如何在Qt中使用自定义titleBar移动窗口

Question

I'm beginner in Qt and I want to drag and move Window using my own custom titleBar(QLabel).

The Qt code:

void MainWindow::mousePressEvent(QMouseEvent *event)
{
    mpos = event->pos();
}

void MainWindow::mouseMoveEvent(QMouseEvent *event)
{
    if (event->buttons() & Qt::LeftButton) 
    {
        QPoint diff = event->pos() - mpos;
        QPoint newpos = this->pos() + diff;
        this->move(newpos);
    }
}

This code allow me to move window by mouse pressed on any QWidget but I want to move window by mouse pressed on QLabel.

Answer 1

I know that its kinda late, but I solved this issue. The code is very similar to the implementation that Farhad suggested, but to solve the "jumping" window, you need to update the current position of the mouse also in the event filter:

 if (object == ui->frame_title && event->type() == QEvent::MouseButtonPress)
        {
            QMouseEvent* mouseEvent = (QMouseEvent*)event;
            if (pressed == false){
                current = mouseEvent->pos();
            }
            pressed = true;
            return true;
        }

Adding this, you get the current mouse location when the user first press the left-click.

Here is the full implementation:

void MainWindow::mousePressEvent(QMouseEvent *event)
{
    current = event->pos();
}

void MainWindow::mouseMoveEvent(QMouseEvent *event)
{

    if(pressed)
        this->move(mapToParent(event->pos() - current));
}

bool MainWindow::eventFilter(QObject *object, QEvent *event)
{
    if (object == ui->frame_title && event->type() == QEvent::MouseButtonPress)
    {
        QMouseEvent* mouseEvent = (QMouseEvent*)event;
        if (pressed == false){
            current = mouseEvent->pos();
        }
        pressed = true;
        return true;
    }
    if (object == ui->frame_title && event->type() == QEvent::MouseButtonRelease)
    {
        pressed = false;
        return true;
    }
    else
        return false;
}

Then in your constructor, just add (frame_title is my titlebar):

ui->frame_title->installEventFilter(this);

Answer 2

You can re-implement QLabel class and impalement mousePressEvent

Example :

header file

#ifndef MYLABLE_H

#define MYLABLE_H

#include <QEvent>
#include <QObject>
#include <QLabel>

class MyLable : public QLabel
{
    Q_OBJECT
public:
    explicit MyLable(QWidget *parent = 0);

    QPoint mpos;

signals:

public slots:



    // QWidget interface
protected:
    void mousePressEvent(QMouseEvent *);
};

#endif // MYLABLE_H

.cpp

#include "mylable.h"

#include <QMouseEvent>

MyLable::MyLable(QWidget *parent) : QLabel(parent)
{
}

void MyLable::mousePressEvent(QMouseEvent * event)
{
    if (event->buttons() & Qt::LeftButton)
    {
        QPoint diff = event->pos() - mpos;
        QPoint newpos = this->pos() + diff;
        this-> parentWidget()->move(newpos);
    }
}

Answer 3

I suggest you to use eventFilter to get event MousePress and MouseRelease :

void MainApp::mousePressEvent(QMouseEvent *event)
{
    current = event->pos();
}

void MainApp::mouseMoveEvent(QMouseEvent *event)
{
    if(pressed)
        this->move(mapToParent(event->pos() - current));
}

bool MainApp::eventFilter(QObject *object, QEvent *event)
{
    if (object == ui->label && event->type() == QEvent::MouseButtonPress)
    {
        pressed = true;
        return true;
    }
    if (object == ui->label && event->type() == QEvent::MouseButtonRelease)
    {
        pressed = false;
        return true;
    }
    else
        return false;
}

This is a sample project for your question on github download here.