRenderSize()
-{
-    // The HTML canvas has two sizes: the CSS size and the canvas render size.
-    // The CSS size is determined according to standard CSS rules, while the
-    // render size is set using the "width" and "height" attributes. The render
-    // size must be set manually and is not auto-updated on CSS size change.
-    // Setting the render size to a value larger than the CSS size enables high-dpi
-    // rendering.
-
-    double css_width;
-    double css_height;
-    emscripten_get_element_css_size(0, &css_width, &css_height);
-    QSizeF cssSize(css_width, css_height);
-
-    QWasmScreen *screen = QWasmIntegration::get()->m_screen;
-    QSizeF canvasSize = cssSize * screen->devicePixelRatio();
-
-    set_canvas_size(canvasSize.width(), canvasSize.height());
-    screen->setGeometry(QRect(QPoint(0, 0), cssSize.toSize()));
-    QWasmIntegration::get()->m_compositor->redrawWindowContent();
-}
-
 QPlatformClipboard* QWasmIntegration::clipboard() const
 {
     if (!m_clipboard)

src/plugins/platforms/wasm/qwasmintegration.h

@@ -78,7 +78,7 @@ public:
 
     static QWasmIntegration *get() { return s_instance; }
     static void QWasmBrowserExit();
-    static void updateQScreenAndCanvasRenderSize();
+    QStringList canvasIds;
 
 private:
     mutable QWasmFontDatabase *m_fontDb;
@@ -86,7 +86,6 @@ private:
     mutable QWasmScreen *m_screen;
     mutable QWasmEventTranslator *m_eventTranslator;
     mutable QWasmEventDispatcher *m_eventDispatcher;
-    static int uiEvent_cb(int eventType, const EmscriptenUiEvent *e, void *userData);
     mutable QHash<QWindow *, QWasmBackingStore *> m_backingStores;
 
     mutable QWasmClipboard *m_clipboard;

src/plugins/platforms/wasm/qwasmopenglcontext.cpp

@@ -28,7 +28,7 @@
 ****************************************************************************/
 
 #include "qwasmopenglcontext.h"
-
+#include "qwasmintegration.h"
 #include <EGL/egl.h>
 
 QT_BEGIN_NAMESPACE
@@ -57,7 +57,9 @@ void QWasmOpenGLContext::maybeRecreateEmscriptenContext(QPlatformSurface *surfac
             emscripten_webgl_destroy_context(m_context);
 
         // Create new context
-        const char *canvasId = 0; // (use default canvas) FIXME: get the actual canvas from the surface.
+        QWasmScreen *wasmScreen = QWasmIntegration::get()->screen();
+        const QString canvasId = wasmScreen->m_canvasId;
+         // FIXME: get the actual canvas from the surface.
         m_context = createEmscriptenContext(canvasId, m_requestedFormat);
 
         // Register context-lost callback.
@@ -73,11 +75,11 @@ void QWasmOpenGLContext::maybeRecreateEmscriptenContext(QPlatformSurface *surfac
             return true;
         };
         bool capture = true;
-        emscripten_set_webglcontextlost_callback(canvasId, this, capture, callback);
+        emscripten_set_webglcontextlost_callback(canvasId.toLocal8Bit().constData(), this, capture, callback);
     }
 }
 
-EMSCRIPTEN_WEBGL_CONTEXT_HANDLE QWasmOpenGLContext::createEmscriptenContext(const char *canvasId, QSurfaceFormat format)
+EMSCRIPTEN_WEBGL_CONTEXT_HANDLE QWasmOpenGLContext::createEmscriptenContext(const QString &canvasId, QSurfaceFormat format)
 {
     EmscriptenWebGLContextAttributes attributes;
     emscripten_webgl_init_context_attributes(&attributes); // Populate with default attributes
@@ -96,7 +98,7 @@ EMSCRIPTEN_WEBGL_CONTEXT_HANDLE QWasmOpenGLContext::createEmscriptenContext(cons
     attributes.depth = format.depthBufferSize() > 0;
     attributes.stencil = format.stencilBufferSize() > 0;
 
-    EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context(canvasId, &attributes);
+    EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context(canvasId.toLocal8Bit().constData(), &attributes);
 
     return context;
 }

src/plugins/platforms/wasm/qwasmopenglcontext.h

@@ -51,7 +51,7 @@ public:
 
 private:
     void maybeRecreateEmscriptenContext(QPlatformSurface *surface);
-    static EMSCRIPTEN_WEBGL_CONTEXT_HANDLE createEmscriptenContext(const char *canvasId, QSurfaceFormat format);
+    static EMSCRIPTEN_WEBGL_CONTEXT_HANDLE createEmscriptenContext(const QString &canvasId, QSurfaceFormat format);
 
     bool m_contextLost = false;
     QSurfaceFormat m_requestedFormat;

src/plugins/platforms/wasm/qwasmscreen.cpp

@@ -114,4 +114,33 @@ void QWasmScreen::setGeometry(const QRect &rect)
     resizeMaximizedWindows();
 }
 
+static void set_canvas_size(double width, double height, const char *canvasId)
+{
+    emscripten::val canvas = emscripten::val::global(canvasId);
+    canvas.set("width", width);
+    canvas.set("height", height);
+}
+
+void QWasmScreen::updateQScreenAndCanvasRenderSize(const QString &canvasId)
+{
+    // The HTML canvas has two sizes: the CSS size and the canvas render size.
+    // The CSS size is determined according to standard CSS rules, while the
+    // render size is set using the "width" and "height" attributes. The render
+    // size must be set manually and is not auto-updated on CSS size change.
+    // Setting the render size to a value larger than the CSS size enables high-dpi
+    // rendering.
+
+    double css_width;
+    double css_height;
+    emscripten_get_element_css_size(canvasId.toLocal8Bit().constData(), &css_width, &css_height);
+    QSizeF cssSize(css_width, css_height);
+
+    QWasmScreen *screen = QWasmIntegration::get()->screen();
+    QSizeF canvasSize = cssSize * screen->devicePixelRatio();
+
+    set_canvas_size(canvasSize.width(), canvasSize.height(), canvasId.toLocal8Bit().constData());
+    screen->setGeometry(QRect(QPoint(0, 0), cssSize.toSize()));
+    QWasmIntegration::get()->compositor()->redrawWindowContent();
+}
+
 QT_END_NAMESPACE

src/plugins/platforms/wasm/qwasmscreen.h

@@ -64,10 +64,12 @@ public:
     QWindow *topLevelAt(const QPoint &p) const override;
 
     void invalidateSize();
+    static void updateQScreenAndCanvasRenderSize(const QString &);
+    QString m_canvasId;
+    void setCanvas(const QString &canvasId) { m_canvasId = canvasId; }
 
 public slots:
     void setGeometry(const QRect &rect);
-protected:
 
 private:
     QWasmCompositor *m_compositor;