QT画图的一个简单问题

[suxingtian]

QT 按照例子做的，
现象是 ，每次画的时候会把上次的结束点作为起点开始画。
估计是mouseMoveEvent事件有概率在mousePressEvent之前触发
试着增加一些标志判断，还是没搞好。。。

#include "dialog.h"
#include "ui_dialog.h"
#include <QDebug>
Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
    resize(600,500);
    pix = QPixmap(200,200);
    pix.fill(Qt::white);
    isDrawing = false;
    scale = 1;
    pushBtn = new QPushButton(this);
    pushBtn->setText(tr("zoomIn"));
    pushBtn->move(500,450);
    connect(pushBtn,SIGNAL(clicked()),this,SLOT(zoomIn()));
}

Dialog::~Dialog()
{
    delete ui;
}

void Dialog::paintEvent(QPaintEvent *event)
{
    QPainter pp(&pix);
    pp.drawLine(lastPoint,endPoint);
    lastPoint = endPoint;
    QPainter painter(this);
    painter.drawPixmap(0,0,pix);
}
void Dialog::mousePressEvent(QMouseEvent *event)
{
    if(event->button()==Qt::LeftButton)
    {
        lastPoint = event->pos();
    }
}
void Dialog::mouseMoveEvent(QMouseEvent *event)
{
    if(event->buttons()&Qt::LeftButton)
    {
        endPoint = event->pos();
        update();
    }
}
void Dialog::mouseReleaseEvent(QMouseEvent *event)
{
   if(event->button() == Qt::LeftButton)
   {
       endPoint = event->pos();
       update();
   }
}


//void Dialog::zoomIn()
//{
//    scale *= 2;
//    update();
//}

[赵4老师]

参考MFC CRectTracker

[suxingtian]

我在win7下同样的代码没有问题。之前的是win10下搞的