Qt 在Label上面绘制罗盘

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 point

QTransform 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

Qt

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