Metadata & Watermarks

This section covers document metadata updates and adding custom semi-transparent watermark text to PDF pages.

1. Edit Metadata

Update author, subject, title, creator, keywords, and producer details.

Signature

interface MetadataOptions {
  title?: string;
  author?: string;
  subject?: string;
  creator?: string;
  keywords?: string[];
  producer?: string;
}

function editMetadata(
  file: File | Blob | ArrayBuffer | Uint8Array,
  metadataOptions: MetadataOptions
): Promise<Uint8Array>

Example

import { editMetadata } from "@manojcoder/pdf-utils";

async function updateMeta(file: File) {
  const metadata = {
    title: "Official Quarterly Report",
    author: "Manoj Kumawat",
    keywords: ["Finance", "Audit"]
  };
  const bytes = await editMetadata(file, metadata);
  const blob = new Blob([bytes], { type: "application/pdf" });
  // Process blob...
}

2. Add Watermark

Overlay a diagonal text stamp on all pages.

Signature

interface WatermarkOptions {
  fontSize?: number;
  opacity?: number;
  rotation?: number; // angle in degrees
  color?: string; // Hex color code
}

function addWatermark(
  file: File | Blob | ArrayBuffer | Uint8Array,
  text: string,
  options?: WatermarkOptions
): Promise<Uint8Array>

Example

import { addWatermark } from "@manojcoder/pdf-utils";

async function stampFile(file: File) {
  const options = {
    fontSize: 60,
    opacity: 0.2,
    rotation: 45,
    color: "#FF0000" // Red watermark
  };
  const bytes = await addWatermark(file, "INTERNAL ONLY", options);
  const blob = new Blob([bytes], { type: "application/pdf" });
  // Process blob...
}