typedef struct CGAffineTransform CGAffineTransform;
struct CGAffineTransform {
CGFloat a, b, c, d;
CGFloat tx, ty;
};
const CGAffineTransform CGAffineTransformIdentity；
CGAffineTransform CGAffineTransformMake(CGFloat a, CGFloat b,
CGFloat c, CGFloat d, CGFloat tx, CGFloat ty)；
CGAffineTransform CGAffineTransformMakeTranslation(CGFloat tx,
CGFloat ty) ;
//大小变化
CGAffineTransform CGAffineTransformMakeScale(CGFloat sx, CGFloat sy)；
//旋转
CGAffineTransform CGAffineTransformMakeRotation(CGFloat angle)；
bool CGAffineTransformIsIdentity(CGAffineTransform t)；
CGAffineTransform CGAffineTransformTranslate(CGAffineTransform t,
CGFloat tx, CGFloat ty)；
//在t的基础上放大变化
CGAffineTransform CGAffineTransformScale(CGAffineTransform t,
CGFloat sx, CGFloat sy) ；
CGAffineTransform CGAffineTransformInvert(CGAffineTransform t)；
CGAffineTransform CGAffineTransformConcat(CGAffineTransform t1,
CGAffineTransform t2)；
bool CGAffineTransformEqualToTransform(CGAffineTransform t1,
CGAffineTransform t2)；
CGPoint CGPointApplyAffineTransform(CGPoint point,
CGAffineTransform t)；
GSize CGSizeApplyAffineTransform(CGSize size, CGAffineTransform t)；
CGRect CGRectApplyAffineTransform(CGRect rect, CGAffineTransform t)；