UIImage的旋转

以下两种方式都是用于UIImage的旋转
+(UIImage *)rotate: (UIImage *)image
{
   
double angle = 45;
   
CGSize s = {image.size.width, image.size.height};

    UIGraphicsBeginImageContext(s);

    CGContextRef ctx =
UIGraphicsGetCurrentContext();

    CGContextTranslateCTM(ctx,
0,image.size.height);

    CGContextScaleCTM(ctx,
1.0, -1.0);

    
   
CGContextRotateCTM(ctx,
2*M_PI*angle/360);
   
CGContextDrawImage(ctx,CGRectMake(0,0,image.size.width,
image.size.height),image.CGImage);

    UIImage *newImage =
UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();
   
return newImage;

    
}

+ (UIImage *)scaleAndRotateImage:(UIImage *)image  {

    
   
CGImageRef imgRef = image.CGImage;

    
   
CGFloat width = CGImageGetWidth(imgRef);
   
CGFloat height = CGImageGetHeight(imgRef);

    

    CGAffineTransform transform =
CGAffineTransformIdentity;
   
CGRect bounds = CGRectMake(0,
0, width, height);

    
   
CGFloat boundHeight;

    
    boundHeight = bounds.size.height;
    bounds.size.height = bounds.size.width;
    bounds.size.width = boundHeight;

    transform = CGAffineTransformMakeScale(-1.0,
1.0);
    transform =
CGAffineTransformRotate(transform,
M_PI / 2.0);
//use angle/360 *MPI

    

    UIGraphicsBeginImageContext(bounds.size);

    CGContextRef context =
UIGraphicsGetCurrentContext();
   
CGContextConcatCTM(context, transform);
   
CGContextDrawImage(context,
CGRectMake(0,
0, width, height), imgRef);

    UIImage *imageCopy =
UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    
   
return imageCopy;

    
}