Fix Touch Issue

[Fifteen15Studios]

Fix issue where touching the first item in a pie chart does not always register properly.

Summary by CodeRabbit

• Bug Fixes
  • Improved click-detection accuracy for pie charts, particularly at angle boundaries.

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[coderabbitai]

📝 Walkthrough

Walkthrough

The PieChart click-detection logic is enhanced by adding modulo 360 normalization to two angles—touchAngle and normalizedAngle—to properly handle angle wrap-around edge cases during user interaction detection.

Changes

Cohort / File(s)	Summary
PieChart Click-Detection charty/src/commonMain/kotlin/com/himanshoe/charty/pie/PieChart.kt	Added modulo 360 normalization to touchAngle and normalizedAngle in click-detection logic to handle angle wrap-around edge cases.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🥕 A rabbit's note on angles true,
Spinning 'round at 360 we go,
Modulo keeps clicks right on cue,
No wraparound steals the show! 🥧

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Title check	❓ Inconclusive	The title 'Fix Touch Issue' is vague and generic. While it relates to the changeset (touch detection in PieChart), it lacks specificity about what the actual fix is—the modulo 360 normalization for angle calculations.	Consider a more descriptive title such as 'Fix pie chart touch detection with angle normalization' or 'Normalize angles in pie chart click detection to fix touch registration issues'.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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[Fifteen15Studios]

This can be a little prettier, and use your constant, by using the following lines instead:

else touchAngle %= FULL_CIRCLE_DEGREES

and

else normalizedAngle %= FULL_CIRCLE_DEGREES

And technically normalizedAngle is the one the fixes the issue, but both should be properly adjusted to be below 360.

[Fifteen15Studios]

This bug is caused when config.startAngleDegrees is negative, such as the default of -90f, and the user clicks somewhere in the top right quarter of the circle. (Less than config.startAngleDegrees from the X axis.) When this happens, the touch angle is between 270 and 360, then normalizedAngle is set to touchAngle - config.startAngleDegrees which is more than 360 degrees.

Example: config.startAngleDegrees = -90f and Touch is at 280 degrees.

touchAngle - config.startAngleDegrees becomes 280 -(-90) or 280 + 90 which is 370.

When the comparison is made of normalizedAngle < currentAngle + sweepAngle, normalizedAngle is always going to be larger, since it is more than a full circular rotation, so this can never be true. By using mod 360, we change normalizedAngle from 370 to 10, which satisfies this comparison.