32.QT绘图

• widget.h

   #ifndef WIDGET_H
   #define WIDGET_H
  
   #include <QWidget>
   #include <QPainter>
   #include <QPen>
   #include <QEvent>
  
   namespace Ui {
   class Widget;
   }
  
   class Widget : public QWidget
   {
       Q_OBJECT
  
   public:
       explicit Widget(QWidget *parent = );
       ~Widget();
  20     void paintEvent(QPaintEvent *e);
  21     QPainter *painter;
  
   private:
       Ui::Widget *ui;
   };
  
   #endif // WIDGET_H

• widget.cpp

   #include "widget.h"
   #include "ui_widget.h"
  
   Widget::Widget(QWidget *parent) :
       QWidget(parent),
       ui(new Ui::Widget)
   {
       ui->setupUi(this);
       setGeometry(,,,);
   }
  
   Widget::~Widget()
   {
       delete ui;
   }
  
   void Widget::paintEvent(QPaintEvent *e)
   {
       painter = new QPainter;
       painter->begin(this);
       painter->setPen(QPen(Qt::blue,,Qt::DashDotLine));
  
       //画刷
       painter->setBrush(QBrush(Qt::red,Qt::SolidPattern));
       //画矩形
       //painter->drawRect(20,20,180,180);
       //画椭圆
       //painter->drawEllipse(20,20,190,160);
       //画点
       //painter->drawPoint(100,100);
       //画曲线
      // painter->drawArc(20,20,210,160,500,1000);
  
       /*
           case Line:                                             //直线
               p.drawLine(rect.topLeft(),rect.bottomRight());     break;
           case Rectangle:                                        //长方形
               p.drawRect(rect);    break;
           case RoundRect:                                        //圆角方形
               p.drawRoundRect(rect);     break;
           case Ellipse:                                          //椭圆形
               p.drawEllipse(rect);     break;
           case Polygon:                                          //多边形
               p.drawPolygon(points,4);     break;
           case Polyline:                                      //多边线
               p.drawPolyline(points,4);     break;
           case Points:                                          //点
               p.drawPoints(points,4);     break;
           case Arc:                                              //弧
               p.drawArc(rect,startAngle,spanAngle);     break;
           case Path:                                             //路径
               p.drawPath(path);     break;
           case Text:                                            //文字
               p.drawText(rect,Qt::AlignCenter,tr("Hello Qt!"));    break;
           case Pixmap:                                          //图片
               p.drawPixmap(150,150,QPixmap("butterfly.png"));     break;
           default:     break;
  
          painter->drawLine(QPoint(30,30),QPoint(60,180));
          painter->drawText(this->rect(),Qt::AlignCenter,tr("Hello Qthello haihua!"));
          painter->drawPixmap(150,150,QPixmap("1.png"));
       */
  
       //画线
       //painter->drawLine(QPoint(30,30),QPoint(60,180));
       //painter->drawText(this->rect(),Qt::AlignCenter,tr("Hello"));
       //画图
       painter->drawPixmap(,,QPixmap("1.png"));
       painter->end();
   }