86 lines
3.1 KiB
Swift
86 lines
3.1 KiB
Swift
import Foundation
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import AppKit // NSImage
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private import CoreUI // CUICatalog
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private import os // OSLog
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private let log = OSLog(subsystem: Bundle.main.bundleIdentifier!, category: "AssetCarReader")
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public class CarReader {
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private let catalog: CUICatalog
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public init?(_ data: Data) {
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do {
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catalog = try data.withUnsafeBytes { try CUICatalog(bytes: $0.baseAddress!, length: UInt64(data.count)) }
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} catch {
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os_log(.error, log: log, "[asset-car] ERROR: could not open catalog: %{public}@", error.localizedDescription)
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return nil
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}
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}
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/// Use `CUICatalog` to extract an image from `Assets.car`
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public func imageFromAssetsCar(_ imageName: String) -> NSImage? {
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if let validName = verifyNameExists(imageName, in: catalog) {
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if let bestImage = findHighestResolutionIcon(catalog.images(withName: validName)) {
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os_log(.debug, log: log, "[asset-car] using Assets.car with key %{public}@", validName)
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return NSImage(cgImage: bestImage.image, size: bestImage.size)
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}
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}
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return nil;
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}
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// MARK: - Private methods
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/// Helper method to check available icon names. Will return a valid name or `nil` if no image with that key is found.
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private func verifyNameExists(_ imageName: String, in catalog: CUICatalog) -> String? {
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if let availableNames = catalog.allImageNames(), !availableNames.contains(imageName) {
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// Theoretically this should never happen. Assuming the image name is found in an image file.
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os_log(.info, log: log, "[asset-car] WARN: key '%{public}@' does not match any available key", imageName)
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if let alternativeName = searchAlternativeName(imageName, inAvailable: availableNames) {
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os_log(.info, log: log, "[asset-car] falling back to '%{public}@'", alternativeName)
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return alternativeName
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}
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os_log(.debug, log: log, "[asset-car] available keys: %{public}@", catalog.allImageNames() ?? [])
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return nil
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}
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return imageName;
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}
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/// If exact name does not exist in catalog, search for a name that shares the same prefix.
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/// E.g., "AppIcon60x60" may match "AppIcon" or "AppIcon60x60_small"
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private func searchAlternativeName(_ originalName: String, inAvailable availableNames: [String]) -> String? {
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var bestOption: String? = nil
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var bestDiff: Int = 999
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for option in availableNames {
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if option.hasPrefix(originalName) || originalName.hasPrefix(option) {
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let thisDiff = max(originalName.count, option.count) - min(originalName.count, option.count)
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if thisDiff < bestDiff {
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bestDiff = thisDiff
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bestOption = option
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}
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}
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}
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return bestOption
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}
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/// Given a list of `CUINamedImage`, return the one with the highest resolution. Vector graphics are ignored.
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private func findHighestResolutionIcon(_ availableImages: [CUINamedImage]) -> CUINamedImage? {
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var largestWidth: CGFloat = 0
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var largestImage: CUINamedImage? = nil
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// cast to NSArray is necessary as otherwise this will crash
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for img in availableImages as NSArray {
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guard let img = img as? CUINamedImage else {
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continue // ignore CUINamedMultisizeImageSet
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}
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let w = img.size.width
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if w > largestWidth {
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largestWidth = w
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largestImage = img
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}
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}
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return largestImage
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}
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}
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