Qt 窗口 无边框化，移动，大小调整

在软件开发中，有时需要无边框界面，并且可以拖动,可关闭；

效果：

 主要实现如下：

构造函数：

this->setWindowFlags(Qt::FramelessWindowHint);

    setWindowFlags(Qt::FramelessWindowHint | Qt::Tool | Qt::WindowStaysOnTopHint);
    setWindowOpacity(0.9);

    setMouseTracking(true);

鼠标处理：

void TestDialog::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        this->m_drag = true;
        this->dragPos = event->pos();
        this->resizeDownPos = event->globalPos();
        this->mouseDownRect = this->rect();
    }
}
void TestDialog::mouseMoveEvent(QMouseEvent * event)
{
    if (resizeRegion != Default)
    {
        handleResize();
        return;
    }
    if(m_move) {
        move(event->globalPos() - dragPos);
        return;
    }
    QPoint clientCursorPos = event->pos();
    QRect r = this->rect();
    QRect resizeInnerRect(resizeBorderWidth, resizeBorderWidth, r.width() - 2*resizeBorderWidth, r.height() - 2*resizeBorderWidth);
    if(r.contains(clientCursorPos) && !resizeInnerRect.contains(clientCursorPos)) { //调整窗体大小
        ResizeRegion resizeReg = getResizeRegion(clientCursorPos);
        setResizeCursor(resizeReg);
        if (m_drag && (event->buttons() & Qt::LeftButton)) {
            resizeRegion = resizeReg;
            handleResize();
        }
    }
    else { //移动窗体
        setCursor(Qt::ArrowCursor);
        if (m_drag && (event->buttons() & Qt::LeftButton)) {
            m_move = true;
            move(event->globalPos() - dragPos);
        }
    }
}
void TestDialog::mouseReleaseEvent(QMouseEvent *event)
{
    m_drag = false;
    if(m_move) {
        m_move = false;
        handleMove(event->globalPos()); //鼠标放开后若超出屏幕区域自动吸附于屏幕顶部/左侧/右侧
    }
    resizeRegion = Default;
    setCursor(Qt::ArrowCursor);
}
void TestDialog::setResizeCursor(ResizeRegion region)
{
    switch (region)
    {
    case North:
    case South:
        setCursor(Qt::SizeVerCursor);
        break;
    case East:
    case West:
        setCursor(Qt::SizeHorCursor);
        break;
    case NorthWest:
    case SouthEast:
        setCursor(Qt::SizeFDiagCursor);
        break;
    default:
        setCursor(Qt::SizeBDiagCursor);
        break;
    }
}
ResizeRegion TestDialog::getResizeRegion(QPoint clientPos)
{
    if (clientPos.y() <= resizeBorderWidth) {
        if (clientPos.x() <= resizeBorderWidth)
            return NorthWest;
        else if (clientPos.x() >= this->width() - resizeBorderWidth)
            return NorthEast;
        else
            return North;
    }
    else if (clientPos.y() >= this->height() - resizeBorderWidth) {
        if (clientPos.x() <= resizeBorderWidth)
            return SouthWest;
        else if (clientPos.x() >= this->width() - resizeBorderWidth)
            return SouthEast;
        else
            return South;
    }
    else {
        if (clientPos.x() <= resizeBorderWidth)
            return West;
        else
            return East;
    }
}
void TestDialog::handleMove(QPoint pt)
{
    QPoint currentPos = pt - dragPos;
    if(currentPos.x()<desktop->x()) { //吸附于屏幕左侧
        currentPos.setX(desktop->x());
    }
    else if (currentPos.x()+this->width()>desktop->width()) { //吸附于屏幕右侧
        currentPos.setX(desktop->width()-this->width());
    }
    if(currentPos.y()<desktop->y()) { //吸附于屏幕顶部
        currentPos.setY(desktop->y());
    }
    move(currentPos);
}
void TestDialog::handleResize()
{
    int xdiff = QCursor::pos().x() - resizeDownPos.x();
    int ydiff = QCursor::pos().y() - resizeDownPos.y();
    switch (resizeRegion)
    {
    case East:
    {
        resize(mouseDownRect.width()+xdiff, this->height());
        break;
    }
    case West:
    {
        resize(mouseDownRect.width()-xdiff, this->height());
        move(resizeDownPos.x()+xdiff, this->y());
        break;
    }
    case South:
    {
        resize(this->width(),mouseDownRect.height()+ydiff);
        break;
    }
    case North:
    {
        resize(this->width(),mouseDownRect.height()-ydiff);
        move(this->x(), resizeDownPos.y()+ydiff);
        break;
    }
    case SouthEast:
    {
        resize(mouseDownRect.width() + xdiff, mouseDownRect.height() + ydiff);
        break;
    }
    case NorthEast:
    {
        resize(mouseDownRect.width()+xdiff, mouseDownRect.height()-ydiff);
        move(this->x(), resizeDownPos.y()+ydiff);
        break;
    }
    case NorthWest:
    {
        resize(mouseDownRect.width()-xdiff, mouseDownRect.height()-ydiff);
        move(resizeDownPos.x()+xdiff, resizeDownPos.y()+ydiff);
        break;
    }
    case SouthWest:
    {
        resize(mouseDownRect.width()-xdiff, mouseDownRect.height()+ydiff);
        move(resizeDownPos.x()+xdiff, this->y());
        break;
    }
    }
}