Qt 圆角矩形+鼠标左键拖动窗口

 #ifndef MAINWINDOW_H
 #define MAINWINDOW_H

 #include <QMainWindow>

 namespace Ui {
 class MainWindow;
 }

 class MainWindow : public QMainWindow
 {
     Q_OBJECT

 public:
     explicit MainWindow(QWidget *parent = );
     ~MainWindow();

 protected:
     void paintEvent(QPaintEvent *event);
     void mousePressEvent(QMouseEvent *event);
     void mouseMoveEvent(QMouseEvent *event);
     void mouseReleaseEvent(QMouseEvent *event);

 private:
     Ui::MainWindow *ui;

     QPoint m_pos;
     bool m_drag;
 };

 #endif // MAINWINDOW_H

 #include "mainwindow.h"
 #include "ui_mainwindow.h"

 #include <QPainter>
 #include <QBitmap>
 #include <QMouseEvent>

 MainWindow::MainWindow(QWidget *parent)
     : QMainWindow(parent),
       ui(new Ui::MainWindow)
 {
     ui->setupUi(this);

     ui->menuBar->close();
     ui->mainToolBar->close();
     ui->statusBar->close();

     setFixedSize(, );
     setWindowFlags(Qt::FramelessWindowHint);

     m_drag = false;
 }

 MainWindow::~MainWindow()
 {
     delete ui;
 }

 void MainWindow::paintEvent(QPaintEvent *event)
 {
     Q_UNUSED(event);
     QBitmap bitmap(this->size());
     QPainter painter(&bitmap);
     painter.fillRect(this->rect(), Qt::white);
     painter.setBrush(QColor(, , ));
     painter.setRenderHint(QPainter::Antialiasing);
     painter.setPen(QPen(Qt::blue, , Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin));
     painter.drawRoundedRect(this->rect(), , );
     this->setMask(bitmap);
 }

 void MainWindow::mousePressEvent(QMouseEvent *event)
 {
     if (Qt::LeftButton == event->button()) {
         m_drag = true;
         m_pos = event->pos();
     }
 }

 void MainWindow::mouseMoveEvent(QMouseEvent *event)
 {
     Q_UNUSED(event);

     if (m_drag) {
         this->move(event->globalPos() - m_pos);
     }
 }

 void MainWindow::mouseReleaseEvent(QMouseEvent *event)
 {
     Q_UNUSED(event);
     m_drag = false;
 }