Qt 绘制线段

2024-02-16 16:01:10

float x1 = lastPoint.x(); //lastPoint 起点
float y1 = lastPoint.y();
float x2 = endPoint.x(); //endPoint 终点
float y2 = endPoint.y();
float l = 10.0; //箭头的那长度
float a = 0.5; //箭头与线段角度
float x3 = x2 - l * cos(atan2((y2 - y1) , (x2 - x1)) - a);
float y3 = y2 - l * sin(atan2((y2 - y1) , (x2 - x1)) - a);
float x4 = x2 - l * sin(atan2((x2 - x1) , (y2 - y1)) - a);
float y4 = y2 - l * cos(atan2((x2 - x1) , (y2 - y1)) - a);
painter.drawLine(x1,y1,x3,y3);
painter.drawLine(x1,y1,x4,y4);
painter.drawLine(lastPoint,endPoint);