QT06

//实现自己绘制图形  3.22
#include "MyWidget.h"
#include <QApplication>
#include <QPainter>
#include <QPixmap>
#include <QMoveEvent>
#include <QDebug>

MyWidget::MyWidget(QWidget *parent) : QWidget(parent)
{
    button = new MyButton("mybutton!",this);
    connect(button,SIGNAL(clicked()),this,SLOT(slotButtonClicked()));
}

void MyWidget::slotButtonClicked()
{
    qDebug() << "button is clicked!";
}

void MyWidget::paintEvent(QPaintEvent *event)
{

    QPainter p(this);
    for(int i=0;i<_lines.size();i++)
    {
        const QVector<QPoint>& line = _lines.at(i);       //需要绘制哪条线
        for(int j=0;j<line.size()-1;j++)    //这里<的是size()-1
        {
            p.drawLine(line.at(j),line.at(j+1));
        }
    }

//    for(int i = 0; i < this->_line.size() -1; i++)
//    {
//        p.drawLine(_line.at(i),_line.at(i+1));
//    }
}
void MyWidget::mouseMoveEvent(QMouseEvent *event)
{
//    //不能在这里面创建QPainter对象
//    _line.append(event->pos());
//    update();               //一定要重绘

    if(_lines.size() ==0)
    {
        QVector<QPoint> line;
        _lines.append(line);
    }
    QVector<QPoint>& lastline = _lines.last();
    lastline.append(event->pos());
    update();
}
void MyWidget::mousePressEvent(QMouseEvent *event)
{
    QVector<QPoint> line;
    _lines.append(line);        //添加一条线

    QVector<QPoint>& lastline = _lines.last();
    lastline.append(event->pos());

//    _line.append(event->pos());                     //将点保存到容器里面
//    //update();
}
void MyWidget::mouseReleaseEvent(QMouseEvent *event)
{
//    _line.append(event->pos());
//    //update();

    QVector<QPoint>& lastline = _lines.last();
    lastline.append(event->pos());
}




int main(int argc,char* argv[])
{
    QApplication app(argc,argv);

    MyWidget w;
    w.show();

    return app.exec();
}