razvandimescu/gopdf v0.8.0

v0.8.0 — Size-constrained PDF merge

on GitHub

What's new

Size-constrained merge (MergeWithOptions)

Control the output size of merged PDFs with three oversize behaviors:

• OversizeFail — merge normally, return *OversizeError if output exceeds limit
• OversizeTruncate — include as many pages as fit within the limit
• OversizeShrink — two-pass optimization: lossless first (stream dedup + metadata stripping), then JPEG recompression at ratio-derived quality to hit the target

res, err := m.MergeWithOptions(pdf.MergeOptions{
    MaxSize:          20 * 1024 * 1024, // 20 MB
    OversizeBehavior: pdf.OversizeShrink,
})

Optimizations applied automatically

• Stream deduplication — SHA-256 content hashing across all sources; identical fonts, logos, and images are written once
• Metadata stripping — removes XMP metadata, structure trees, thumbnails, output intents
• JPEG recompression — decodes and re-encodes DCTDecode images at a quality derived from maxSize / actualSize; skips images where recompression would produce a larger result or the source is < 4KB

Real-world results (63 PDFs, 94 pages)

Other changes

• Writer gains Len(), checkpoint/restore for truncation rollback
• Merger.Add caches the *Reader to avoid double-parsing
• Extracted buildMergedPDF and filterNames helpers
• estimateFinishedSize moved to Writer method
• 10 new tests covering all behaviors and edge cases