怎么用java画箭头

怎么用java画箭头

public void paintk(GC g, int x1, int y1, int x2, int y2) {

double H = 10 ; // 箭头高度
double L = 7 ; // 底边的一半
int x3 = 0 ;
int y3 = 0 ;
int x4 = 0 ;
int y4 = 0 ;
double awrad = Math.atan(L / H); // 箭头角度
double arraow_len = Math.sqrt(L * L + H * H); // 箭头的长度
double [] arrXY_1 = rotateVec(x2 - x1, y2 - y1, awrad, true , arraow_len);
double [] arrXY_2 = rotateVec(x2 - x1, y2 - y1, - awrad, true , arraow_len);
double x_3 = x2 - arrXY_1[ 0 ]; // (x3,y3)是第一端点
double y_3 = y2 - arrXY_1[ 1 ];
double x_4 = x2 - arrXY_2[ 0 ]; // (x4,y4)是第二端点
double y_4 = y2 - arrXY_2[ 1 ];

Double X3 = new Double(x_3);
x3 = X3.intValue();
Double Y3 = new Double(y_3);
y3 = Y3.intValue();
Double X4 = new Double(x_4);
x4 = X4.intValue();
Double Y4 = new Double(y_4);
y4 = Y4.intValue();
// g.setColor(SWT.COLOR_WHITE);
// 画线
g.drawLine(x1, y1, x2, y2);
// 画箭头的一半
g.drawLine(x2, y2, x3, y3);
// 画箭头的另一半
g.drawLine(x2, y2, x4, y4);

}



public double [] rotateVec( int px, int py, double ang, boolean isChLen,
double newLen) {

double mathstr[] = new double [ 2 ];
// 矢量旋转函数，参数含义分别是x分量、y分量、旋转角、是否改变长度、新长度
double vx = px * Math.cos(ang) - py * Math.sin(ang);
double vy = px * Math.sin(ang) + py * Math.cos(ang);
if (isChLen) {
double d = Math.sqrt(vx * vx + vy * vy);
vx = vx / d * newLen;
vy = vy / d * newLen;
mathstr[ 0 ] = vx;
mathstr[ 1 ] = vy;
}
return mathstr;
}

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