「Objective-C」iosで画像の幾何学変換のサンプルコード

2015年2月9日

参考ソースコード：
+ (UIImage *)thumbnailWithImageWithoutScale:(UIImage *)image
size:(CGSize)asize
{
UIImage *newimage = nil;
if (image)
{
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));
[image drawInRect:rect];
newimage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
return newimage;
}