iphone处理图片的两个方法

获取图片中间的正方形

+(UIImage*)smallImage:(UIImage*)bigImg

{

CGSize imgsize = bigImg.size;

 

NSInteger w = imgsize.width>imgsize.height?imgsize.height:imgsize.width;

CGRect rect;

if(imgsize.width>imgsize.height)

{

rect = CGRectMake((imgsize.width-imgsize.height)/2, 0, w, w);

}

else {

rect = CGRectMake(0, (imgsize.height-imgsize.width)/2, w, w);

}

CGImageRef imageRef = CGImageCreateWithImageInRect([bigImg CGImage], rect);

  UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];

  CGImageRelease(imageRef);

  return croppedImage;

}

按照等比例缩放后的图片

+(UIImage*)CompressImage:(UIImage*)bigImg

{

CGSize imgsize = bigImg.size;

 

CGRect rect = CGRectMake(0, 0, imgsize.width, imgsize.height);

CGImageRef imageRef = CGImageCreateWithImageInRect([bigImg CGImage], rect);

  UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];

  CGImageRelease(imageRef);

 

int h = croppedImage.size.height;

int w = croppedImage.size.width;

float b = (float)kAppIconWeidth/w < (float)kAppIconHeight/h ? (float)kAppIconWeidth/w : (float)kAppIconHeight/h;

UIImage *img = nil;

CGSize itemSize = CGSizeMake(b*w, b*h);

UIGraphicsBeginImageContext(itemSize);

CGRect imageRect = CGRectMake(0, 0, b*w, b*h);

[croppedImage drawInRect:imageRect];

img = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

 

return img;

}

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