使用Qt的鼠標支持，模擬實現粗略的畫板連線

頭文件：

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>  //模板類
#include <QPoint>
#include <QDebug>

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

signals:

public slots:

private:
    void paintEvent(QPaintEvent *event);//繪畫函數

    void mouseDoubleClickEvent(QMouseEvent *event);//鼠標雙擊
    void mouseMoveEvent(QMouseEvent *event);    //鼠標移動
    void mousePressEvent(QMouseEvent *event);   //鼠標按下
    void mouseReleaseEvent(QMouseEvent *event); //鼠標擡起
private:
    bool m_pressedFlag;    //獲取鼠標狀態，擡起還是按下
    QVector<QPoint> m_points;   //保存鼠標移動的座標
};

#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();
    //設置背景色
    painter.setBrush(QColor(0xFF,0xFF,0xFF));
    painter.drawRect(0,0,width,height);
    //設置線條顏色
    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);//畫線函數，連接兩個點
        }
    }
}
//鼠標雙擊函數
void QShuWidget::mouseDoubleClickEvent(QMouseEvent *event)
{
    QWidget::mouseDoubleClickEvent(event);
}
//鼠標移動函數
void QShuWidget::mouseMoveEvent(QMouseEvent *event)
{
    if(m_pressedFlag)
    {
        QPoint poin = event->pos();
        m_points.append(poin);
//        qDebug("(%d,%d)",poin.x(),poin.y());//鼠標按下，移動時，打印座標
        update();   //更新,重繪
    }
}
//鼠標按下
void QShuWidget::mousePressEvent(QMouseEvent *event)
{
    m_pressedFlag = true;
    m_points.clear();
}
//鼠標擡起
void QShuWidget::mouseReleaseEvent(QMouseEvent *event)
{
    m_pressedFlag = false;
}

效果圖：