《IOS5基础教程》随书源代码

/* * CGPointUtils.c * PinchMe * * Created by Jeff LaMarche on 8/2/08. * Copyright 2008 __MyCompanyName__. All rights reserved. * */ #include "CGPointUtils.h" #include <math.h> #define degreesToRadian(x) (M_PI * x / 180.0) #define radiansToDegrees(x) (180.0 * x / M_PI) CGFloat distanceBetweenPoints (CGPoint first, CGPoint second) { CGFloat deltaX = second.x - first.x; CGFloat deltaY = second.y - first.y; return sqrt(deltaX*deltaX + deltaY*deltaY ); }; CGFloat angleBetweenPoints(CGPoint first, CGPoint second) { CGFloat height = second.y - first.y; CGFloat width = first.x - second.x; CGFloat rads = atan(height/width); return radiansToDegrees(rads); //degs = degrees(atan((top - bottom)/(right - left))) } CGFloat angleBetweenLines(CGPoint line1Start, CGPoint line1End, CGPoint line2Start, CGPoint line2End) { CGFloat a = line1End.x - line1Start.x; CGFloat b = line1End.y - line1Start.y; CGFloat c = line2End.x - line2Start.x; CGFloat d = line2End.y - line2Start.y; CGFloat rads = acos(((a*c) + (b*d)) / ((sqrt(a*a + b*b)) * (sqrt(c*c + d*d)))); return radiansToDegrees(rads); }