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 = 0);
      ~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(120,120,600,600);
  }
  
  Widget::~Widget()
  {
      delete ui;
  }
  
  void Widget::paintEvent(QPaintEvent *e)
  {
      painter = new QPainter;
      painter->begin(this);
      painter->setPen(QPen(Qt::blue,10,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(0,0,QPixmap("1.png"));
      painter->end();
  }