自己写的一个小小的电子罗盘的一个小程序，不过是项目的一部分，只可以贴绘制部分代码
效果如下图
首先开始自己写的时候，虽然知道Qt 的坐标系是从左上角开始的，所以，使用了算法，在绘制后，在移动回来，但是只有45度的时候可以实现，其它角度都是有问题的。
和前辈请教，先移动坐标在绘制，在使用过程中，忘记调用
painter1.save();函数，到时失败，仔细检查是才发现少些了一行。
上核心代码
void MainWidget::draw_Direction()
{QPainter painter1(ui->label_Direction);painter1.setRenderHint(QPainter::Antialiasing,true);painter1.setPen(QPen(QColor(Qt::blue),1.5,Qt::SolidLine,Qt::FlatCap));/** move pointQTransform t_y;t_y.rotate(-90,Qt::YAxis);painter1.setTransform(t_y);int temp =30;QTransform t_z;t_z.rotate(temp,Qt::ZAxis);painter1.setTransform(t_z);painter1.translate(0+135*qCos(30*PI/180.0),0-135*qSin(30*PI/180.0));painter1.translate(0-39+96,0-39-96);painter1.translate((0-(((135/(qCos(45*PI/180.0)))*qSin((temp+45)*PI/180.0)-135)*(qSin(temp*PI/180.0)))+(135-((135/(qCos(45*PI/180.0)))*qCos((temp+45)*PI/180.0)))),((0-(((135/(qCos(45*PI/180.0)))*qSin((temp+45)*PI/180.0)-135)*(qCos(temp*PI/180.0))))-(135-((135/(qCos(45*PI/180.0)))*qSin((temp+45)*PI/180.0)))));painter1.translate(0-((TEMP_R*qSin((temp+45)*PI/180.0))-135)*qCos((temp)*PI/180.0)+(TEMP_R*qCos((temp)*PI/180.0))* qCos((temp)*PI/180.0),0-((TEMP_R*qSin((temp+45)*PI/180.0))-135)*qSin((temp)*PI/180.0)-(TEMP_R*qCos((temp)*PI/180.0))* qSin((temp)*PI/180.0));qDebug()<<(TEMP_R*qCos((temp)*PI/180.0))* qSin((temp)*PI/180.0);*/painter1.translate(135,135);painter1.save();painter1.rotate(num_Angle);for(int i = 0;i<360;){if((i%90) == 0){painter1.drawLine(0+(95*qSin(i*PI/180.0)),0-(95*qCos(i*PI/180.0)),0+(100*qSin(i*PI/180.0)),0-(100*qCos(i*PI/180.0)));i=i+30;}painter1.drawLine(0+(95*qSin(i*PI/180.0)),0-(95*qCos(i*PI/180.0)),0+(110*qSin(i*PI/180.0)),0-(110*qCos(i*PI/180.0)));i=i+30;}for(int j = 0;j<360;){if((j%30) == 0 || (j%90) == 0){j= j+10;}painter1.drawLine(0+(100*qSin(j*PI/180.0)),0-(100*qCos(j*PI/180.0)),0+(110*qSin(j*PI/180.0)),0-(110*qCos(j*PI/180.0)));j=j+10;}painter1.setPen(QPen(QColor(Qt::blue),3,Qt::SolidLine,Qt::FlatCap));QRect rect1(-7,-113,15,15);QRect rect1_1(-7,-95,15,15);QRect rect2(-112,-9,15,15);QRect rect3(-7,103,15,15);QRect rect4(100,-9,15,15);QString str_N = "N";QString str_S = "S";QString str_W = "W";QString str_E = "E";QFont font("宋体",16,QFont::Bold);painter1.setFont(font);painter1.drawText(rect1,Qt::AlignCenter,str_N);painter1.drawText(rect2,Qt::AlignCenter,str_W);painter1.drawText(rect3,Qt::AlignCenter,str_S);painter1.drawText(rect4,Qt::AlignCenter,str_E);QPixmap pixmap_pointer;pixmap_pointer.load(":/Global/Source/Global/Pointer.png");painter1.drawPixmap(rect1_1,pixmap_pointer);painter1.restore();QRect rect_pixmap(-15,-15,30,30);QPixmap pixmap_plane;pixmap_plane.load(":/Global/Source/Global/Plane.png");painter1.drawPixmap(rect_pixmap,pixmap_plane);
}
至于好多人不知道怎么在Lable上面绘图，可以参考我以前写的
Qt 在控件上面绘图 label，pushbutton。。。。。
http://blog.csdn.net/z609932088/article/details/50952086
