QT实现无边框窗体的最小化，最大化/还原，关闭，拖动和双击最大化等功能

在窗体没有标题栏属性的情况下，窗体的最小化，最大化/还原，关闭，拖动和双击最大化等功能需要自定义。

本例介绍如何实现化，最大化/还原，关闭，拖动和双击最大化等功能，目前只是一个简单的Demo，后期将会在此Demo的基础上加上窗体的拉伸，再后期将会加上美化界面的代码。凡是复杂的功能都是由简单的功能发展而来的。

刚开始写博客，再加上时间都是挤压出来，自然是不会有很精美的排版，既然精美不了，那就简洁吧。

本例的知识点涉及了按钮的创建，布局，信号与槽，主要还是重写以下几个事件：

void mousePressEvent(QMouseEvent*event);

void mouseMoveEvent(QMouseEvent*event);

void mouseReleaseEvent(QMouseEvent*event);

void mouseDoubleClickEvent(QMouseEvent*event);

源码： widget.h

/*

* @author: landspace

* @date: 2017-7-20 19:05:59

* @version: 1.0

* @brief: To achieve the borderless form to minimize, maximize, restore, close, drag and other functions

*

**/

#ifndef WIDGET_H

#define WIDGET_H

#include <QWidget>

#include <QPushButton>

#include <QMouseEvent>

#include <QDesktopWidget>

namespace Ui {

class Widget;

}

class Widget : public QWidget

{

Q_OBJECT

public:

    explicit Widget(QWidget*parent = 0);

~Widget();

private:

    Ui::Widget*ui;

    QPushButton*m_closeBtn;

    QPushButton*m_normalBtn;

    QPushButton*m_minBtn;

QPoint m_mousePos;

QPoint m_windowPos;

QRect clientRect;

QDesktopWidget* desktop;

    QRect*rect;

int lengthToMouse;

double ratio; // 比例

bool isMaxWindow;

bool m_mousePressed;

protected:

void mousePressEvent(QMouseEvent*event);

void mouseMoveEvent(QMouseEvent*event);

void mouseReleaseEvent(QMouseEvent*event);

void mouseDoubleClickEvent(QMouseEvent*event);

void updateNormalBtn();

public slots:

void maxRestoreSlot();

};

#endif // WIDGET_H

源码： widget.cpp

/*

* @author: landspace

* @date: 2017-7-20 19:05:59

* @version: 1.0

* @brief: To achieve the borderless form to minimize, maximize, restore, close, drag and other functions

*

**/

#include "widget.h"

#include "ui_widget.h"

#include <QHBoxLayout>

#include <QVBoxLayout>

Widget::Widget(QWidget*parent) :

QWidget(parent),

ui(new Ui::Widget)

{

ui->setupUi(this);

setMinimumSize(800,600);

setWindowFlag(Qt::FramelessWindowHint); // 隐藏标题栏

isMaxWindow = false;

clientRect = QApplication::desktop()->availableGeometry(); //用户可用窗口大小

rect = new QRect(0, 0, clientRect.width(), 30); // 鼠标点击的有效区域

m_minBtn = new QPushButton(tr("最小化"),this);

m_normalBtn = new QPushButton(tr("最大化"),this);

m_closeBtn = new QPushButton(tr("关闭"),this);

// 布局（把按钮布局到右上角）

    QHBoxLayout*hbLayout = new QHBoxLayout();

hbLayout->addStretch();

hbLayout->addWidget(m_minBtn);

hbLayout->addWidget(m_normalBtn);

hbLayout->addWidget(m_closeBtn);

    QVBoxLayout*vbLayout = new QVBoxLayout(this);

vbLayout->addLayout(hbLayout);

vbLayout->addStretch();

connect(m_minBtn,&QPushButton::clicked,this,&Widget::showMinimized);

connect(m_normalBtn,&QPushButton::clicked,this,&Widget::maxRestoreSlot);

connect(m_closeBtn,&QPushButton::clicked,this,&Widget::close);

}

Widget::~Widget()

{

delete ui;

}

void Widget::mouseDoubleClickEvent(QMouseEvent*event)

{

//    this->isMaximized() ? this->showNormal() : this->showMaximized();

if(rect->contains(this->mapFromGlobal(QCursor::pos())) == true) // 指定区域内

maxRestoreSlot();

}

void Widget::mousePressEvent(QMouseEvent*event)

{

if(rect->contains(this->mapFromGlobal(QCursor::pos())) == true){ // 指定区域内

if(event->button() == Qt::LeftButton){

m_windowPos = this->pos();

m_mousePos = event->globalPos();

this->m_mousePressed = true;

}

}

ratio = 0.0;

double x = m_mousePos.x();

double y = clientRect.width();

ratio = x / y;

    lengthToMouse = 800* ratio; // 利用鼠标在屏幕的比例来设置鼠标在可用窗体的位置

}

void Widget::mouseMoveEvent(QMouseEvent*event)

{

//bool bMaximize = this->isMaximized(); // isMaximized() 不一定返回我们期望的值

int x = m_mousePos.x() - lengthToMouse;

int y = m_mousePos.y() - 2/* - m_mousePos.y()*/;

QPoint point(x,y);

if (m_mousePressed) {

if (isMaxWindow) {

//this->showNormal(); // 拖动最大化的窗口是否需要变成正常？

resize(800, 600);

move(x, y);

isMaxWindow = false;

m_windowPos=point;

} else {

this->move(m_windowPos + (event->globalPos() - m_mousePos));

}

if(event->globalY() < 4){ // 鼠标拖动窗体到屏幕顶端最大化窗体

move(0, 0);

resize(clientRect.width(), clientRect.height());

isMaxWindow = true;

}

if(event->globalX() < 4){// 鼠标拖动窗体到屏幕最左端窗体占左半边屏幕大小

resize(clientRect.width() / 2, clientRect.height());

move(0, 0);

isMaxWindow = false;

}

if(event->globalX() > clientRect.width() - 4){// 鼠标拖动窗体到屏幕最右端窗体占右半边屏幕大小

resize(clientRect.width() / 2, clientRect.height());

move(clientRect.width() / 2, 0);

isMaxWindow = false;

}

}

updateNormalBtn();

}

void Widget::mouseReleaseEvent(QMouseEvent*event)

{

if(event->button() == Qt::LeftButton)

m_mousePressed = false;

}

void Widget::maxRestoreSlot()

{

//this->isMaximized() ? showNormal() : showMaximized();

if(isMaxWindow){

resize(800, 600);

move((clientRect.width() - this->width())/2, (clientRect.height() - this->height())/2); // 居中

    isMaxWindow = false;

}else{

//showMaximized();

resize(clientRect.width(), clientRect.height());

move(0, 0);

isMaxWindow = true;

}

updateNormalBtn();

}

void Widget::updateNormalBtn()

{

isMaxWindow ? m_normalBtn->setText(tr("还原")) : m_normalBtn->setText(tr("最大化"));

}

窗体界面如下：



案例源码以上传到：http://download.csdn.net/detail/qq_33218979/9905608