Created
February 15, 2018 20:14
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Swift macOS generate image previews of files on disk
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| func generatePreview() { | |
| guard let fileURL = upload?.fileURL else { return } | |
| do { | |
| let values = try fileURL.resourceValues(forKeys: [URLResourceKey.typeIdentifierKey]) | |
| if let type = values.typeIdentifier, | |
| UTTypeConformsTo(type as CFString, kUTTypeImage) { | |
| if let imageData = FileManager.default.contents(atPath: fileURL.path) { | |
| self.imagePreview.image = NSImage(data: imageData) | |
| } | |
| } | |
| } | |
| catch { | |
| Logger.error("Failed to lookup resource values") | |
| } | |
| } |
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| import AppKit | |
| import QuickLook | |
| extension NSImage { | |
| static func previewForFile(path fileURL: URL, ofSize size: CGSize, asIcon: Bool) -> NSImage? { | |
| let dict = [ | |
| kQLThumbnailOptionIconModeKey: NSNumber(booleanLiteral: asIcon) | |
| ] as CFDictionary | |
| let ref = QLThumbnailImageCreate(kCFAllocatorDefault, fileURL as CFURL, size, dict) | |
| if let cgImage = ref?.takeUnretainedValue() { | |
| // Take advantage of NSBitmapImageRep's -initWithCGImage: initializer, new in Leopard, | |
| // which is a lot more efficient than copying pixel data into a brand new NSImage. | |
| // Thanks to Troy Stephens @ Apple for pointing this new method out to me. | |
| let bitmapImageRep = NSBitmapImageRep.init(cgImage: cgImage) | |
| let newImage = NSImage.init(size: bitmapImageRep.size) | |
| newImage.addRepresentation(bitmapImageRep) | |
| ref?.release() | |
| return newImage | |
| } else { | |
| // If we couldn't get a Quick Look preview, fall back on the file's Finder icon. | |
| let icon = NSWorkspace.shared.icon(forFile: fileURL.path) | |
| icon.size = size | |
| return icon | |
| } | |
| } | |
| } |
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NSImage+QuickLook original taken from https://github.com/incbee/NSImage-QuickLook and ported to swift4