實名認證功能在很多APP中都有，最近我們也加入了上傳證件照功能，需要將裁剪后的身份證上傳后臺去校驗立莉，感覺也不難屁商，我就使用了常用的類庫對圖片進行裁剪:
extension UIImage {
func cropping(to rect: CGRect) -> UIImage{
var rect = rect
rect.origin.x *= self.scale
rect.origin.y *= self.scale
rect.size.width *= self.scale
rect.size.height *= self.scale
let imageRef = self.cgImage!.cropping(to: rect)
let image = UIImage.init(cgImage: imageRef!)
return image
}
}
咦烟很，不是我想要的樣子。為什么呢蜡镶？后來發(fā)現拍照出來的照片并不是像素是3020*4030雾袱，并不是我們認為的屏幕大小相同的尺寸，所以即使根據屏幕比也得不到準確的位置官还。實際我使用iPhone 12拍攝得到這樣尺寸的照片：
image.png
計算卡片所在位置
根據寬高比計算要截取身份證在圖片中的位置：
卡片的寬高比：1150 / 1940 = 0.59
卡片和照片的寬度比：1940 / 3020 = 0.64
卡片Y軸位置比：750 / 4030 = 0.18
實現如下芹橡，具體要根據自己卡片所在位置計算
func cropping(originImg: UIImage) -> UIImage? {
let originSize = originImg.size
let cardW = originSize.width * 0.64
let cardH = cartW * 0.59
let cardX = (originSize.width - cartW) / 2
let cardY = originSize.height * 0.18
let croppingRect = CGRect(x: cardX, y: cardY, width: cardW, height: cardH)
guard let sourceImageRef = originImg.cgImage else { return nil }
guard let newImageRef = sourceImageRef.cropping(to: croppingRect) else { return nil }
let thumbImage = UIImage.init(cgImage: newImageRef)
return thumbImage
}
照片旋轉問題
在這里還遇到一個問題就是拍照后的照片旋轉問題，UIImage在UIImageView顯示是沒有問題的望伦，但是在裁剪的時候得到的就是旋轉的照片林说，這里直說解決方法
extension UIImage {
func fixOrientation() -> UIImage{
if self.imageOrientation == .up{
return self
}
var transform = CGAffineTransform.identity
switch self.imageOrientation {
case .down, .downMirrored:
transform = transform.translatedBy(x:self.size.width, y:self.size.height)
transform = transform.rotated(by: .pi)
break
case .left, .leftMirrored:
transform = transform.translatedBy(x:self.size.width, y:0)
transform = transform.rotated(by: .pi/2)
break
case .right, .rightMirrored:
transform = transform.translatedBy(x:0, y:self.size.height)
transform = transform.rotated(by: -.pi/2)
break
default:
break
}
switch self.imageOrientation {
case .upMirrored, .downMirrored:
transform = transform.translatedBy(x:self.size.width, y:0)
transform = transform.scaledBy(x:-1, y:1)
break
case .leftMirrored, .rightMirrored:
transform = transform.translatedBy(x:self.size.height, y:0);
transform = transform.scaledBy(x:-1, y:1)
break
default:
break
}
let ctx = CGContext(data:nil, width:Int(self.size.width), height:Int(self.size.height), bitsPerComponent:self.cgImage!.bitsPerComponent, bytesPerRow:0, space:self.cgImage!.colorSpace!, bitmapInfo:self.cgImage!.bitmapInfo.rawValue)
ctx?.concatenate(transform)
switch self.imageOrientation {
case .left, .leftMirrored, .right, .rightMirrored:
ctx?.draw(self.cgImage!, in:CGRect(x:CGFloat(0), y:CGFloat(0), width:CGFloat(size.height), height:CGFloat(size.width)))
break
default:
ctx?.draw(self.cgImage!, in:CGRect(x:CGFloat(0), y:CGFloat(0), width:CGFloat(size.width), height:CGFloat(size.height)))
break
}
let cgimg:CGImage = (ctx?.makeImage())!
let img = UIImage(cgImage: cgimg)
return img
}
}
使用方式
let newImg = image.fixOrientation()
let thumbImage = cropping(originImg: newImg)
我是大自然的搬磚工，希望能夠幫到你屯伞，謝謝~
