iOS 将图片等比例缩放

iOS 将图片等比例缩放

代码如下:

- (UIImage *)thumbnailWithImageWithoutScale:(UIImage *)image size:(CGSize)asize
{

UIImage *newimage;

if (nil == image)
{
newimage =
nil;
}
else {

CGSize oldsize = image.size;

CGRect rect;

if (asize.width/asize.height > oldsize.width/oldsize.height)
{
rect.size.width = asize.height*oldsize.width/oldsize.height;
rect.size.height = asize.height;
rect.origin.x = (asize.width
- rect.size.width)/2;
rect.origin.y =
0;
}
else {
rect.size.width = asize.width;
rect.size.height = asize.width*oldsize.height/oldsize.width;
rect.origin.x =
0;
rect.origin.y = (asize.height
- rect.size.height)/2;
}

UIGraphicsBeginImageContext(asize);

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetFillColorWithColor(context, [[UIColor
clearColor] CGColor]);

UIRectFill(CGRectMake(0,
0, asize.width, asize.height));//clear background
[image
drawInRect:rect];
newimage =
UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();
}

return newimage;
}