iPhone如何使两个连接的线跟随到的位置？

我用核心graphics和graphics做了一个讲话泡泡的尾巴

讲话布雷的尾巴应该移动到任何一点，如我所愿。

问题是当尾巴的末端部分（尖尖的部分）向下时，它工作正常。

但是，当泡沫倒挂时，就像泡沫部分在底部，尾部是在上面

顶部，尾部2连线互相交叉，形成一个X，当它应该是/

可以someonle请帮我吗？

double angle(CGPoint p1, CGPoint p2) { //BOOL bRev = TRUE; double dx = p2.x - p1.x; double dy = p2.y - p1.y; if (dx == 0 && dy == 0) return 0.0 if (dy == 0) { if (dx > 0) return 0.0; else return M_PI; } if (dx == 0) { if (dy > 0) { double ang = M_PI/2.0; //if (bRev) ang = M_PI*2 - ang; return ang; } else { double ang = M_PI/2.0 * 3; //if (bRev) ang = M_PI*2 - ang; return ang; } } if (dx > 0) { if (dy > 0) { double ang = atan((double)dy/(double)dx); // 1사분면 //if (bRev) ang = M_PI*2 - ang; return ang; } else { double ang = atan((double)dy/(double)dx) + 2.0*M_PI; // 4사분면 //if (bRev) ang = M_PI*2 - ang; return ang; } } else { double ang = atan((double)dy/(double)dx) + M_PI; //if (bRev) ang = M_PI*2 - ang; return ang; } return 0.0; } - (double)degree:(CGPoint)p1 and:(CGPoint)p2 { double rad = angle(p1, p2); double deg = rad * 180.0 / M_PI; if (deg >= 360.0) deg = deg - 360.0; return (deg); } - (CGPoint)getPoint:(CGPoint)cPt Len:(int)len BaseDegree:(double)d1 MoveDegree:(double)d2 { double radian = 3.14/180.0; CGPoint pt1; pt1.x = cPt.x + len*cos((d2-d1)*radian); pt1.y = cPt.y - len*sin((d2-d1)*radian); return pt1; } - (void)drawRect:(CGRect)rect{ double degree1 = [self degree:CGPointMake(view.frame.origin.x(view.frame.size.width)/2, view.frame.origin.y+(view.frame.size.height)/2) and:lastPt]; CGPoint cpt = CGPointMake(view.frame.origin.x+(view.frame.size.width)/2, view.frame.origin.y+(view.frame.size.height)/2); CGPoint p1 = [self getPoint:cpt Len:10 BaseDegree:degree1 MoveDegree:90]; CGPoint p2 = [self getPoint:cpt Len:10 BaseDegree:degree1 MoveDegree:-90]; CGPathMoveToPoint(ctx, nil, p1.x, p1.y); CGPathAddLineToPoint(ctx, nil, lastPt.x, lastPt.y); CGPathAddLineToPoint(ctx, nil, lastPt.x-2, lastPt.y+2); CGPathAddLineToPoint(ctx, nil, lastPt.x-4, lastPt.y); CGPathAddLineToPoint(ctx, nil, p2.x, p2.y); } 

Answer 1

在你的代码中，当你画线时，你正在计算开始点和结束点，但是最后你会看到：

 CGPathAddLineToPoint(ctx, nil, lastPt.x, lastPt.y); CGPathAddLineToPoint(ctx, nil, lastPt.x-2, lastPt.y+2); CGPathAddLineToPoint(ctx, nil, lastPt.x-4, lastPt.y); 

所以你总是把泡泡的底部/顶部/侧面的小V作为一个固定的正确的方式从左上angular，中间底部，右上angular，不pipe你正在画的是哪个方向。

你需要改变这一点，以确保那些-2 / +2响应你是哪种方式 – 例如，当你颠倒的时候，它应该以

 CGPathAddLineToPoint(ctx, nil, lastPt.x+4, lastPt.y); CGPathAddLineToPoint(ctx, nil, lastPt.x+2, lastPt.y-2); CGPathAddLineToPoint(ctx, nil, lastPt.x, lastPt.y); 

除了它应该被计算，不只是硬编码。