先看效果：

 N年前的QQ就可以吸附到屏幕边缘，聊天时候非常方便，不用点击状态栏图标即可呼出QQ界面

自己尝试做了一个糙版的屏幕吸附效果。

关键代码：

void Widget::mouseMoveEvent(QMouseEvent *e)
{
    int dx = e->globalX() - lastPoint_.x();
    int dy = e->globalY() - lastPoint_.y();

    int targetx,targety;
    bool enableAnimation = false;

    if(mousePress_ == false) {
        return;
    }

    //! 垂直方向
    if(this->y() < EdgeAttachMargin && this->y() != 0) {
        //! 吸附顶部
        targety = 0;
        enableAnimation = true;
    } else {
        targety = this->y();
    }

    //! 水平方向
    if(this->x() < EdgeAttachMargin && this->x() != 0) {
        //! 吸附左边
        enableAnimation = 1;
        targetx = 0;
    } else {
        int rightx = this->x()+this->width();
        if(rightx > (QApplication::desktop()->width()-EdgeAttachMargin) && rightx != QApplication::desktop()->width()) {
            //! 吸附右边
            targetx = QApplication::desktop()->width()-this->width();
            enableAnimation = 1;
        } else {
            targetx = this->x();
        }
    }

    if(1 == enableAnimation){
        if(targetx == 0) {
            hideType_ = HideType::to_xleft;
        } else if(targetx == QApplication::desktop()->width()-this->width()) {
            hideType_ = HideType::to_xright;
        } else if(targety == 0) {
            hideType_ = HideType::to_y;
        }

        startAnimation(QPoint(targetx,targety),QPoint(this->x(),this->y()));
    } else {
        if(hideType_ == HideType::xleft) {
            int adjustX = x();
            int adjustY = y() + dy;
            if(dx > EdgeAttachMargin) {
                adjustX = x() + dx;
                hideType_ = HideType::none;
                lastPoint_.rx() = e->globalX();
            }
            this->move(adjustX, adjustY);
            lastPoint_.ry() = e->globalY();
        } else if (hideType_ == HideType::xright) {
            int adjustX = x();
            int adjustY = y() + dy;
            if(dx < -EdgeAttachMargin) {
                adjustX = x() + dx;
                hideType_ = HideType::none;
                lastPoint_.rx() = e->globalX();
            }
            this->move(adjustX, adjustY);
            lastPoint_.ry() = e->globalY();
        } else if(hideType_ == HideType::y) {
            int adjustX = x() + dx;
            int adjustY = y();
            if(dy > EdgeAttachMargin) {
                adjustY = y() + dy;
                hideType_ = HideType::none;
                lastPoint_.ry() = e->globalY();
            }
            this->move(adjustX, adjustY);
            lastPoint_.rx() = e->globalX();
        } else {
            int adjustX = x() + dx;
            int adjustY = y() + dy;
            if(adjustX < 0) adjustX = 0;
            if(adjustX > QApplication::desktop()->width() - width()) adjustX = QApplication::desktop()->width() - width();
            if(adjustY < 0) adjustY = 0;
            if(adjustY > QApplication::desktop()->availableGeometry().height() - height()) adjustY = QApplication::desktop()->availableGeometry().height() - height();
            this->move(adjustX, adjustY);
            lastPoint_   = e->globalPos();
        }
    }
}

鼠标悬停展开 / 离去收缩功能，

主要依据void enterEvent(QEvent *event); & void leaveEvent(QEvent *event);两个函数展开

动画效果使用QPropertyAnimation进行，可以参见另一篇博文中的例子：https://blog.csdn.net/wisdomroc/article/details/135975578

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全套代码链接：Qt实现窗口吸附屏幕边缘 & 自动收缩