qt 界面去掉系统边框

该代码在Qt5框架编辑，使用该类时， 直接继承这个类就可以了。 实现了拖拽功能和关闭功能，如果需要放大缩小功能， 需自己实现。

 1 #ifndef CUSTOMIZE_QWIDGET_H
#define CUSTOMIZE_QWIDGET_H
#include <QWidget>
#include <QMouseEvent>

class CustomizeQWidget : public QWidget
{
    Q_OBJECT
public:
    explicit CustomizeQWidget(QWidget *parent = 0);
    ~CustomizeQWidget();
public slots:
    void on_button_close_clicked();
private:
    void paintEvent(QPaintEvent *);
    void mousePressEvent(QMouseEvent *event);
    void mouseMoveEvent(QMouseEvent *event);
private:
    QPoint m_last_mouse_position;
};
#endif // CUSTOMIZE_QWIDGET_H

#include "customize_qwidget.h"
#include <QStyleOption>
#include <QPainter>
#include <QBrush>

CustomizeQWidget::CustomizeQWidget(QWidget *parent)
    : QWidget(parent)
{
    this -> setWindowFlags(Qt::FramelessWindowHint);
}

CustomizeQWidget::~CustomizeQWidget()
{
}

void CustomizeQWidget::paintEvent(QPaintEvent *)
{
    QStyleOption opt;
    opt.init(this);
    QPainter p(this);
    style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);
}

void CustomizeQWidget::mousePressEvent(QMouseEvent *event)
{
    if(event->button() == Qt::LeftButton)
    {
        m_last_mouse_position = event->globalPos();
    }
}

void CustomizeQWidget::mouseMoveEvent(QMouseEvent *event)
{
    if (!event->buttons().testFlag(Qt::LeftButton))
            return;
    const QPoint position = pos() + event->globalPos() - m_last_mouse_position; //the position of mainfrmae + (current_mouse_position - last_mouse_position)
    move(position.x(), position.y());
    m_last_mouse_position = event->globalPos();
}

void CustomizeQWidget::on_button_close_clicked()
{
    this->close();
}