rantlab post 1.1

gistfile1.matlab

+ (CGPathRef )createPathWithArrowFromPoint:(CGPoint)startPoint
                                   toPoint:(CGPoint)endPoint
                                 tailWidth:(CGFloat)tailWidth
                                 headWidth:(CGFloat)headWidth
                                headLength:(CGFloat)headLength
                                    wiggle:(CGFloat)wiggle
{
    CGFloat length = hypotf(endPoint.x - startPoint.x, endPoint.y - startPoint.y);
    
    CGPoint points[9];
    
    CGFloat deflection = wiggle*length/4.0;
    CGFloat tailLength = length - headLength;
    CGFloat halfTail = tailWidth/2.0;
    
    points[0] = CGPointMake(0, halfTail);
    points[1] = CGPointMake(tailLength/2, deflection + halfTail);
    points[2] = CGPointMake(tailLength, halfTail);
    points[3] = CGPointMake(tailLength, headWidth / 2);
    points[4] = CGPointMake(length, 0);
    points[5] = CGPointMake(tailLength, -headWidth / 2);
    points[6] = CGPointMake(tailLength, -halfTail);
    points[7] = CGPointMake(tailLength/2,  -halfTail + deflection);
    points[8] = CGPointMake(0, -halfTail);
    
    CGAffineTransform transform = [self transformForStartPoint:startPoint
                                                      endPoint:endPoint
                                                        length:length];
    
    CGMutablePathRef cgPath = CGPathCreateMutable();
    CGPathMoveToPoint(cgPath, &transform, points[0].x, points[0].y);

    CGPathAddQuadCurveToPoint(cgPath, &transform, points[1].x, points[1].y, points[2].x, points[2].y);
    
    CGPathAddLineToPoint(cgPath, &transform, points[3].x, points[3].y);
    CGPathAddLineToPoint(cgPath, &transform, points[4].x, points[4].y);
    CGPathAddLineToPoint(cgPath, &transform, points[5].x, points[5].y);
    CGPathAddLineToPoint(cgPath, &transform, points[6].x, points[6].y);

    CGPathAddQuadCurveToPoint(cgPath, &transform, points[7].x, points[7].y, points[8].x, points[8].y);    

    CGPathCloseSubpath(cgPath);
    
    return cgPath;
}

+ (CGAffineTransform)transformForStartPoint:(CGPoint)startPoint
                                   endPoint:(CGPoint)endPoint
                                     length:(CGFloat)length
{
    CGFloat cosine = (endPoint.x - startPoint.x) / length;
    CGFloat sine = (endPoint.y - startPoint.y) / length;
    return (CGAffineTransform){ cosine, sine, -sine, cosine, startPoint.x, startPoint.y };
}