我需要按比例縮小圖像，但要采用清晰的方式。例如，在Photoshop中，圖像尺寸縮小選項(xiàng)為“ Bicubic Smoother”（模糊）和“ Bicubic Sharper”。該圖像縮小算法是在某個(gè)地方開(kāi)源或記錄的，還是SDK提供了執(zhí)行此操作的方法？
3 回答
慕斯王
TA貢獻(xiàn)1864條經(jīng)驗(yàn) 獲得超2個(gè)贊
如果有人正在尋找Swift版本，這是@Dan Rosenstark接受的答案的Swift版本：
func resizeImage(image: UIImage, newHeight: CGFloat) -> UIImage {
let scale = newHeight / image.size.height
let newWidth = image.size.width * scale
UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight))
image.drawInRect(CGRectMake(0, 0, newWidth, newHeight))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage
}
眼眸繁星
TA貢獻(xiàn)1873條經(jīng)驗(yàn) 獲得超9個(gè)贊
對(duì)于那些使用Swift的人，這是Swift中公認(rèn)的答案：
func resizeImage(image: UIImage, newSize: CGSize) -> (UIImage) {
let newRect = CGRectIntegral(CGRectMake(0,0, newSize.width, newSize.height))
let imageRef = image.CGImage
UIGraphicsBeginImageContextWithOptions(newSize, false, 0)
let context = UIGraphicsGetCurrentContext()
// Set the quality level to use when rescaling
CGContextSetInterpolationQuality(context, kCGInterpolationHigh)
let flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, newSize.height)
CGContextConcatCTM(context, flipVertical)
// Draw into the context; this scales the image
CGContextDrawImage(context, newRect, imageRef)
let newImageRef = CGBitmapContextCreateImage(context) as CGImage
let newImage = UIImage(CGImage: newImageRef)
// Get the resized image from the context and a UIImage
UIGraphicsEndImageContext()
return newImage
}
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