Refactor BuildBitArrayFromSegment

[Shane32]

Building on #670 towards multi-mode support

Summary by CodeRabbit

• New Features
  • Improved QR code generation with enhanced ECI (extended character encoding) handling for more reliable international character support across versions.
• Refactor
  • Simplified and consolidated how segment data is serialized into the final bit stream, improving maintainability and clarifying data flow.

[coderabbitai]

📝 Walkthrough

Walkthrough

Moves segment bit-array construction into DataSegment by adding a constructor and methods (ToBitArray, WriteTo). QRCodeGenerator now calls segment.ToBitArray(version) and the former private helper BuildBitArrayFromSegment is removed.

Changes

Cohort / File(s)	Summary of changes
DataSegment API extension QRCoder/QRCodeGenerator/DataSegment.cs	Added public DataSegment(EncodingMode encodingMode, int characterCount, BitArray data, EciMode eciMode); added public BitArray ToBitArray(int version) to produce a complete segment bit array; added public int WriteTo(BitArray bitArray, int startIndex, int version) to serialize ECI, mode, count and data into an existing BitArray.
Generator callsite refactor QRCoder/QRCodeGenerator.cs	Replaced calls to BuildBitArrayFromSegment(segment, version) with segment.ToBitArray(version) and removed the private BuildBitArrayFromSegment(DataSegment, int) helper and its implementation.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  actor Caller
  participant QRCodeGenerator
  participant DataSegment

  Caller->>QRCodeGenerator: Generate(...)
  QRCodeGenerator->>DataSegment: ToBitArray(version)
  activate DataSegment
  DataSegment->>DataSegment: WriteTo(new BitArray, 0, version)
  DataSegment-->>QRCodeGenerator: BitArray (segment)
  deactivate DataSegment
  QRCodeGenerator->>QRCodeGenerator: Combine segment bit arrays into payload
  QRCodeGenerator-->>Caller: Final QR code payload

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• Refactor conversion of text to data segments #670 — Overlaps previous refactor that introduced segment-based helpers and BuildBitArrayFromSegment; this PR removes that helper in favor of DataSegment.ToBitArray.

Suggested reviewers

• gfoidl

Pre-merge checks and finishing touches

✅ Passed checks (3 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%.
Title Check	✅ Passed	The title accurately summarizes the key change by indicating the refactor of the BuildBitArrayFromSegment method, which is the primary focus of the pull request, without including unnecessary details.

✨ 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 build_bitarray

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (1)

QRCoder/QRCodeGenerator/DataSegment.cs (1)

86-90: ECI assignment values are correct; add validation for future ≥128 values
Verified EciMode enum matches the QR spec (Default=0, Iso8859_1=3, Iso8859_2=4, Utf8=26) and all values <128. Recommend adding a guard or documentation note in DataSegment.cs noting that ECI values ≥128 require 16/24-bit encoding per ISO/IEC 18004.

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between ab04613 and afefd63.

📒 Files selected for processing (2)

• QRCoder/QRCodeGenerator.cs (1 hunks)
• QRCoder/QRCodeGenerator/DataSegment.cs (2 hunks)

🧰 Additional context used

🧬 Code graph analysis (1)

QRCoder/QRCodeGenerator/DataSegment.cs (1)

QRCoder/QRCodeGenerator.cs (6)

• BitArray (991-1000)
• BitArray (1010-1051)
• BitArray (1074-1150)
• DecToBin (868-878)
• EncodingMode (743-758)
• GetCountIndicatorLength (886-946)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (6)

• GitHub Check: Test .NET Framework 4.6.2
• GitHub Check: Test .NET 6.0 Windows
• GitHub Check: Test .NET 5.0 Windows
• GitHub Check: Test .NET Core 3.1
• GitHub Check: Test .NET Core 2.1
• GitHub Check: additional-tests

🔇 Additional comments (3)

QRCoder/QRCodeGenerator.cs (1)

119-119: LGTM!

Clean refactoring that moves the bit array construction logic into the DataSegment type. The new instance method approach follows good OO principles by keeping behavior with data.

QRCoder/QRCodeGenerator/DataSegment.cs (2)

35-48: LGTM!

The constructor properly initializes all DataSegment fields including the new EciMode parameter.

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62-72: LGTM!

The method correctly allocates a BitArray of the required size and delegates the serialization logic to WriteTo.