feat: add pdfkit subsets mixin

Author: diegomura

packages/pdfkit/src/document.js

@@ -1,3 +1,8 @@
+/*
+PDFDocument - represents an entire PDF document
+By Devon Govett
+*/
+
 import stream from 'stream';
 import PDFObject from './object';
 import PDFReference from './reference';
@@ -15,11 +20,12 @@ import MarkingsMixin from './mixins/markings';
 import AcroFormMixin from './mixins/acroform';
 import AttachmentsMixin from './mixins/attachments';
 import MetadataMixin from './mixins/metadata';
+import SubsetMixin from './mixins/subsets';
 import capitalize from './utils/capitalize';
 
 class PDFDocument extends stream.Readable {
   constructor(options = {}) {
-    super();
+    super(options);
     this.options = options;
 
     // PDF version
@@ -93,6 +99,7 @@ class PDFDocument extends stream.Readable {
     this.initText();
     this.initImages();
     this.initOutline();
+    this.initSubset(options);
     // this.initMarkings(options)
 
     // Initialize the metadata
@@ -267,6 +274,10 @@ class PDFDocument extends stream.Readable {
     this.endOutline();
     // this.endMarkings();
 
+    if (this.subset) {
+      this.endSubset();
+    }
+
     this._root.end();
     this._root.data.Pages.end();
     this._root.data.Names.end();
@@ -370,5 +381,6 @@ mixin(OutlineMixin);
 mixin(MarkingsMixin);
 mixin(AcroFormMixin);
 mixin(AttachmentsMixin);
+mixin(SubsetMixin);
 
 export default PDFDocument;

packages/pdfkit/src/mixins/pdfa.js

@@ -0,0 +1,58 @@
+import fs from 'fs';
+
+export default {
+  initPDFA(pSubset) {
+    if (pSubset.charAt(pSubset.length - 3) === '-') {
+      this.subset_conformance = pSubset
+        .charAt(pSubset.length - 1)
+        .toUpperCase();
+      this.subset = parseInt(pSubset.charAt(pSubset.length - 2));
+    } else {
+      // Default to Basic conformance when user doesn't specify
+      this.subset_conformance = 'B';
+      this.subset = parseInt(pSubset.charAt(pSubset.length - 1));
+    }
+  },
+
+  endSubset() {
+    this._addPdfaMetadata();
+    this._addColorOutputIntent();
+  },
+
+  _addColorOutputIntent() {
+    const iccProfile = fs.readFileSync(
+      `${__dirname}/data/sRGB_IEC61966_2_1.icc`
+    );
+
+    const colorProfileRef = this.ref({
+      Length: iccProfile.length,
+      N: 3
+    });
+    colorProfileRef.write(iccProfile);
+    colorProfileRef.end();
+
+    const intentRef = this.ref({
+      Type: 'OutputIntent',
+      S: 'GTS_PDFA1',
+      Info: new String('sRGB IEC61966-2.1'),
+      OutputConditionIdentifier: new String('sRGB IEC61966-2.1'),
+      DestOutputProfile: colorProfileRef
+    });
+    intentRef.end();
+
+    this._root.data.OutputIntents = [intentRef];
+  },
+
+  _getPdfaid() {
+    return `
+        <rdf:Description xmlns:pdfaid="http://www.aiim.org/pdfa/ns/id/" rdf:about="">
+            <pdfaid:part>${this.subset}</pdfaid:part>
+            <pdfaid:conformance>${this.subset_conformance}</pdfaid:conformance>
+        </rdf:Description>
+        `;
+  },
+
+  _addPdfaMetadata() {
+    this.appendXML(this._getPdfaid());
+  }
+};

packages/pdfkit/src/mixins/pdfua.js

@@ -0,0 +1,21 @@
+export default {
+  initPDFUA() {
+    this.subset = 1;
+  },
+
+  endSubset() {
+    this._addPdfuaMetadata();
+  },
+
+  _addPdfuaMetadata() {
+    this.appendXML(this._getPdfuaid());
+  },
+
+  _getPdfuaid() {
+    return `
+        <rdf:Description xmlns:pdfuaid="http://www.aiim.org/pdfua/ns/id/" rdf:about="">
+            <pdfuaid:part>${this.subset}</pdfuaid:part>
+        </rdf:Description>
+        `;
+  }
+};

packages/pdfkit/src/mixins/subsets.js

@@ -0,0 +1,29 @@
+import PDFA from './pdfa';
+import PDFUA from './pdfua';
+
+export default {
+  _importSubset(subset) {
+    Object.assign(this, subset);
+  },
+
+  initSubset(options) {
+    switch (options.subset) {
+      case 'PDF/A-1':
+      case 'PDF/A-1a':
+      case 'PDF/A-1b':
+      case 'PDF/A-2':
+      case 'PDF/A-2a':
+      case 'PDF/A-2b':
+      case 'PDF/A-3':
+      case 'PDF/A-3a':
+      case 'PDF/A-3b':
+        this._importSubset(PDFA);
+        this.initPDFA(options.subset);
+        break;
+      case 'PDF/UA':
+        this._importSubset(PDFUA);
+        this.initPDFUA();
+        break;
+    }
+  }
+};