# Description of Changes
TLDR
- Updated `PdfToPdfARequest` to include PDF/X in supported output
formats
- Expanded input handling and model validation for PDF/A and PDF/X
- Added Ghostscript as a preferred backend for PDF/A and PDF/X
conversions
- Implemented PDF/X-specific conversion logic with detailed validation
- Updated UI templates to separate PDF/A and PDF/X format options
- Updated error handling and warnings during conversion processes
This PR replaces the PDF/A conversion system with Ghostscript as the
primary method, which less warning prone output compared to the previous
LibreOffice approach. It also adds PDF/X format support for print
production workflows.
### Better PDF/A Compliance
- Ghostscript produces standards-compliant PDF/A with fewer validation
errors
- Previous LibreOffice method generates files with structural errors and
validation warnings
- Automatic fallback to PDFBox/LibreOffice if Ghostscript unavailable
- Built-in validation using PDFBox Preflight catches issues early
### New PDF/X Support
Print production workflows now supported with PDF/X-1, PDF/X-3, and
PDF/X-4 formats for professional printing requirements.
### More Reliable Output
- Deterministic conversion results
- Better font embedding and subsetting
- Proper ICC profile and color space handling
- Improved resource cleanup prevents memory leaks
### Ghostscript Integration
- `buildGhostscriptCommand()` / `buildGhostscriptCommandX()` -
Constructs CLI arguments
- `convertWithGhostscript()` / `convertWithGhostscriptX()` - Executes
conversion
- `isGhostscriptAvailable()` - Checks installation
- `prepareColorProfiles()` - Sets up ICC profiles
- `createPdfaDefFile()` - Generates PostScript definitions
### Conversion Flow
- `handlePdfAConversion()` - Routes PDF/A with Ghostscript primary,
PDFBox fallback
- `handlePdfXConversion()` - Routes PDF/X using Ghostscript
- `convertWithPdfBoxMethod()` - Refactored fallback method
### Validation
- `validatePdfaOutput()` - Validates using PDFBox Preflight
- `validateAndWarnPdfA()` - Logs warnings instead of failing
- `buildPreflightErrorMessage()` - Formats detailed errors
### Font Handling
Updated `embedMissingFonts()` prevents stream exhaustion by loading font
bytes once and creating fresh InputStreams for multiple load attempts.
### Utilities
- `findUnembeddedFontNames()` - Identifies unembedded fonts
- `deleteQuietly()` - Recursively deletes temp directories
- `sanitizePdfA()` - Removes incompatible elements
- `removeElementsForPdfA()` - Removes Optional Content and transparency
- `mergeAndAddXmpMetadata()` - Handles XMP metadata
- `preProcessHighlights()` - Pre-processes annotations
- Transparency detection: `isTransparencyGroup()`,
`hasTransparentImages()`, `detectTransparentXObjects()`
### PDF/A
- PDF/A-1b: Strict compliance
- PDF/A-2b: Extended features (default)
- PDF/A-3b: Embedded files support
### PDF/X
- PDF/X-1: Standard print exchange
- PDF/X-3: Color-managed with ICC profiles
- PDF/X-4: Transparency support
As mentioned greatest benefit is the new Ghostscript conversion is able
to deliver fewer warning/zero error PDF/A files compared to the
LibreOffice. Sometimes however, both succeed without warnings. Here are
some samples:
<img width="1876" height="675" alt="image"
src="https://github.com/user-attachments/assets/ee71c2f3-e5ee-45ec-ba61-8d0ffc53b386"
/>
<img width="1876" height="675" alt="image"
src="https://github.com/user-attachments/assets/d620402b-cced-47b2-808d-01bde80eceb2"
/>
<img width="1876" height="675" alt="image"
src="https://github.com/user-attachments/assets/e3052d23-883b-43fc-9953-603067bee8bf"
/>
<img width="1876" height="675" alt="image"
src="https://github.com/user-attachments/assets/13251ab9-c449-4c4a-a326-521ef1929ad2"
/>
There is also some size difference, (not sure why) but generally that
also favors Ghostscript:
<img width="978" height="340" alt="image"
src="https://github.com/user-attachments/assets/5ccf4ea2-c6ef-4751-abd0-5b8445c90861"
/>
### Front-end
<img width="978" height="632" alt="image"
src="https://github.com/user-attachments/assets/74789d20-fb79-48d6-a35b-19f519a9f898"
/>
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---
## Checklist
### General
- [X] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [X] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [X] I have performed a self-review of my own code
- [X] My changes generate no new warnings
### Documentation
- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)
### Translations (if applicable)
- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)
### UI Changes (if applicable)
- [X] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)
### Testing (if applicable)
- [X] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.
---------
Signed-off-by: Balázs Szücs <bszucs1209@gmail.com>
