Qt源码分析--QWidget(8)--Mouse and keyboard grabbing

最新推荐文章于 2024-07-30 14:06:04 发布

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最新推荐文章于 2024-07-30 14:06:04 发布

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分类专栏： Qt 源码分析 C++ 文章标签： qt c++

本文链接：https://blog.youkuaiyun.com/exlink2012/article/details/123640369

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1.void grabMouse();

void QWidget::grabMouse()
{
    grabMouseForWidget(this);
}

#ifndef QT_NO_CURSOR
static void grabMouseForWidget(QWidget *widget, const QCursor *cursor = 0)
#else
static void grabMouseForWidget(QWidget *widget)
#endif
{
    if (qt_mouseGrb)
        qt_mouseGrb->releaseMouse();
    mouseGrabWithCursor = false;
    if (QWindow *window = grabberWindow(widget)) {
#ifndef QT_NO_CURSOR
        if (cursor) {
            mouseGrabWithCursor = true;
            QGuiApplication::setOverrideCursor(*cursor);
        }
#endif // !QT_NO_CURSOR
        window->setMouseGrabEnabled(true);
    }
    qt_mouseGrb = widget;
    qt_pressGrab = 0;
}

qt_mouseGrb设置为widget，此widget接收所有鼠标事件，直到调用releaseMouse()函数。

2.void releaseMouse();

void QWidget::releaseMouse()
{
    releaseMouseGrabOfWidget(this);
}

static void releaseMouseGrabOfWidget(QWidget *widget)
{
    if (qt_mouseGrb == widget) {
        if (QWindow *window = grabberWindow(widget)) {
#ifndef QT_NO_CURSOR
            if (mouseGrabWithCursor) {
                QGuiApplication::restoreOverrideCursor();
                mouseGrabWithCursor = false;
            }
#endif // !QT_NO_CURSOR
            window->setMouseGrabEnabled(false);
        }
    }
    qt_mouseGrb = 0;
}

3.void grabKeyboard();

void QWidget::grabKeyboard()
{
    if (keyboardGrb)
        keyboardGrb->releaseKeyboard();
    if (QWindow *window = grabberWindow(this))
        window->setKeyboardGrabEnabled(true);
    keyboardGrb = this;
}

bool QWindow::setKeyboardGrabEnabled(bool grab)
{
    Q_D(QWindow);
    if (d->platformWindow)
        return d->platformWindow->setKeyboardGrabEnabled(grab);
    return false;
}

4.void releaseKeyboard();

void QWidget::releaseKeyboard()
{
    if (keyboardGrb == this) {
        if (QWindow *window = grabberWindow(this))
            window->setKeyboardGrabEnabled(false);
        keyboardGrb = 0;
    }
}

static inline QWindow *grabberWindow(const QWidget *w)
{
    QWindow *window = w->windowHandle();
    if (!window)
        if (const QWidget *nativeParent = w->nativeParentWidget())
            window = nativeParent->windowHandle();
    return window;
}

先获取的QWidget的窗口句柄，然后设置keyboardGrb=0；

5.static QWidget *mouseGrabber();

/*!
    \fn QWidget *QWidget::mouseGrabber()
    Returns the widget that is currently grabbing the mouse input.
    If no widget in this application is currently grabbing the mouse,
    \nullptr is returned.
    \sa grabMouse(), keyboardGrabber()
*/
QWidget *QWidget::mouseGrabber()
{
    if (qt_mouseGrb)
        return qt_mouseGrb;
    return qt_pressGrab;
}

6.static QWidget *keyboardGrabber();

/*!
    \fn QWidget *QWidget::keyboardGrabber()
    Returns the widget that is currently grabbing the keyboard input.
    If no widget in this application is currently grabbing the
    keyboard, \nullptr is returned.
    \sa grabMouse(), mouseGrabber()
*/
QWidget *QWidget::keyboardGrabber()
{
    return keyboardGrb;
}