Font Subsetting

This guide will show you how to optimize a PDF document by using only a subset of a font file to reduce the PDF document size.

Before you begin #

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.

Clone the project repository #

In your terminal, clone the 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 compress folder in the unipdf-examples directory.

cd unipdf-examples/compress

How it works #

Lines 13-22 import the UniPDF packages and other required dependencies.

The init function in lines 24-31 authenticates your request with your UNIDOC_LICENSE_API_KEY.

The main function in lines 32-89 is just like any other function when we want to create a regular PDF file, one difference would be on line 70-72 where we declaring an options to enable font subsetting for all the font files used in the document.

Run the code #

Run this command to add a line annotation to the specified page in a PDF. This will also get all the required dependencies to run the program.

go run pdf_annotate_add_line.go input.pdf output.pdf

Sample output #

Running the code example will show you some info on how much compression is made, similar like the following.

Original file: input.pdf
Original size: 266845 bytes
Optimized file: output.pdf
Optimized size: 124868 bytes
Compression ratio: 53.21%
Processing time: 366.40 ms