glib/demo/signature.c - third_party/poppler - Git at Google

 /*
  * Copyright (C) 2022-2023 Jan-Michael Brummer <jan.brummer@tabos.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2, or (at your option)
  * any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
  */

 #include <gtk/gtk.h>
 #include <string.h>

 #include "signature.h"
 #include "utils.h"

 typedef struct
 {
     PopplerDocument *doc;
     PopplerPage *page;
     GtkWidget *darea;
     cairo_surface_t *surface;
     gint num_page;
     gint redraw_idle;
     GdkPoint start;
     GdkPoint stop;
     gboolean started;
     GdkCursorType cursor;
     GtkWidget *main_box;
     gdouble scale;
 } PgdSignatureDemo;

 /* Render area */
 static cairo_surface_t *pgd_signature_render_page(PgdSignatureDemo *demo)
 {
     cairo_t *cr;
     PopplerPage *page;
     gdouble width, height;
     cairo_surface_t *surface = NULL;

     page = poppler_document_get_page(demo->doc, demo->num_page);
     if (!page) {
         return NULL;
     }

     poppler_page_get_size(page, &width, &height);

     width *= demo->scale;
     height *= demo->scale;
     gtk_widget_set_size_request(demo->darea, width, height);

     surface = cairo_image_surface_create(CAIRO_FORMAT_RGB24, width, height);
     cr = cairo_create(surface);

     if (demo->scale != 1.0) {
         cairo_scale(cr, demo->scale, demo->scale);
     }

     cairo_save(cr);
     cairo_set_source_rgb(cr, 1, 1, 1);

     cairo_rectangle(cr, 0, 0, width, height);
     cairo_fill(cr);
     cairo_restore(cr);

     cairo_save(cr);
     poppler_page_render(page, cr);
     cairo_restore(cr);

     cairo_destroy(cr);
     g_object_unref(page);

     return surface;
 }

 static void draw_selection_rect(PgdSignatureDemo *demo, cairo_t *cr)
 {
     gint pos_x1, pos_x2, pos_y1, pos_y2;
     gint x, y, w, h;

     pos_x1 = demo->start.x;
     pos_y1 = demo->start.y;
     pos_x2 = demo->stop.x;
     pos_y2 = demo->stop.y;

     x = MIN(pos_x1, pos_x2);
     y = MIN(pos_y1, pos_y2);
     w = ABS(pos_x1 - pos_x2);
     h = ABS(pos_y1 - pos_y2);

     if (w <= 0 || h <= 0) {
         return;
     }

     cairo_save(cr);

     cairo_rectangle(cr, x + 1, y + 1, w - 2, h - 2);
     cairo_set_source_rgba(cr, 0.2, 0.6, 0.8, 0.2);
     cairo_fill(cr);

     cairo_rectangle(cr, x + 0.5, y + 0.5, w - 1, h - 1);
     cairo_set_source_rgba(cr, 0.2, 0.6, 0.8, 0.35);
     cairo_set_line_width(cr, 1);
     cairo_stroke(cr);

     cairo_restore(cr);
 }

 static gboolean pgd_signature_view_drawing_area_draw(GtkWidget *area, cairo_t *cr, PgdSignatureDemo *demo)
 {
     if (demo->num_page == -1) {
         return FALSE;
     }

     if (!demo->surface) {
         demo->surface = pgd_signature_render_page(demo);
         if (!demo->surface) {
             return FALSE;
         }
     }

     cairo_set_source_surface(cr, demo->surface, 0, 0);
     cairo_paint(cr);

     if (demo->started) {
         draw_selection_rect(demo, cr);
     }

     return TRUE;
 }

 static gboolean pgd_signature_viewer_redraw(PgdSignatureDemo *demo)
 {
     cairo_surface_destroy(demo->surface);
     demo->surface = NULL;

     gtk_widget_queue_draw(demo->darea);

     demo->redraw_idle = 0;

     return FALSE;
 }

 static void pgd_signature_viewer_queue_redraw(PgdSignatureDemo *demo)
 {
     if (demo->redraw_idle == 0) {
         demo->redraw_idle = g_idle_add((GSourceFunc)pgd_signature_viewer_redraw, demo);
     }
 }

 static void pgd_signature_page_selector_value_changed(GtkSpinButton *spinbutton, PgdSignatureDemo *demo)
 {
     demo->num_page = (gint)gtk_spin_button_get_value(spinbutton) - 1;
     pgd_signature_viewer_queue_redraw(demo);

     demo->page = poppler_document_get_page(demo->doc, demo->num_page);
 }

 static void pgd_signature_drawing_area_realize(GtkWidget *area, PgdSignatureDemo *demo)
 {
     gtk_widget_add_events(area, GDK_POINTER_MOTION_HINT_MASK | GDK_BUTTON1_MOTION_MASK | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK);
 }

 char *password_callback(const char *in)
 {
     GtkWidget *dialog;
     GtkWidget *box;
     GtkWidget *entry;
     char *ret;

     dialog = gtk_message_dialog_new(NULL, GTK_DIALOG_MODAL, GTK_MESSAGE_QUESTION, GTK_BUTTONS_OK_CANCEL, "Enter password");
     gtk_message_dialog_format_secondary_text(GTK_MESSAGE_DIALOG(dialog), "Enter password to open: %s", in);
     gtk_dialog_set_default_response(GTK_DIALOG(dialog), GTK_RESPONSE_OK);

     box = gtk_message_dialog_get_message_area(GTK_MESSAGE_DIALOG(dialog));
     entry = gtk_entry_new();
     gtk_entry_set_activates_default(GTK_ENTRY(entry), TRUE);
     gtk_entry_set_visibility(GTK_ENTRY(entry), FALSE);
     gtk_box_pack_end(GTK_BOX(box), entry, TRUE, TRUE, 6);
     gtk_widget_show_all(box);

     gtk_dialog_run(GTK_DIALOG(dialog));
     ret = g_strdup(gtk_entry_get_text(GTK_ENTRY(entry)));
     gtk_widget_destroy(dialog);

     return ret;
 }

 static void pgd_signature_update_cursor(PgdSignatureDemo *demo, GdkCursorType cursor_type)
 {
     GdkCursor *cursor = NULL;

     if (cursor_type == demo->cursor) {
         return;
     }

     if (cursor_type != GDK_LAST_CURSOR) {
         cursor = gdk_cursor_new_for_display(gtk_widget_get_display(demo->main_box), cursor_type);
     }

     demo->cursor = cursor_type;

     gdk_window_set_cursor(gtk_widget_get_window(demo->main_box), cursor);
     gdk_display_flush(gtk_widget_get_display(demo->main_box));
     if (cursor) {
         g_object_unref(cursor);
     }
 }

 static void pgd_signature_start_signing(GtkWidget *button, PgdSignatureDemo *demo)
 {
     demo->start.x = 0;
     demo->start.y = 0;
     demo->stop.x = 0;
     demo->stop.y = 0;
     demo->started = TRUE;
     pgd_signature_update_cursor(demo, GDK_TCROSS);
 }

 static gboolean pgd_signature_drawing_area_button_press(GtkWidget *area, GdkEventButton *event, PgdSignatureDemo *demo)
 {
     if (!demo->page || event->button != 1 || !demo->started) {
         return FALSE;
     }

     demo->start.x = event->x;
     demo->start.y = event->y;
     demo->stop = demo->start;

     pgd_signature_viewer_queue_redraw(demo);

     return TRUE;
 }

 static gboolean pgd_signature_drawing_area_motion_notify(GtkWidget *area, GdkEventMotion *event, PgdSignatureDemo *demo)
 {
     gdouble width, height;

     if (!demo->page || demo->start.x == -1 || !demo->started) {
         return FALSE;
     }

     demo->stop.x = event->x;
     demo->stop.y = event->y;

     poppler_page_get_size(demo->page, &width, &height);
     width *= demo->scale;
     height *= demo->scale;

     /* Keep the drawing within the page */
     demo->stop.x = CLAMP(demo->stop.x, 0, width);
     demo->stop.y = CLAMP(demo->stop.y, 0, height);

     pgd_signature_viewer_queue_redraw(demo);

     return TRUE;
 }

 static void on_signing_done(GObject *source, GAsyncResult *result, gpointer user_data)
 {
     PopplerDocument *document = POPPLER_DOCUMENT(source);
     GError *error = NULL;
     gboolean ret = poppler_document_sign_finish(document, result, &error);

     g_print("%s: result %d\n", __FUNCTION__, ret);
     if (error) {
         g_print("Error: %s", error->message);
         g_error_free(error);
     }
 }

 static gboolean pgd_signature_drawing_area_button_release(GtkWidget *area, GdkEventButton *event, PgdSignatureDemo *demo)
 {
     if (!demo->page || event->button != 1 || !demo->started) {
         return FALSE;
     }

     demo->started = FALSE;
     pgd_signature_update_cursor(demo, GDK_LAST_CURSOR);

     /* poppler_certificate_set_nss_dir ("./glib/demo/cert"); */
     poppler_set_nss_password_callback(password_callback);
     GList *available_certificates = poppler_get_available_signing_certificates();

     if (available_certificates) {
         char *signature;
         char *signature_left;
         PopplerSigningData *data = poppler_signing_data_new();
         PopplerRectangle rect;
         PopplerCertificateInfo *certificate_info;
         time_t t;
         double width, height;

         certificate_info = available_certificates->data;
         time(&t);

         poppler_signing_data_set_certificate_info(data, certificate_info);
         poppler_signing_data_set_page(data, demo->num_page);
         poppler_signing_data_set_field_partial_name(data, g_uuid_string_random());
         poppler_signing_data_set_destination_filename(data, "test.pdf");
         poppler_signing_data_set_reason(data, "I'm the author");
         poppler_signing_data_set_location(data, "At my desk");

         poppler_page_get_size(demo->page, &width, &height);

         rect.x1 = demo->start.x > demo->stop.x ? demo->stop.x : demo->start.x;
         rect.y1 = demo->start.y > demo->stop.y ? demo->stop.y : demo->start.y;
         rect.x2 = demo->start.x > demo->stop.x ? demo->start.x : demo->stop.x;
         rect.y2 = demo->start.y > demo->stop.y ? demo->start.y : demo->stop.y;

         /* Adjust scale */
         rect.x1 /= demo->scale;
         rect.y1 /= demo->scale;
         rect.x2 /= demo->scale;
         rect.y2 /= demo->scale;

         rect.y1 = height - rect.y1;
         rect.y2 = height - rect.y2;

         poppler_signing_data_set_signature_rectangle(data, &rect);

         signature = g_strdup_printf("Digitally signed by %s\nDate: %s", poppler_certificate_info_get_subject_common_name(certificate_info), ctime(&t));
         poppler_signing_data_set_signature_text(data, signature);
         g_free(signature);

         signature_left = g_strdup_printf("%s", poppler_certificate_info_get_subject_common_name(certificate_info));
         poppler_signing_data_set_signature_text_left(data, signature_left);
         g_free(signature_left);

         poppler_document_sign(demo->doc, data, NULL, on_signing_done, NULL);
     }

     return TRUE;
 }

 static void pgd_signature_scale_selector_value_changed(GtkSpinButton *spinbutton, PgdSignatureDemo *demo)
 {
     demo->scale = gtk_spin_button_get_value(spinbutton);
     pgd_signature_viewer_queue_redraw(demo);
 }

 /* Main UI */
 GtkWidget *pgd_signature_create_widget(PopplerDocument *document)
 {
     PgdSignatureDemo *demo;
     GtkWidget *label;
     GtkWidget *vbox;
     GtkWidget *button;
     GtkWidget *hbox, *page_selector;
     GtkWidget *scale_hbox, *scale_selector;
     GtkWidget *swindow;
     gchar *str;
     gint n_pages;

     demo = g_new0(PgdSignatureDemo, 1);
     demo->cursor = GDK_LAST_CURSOR;
     demo->doc = g_object_ref(document);
     demo->scale = 1.0;

     n_pages = poppler_document_get_n_pages(document);

     vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 12);

     hbox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 6);

     label = gtk_label_new("Page:");
     gtk_box_pack_start(GTK_BOX(hbox), label, FALSE, TRUE, 0);
     gtk_widget_show(label);

     page_selector = gtk_spin_button_new_with_range(1, n_pages, 1);
     g_signal_connect(G_OBJECT(page_selector), "value-changed", G_CALLBACK(pgd_signature_page_selector_value_changed), (gpointer)demo);
     gtk_box_pack_start(GTK_BOX(hbox), page_selector, FALSE, TRUE, 0);
     gtk_widget_show(page_selector);

     str = g_strdup_printf("of %d", n_pages);
     label = gtk_label_new(str);
     gtk_box_pack_start(GTK_BOX(hbox), label, FALSE, TRUE, 0);
     gtk_widget_show(label);
     g_free(str);

     scale_hbox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 6);

     label = gtk_label_new("Scale:");
     gtk_box_pack_start(GTK_BOX(scale_hbox), label, TRUE, TRUE, 0);
     gtk_widget_show(label);

     scale_selector = gtk_spin_button_new_with_range(0, 10.0, 0.1);
     gtk_spin_button_set_value(GTK_SPIN_BUTTON(scale_selector), 1.0);
     g_signal_connect(G_OBJECT(scale_selector), "value-changed", G_CALLBACK(pgd_signature_scale_selector_value_changed), (gpointer)demo);
     gtk_box_pack_start(GTK_BOX(scale_hbox), scale_selector, TRUE, TRUE, 0);
     gtk_widget_show(scale_selector);

     gtk_box_pack_start(GTK_BOX(hbox), scale_hbox, FALSE, TRUE, 0);
     gtk_widget_show(scale_hbox);

     gtk_box_pack_start(GTK_BOX(vbox), hbox, FALSE, TRUE, 0);

     button = gtk_button_new_with_mnemonic("_Sign");
     g_signal_connect(G_OBJECT(button), "clicked", G_CALLBACK(pgd_signature_start_signing), (gpointer)demo);
     gtk_box_pack_end(GTK_BOX(hbox), button, FALSE, FALSE, 0);
     gtk_widget_show(button);

     gtk_widget_show(hbox);

     /* Demo Area (Render) */
     demo->darea = gtk_drawing_area_new();
     g_signal_connect(demo->darea, "draw", G_CALLBACK(pgd_signature_view_drawing_area_draw), demo);
     g_signal_connect(demo->darea, "realize", G_CALLBACK(pgd_signature_drawing_area_realize), (gpointer)demo);
     g_signal_connect(demo->darea, "button_press_event", G_CALLBACK(pgd_signature_drawing_area_button_press), (gpointer)demo);
     g_signal_connect(demo->darea, "motion_notify_event", G_CALLBACK(pgd_signature_drawing_area_motion_notify), (gpointer)demo);
     g_signal_connect(demo->darea, "button_release_event", G_CALLBACK(pgd_signature_drawing_area_button_release), (gpointer)demo);

     swindow = gtk_scrolled_window_new(NULL, NULL);
 #if GTK_CHECK_VERSION(3, 7, 8)
     gtk_container_add(GTK_CONTAINER(swindow), demo->darea);
 #else
     gtk_scrolled_window_add_with_viewport(GTK_SCROLLED_WINDOW(swindow), demo->darea);
 #endif
     gtk_widget_show(demo->darea);

     gtk_widget_show(swindow);

     gtk_box_pack_start(GTK_BOX(vbox), swindow, TRUE, TRUE, 0);

     demo->main_box = vbox;

     demo->num_page = 0;
     demo->page = poppler_document_get_page(demo->doc, demo->num_page);
     pgd_signature_viewer_queue_redraw(demo);

     return vbox;
 }
	/*
	* Copyright (C) 2022-2023 Jan-Michael Brummer <jan.brummer@tabos.org>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2, or (at your option)
	* any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
	*/

	#include <gtk/gtk.h>
	#include <string.h>

	#include "signature.h"
	#include "utils.h"

	typedef struct
	{
	PopplerDocument *doc;
	PopplerPage *page;
	GtkWidget *darea;
	cairo_surface_t *surface;
	gint num_page;
	gint redraw_idle;
	GdkPoint start;
	GdkPoint stop;
	gboolean started;
	GdkCursorType cursor;
	GtkWidget *main_box;
	gdouble scale;
	} PgdSignatureDemo;

	/* Render area */
	static cairo_surface_t pgd_signature_render_page(PgdSignatureDemo demo)
	{
	cairo_t *cr;
	PopplerPage *page;
	gdouble width, height;
	cairo_surface_t *surface = NULL;

	page = poppler_document_get_page(demo->doc, demo->num_page);
	if (!page) {
	return NULL;
	}

	poppler_page_get_size(page, &width, &height);

	width *= demo->scale;
	height *= demo->scale;
	gtk_widget_set_size_request(demo->darea, width, height);

	surface = cairo_image_surface_create(CAIRO_FORMAT_RGB24, width, height);
	cr = cairo_create(surface);

	if (demo->scale != 1.0) {
	cairo_scale(cr, demo->scale, demo->scale);
	}

	cairo_save(cr);
	cairo_set_source_rgb(cr, 1, 1, 1);

	cairo_rectangle(cr, 0, 0, width, height);
	cairo_fill(cr);
	cairo_restore(cr);

	cairo_save(cr);
	poppler_page_render(page, cr);
	cairo_restore(cr);

	cairo_destroy(cr);
	g_object_unref(page);

	return surface;
	}

	static void draw_selection_rect(PgdSignatureDemo demo, cairo_t cr)
	{
	gint pos_x1, pos_x2, pos_y1, pos_y2;
	gint x, y, w, h;

	pos_x1 = demo->start.x;
	pos_y1 = demo->start.y;
	pos_x2 = demo->stop.x;
	pos_y2 = demo->stop.y;

	x = MIN(pos_x1, pos_x2);
	y = MIN(pos_y1, pos_y2);
	w = ABS(pos_x1 - pos_x2);
	h = ABS(pos_y1 - pos_y2);

	if (w <= 0 \|\| h <= 0) {
	return;
	}

	cairo_save(cr);

	cairo_rectangle(cr, x + 1, y + 1, w - 2, h - 2);
	cairo_set_source_rgba(cr, 0.2, 0.6, 0.8, 0.2);
	cairo_fill(cr);

	cairo_rectangle(cr, x + 0.5, y + 0.5, w - 1, h - 1);
	cairo_set_source_rgba(cr, 0.2, 0.6, 0.8, 0.35);
	cairo_set_line_width(cr, 1);
	cairo_stroke(cr);

	cairo_restore(cr);
	}

	static gboolean pgd_signature_view_drawing_area_draw(GtkWidget area, cairo_t cr, PgdSignatureDemo *demo)
	{
	if (demo->num_page == -1) {
	return FALSE;
	}

	if (!demo->surface) {
	demo->surface = pgd_signature_render_page(demo);
	if (!demo->surface) {
	return FALSE;
	}
	}

	cairo_set_source_surface(cr, demo->surface, 0, 0);
	cairo_paint(cr);

	if (demo->started) {
	draw_selection_rect(demo, cr);
	}

	return TRUE;
	}

	static gboolean pgd_signature_viewer_redraw(PgdSignatureDemo *demo)
	{
	cairo_surface_destroy(demo->surface);
	demo->surface = NULL;

	gtk_widget_queue_draw(demo->darea);

	demo->redraw_idle = 0;

	return FALSE;
	}

	static void pgd_signature_viewer_queue_redraw(PgdSignatureDemo *demo)
	{
	if (demo->redraw_idle == 0) {
	demo->redraw_idle = g_idle_add((GSourceFunc)pgd_signature_viewer_redraw, demo);
	}
	}

