56 lines
1.6 KiB
Swift
56 lines
1.6 KiB
Swift
//
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// https://mczachurski.dev
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// Copyright © 2023 Marcin Czachurski and the repository contributors.
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// Licensed under the Apache License 2.0.
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//
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import UIKit
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extension UIImage.Orientation {
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var exifOrientation: Int32 {
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switch self {
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case .up: return 1
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case .down: return 3
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case .left: return 8
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case .right: return 6
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case .upMirrored: return 2
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case .downMirrored: return 4
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case .leftMirrored: return 5
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case .rightMirrored: return 7
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@unknown default: return 1
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}
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}
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}
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extension UIImage {
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func resized(to targetSize: CGSize) -> UIImage {
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guard let sourceImage = CIImage(image: self, options: [.applyOrientationProperty: true]) else {
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return self
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}
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// We have to store correct image orientation.
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let orientedImage = sourceImage.oriented(forExifOrientation: self.imageOrientation.exifOrientation)
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// Filter.
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let resizeFilter = CIFilter(name: "CILanczosScaleTransform")!
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// Compute scale.
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let scale = targetSize.width / orientedImage.extent.width
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// Apply resizing
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resizeFilter.setValue(orientedImage, forKey: kCIInputImageKey)
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resizeFilter.setValue(scale, forKey: kCIInputScaleKey)
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resizeFilter.setValue(1.0, forKey: kCIInputAspectRatioKey)
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guard let result = resizeFilter.value(forKey: kCIOutputImageKey) as? CIImage else {
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return self
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}
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guard let resizedCGImage = CIContext(options: nil).createCGImage(result, from: result.extent) else {
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return self
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}
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return UIImage(cgImage: resizedCGImage)
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}
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}
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