generated from jric11/baseProject
121 lines
5.3 KiB
Markdown
121 lines
5.3 KiB
Markdown
# Standards and Conformance
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Back to root overview: [README.md](../README.md#in-depth-documentation)
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## PDF/A Archival
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`tc-lib-pdf` supports PDF/A output for long-term archival workflows (ISO 19005). Pass the mode string as the `mode` argument to the `Tcpdf` constructor:
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```php
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// PDF/A-1b (default conformance level when suffix is omitted)
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa1');
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// Explicit conformance levels
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa1a'); // PDF/A-1a
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa1b'); // PDF/A-1b
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa2a'); // PDF/A-2a
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa2b'); // PDF/A-2b
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa2u'); // PDF/A-2u
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa3a'); // PDF/A-3a
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa3b'); // PDF/A-3b
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa3u'); // PDF/A-3u
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```
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| Mode suffix | Conformance | Unicode ToUnicode | Tagged structure |
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|-------------|-------------|-------------------|------------------|
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| `a` | Level A | required | required |
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| `b` | Level B | required | not required |
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| `u` | Level U (parts 2/3 only) | required | not required |
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PDF/A-3 supports embedding arbitrary file attachments (for example XML invoice payloads). This is the basis for **Factur-X / ZUGFeRD** workflows - embed the structured XML in a PDF/A-3 document and register the relationship via XMP metadata:
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```php
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfa3');
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// ... build document ...
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$pdf->addContentAsEmbeddedFile(
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file: 'factur-x.xml',
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content: $invoiceXML,
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mime: 'text/xml',
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afrel: \Com\Tecnick\Pdf\AFRelationship::Alternative,
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);
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$pdf->setCustomXMP('x:xmpmeta.rdf:RDF.rdf:Description.pdfaExtension:schemas.rdf:Bag', $xmpBag);
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```
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Runnable example (invoice with embedded Factur-X XML): [examples/E001_invoice.php](../examples/E001_invoice.php).
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## PDF/X Conformance
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`tc-lib-pdf` supports multiple PDF/X profiles for print-exchange workflows. Pass the mode string as the `mode` argument to the `Tcpdf` constructor:
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```php
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// Generic PDF/X alias (maps to the library's baseline print-exchange workflow)
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfx');
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// Specific variants
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfx1a'); // PDF/X-1a:2003
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfx3'); // PDF/X-3:2003
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfx4'); // PDF/X-4:2010
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfx5'); // PDF/X-5g:2010
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```
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Each variant automatically applies the appropriate conformance constraints:
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| Mode | Min PDF version | Transparency | Process colors | GTS_PDFXVersion |
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|------|-----------------|--------------|----------------|-----------------|
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| `pdfx` / `pdfx3` | 1.3 | blocked | CMYK forced | PDF/X-3:2003 |
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| `pdfx1a` | 1.3 | blocked | CMYK forced | PDF/X-1a:2003 |
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| `pdfx4` | 1.6 | allowed | unrestricted | PDF/X-4:2010 |
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| `pdfx5` | 1.6 | allowed | unrestricted | PDF/X-5g:2010 |
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All PDF/X modes suppress encryption and JavaScript (not permitted by the ISO 15930 standard).
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Runnable examples: [examples/E010_pdfx.php](../examples/E010_pdfx.php) through [examples/E014_pdfx5.php](../examples/E014_pdfx5.php).
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## PDF/UA Accessibility
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`tc-lib-pdf` supports tagged PDF output conforming to PDF/UA (ISO 14289). Pass the mode string as the `mode` argument to the `Tcpdf` constructor:
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```php
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// Generic PDF/UA alias
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfua');
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// Specific parts
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfua1'); // PDF/UA-1 (PDF 1.7)
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$pdf = new \Com\Tecnick\Pdf\Tcpdf(mode: 'pdfua2'); // PDF/UA-2 (PDF 2.0)
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```
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When a PDF/UA mode is active the library automatically:
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- Writes a `StructTreeRoot` with a `ParentTree` that maps every page to its tagged content blocks
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- Emits `MarkInfo << /Marked true >>` in the document catalog
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- Sets `/Lang` (defaults to `en-US` when not explicitly provided)
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- Forces `ViewerPreferences /DisplayDocTitle true`
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- Maps HTML heading elements (`h1`-`h6`) to PDF structure roles `H1`-`H6` with level-clamping to prevent skipped heading levels
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- Tags text content with MCIDs and wraps each run in the appropriate structure element (`P`, `H1`-`H6`, `Link`, etc.)
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- Tags `<img>` elements as `Figure` with their `alt` attribute written as `/Alt` in the structure element
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- Emits `ActualText` entries for ligatures and special glyphs so text extraction and screen readers work correctly
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- Provides Artifact marked-content helpers for non-semantic content (`beginArtifact()`, `endArtifact()`, `addArtifactContent()`)
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To provide the document language explicitly:
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```php
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$pdf->setLanguageArray(['a_meta_language' => 'de-DE']);
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```
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To tag decorative or repeated content as Artifact (for example headers, footers, and page numbers):
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```php
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$pid = $pdf->addPage()['pid'];
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$headerOperators = $pdf->graph->getLine(10, 10, 200, 10);
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$pdf->addArtifactContent($headerOperators, $pid, 'Pagination', 'Header');
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$footerText = $pdf->getTextCell('Page 1', 180, 280, 20, 5);
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$pdf->addArtifactContent($footerText, $pid, 'Pagination', 'Footer');
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```
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In PDF/UA mode, the built-in `defaultPageContent()` page-number footer is emitted as `Artifact` with
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`/Type /Pagination /Subtype /Footer`.
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Runnable examples: [examples/E015_pdfua.php](../examples/E015_pdfua.php) through [examples/E017_pdfua2.php](../examples/E017_pdfua2.php).
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