Sample CodemacOSReviewed 2026-07-21View on Apple Developer

Applying tone curve adjustments to images

At a glance

Item Summary
Purpose Use the vImage library’s polynomial transform to apply tone curve adjustments to images.
App architecture A Swift sample with the source-visible chain vImage_PolynomialAppContentViewPolynomialTransformerAccelerate APIs.
Main patterns SwiftUI environment injection, Binding-based state propagation, Publisher-backed observable state
Project style 6 scanned source file(s) across Swift, organized around ranked entry, type, and file boundaries.

Project structure

Source bundle/
├── vImage-Polynomial/
│   ├── vImage_PolynomialApp.swift
│   ├── ContentView.swift
│   ├── PolynomialTransformer.swift
│   ├── PolynomialEditor.swift
│   ├── PolynomialTransformer+LAPACK.swift
│   ├── PolynomialTransformer+ImageResize.swift
│   ├── Info.plist
│   └── vImage_Polynomial.entitlements
├── Configuration/
│   └── SampleCode.xcconfig
└── vImage-Polynomial.xcodeproj/
    ├── .xcodesamplecode.plist
    └── project.pbxproj

Structure observations

  • Architecturally prominent files are ranked from entry points and role-named declarations; resource-only paths are omitted.
  • Primary languages: Swift.
  • The verified tree contains 5 project/configuration file(s) and 5 source declaration(s).

Overall architecture

Reference code

vImage-Polynomial/vImage_PolynomialApp.swift:11 — architecture anchor

@main
struct vImagePolynomialApp: App {
    // ...
}

Interpretation

The arrows summarize the source-visible entry, role-named types or folders, and framework direction; when nodes come from structural folders, the sequence is a high-level interpretation rather than proof that every adjacent node calls the next. Ownership is claimed only where the next section cites a stored property or assignment. The diagram is intentionally limited to the dominant path into Accelerate.

Ownership and state

Ownership evidence

vImage-Polynomial/vImage_PolynomialApp.swift:13 — stored dependency or nearest verified ownership anchor

    @StateObject private var polynomialTransformer = PolynomialTransformer()
Owner Object or state Relationship Mutation authority
vImagePolynomialApp PolynomialTransformer (polynomialTransformer) owns wrapper-managed state Owning lexical scope
ContentView PolynomialTransformer (polynomialTransformer) receives environment-provided state The environment provider is authoritative
PolynomialTransformer PixelBuffer (srcInterleavedBuffer) stores or receives App/module collaborators
PolynomialTransformer PixelBuffer (destInterleavedBuffer) stores or receives App/module collaborators

Composition arrows indicate a source-visible construction expression or locally owned value state; aggregation means the owner stores or receives a dependency without proving exclusive lifetime ownership.

Class and protocol design

vImage-Polynomial/vImage_PolynomialApp.swift:12 — representative type boundary

struct vImagePolynomialApp: App {
    // ...
}
Type Responsibility Depends on or conforms to
vImagePolynomialApp Application entry and top-level composition App
ContentView User-interface presentation and input forwarding View
PolynomialTransformer Transforms feature data or representations ObservableObject
PolynomialEditor Represents a feature value or composable behavior View
LAPACKError Represents feature failure conditions Swift.Error

No local protocol conformance is claimed as protocol-oriented design; external framework conformances are listed only as dependencies.

Access control

Symbol Access Verified effect Likely rationale
selectNewImage (vImage-Polynomial/ContentView.swift:14) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: keep state mutation or dependency lifetime inside the owning implementation.
selectedIndex (vImage-Polynomial/PolynomialEditor.swift:16) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: keep state mutation or dependency lifetime inside the owning implementation.
polynomialTransformer (vImage-Polynomial/vImage_PolynomialApp.swift:13) private Use is restricted to the lexical declaration and same-file extensions allowed by Swift. Inference: keep state mutation or dependency lifetime inside the owning implementation.

Reference code

vImage-Polynomial/ContentView.swift:14 — representative boundary

struct ContentView: View {
    // ...
    @State private var selectNewImage = false
    // ...
}

Swift declarations without a modifier are internal; explicit private, fileprivate, private(set), public, or open entries above are interpreted by language semantics. Objective-C/C samples instead rely on header and implementation boundaries, which are not equivalent to Swift lexical privacy.

Logic ownership and placement

Logic Owning type or file Placement rationale
Application entry and top-level composition vImagePolynomialApp The source’s App suffix makes this role explicit.
Transforms feature data or representations PolynomialTransformer The source’s Transformer suffix makes this role explicit.
User-interface presentation and input forwarding ContentView The source’s View suffix makes this role explicit.

Design patterns

Pattern Source evidence Purpose or tradeoff
SwiftUI environment injection vImage-Polynomial/ContentView.swift:13 The environment supplies state or a capability without threading it through every initializer.
Binding-based state propagation vImage-Polynomial/PolynomialEditor.swift:14 A binding exposes controlled read/write access while the upstream owner remains authoritative.
Publisher-backed observable state vImage-Polynomial/PolynomialTransformer.swift:43 Published properties notify observers while mutation remains with the state object.

Naming conventions

  • Types: App: vImagePolynomialApp; Transformer: PolynomialTransformer; View: ContentView.
  • Protocols: no local protocol declaration in the scanned source.
  • Methods: setup, populatePlanarSourceBuffers, applyPolynomialsToAllChannels, calculateAndApplyPolynomial, displayPlanarDestinationBuffers, calculateCoefficients, resetValues, zeroValues.
  • Files: vImage-Polynomial/ContentView.swift, vImage-Polynomial/PolynomialTransformer.swift, vImage-Polynomial/PolynomialEditor.swift.

Architecture takeaways

  • vImage_PolynomialApp is the main source-visible entry or composition anchor for this sample.
  • Framework work reaches Accelerate, SwiftUI, Cocoa, PhotosUI through a deliberately small high-level chain; the detailed API graph remains inside the cited implementation files.
  • Stored-property evidence identifies lifecycle collaboration; it does not by itself prove exclusive object ownership.
  • Access-control conclusions separate verified language visibility from the likely design rationale.
  • The source does not justify labeling the design protocol-oriented.

Source map

Source file Relevant symbols
vImage-Polynomial/vImage_PolynomialApp.swift vImagePolynomialApp
vImage-Polynomial/ContentView.swift ContentView, ContentView_Previews
vImage-Polynomial/PolynomialTransformer.swift PolynomialTransformer
vImage-Polynomial/PolynomialEditor.swift PolynomialEditor
vImage-Polynomial/PolynomialTransformer+LAPACK.swift LAPACKError
vImage-Polynomial/PolynomialTransformer+ImageResize.swift Feature implementation