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Simplify NSImageRep-checking logic to use Bundle. #1217

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merged 1 commit into from
Jul 10, 2025
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Simplify NSImageRep-checking logic to use Bundle. #1217

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57 changes: 22 additions & 35 deletions Sources/Overlays/_Testing_AppKit/Attachments/NSImage+AttachableAsCGImage.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,27 @@
public import AppKit
@_spi(Experimental) public import _Testing_CoreGraphics

extension NSImageRep {
/// AppKit's bundle.
private static let _appKitBundle: Bundle = Bundle(for: NSImageRep.self)

/// Whether or not this image rep's class is effectively thread-safe and can
/// be treated as if it conforms to `Sendable`.
fileprivate var isEffectivelySendable: Bool {
if isMember(of: NSImageRep.self) || isKind(of: NSCustomImageRep.self) {
// NSImageRep itself is an abstract class. NSCustomImageRep includes an
// arbitrary rendering block that may not be concurrency-safe in Swift.
return false
}

// Treat all other classes declared in AppKit as safe. We can't reason about
// classes declared in other bundles, so treat them all as if they're unsafe.
return Bundle(for: Self.self) == Self._appKitBundle
}
}

// MARK: -

@_spi(Experimental)
extension NSImage: AttachableAsCGImage {
public var attachableCGImage: CGImage {
Expand All @@ -32,29 +53,6 @@ extension NSImage: AttachableAsCGImage {
return maxRepWidth ?? 1.0
}

/// Get the base address of the loaded image containing `class`.
///
/// - Parameters:
/// - class: The class to look for.
///
/// - Returns: The base address of the image containing `class`, or `nil` if
/// no image was found (for instance, if the class is generic or dynamically
/// generated.)
///
/// "Image" in this context refers to a binary/executable image.
private static func _baseAddressOfImage(containing `class`: AnyClass) -> UnsafeRawPointer? {
let classAsAddress = Unmanaged.passUnretained(`class` as AnyObject).toOpaque()

var info = Dl_info()
guard 0 != dladdr(classAsAddress, &info) else {
return nil
}
return .init(info.dli_fbase)
}

/// The base address of the image containing AppKit's symbols, if known.
private static nonisolated(unsafe) let _appKitBaseAddress = _baseAddressOfImage(containing: NSImageRep.self)

public func _makeCopyForAttachment() -> Self {
// If this image is of an NSImage subclass, we cannot reliably make a deep
// copy of it because we don't know what its `init(data:)` implementation
Expand All @@ -69,18 +67,7 @@ extension NSImage: AttachableAsCGImage {

// Check whether the image contains any representations that we don't think
// are safe. If it does, then make a "safe" copy.
let allImageRepsAreSafe = representations.allSatisfy { imageRep in
// NSCustomImageRep includes an arbitrary rendering block that may not be
// concurrency-safe in Swift.
if imageRep is NSCustomImageRep {
return false
}

// Treat all other classes declared in AppKit as safe. We can't reason
// about classes declared in other modules, so treat them all as if they
// are unsafe.
return Self._baseAddressOfImage(containing: type(of: imageRep)) == Self._appKitBaseAddress
}
let allImageRepsAreSafe = representations.allSatisfy(\.isEffectivelySendable)
if !allImageRepsAreSafe, let safeCopy = tiffRepresentation.flatMap(Self.init(data:)) {
// Create a "safe" copy of this image by flattening it to TIFF and then
// creating a new NSImage instance from it.
Expand Down