Address the Codacy findings on #6 (TIFF/EMF/WMF tests, input validation)

[davidnmbond]

Codacy's analysis of #6 raised 7 new issues (2 high). This addresses the actionable ones.

• ImageHeaderReader (TIFF): an unsupported field type on a required field (width/height) now throws InvalidDataException; optional resolution fields fall back to 96 dpi; other tags have an explicit default branch; a TIFF without width and height is rejected.
• ExcelDrawings.AddPicture(FileInfo): throws ArgumentNullException instead of a bare Exception.
• ExcelHeaderFooter.InsertPicture: validates the image before the picture placeholder is appended to the section text, so rejected data leaves nothing behind; null FileInfo guarded.
• Tests (new, cross-platform): TIFF in both byte orders, centimetre resolution, missing/optional/required fields, truncated and wild offsets; EMF and WMF sizes and truncation; InsertPicture from bytes, stream and file, duplicate section, invalid data and null arguments.

Not changed: Codacy also flagged the removed test exclusions in ci.yml ("re-enables documented failures"). That is a false positive: the exclusions were removed because their root causes were fixed in #6, and the Linux CI run passes with none.

Verified locally: full suite 1199 passed, 0 failed, 214 skipped.

🤖 Generated with Claude Code

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

View in Codacy

🟢 Metrics 31 complexity · 0 duplication

Metric	Results
Complexity	31
Duplication	0

View in Codacy

🟢 Coverage 100.00% diff coverage · +0.31% coverage variation

Metric	Results
Coverage variation	✅ +0.31% coverage variation (-1.00%)
Diff coverage	✅ 100.00% diff coverage

View coverage diff in Codacy

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (22a7e64)	47272	30474	64.47%
Head commit (1839c9f)	47464 (+192)	30745 (+271)	64.78% (+0.31%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#7)	201	201	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

AI Reviewer: first review requested successfully. AI can make mistakes. Always validate suggestions.

_{TIP This summary will be updated as you push new changes.}

[codacy-production]

Pull Request Overview

👀 Worth a closer look

Malformed TIFF offsets may escape the image-reader contract as overflow or range exceptions instead of InvalidDataException; this warrants review before relying on the stated validation behavior. ImageHeaderReader is also relatively complex, though existing coverage is strong and no uncovered complex files were reported.

1 comment outside of the diff

PanoramicData.EPPlus/Compatibility/ImageHeaderReader.cs

_{line 202 🟡 MEDIUM RISK}
Suggestion: Consider extracting TIFF entry decoding and/or IFD traversal into focused private helpers while preserving required dimension validation and optional resolution fallback.

Test suggestions

• TIFF parsing in little- and big-endian byte order
• TIFF centimetre resolution conversion
• TIFF missing dimensions and unsupported required/optional field types
• TIFF truncation and invalid offsets
• EMF dimensions and truncation handling
• WMF dimensions, custom units, and truncation handling
• Header/footer picture insertion from bytes, streams, and files
• Duplicate-section, invalid-image, and null-argument validation
• ExcelDrawings.AddPicture null FileInfo validation

_{TIP Improve review quality by adding custom instructions
TIP How was this review? Give us feedback}

[codacy-production]

_{🟡 MEDIUM RISK}

Validate the TIFF value offset and required byte range against the input length before reading, and translate invalid offsets or ranges into InvalidDataException.