76 lines
2.5 KiB
Swift
76 lines
2.5 KiB
Swift
// Copyright 2024-present 650 Industries. All rights reserved.
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/**
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Transformer that makes sure the image is oriented up and not mirrored.
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Guarantees that the original pixel data matches the displayed orientation.
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*/
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internal struct ImageFixOrientationTransformer: ImageTransformer {
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func transform(image: UIImage) async throws -> UIImage {
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guard let cgImage = image.cgImage else {
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throw ImageNotFoundException()
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}
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guard var colorSpace = cgImage.colorSpace else {
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// That should never happen as `colorSpace` is empty only when the image is a mask.
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throw ImageColorSpaceNotFoundException()
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}
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if !colorSpace.supportsOutput {
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colorSpace = CGColorSpaceCreateDeviceRGB()
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}
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var transform = CGAffineTransform.identity
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switch image.imageOrientation {
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case .down, .downMirrored:
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transform = transform.translatedBy(x: image.size.width, y: image.size.height)
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transform = transform.rotated(by: Double.pi)
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case .left, .leftMirrored:
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transform = transform.translatedBy(x: image.size.width, y: 0)
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transform = transform.rotated(by: Double.pi / 2)
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case .right, .rightMirrored:
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transform = transform.translatedBy(x: 0, y: image.size.height)
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transform = transform.rotated(by: -Double.pi / 2)
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default:
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break
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}
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switch image.imageOrientation {
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case .upMirrored, .downMirrored:
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transform = transform.translatedBy(x: image.size.width, y: 0)
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transform = transform.scaledBy(x: -1, y: 1)
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case .leftMirrored, .rightMirrored:
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transform = transform.translatedBy(x: image.size.height, y: 0)
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transform = transform.scaledBy(x: -1, y: 1)
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default:
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break
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}
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let context = CGContext(
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data: nil,
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width: Int(image.size.width),
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height: Int(image.size.height),
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bitsPerComponent: cgImage.bitsPerComponent,
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bytesPerRow: 0,
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space: colorSpace,
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bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
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)
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guard let context = context else {
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throw ImageContextLostException()
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}
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context.concatenate(transform)
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switch image.imageOrientation {
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case .left, .leftMirrored, .right, .rightMirrored:
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context.draw(cgImage, in: CGRect(x: 0, y: 0, width: image.size.height, height: image.size.width))
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default:
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context.draw(cgImage, in: CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height))
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}
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guard let newCGImage = context.makeImage() else {
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throw ImageDrawingFailedException()
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}
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return UIImage(cgImage: newCGImage)
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}
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}
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