类QPainter的常用语句：
void PainterTest::paintEvent(QPaintEvent *)
{QPainter painter(this);/*QPen pen; //画笔pen.setColor(QColor(255,0,0));QBrush brush(QColor(0,255,0,125)); //画刷*/QPen pen(Qt::DotLine);QBrush brush(Qt::blue);brush.setStyle(Qt::HorPattern);painter.setPen(pen); //添加画笔painter.setBrush(brush); //添加画刷/*画弧形*/QRectF rectangle(10.0, 20.0, 80.0, 60.0); //矩形int startAngle = 30 * 16; //起始角度int spanAngle = 120 * 16; //跨越度数/*设置渐变*/QLinearGradient linearGradient(100,150,300,150);//从点（100，150）开始到点（300，150）结束，确定一条直线linearGradient.setColorAt(0,Qt::red);linearGradient.setColorAt(0.2,Qt::black);linearGradient.setColorAt(0.4,Qt::yellow);linearGradient.setColorAt(0.6,Qt::white);linearGradient.setColorAt(0.8,Qt::green);linearGradient.setColorAt(1,Qt::blue);//将直线开始点设为0，终点设为1，然后分段设置颜色painter.setBrush(linearGradient);/*圆锥渐变*/// QConicalGradient conicalGradient(50,50,0);//圆心为（50，50），开始角度为0// conicalGradient.setColorAt(0,Qt::green);//conicalGradient.setColorAt(1,Qt::white); //从圆心的0度角开始逆时针填充//painter.setBrush(conicalGradient);/*矩形框中画字体*/QRectF ff(10,10,30,40); //设置一个矩形painter.drawRect(ff); //为了更直观地看到字体的位置，我们绘制出这个矩形painter.setPen(QColor(Qt::blue));//设置画笔颜色为红色painter.drawText(ff,Qt::AlignHCenter,"World");/*设置字体*/QFont font("Arial",20,QFont::Bold,true);//设置字体的类型，大小，加粗，斜体font.setUnderline(true);//设置下划线font.setOverline(true);//设置上划线font.setCapitalization(QFont::SmallCaps);//设置大小写font.setLetterSpacing(QFont::AbsoluteSpacing,5);//设置间距painter.setFont(font);painter.drawLine(0,0,100,100);//画直线painter.drawArc(rectangle, startAngle, spanAngle);//画弧线painter.drawRect(100,100,200,100);//又画了个矩形painter.drawEllipse(100,0,200,200);//画圆}
QpinterPath类常用函数：
void PainterTest::paintEvent(QPaintEvent *)
{QPainterPath path;path.lineTo(100,100);path.lineTo(200,100);path.addEllipse(100,100,50,50);path.lineTo(200,200);QPainter painter(this);painter.setPen(Qt::green);painter.setBrush(Qt::yellow);painter.drawPath(path);QPainterPath path2;path2.addPath(path);path2.translate(100,0);path2.moveTo(100,100);//可见moveTo函数可以改变当前点的位置path2.lineTo(300,300);painter.drawPath(path2);}
void PainterTest::paintEvent(QPaintEvent *)
{QPainter painter(this);QPixmap pix;pix.load("images/4.ico");painter.drawPixmap(0,0,100,100,pix);painter.translate(50,50); //让图片的中心作为旋转的中心painter.rotate(90); //顺时针旋转90度qreal width = pix.width(); //获得以前图片的宽和高qreal height = pix.height();pix = pix.scaled(width*2,height*2,Qt::KeepAspectRatio);//将图片的宽和高都扩大两倍，并且在给定的矩形内保持宽高的比值painter.drawPixmap(100,100,pix);}