Return nil for the average color of a fully transparent image

[WuColin-1]

Summary

CGImage.averageColor(alphaThreshold:makeOpaque:) returns a color with all-NaN components when every pixel is below the alpha threshold. This makes it return nil instead.

Cause

Pixels below the threshold are excluded from includedPixelCount. When all of them are excluded, the final step divides the color totals by includedPixelCount * 255, which is zero, so each component becomes 0 / 0. A fully transparent capture of the menu bar is enough to trigger this, which is more likely with macOS 26/27's transparent menu bar. It's the same problem as jordanbaird#967.

Change

• Return nil when no pixel meets the alpha threshold.

The function already returns nil when it can't read pixel data, so callers already handle this case.

Testing

• Ran the old and new implementations on an 8×8 image:
  • Fully transparent: old returns [nan, nan, nan, nan], new returns nil.
  • Opaque: both return the same color.
• Built main with this change using Xcode 27.0 on macOS 27.0 (26A428).

🤖 Generated with Claude Code

Summary by Sourcery

Bug Fixes:

• Return nil when an image contains no pixels meeting the alpha threshold, preventing NaN average-color components for fully transparent images.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Updates CGImage average-color calculation to return nil when every pixel falls below the alpha threshold, preventing NaN components while preserving normal color averaging.

Flow diagram for transparent-image average color handling

flowchart TD
    A["CGImage.averageColor(alphaThreshold:makeOpaque:)"] --> B["Process image pixels"]
    B --> C{"includedPixelCount > 0"}
    C -->|Yes| D["Calculate average color"]
    C -->|No| E["Return nil"]

Loading

File-Level Changes

Change	Details	Files
Handle images with no pixels eligible for averaging by returning nil before normalization.	Add a guard for an included pixel count of zero. Avoid zero-division and NaN color components for fully transparent or below-threshold images. Preserve existing averaging behavior when at least one pixel passes the alpha threshold.	Ice/Utilities/Extensions.swift

---

Tips and commands

Interacting with Sourcery

• Trigger a new review: Comment @sourcery-ai review on the pull request.
• Continue discussions: Reply directly to Sourcery's review comments.
• Generate a GitHub issue from a review comment: Ask Sourcery to create an
  issue from a review comment by replying to it. You can also reply to a
  review comment with @sourcery-ai issue to create an issue from it.
• Generate a pull request title: Write @sourcery-ai anywhere in the pull
  request title to generate a title at any time. You can also comment
  @sourcery-ai title on the pull request to (re-)generate the title at any time.
• Generate a pull request summary: Write @sourcery-ai summary anywhere in
  the pull request body to generate a PR summary at any time exactly where you
  want it. You can also comment @sourcery-ai summary on the pull request to
  (re-)generate the summary at any time.
• Generate reviewer's guide: Comment @sourcery-ai guide on the pull
  request to (re-)generate the reviewer's guide at any time.
• Resolve all Sourcery comments: Comment @sourcery-ai resolve on the
  pull request to resolve all Sourcery comments. Useful if you've already
  addressed all the comments and don't want to see them anymore.
• Dismiss all Sourcery reviews: Comment @sourcery-ai dismiss on the pull
  request to dismiss all existing Sourcery reviews. Especially useful if you
  want to start fresh with a new review - don't forget to comment
  @sourcery-ai review to trigger a new review!

Customizing Your Experience

Access your dashboard to:

• Enable or disable review features such as the Sourcery-generated pull request
  summary, the reviewer's guide, and others.
• Change the review language.
• Add, remove or edit custom review instructions.
• Adjust other review settings.

Getting Help

• Contact our support team for questions or feedback.
• Visit our documentation for detailed guides and information.
• Keep in touch with the Sourcery team by following us on X/Twitter, LinkedIn or GitHub.

[sourcery-ai]

Hey - I've reviewed your changes and they look great!

Sourcery assessment

Approved.

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook