main.c

/* OS: Arch Linux
 * Kernel: Linux 4.19.4
 * Compiler: GCC 8.2.1
 * GUI toolkit: GTK+ 3.24
 * PDF renderer: Poppler 0.71
 *
 * Compile with "gcc main.c `pkg-config --cflags --libs gtk+-3.0 poppler-glib`"
 * Run with "a.out /absolute/path/to/file.pdf text-to-find"
 */

#include <gtk/gtk.h>
#include <poppler.h>
#include <string.h>
#define PAGE 0
#define SWAP(x, y) do {x = x + y;y = x - y;x = x - y;} while (0)

struct Program
{
    GtkWidget *window;
    GtkWidget *drawing_area;
    PopplerDocument *doc;
    PopplerPage *page;
    GList *selections;
};

// render page and found text onto drawing area
static gboolean render_page(GtkWidget *drawing_area, cairo_t *cr, struct Program *program)
{
    PopplerColor fg, bg;

    fg.red = 0xffff;
    fg.blue = 0xffff;
    fg.green = 0xffff;

    bg.red = 0x0;
    bg.blue = 0x0;
    bg.green = 0x0;

    double page_width, page_height;
    poppler_page_get_size(program->page, &page_width, &page_height);

    cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
    cairo_rectangle(cr, 0.0, 0.0, page_width, page_height);
    cairo_fill(cr);

    poppler_page_render(program->page, cr);

    for (GList *item = program->selections;item != NULL;item = item->next)
    {
        PopplerRectangle *rectangle = (PopplerRectangle *) item->data;

        // comment out these lines to get the right selection!
        /*
        SWAP(rectangle->x1, rectangle->x2);
        SWAP(rectangle->y1, rectangle->y2);
        rectangle->y1 = page_height - rectangle->y1;
        rectangle->y2 = page_height - rectangle->y2;
        */

        poppler_page_render_selection(program->page, cr, rectangle, NULL, POPPLER_SELECTION_GLYPH, &fg, &bg);
    }

    return TRUE;
}

// open document and page
static gboolean open_page(struct Program *program, char *filename)
{
    char *filename_uri = (char *) g_malloc(sizeof(char) * (strlen(filename) + strlen("file://") + 1));
    strcpy(filename_uri, "file://");
    strcat(filename_uri, filename);

    program->doc = poppler_document_new_from_file(filename_uri, NULL, NULL);
    if (program->doc == NULL)
        return FALSE;

    program->page = poppler_document_get_page(program->doc , PAGE);

    g_free(filename_uri);

    return TRUE;
}

// search for text
static void find_text(struct Program *program, char *text)
{
    program->selections = poppler_page_find_text(program->page, text);
}

// create and show window
static void create_window(struct Program *program)
{
    program->window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_default_size(GTK_WINDOW(program->window), 400, 600);
    g_signal_connect(program->window, "delete-event", G_CALLBACK(gtk_main_quit), NULL);

    program->drawing_area = gtk_drawing_area_new();
    g_signal_connect(program->drawing_area, "draw", G_CALLBACK(render_page), program);

    gtk_container_add(GTK_CONTAINER(program->window), program->drawing_area);

    gtk_widget_show_all(program->window);
}

int main(int argc, char **argv)
{
    if (argc != 3)
        return -1;

    gtk_init(&argc, &argv);

    struct Program program;

    create_window(&program);

    if (!open_page(&program, argv[1]))
        return -1;

    find_text(&program, argv[2]);

    gtk_widget_queue_draw(program.drawing_area);

    gtk_main();

    return 0;
}