使用Qt的鼠标支持，模拟实现粗略的画板连线

头文件：

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "qshuwidget.h"

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

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

private:
Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H
qshuwidget.h
#ifndef QSHUWIDGET_H
#define QSHUWIDGET_H

#include <QWidget>
#include <QPainter>
#include <QPaintEvent>
#include <QMouseEvent>
#include <QVector> //模板类
#include <QPoint>
#include <QDebug>

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

signals:

public slots:

private:
void paintEvent(QPaintEvent *event);//绘画函数

void mouseDoubleClickEvent(QMouseEvent *event);//鼠标双击
void mouseMoveEvent(QMouseEvent *event); //鼠标移动
void mousePressEvent(QMouseEvent *event); //鼠标按下
void mouseReleaseEvent(QMouseEvent *event); //鼠标抬起
private:
bool m_pressedFlag; //获取鼠标状态，抬起还是按下
QVector<QPoint> m_points; //保存鼠标移动的坐标
};

#endif // QSHUWIDGET_H
源文件：
main.cpp

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
// w.show();

QShuWidget s;
s.resize(400,300);
s.move(200,200);
s.show();
return a.exec();
}
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"

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

MainWindow::~MainWindow()
{
delete ui;
}qshuwidget.cpp
#include "qshuwidget.h"

QShuWidget::QShuWidget(QWidget *parent) :
QWidget(parent)
{
m_pressedFlag = false;
}

void QShuWidget::paintEvent(QPaintEvent *event)
{
QPainter painter(this);

int width = this->width();
int height = this->height();
//设置背景色
painter.setBrush(QColor(0xFF,0xFF,0xFF));
painter.drawRect(0,0,width,height);
//设置线条颜色
painter.setPen(QColor(0xFF,0,0));
if(m_pressedFlag)
{
for(int i = 0; i < m_points.size()-1; i++)
{
QPoint point1 = m_points[i];
QPoint point2 = m_points[i+1];
painter.drawLine(point1,point2);//画线函数，连接两个点
}
}
}
//鼠标双击函数
void QShuWidget::mouseDoubleClickEvent(QMouseEvent *event)
{
QWidget::mouseDoubleClickEvent(event);
}
//鼠标移动函数
void QShuWidget::mouseMoveEvent(QMouseEvent *event)
{
if(m_pressedFlag)
{
QPoint poin = event->pos();
m_points.append(poin);
// qDebug("(%d,%d)",poin.x(),poin.y());//鼠标按下，移动时，打印坐标
update(); //更新,重绘
}
}
//鼠标按下
void QShuWidget::mousePressEvent(QMouseEvent *event)
{
m_pressedFlag = true;
m_points.clear();
}
//鼠标抬起
void QShuWidget::mouseReleaseEvent(QMouseEvent *event)
{
m_pressedFlag = false;
}
效果图：