Poppler

What it is

Poppler is a PDF rendering library based on the xpdf-3.0 code base. It provides tools and APIs to extract text, render pages, and manipulate PDF files in C and C++ applications.

Poppler provides both command-line utilities (like `pdftotext`, `pdftoppm`) and library APIs for C/C++. You can render PDF pages to images, extract text, read metadata, and manipulate PDF content programmatically.

Installation

sudo apt install libpoppler-dev poppler-utils

Getting started

The smallest useful thing you can do with it, and what each part means.

Extracting text from PDF using pdftotext

c

# Terminal command
pdftotext input.pdf output.txt

Converts the contents of a PDF file to a plain text file using the Poppler utility.

Rendering PDF page to image using pdftoppm

c

# Terminal command
pdftoppm -png input.pdf output

Renders PDF pages as PNG images; each page will produce a separate image file.

Advanced usage

Where the library earns its place over a simpler alternative.

Using Poppler C++ API to open a PDF document

c

1234567891011#include <poppler-document.h>
#include <poppler-page.h>
#include <iostream>

int main() {
    poppler::document* doc = poppler::document::load_from_file("input.pdf");
    if (!doc) { std::cerr << "Failed to open PDF." << std::endl; return 1; }
    std::cout << "Number of pages: " << doc->pages() << std::endl;
    delete doc;
    return 0;
}

Loads a PDF document using Poppler C++ API and prints the number of pages.

Extracting text from a page

c

123456789101112131415#include <poppler-document.h>
#include <poppler-page.h>
#include <iostream>

int main() {
    auto doc = poppler::document::load_from_file("input.pdf");
    if (!doc) return 1;
    auto page = doc->create_page(0);
    if (page) {
        std::cout << page->text().to_latin1() << std::endl;
        delete page;
    }
    delete doc;
    return 0;
}

Extracts text from the first page of a PDF document using Poppler's C++ API.

Rendering a page to an image

c

// Use poppler-page.h and poppler-image.h
// Render page to an image buffer for GUI applications or saving as PNG

Poppler allows rendering pages to images programmatically for display or saving.

Errors and fixes

The failures you are most likely to hit, and what actually resolves them.

Failed to load PDF: Check that the PDF path is correct and the file is not corrupted.
Null page object: Verify that the page index is within the range of available pages in the document.
Text extraction empty: Some PDFs may use non-standard encoding; try using alternative extraction methods or OCR if necessary.

Best practices

Always check for null pointers when loading documents or pages.
Release memory for documents, pages, and images to prevent leaks.
Use the latest Poppler version for better PDF feature support and security fixes.
For large PDFs, process pages sequentially to avoid excessive memory usage.
Prefer Poppler's C++ API for fine-grained control in applications.

Background

Why it exists, and what it was reacting to.

Poppler was developed to provide a robust and efficient open-source PDF rendering solution. It is widely used in Linux desktop applications (like Evince, Okular) and command-line utilities for PDF manipulation, text extraction, and rendering.

Related libraries

Others in Documents & Files for C.

MuPDF

FreeType