editMetadata function & some jsdoc

CONTRIBUTE.md

@@ -15,6 +15,8 @@ Backend functions can have different implementations than their frontend counter
 
 Registering functions will also pass them their dependencies for the specific target platform (Node, Browser)
 
+[Traverse Operations](/public/traverseOperations.js)\
+
 ### Backend
 
 [Register Functions](/functions.js)\

README.md

@@ -96,7 +96,7 @@ Current functions of spdf and their progress in this repo.
 | ✔️   | Multi-Page-Layout      |             |
 | ✔️   | Adjust page size/scale |             |
 | 🚧    | Organize               |             |
-| 🚧    | Change Metadata        |             |
+| ✔️    | Change Metadata        |             |
 | ❌     | Add Watermark          |             |
 
 | Status | Feature                     | Description |

functions.js

@@ -8,6 +8,7 @@ import { rotatePages as dependantRotatePages } from './public/functions/rotatePa
 import { scaleContent as dependantScaleContent} from './public/functions/scaleContent.js';
 import { scalePage as dependantScalePage } from './public/functions/scalePage.js';
 import { splitPDF as dependantSplitPDF } from './public/functions/splitPDF.js';
+import { editMetadata as dependantEditMetadata } from './public/functions/editMetadata.js';
 
 export async function extractPages(snapshot, pagesToExtractArray) {
     return dependantExtractPages(snapshot, pagesToExtractArray, PDFLib);
@@ -35,4 +36,8 @@ export async function scalePage(snapshot, pageSize) {
 
 export async function splitPDF(snapshot, splitAfterPageArray) {
     return dependantSplitPDF(snapshot, splitAfterPageArray, PDFLib);
+}
+
+export async function editMetadata(snapshot, metadata) {
+    return dependantEditMetadata(snapshot, metadata, PDFLib);
 }

public/functions.js

@@ -8,6 +8,7 @@ import { rotatePages as dependantRotatePages } from './functions/rotatePages.js'
 import { scaleContent as dependantScaleContent} from './functions/scaleContent.js';
 import { scalePage as dependantScalePage } from './functions/scalePage.js';
 import { splitPDF as dependantSplitPDF } from './functions/splitPDF.js';
+import { editMetadata as dependantEditMetadata} from "./functions/editMetadata.js";
 
 export async function extractPages(snapshot, pagesToExtractArray) {
     return dependantExtractPages(snapshot, pagesToExtractArray, PDFLib);
@@ -35,4 +36,8 @@ export async function scalePage(snapshot, pageSize) {
 
 export async function splitPDF(snapshot, splitAfterPageArray) {
     return dependantSplitPDF(snapshot, splitAfterPageArray, PDFLib);
+}
+
+export async function editMetadata(snapshot, metadata) {
+    return dependantEditMetadata(snapshot, metadata, PDFLib);
 }

public/functions/editMetadata.js

@@ -0,0 +1,52 @@
+/**
+ * @typedef {Object} Metadata
+ * @property {string | null | undefined} Title - The title of the document.
+ * @property {string | null | undefined} Author - The author of the document.
+ * @property {string | null | undefined} Subject - The subject of the document.
+ * @property {string[] | null | undefined} Keywords - An array of keywords associated with the document.
+ * @property {string | null | undefined} Producer - The producer of the document.
+ * @property {string | null | undefined} Creator - The creator of the document.
+ * @property {Date | null | undefined} CreationDate - The date when the document was created.
+ * @property {Date | null | undefined} ModificationDate - The date when the document was last modified.
+ */
+
+/**
+ * 
+ * @param {Uint16Array} snapshot
+ * @param {Metadata} metadata - Set property to null or "" to clear, undefined properties will be skipped.
+ * @param {import('pdf-lib')} PDFLib
+ * @returns 
+ */
+export async function editMetadata(snapshot, metadata, PDFLib) {
+    // Load the original PDF file
+    const pdfDoc = await PDFLib.PDFDocument.load(snapshot, {
+        parseSpeed: PDFLib.ParseSpeeds.Fastest,
+    });
+
+    if(metadata.Title !== undefined)
+        pdfDoc.setTitle(metadata.Title);
+
+    if(metadata.Author !== undefined)
+        pdfDoc.setAuthor(metadata.Author)
+
+    if(metadata.Subject !== undefined)
+        pdfDoc.setSubject(metadata.Subject)
+    
+    if(metadata.Keywords !== undefined)
+        pdfDoc.setKeywords(metadata.Keywords)
+    
+    if(metadata.Producer !== undefined)
+        pdfDoc.setProducer(metadata.Producer)
+
+    if(metadata.Creator !== undefined)
+        pdfDoc.setCreator(metadata.Creator)
+
+    if(metadata.CreationDate !== undefined)
+        pdfDoc.setCreationDate(metadata.CreationDate)
+
+    if(metadata.ModificationDate !== undefined)
+        pdfDoc.setModificationDate(metadata.ModificationDate)
+
+    // Serialize the modified document
+    return pdfDoc.save();
+};

public/traverseOperations.js

@@ -1,5 +1,12 @@
 import { organizeWaitOperations } from "./organizeWaitOperations.js";
 
+/**
+ * 
+ * @param {*} operations 
+ * @param {*} input 
+ * @param {import('./functions.js')} Functions 
+ * @returns 
+ */
 export async function * traverseOperations(operations, input, Functions) {
     const waitOperations = organizeWaitOperations(operations);
     let results = [];
@@ -90,6 +97,12 @@ export async function * traverseOperations(operations, input, Functions) {
                     input = splits;
                 });
                 break;
+            case "editMetadata":
+                yield* nToN(input, operation, async (input) => {
+                    input.fileName += "_metadataEdited";
+                    input.buffer = await Functions.editMetadata(input.buffer, operation.values["metadata"]);
+                });
+                break;
             default:
                 throw new Error(`${operation.type} not implemented yet.`);
                 break;