Qt绘制各种图形

重载绘图事件：

protected:void    paintEvent(QPaintEvent *event) Q_DECL_OVERRIDE;void Widget::paintEvent(QPaintEvent *event)
{
进行绘图操作
}

绘图前操作：

//基本绘图QPainter    painter(this);//创建QPainter对象painter.setRenderHint(QPainter::Antialiasing);//painter.setRenderHint(QPainter::TextAntialiasing);//int W=this->width(); //绘图区宽度int H=this->height(); //绘图区高度QRect   rect(W/4,H/4,W/2,H/2); //中间区域矩形框//设置画笔QPen    pen;pen.setWidth(3); //线宽pen.setColor(Qt::red); //划线颜色//Qt::NoPen,Qt::SolidLine, Qt::DashLine, Qt::DotLine,Qt::DashDotLine,Qt::DashDotDotLine,Qt::CustomDashLinepen.setStyle(Qt::SolidLine);//线的类型，实线、虚线等//Qt::FlatCap, Qt::SquareCap,Qt::RoundCappen.setCapStyle(Qt::FlatCap);//线端点样式//Qt::MiterJoin,Qt::BevelJoin,Qt::RoundJoin,Qt::SvgMiterJoinpen.setJoinStyle(Qt::BevelJoin);//线的连接点样式painter.setPen(pen);//设置画刷
//    QPixmap texturePixmap(":images/images/texture.jpg");QBrush  brush;brush.setColor(Qt::yellow); //画刷颜色brush.setStyle(Qt::SolidPattern); //画刷填充样式
//    brush.setStyle(Qt::TexturePattern); //画刷填充样式
//    brush.setTexture(texturePixmap); //设置材质图片painter.setBrush(brush);

绘图：

    painter.drawLine(rect.left(),rect.top(),rect.right(),rect.bottom());painter.drawRect(rect); //只填充定义的渐变区域painter.drawRect(this->rect()); //填充更大区域，会有延展效果painter.fillRect(rect,Qt::red);painter.drawRoundRect(rect);painter.drawRoundedRect(rect,40,20);painter.drawEllipse(rect);painter.drawPolyline(points,9);painter.drawPolygon(points,9);painter.drawPoints(points,9);painter.translate(100,300);painter.drawPath(starPath);painter.translate(200,0);painter.drawPath(starPath);painter.translate(200,0);painter.drawPath(starPath);painter.drawArc(rect,30*16,80*16);painter.drawChord(rect,90*16,120*16);painter.drawPie(rect,90*16,120*16);painter.drawText(rect,"Hello, QT");

通用函数：

void Widget::myDrawTextureRect()
{QPainter    painter(this);//创建QPainter对象painter.setRenderHint(QPainter::Antialiasing);//painter.setRenderHint(QPainter::TextAntialiasing);//int W=this->width(); //绘图区宽度int H=this->height(); //绘图区高度QRect   rect(W/4,H/4,W/2,H/2); //中间区域矩形框//设置画笔QPen    pen;pen.setWidth(3); //线宽pen.setColor(Qt::red); //划线颜色//Qt::NoPen,Qt::SolidLine, Qt::DashLine, Qt::DotLine,Qt::DashDotLine,Qt::DashDotDotLine,Qt::CustomDashLinepen.setStyle(Qt::SolidLine);//线的类型，实线、虚线等//Qt::FlatCap, Qt::SquareCap,Qt::RoundCappen.setCapStyle(Qt::FlatCap);//线端点样式//Qt::MiterJoin,Qt::BevelJoin,Qt::RoundJoin,Qt::SvgMiterJoinpen.setJoinStyle(Qt::BevelJoin);//线的连接点样式painter.setPen(pen);//设置画刷QPixmap texturePixmap(":images/images/texture.jpg");QBrush  brush;
//   brush.setColor(Qt::yellow); //画刷颜色
//   brush.setStyle(Qt::SolidPattern); //画刷填充样式brush.setStyle(Qt::TexturePattern); //画刷填充样式brush.setTexture(texturePixmap); //设置材质图片painter.setBrush(brush);//绘图painter.drawRect(rect); //只填充定义的渐变区域
}

