QT--鼠标拖动控件

1、mainwindows.h

---

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QMouseEvent>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();


public slots:
    bool eventFilter(QObject *, QEvent *);

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

2、mainwindows.c

---

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

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

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

bool MainWindow::eventFilter(QObject *, QEvent *evt)
{
    static QPoint lastPnt;
    static bool isHover = false;
    if(evt->type() == QEvent::MouseButtonPress)
    {
        QMouseEvent* e = static_cast<QMouseEvent*>(evt);
        if(ui->progressBar->rect().contains(e->pos()) && //is the mouse is clicking the key
            (e->button() == Qt::LeftButton)) //if the mouse click the right key
        {
            lastPnt = e->pos();
            isHover = true;
        }
    }
    else if(evt->type() == QEvent::MouseMove && isHover)
    {
        QMouseEvent* e = static_cast<QMouseEvent*>(evt);
        int dx = e->pos().x() - lastPnt.x();
        int dy=e->pos().y()-lastPnt.y();
       ui->progressBar->move(ui->progressBar->x()+dx,ui->progressBar->y()+dy);
    }else if(evt->type() == QEvent::MouseButtonRelease && isHover)
    {
        isHover = false;
    }
    return false;
}