mergepdf.c

#include <cairo.h>
#include <cairo-pdf.h>
#include <poppler.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
    cairo_surface_t *surface;
    cairo_t *cairo;

    if (argc < 3) {
        fprintf(stderr, "Usage: mergepdf INPUT... OUTPUT\n");
        return 1;
    }

    /* Start our surface with a DIN A4 default. The actual page size will
     * be set per page, corresponding to the page size of the input page.
     */
    surface = cairo_pdf_surface_create(argv[argc - 1], 595.276, 841.89);
    if (cairo_surface_status(surface) != CAIRO_STATUS_SUCCESS) {
        fprintf(stderr, "E: Opening %s: %s\n",
                argv[argc - 1],
                cairo_status_to_string(cairo_surface_status(surface)));
        return 1;
    }

    cairo = cairo_create(surface);
    if (cairo_status(cairo) != CAIRO_STATUS_SUCCESS) {
        fprintf(stderr, "E: Opening %s: %s\n", argv[argc - 1],
                cairo_status_to_string(cairo_status(cairo)));
        return 1;
    }

    for (int i = 1; i < argc - 1
         && cairo_status(cairo) == CAIRO_STATUS_SUCCESS; i++) {
        GError *err = NULL;
        GFile *file;
        PopplerDocument *doc;
        int n_pages;

        file = g_file_new_for_path(argv[i]);
        doc = poppler_document_new_from_gfile(file, NULL, NULL, &err);
        if (doc == NULL) {
            fprintf(stderr, "E: Could not open file %s: %s\n", argv[i],
                    err->message);
            return 2;
        }

        n_pages = poppler_document_get_n_pages(doc);
        for (int pg = 0; pg < n_pages &&
             cairo_status(cairo) == CAIRO_STATUS_SUCCESS; pg++) {
            PopplerPage *page;
            double width;
            double height;

            page = poppler_document_get_page(doc, pg);

            poppler_page_get_size(page, &width, &height);
            cairo_pdf_surface_set_size(surface, width, height);

            poppler_page_render_for_printing(page, cairo);
            cairo_show_page(cairo);

            g_object_unref(page);
        }

        g_object_unref(doc);
    }

    if (cairo_status(cairo) != CAIRO_STATUS_SUCCESS) {
        fprintf(stderr, "E: An error occured while writing: %s\n",
                cairo_status_to_string(cairo_status(cairo)));
        return 1;
    }

    /* Destroy output objects, so the output file is completed. */
    cairo_destroy(cairo);
    cairo_surface_destroy(surface);
    return 0;
}