绘制渐变色：

void Widget::myDrawGradient()
{QPainter    painter(this);//创建QPainter对象painter.setRenderHint(QPainter::Antialiasing);//painter.setRenderHint(QPainter::TextAntialiasing);//int W=this->width(); //绘图区宽度int H=this->height(); //绘图区高度QRect   rect(W/4,H/4,W/2,H/2); //中间区域矩形框//设置画笔
//   QPen    pen;
//   pen.setStyle(Qt::NoPen);//线的类型，实线、虚线等
//   painter.setPen(pen);//线性渐变
//    QLinearGradient  linearGrad(rect.left(),rect.top(),rect.right(),rect.bottom()); //对角线QLinearGradient  linearGrad(rect.left(),rect.top(),rect.right(),rect.top());//从左到右linearGrad.setColorAt(0,Qt::blue);//起点颜色linearGrad.setColorAt(0.5,Qt::green);//起点颜色linearGrad.setColorAt(1,Qt::red);//终点颜色linearGrad.setSpread(QGradient::ReflectSpread);  //展布模式
//QGradient::PadSpread ,QGradient::RepeatSpread, QGradient::ReflectSpreadpainter.setBrush(linearGrad);//径向渐变
//    QRadialGradient  radialGrad(W/2,H/2,qMax(W/8,H/8),W/2,H/2);radialGrad.setColorAt(0,Qt::white);
//    radialGrad.setColorAt(0,Qt::green);
//    radialGrad.setColorAt(1,Qt::blue);
//    radialGrad.setSpread(QGradient::ReflectSpread);
//    //QGradient::PadSpread ,QGradient::RepeatSpread, QGradient::ReflectSpread
//    painter.setBrush(radialGrad);//圆锥型渐变
//    QConicalGradient  coniGrad(W/2,H/2,45);
//    coniGrad.setColorAt(0,Qt::yellow);
//    coniGrad.setColorAt(0.5,Qt::blue);
//    coniGrad.setColorAt(1,Qt::green);coniGrad.setSpread(QGradient::PadSpread); //对于锥形渐变不起作用
//    painter.setBrush(coniGrad);//绘图
//   painter.drawRect(rect); //只填充定义的渐变区域painter.drawRect(this->rect()); //填充更大区域，会有延展效果
}

