Set XMP Media Management Metadata

This guide will show how to set media management XMP metadata.

Before you begin #

First of all you should get your API key from your UniCloud account.

If this is your first time using UniPDF SDK, follow this guide to set up a local development environment.

Project setup #

Clone the project repository #

In your terminal, clone examples repository. It contains the Go code we will be using for this guide.

git clone https://github.com/unidoc/unipdf-examples.git

Navigate to the metadata folder in the unipdf-examples directory.

cd unipdf-examples/metadata

Configure environment variables #

Replace the UNIDOC_LICENSE_API_KEY with your API credentials from your UniCloud account.

Linux/Mac #

export UNIDOC_LICENSE_API_KEY=PUT_YOUR_API_KEY_HERE

Windows #

set UNIDOC_LICENSE_API_KEY=PUT_YOUR_API_KEY_HERE

How it works #

The import section in line 3-13 imports unipdf packages and other necessary libraries. The init function which is defined in lines 15-22 authenticates your request.

The main function defined in lines 24-122 sets the media management metadata. In this function, lines 25-31 the input and the output file paths are processed from the command line argument. The time taken to process the document is measured in lines 34-38. A new pdf reader is instantiated using NewPdfReaderFromFile in lines 41-45.

A new pdfWriter is created from the reader object in lines 48-51 using ToWriter method of the the PdfReader. The section in lines 54-69 extracts metadata from the input file if it already exists, otherwise it creates a new xmputil.Document.

in lines 71-82 a new media management is created xmputil.MediaManagement. The media management options is set in lines 84-92. In lines 93-95 the media management object is set to the XMP document using xmpDoc.SetMediaManagement(mmOptions).

The XMP document is marshaled into XML byte stream in lines 101-104. Then a new PdfObjectStream is created from the byte stream using core.MakeStream(metadataBytes, nil). In lines 113-115 the stream metadata is set to the pdfWriter using SetCatalogMetadata(metadataStream).

Finally the document is written to file using pdfWriter.WriteToFile(outputPath) in lines 118-121.

Run the code #

go run pdf_set_xmp_media_management_metadata.go <input.pdf> <output.pdf>