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 = );
     ~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();
 }