emscripten_request_pointerlock() returns EMSCRIPTEN_RESULT_UNKNOWN_TARGET

8Observer8

I have made an example that calls emscripten_request_pointerlock("screen", false); by mouse click:

void mousePressEvent(QMouseEvent *event) override
{
    EMSCRIPTEN_RESULT result = emscripten_request_pointerlock("screen", false);
    qDebug() << result;
}

It prints -4 to the console that means EMSCRIPTEN_RESULT_UNKNOWN_TARGET.

main.cpp

#include <QtGui/QMouseEvent>
#include <QtGui/QOpenGLFunctions>
#include <QtOpenGL/QOpenGLWindow>
#include <QtWidgets/QApplication>

#ifdef Q_OS_WASM
#include <emscripten.h>
#include <emscripten/html5.h>
#endif

class OpenGLWindow : public QOpenGLWindow, private QOpenGLFunctions
{

public:

    OpenGLWindow()
    {
        setTitle("OpenGL ES 2.0, Qt6, C++");
        resize(350, 350);
    }

private:

    void mousePressEvent(QMouseEvent *event) override
    {
        EMSCRIPTEN_RESULT result = emscripten_request_pointerlock("screen", false);
        qDebug() << result;
    }

    virtual void initializeGL() override
    {
        initializeOpenGLFunctions();
        glClearColor(0.2f, 0.2f, 0.2f, 1.f);
    }

    virtual void paintGL() override
    {
        glClear(GL_COLOR_BUFFER_BIT);
    }
};

int main(int argc, char *argv[])
{
    QApplication::setAttribute(Qt::ApplicationAttribute::AA_UseDesktopOpenGL);
    QApplication app(argc, argv);
    OpenGLWindow w;
    w.show();
    return app.exec();
}

pro

QT += core gui openglwidgets

win32: LIBS += -lopengl32

CONFIG += c++17

wasm: INCLUDEPATH += "C:\emsdk\upstream\emscripten\cache\sysroot\include"

SOURCES += \
    main.cpp

8Observer8

The bug report was closed because You need to handle this in a javascript mouse event and not a Qt mouse event. I will continue here: https://forum.qt.io/topic/157373/emscripten_set_mousedown_callback-does-not-call-the-callback-function

8Observer8

I use screen above because the Qt's html file has this element: <div id="screen"></div> I have tried to use EMSCRIPTEN_EVENT_TARGET_DOCUMENT instead of screen but it returns -1 (it means EMSCRIPTEN_RESULT_NOT_SUPPORTED)

EMSCRIPTEN_RESULT result = emscripten_request_pointerlock(
            EMSCRIPTEN_EVENT_TARGET_DOCUMENT, false);
qDebug() << result;

8Observer8

I have created the bug report: https://bugreports.qt.io/browse/QTBUG-126513

8Observer8

Why cannot I set a mouse down callback from Qt's constructor? It prints nothing when I click:

EM_BOOL mouse_down_callback(int eventType, const EmscriptenMouseEvent *event,
    void *userData)
{
    qDebug() << event->screenX << event->screenY;
    return 0;
}

class OpenGLWindow : public QOpenGLWindow, private QOpenGLFunctions
{
public:
    OpenGLWindow()
    {
        setTitle("OpenGL ES 2.0, Qt6, C++");
        resize(350, 350);
        emscripten_set_mousedown_callback(
            EMSCRIPTEN_EVENT_TARGET_WINDOW,
            NULL,
            1,
            mouse_down_callback
        );
    }

8Observer8

The bug report was closed because You need to handle this in a javascript mouse event and not a Qt mouse event. I will continue here: https://forum.qt.io/topic/157373/emscripten_set_mousedown_callback-does-not-call-the-callback-function