fix: mitigate the UI jumping issue when resizing the window on iPad

[guoyingtao]

Summary by CodeRabbit

• Refactor
  • Updated crop view to batch asynchronous updates with a slight delay, improving handling of rapid crop adjustments.

[Copilot]

Pull Request Overview

This PR addresses a UI jumping issue on iPad during window resizing by implementing a debounce mechanism. The fix prevents rapid, successive UI adjustments that can cause visual flickering when the window dimensions change.

Key Changes:

• Added debounce logic to delay UI adjustments during window resize events
• Introduced a 200ms delay before processing resize-triggered UI updates

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[Copilot]

[nitpick] The debounce delay of 0.2 seconds is a magic number. Consider extracting it to a named constant (e.g., private let debounceDelay: TimeInterval = 0.2) at the class level to improve maintainability and make it easier to adjust if needed.

[coderabbitai]

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Walkthrough

CropView now debounces UI updates by introducing a private DispatchWorkItem that schedules adjustUIForNewCrop completion handling on a 0.2-second delay, replacing immediate execution with batched asynchronous updates while preserving final effects.

Changes

Cohort / File(s)	Change Summary
Debounce UI Updates Sources/Mantis/CropView/CropView.swift	Added private debounceWorkItem property and refactored two completion handlers for adjustUIForNewCrop(...) to schedule UI adjustments and status updates with 0.2-second delay via DispatchWorkItem, canceling previous pending items before scheduling new ones.

Sequence Diagram

sequenceDiagram
    participant User
    participant CropView
    participant DispatchQueue
    participant UISystem

    rect rgb(220, 240, 255)
    Note over User,UISystem: Before: Immediate Execution
    User->>CropView: Trigger crop adjustment
    CropView->>CropView: adjustUIForNewCrop()
    CropView->>UISystem: Update UI
    CropView->>CropView: setBetweenOperationStatus()
    end

    rect rgb(220, 255, 220)
    Note over User,UISystem: After: Debounced Execution
    User->>CropView: Trigger crop adjustment (1st)
    CropView->>DispatchQueue: Schedule work item (0.2s delay)
    User->>CropView: Trigger crop adjustment (2nd)
    CropView->>DispatchQueue: Cancel previous, reschedule (0.2s delay)
    DispatchQueue->>CropView: Execute after 0.2s
    CropView->>CropView: adjustUIForNewCrop()
    CropView->>UISystem: Update UI (batched)
    CropView->>CropView: setBetweenOperationStatus()
    end

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Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

The change is concentrated in a single file with a clear, consistent pattern of debounce logic applied identically to two locations. The implementation is straightforward—adding a private property and replacing two completion handlers with delayed dispatch calls—requiring minimal context and focused verification of timing behavior.

Poem

🐰 A crop so swift, we slow it down,
With debounce's gentle, patient crown,
Two hundred milliseconds to breathe and rest,
Batched updates prove smoother is best!
🥕✨

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title Check	✅ Passed	The pull request title "fix: mitigate the UI jumping issue when resizing the window on iPad" directly aligns with the changes in the changeset. The primary modification introduces debouncing via a 0.2-second delay to UI updates in CropView, which is a standard technique to prevent UI jumping and flickering during rapid operations like window resizing. The title is concise, specific, and clearly communicates the purpose and context of the fix to a reviewer. It avoids vague terminology and accurately represents the main intent of the changes without being misleading.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/477

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📜 Recent review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 1cda2a8 and eed3000.

📒 Files selected for processing (1)

• Sources/Mantis/CropView/CropView.swift (2 hunks)

🧰 Additional context used

🧬 Code graph analysis (1)

Sources/Mantis/CropView/CropView.swift (1)

Sources/Mantis/Protocols/CropViewModelProtocol.swift (1)

• setBetweenOperationStatus (82-84)

🔇 Additional comments (2)

Sources/Mantis/CropView/CropView.swift (2)

66-66: LGTM! Property declaration is appropriate.

The private optional DispatchWorkItem property is correctly declared for storing the pending debounced work item.

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883-892: Good debouncing implementation to fix UI jumping.

The debounce logic correctly prevents multiple rapid UI adjustments during window resizing by cancelling pending work and scheduling a new update. The weak self captures are appropriate.

Consider cancelling the work item in deinit to avoid leaving scheduled work in the dispatch queue after deallocation:

 deinit {
+    debounceWorkItem?.cancel()
     print("CropView deinit.")
 }

Additionally, verify that the 0.2-second delay provides smooth behavior during various iPad window resize scenarios (e.g., rapid repeated resizes, resize then immediate user interaction).

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