绘制各种图形：

void Widget::myDrawShape()
{QPainter    painter(this);//创建QPainter对象painter.setRenderHint(QPainter::Antialiasing);painter.setRenderHint(QPainter::TextAntialiasing);int W=this->width(); //绘图区宽度int H=this->height(); //绘图区高度//设置画笔QPen    pen;pen.setWidth(3); //线宽pen.setColor(Qt::black); //划线颜色//Qt::NoPen,Qt::SolidLine, Qt::DashLine, Qt::DotLine,Qt::DashDotLine,Qt::DashDotDotLine,Qt::CustomDashLinepen.setStyle(Qt::SolidLine);//线的类型，实线、虚线等//Qt::FlatCap, Qt::SquareCap,Qt::RoundCappen.setCapStyle(Qt::FlatCap);//线端点样式//Qt::MiterJoin,Qt::BevelJoin,Qt::RoundJoin,Qt::SvgMiterJoinpen.setJoinStyle(Qt::BevelJoin);//线的连接点样式painter.setPen(pen);//1. drawArc()
//   QRect   rect(W/4,H/4,W/2,H/2);
//   int startAngle = 90 * 16; //起始90°
//   int spanAngle = 90 * 16;   //旋转90°
//   painter.drawArc(rect, startAngle, spanAngle);//2. drawChord()
//   QRect   rect(W/4,H/4,W/2,H/2);
//   int startAngle = 90 * 16; //起始90°
//   int spanAngle = 90 * 16;   //旋转90°
//   painter.drawChord(rect, startAngle, spanAngle);//3.drawConvexPolygon()
//   QPoint points[4]={
//      QPoint(5*W/12,H/4),QPoint(7*W/12,H/4),
//      QPoint(3*W/4,5*H/12),QPoint(3*W/4,7*H/12),QPoint(7*W/12,3*H/4),
//      QPoint(5*W/12,3*H/4),QPoint(W/4,7*H/12),
//      QPoint(W/4,5*H/12),QPoint(5*W/12,H/4)
//   };
//   painter.drawConvexPolygon(points, 4);//4. drawEllipse
//   QRect   rect(W/4,H/4,W/2,H/2);
//   painter.drawEllipse(rect);//5. drawImage
//   QRect   rect(W/4,H/4,W/2,H/2);
//   QImage  image(":images/images/qt.jpg");
//   painter.drawImage(rect, image);//6.  drawLine
//   QLine   Line(W/4,H/4,W/2,H/2);
//   painter.drawLine(Line);//7.  drawLines
//   QRect   rect(W/4,H/4,W/2,H/2);//   QVector<QLine> Lines;
//   Lines.append(QLine(rect.topLeft(),rect.bottomRight()));
//   Lines.append(QLine(rect.topRight(),rect.bottomLeft()));
//   Lines.append(QLine(rect.topLeft(),rect.bottomLeft()));
//   Lines.append(QLine(rect.topRight(),rect.bottomRight()));//   painter.drawLines(Lines);// 8.QPainterPath
//   QRect   rect(W/4,H/4,W/2,H/2);
//   QPainterPath  path;
//   path.addEllipse(rect);
//   path.addRect(rect);
//   painter.drawPath(path);//9.drawPie
//   QRect   rect(W/4,H/4,W/2,H/2);
//   int startAngle = 40 * 16;//起始40°
//   int spanAngle = 120 * 16;//旋转120°
//   painter.drawPie(rect, startAngle, spanAngle);//10. drawPixmap
//   QRect   rect(W/4,H/4,W/2,H/2);
//   QPixmap   pixmap(":images/images/qt.jpg");
//   painter.drawPixmap(rect, pixmap);//11. drawPolygon
//   QPoint points[]={
//      QPoint(5*W/12,H/4),
//      QPoint(3*W/4,5*H/12),
//      QPoint(5*W/12,3*H/4),
//      QPoint(2*W/4,5*H/12),
//   };
//   painter.drawPolygon(points, 4);//12.drawPolyline
//   QPoint points[]={
//      QPoint(5*W/12,H/4),
//      QPoint(3*W/4,5*H/12),
//      QPoint(5*W/12,3*H/4),
//      QPoint(2*W/4,5*H/12)
//   };
//   painter.drawPolyline(points, 4);//13.drawRect
//   QRect   rect(W/4,H/4,W/2,H/2);
//   painter.drawRect(rect);//14.drawRect
//   QRect   rect(W/4,H/4,W/2,H/2);
//   painter.drawRoundedRect(rect,20,20);//14.drawRect
//   QRect   rect(W/4,H/4,W/2,H/2);
//   QFont   font;
//   font.setPointSize(30);
//   font.setBold(true);
//   painter.setFont(font);
//   painter.drawText (rect,"Hello,Qt");//.  eraseRect
//   QRect   rect(W/4,H/4,W/2,H/2);
//   painter.eraseRect(rect);//15. fillRectQRect   rect(W/4,H/4,W/2,H/2);painter.fillRect (rect,Qt::green);//16.   fillPath
//   QRect  rect(W/4,H/4,W/2,H/2);
//   QPainterPath  path;
//   path.addEllipse(rect);
//   path.addRect(rect);
//   painter.fillPath(path,Qt::red);//17.drawPoint
//     painter.drawPoint(QPoint(W/2,H/2));//18. drawPoints
//     QPoint points[]={
//        QPoint(5*W/12,H/4),
//        QPoint(3*W/4,5*H/12),
//        QPoint(2*W/4,5*H/12)
//     };
//     painter.drawPoints(points, 3);
}

绘制图片：

//    QPixmap pixmap;
//    pixmap.load(":/images/images/qt.jpg");
//    painter.drawPixmap(rect.left(),rect.top(),pixmap);