	static void pgd_signature_page_selector_value_changed(GtkSpinButton spinbutton, PgdSignatureDemo demo)
	{
	demo->num_page = (gint)gtk_spin_button_get_value(spinbutton) - 1;
	pgd_signature_viewer_queue_redraw(demo);

	demo->page = poppler_document_get_page(demo->doc, demo->num_page);
	}

	static void pgd_signature_drawing_area_realize(GtkWidget area, PgdSignatureDemo demo)
	{
	gtk_widget_add_events(area, GDK_POINTER_MOTION_HINT_MASK \| GDK_BUTTON1_MOTION_MASK \| GDK_BUTTON_PRESS_MASK \| GDK_BUTTON_RELEASE_MASK);
	}

	char password_callback(const char in)
	{
	GtkWidget *dialog;
	GtkWidget *box;
	GtkWidget *entry;
	char *ret;

	dialog = gtk_message_dialog_new(NULL, GTK_DIALOG_MODAL, GTK_MESSAGE_QUESTION, GTK_BUTTONS_OK_CANCEL, "Enter password");
	gtk_message_dialog_format_secondary_text(GTK_MESSAGE_DIALOG(dialog), "Enter password to open: %s", in);
	gtk_dialog_set_default_response(GTK_DIALOG(dialog), GTK_RESPONSE_OK);

	box = gtk_message_dialog_get_message_area(GTK_MESSAGE_DIALOG(dialog));
	entry = gtk_entry_new();
	gtk_entry_set_activates_default(GTK_ENTRY(entry), TRUE);
	gtk_entry_set_visibility(GTK_ENTRY(entry), FALSE);
	gtk_box_pack_end(GTK_BOX(box), entry, TRUE, TRUE, 6);
	gtk_widget_show_all(box);

	gtk_dialog_run(GTK_DIALOG(dialog));
	ret = g_strdup(gtk_entry_get_text(GTK_ENTRY(entry)));
	gtk_widget_destroy(dialog);

	return ret;
	}

	static void pgd_signature_update_cursor(PgdSignatureDemo *demo, GdkCursorType cursor_type)
	{
	GdkCursor *cursor = NULL;

	if (cursor_type == demo->cursor) {
	return;
	}

	if (cursor_type != GDK_LAST_CURSOR) {
	cursor = gdk_cursor_new_for_display(gtk_widget_get_display(demo->main_box), cursor_type);
	}

	demo->cursor = cursor_type;

	gdk_window_set_cursor(gtk_widget_get_window(demo->main_box), cursor);
	gdk_display_flush(gtk_widget_get_display(demo->main_box));
	if (cursor) {
	g_object_unref(cursor);
	}
	}

	static void pgd_signature_start_signing(GtkWidget button, PgdSignatureDemo demo)
	{
	demo->start.x = 0;
	demo->start.y = 0;
	demo->stop.x = 0;
	demo->stop.y = 0;
	demo->started = TRUE;
	pgd_signature_update_cursor(demo, GDK_TCROSS);
	}

	static gboolean pgd_signature_drawing_area_button_press(GtkWidget area, GdkEventButton event, PgdSignatureDemo *demo)
	{
	if (!demo->page \|\| event->button != 1 \|\| !demo->started) {
	return FALSE;
	}

	demo->start.x = event->x;
	demo->start.y = event->y;
	demo->stop = demo->start;

	pgd_signature_viewer_queue_redraw(demo);

	return TRUE;
	}

	static gboolean pgd_signature_drawing_area_motion_notify(GtkWidget area, GdkEventMotion event, PgdSignatureDemo *demo)
	{
	gdouble width, height;

	if (!demo->page \|\| demo->start.x == -1 \|\| !demo->started) {
	return FALSE;
	}

	demo->stop.x = event->x;
	demo->stop.y = event->y;

	poppler_page_get_size(demo->page, &width, &height);
	width *= demo->scale;
	height *= demo->scale;

	/* Keep the drawing within the page */
	demo->stop.x = CLAMP(demo->stop.x, 0, width);
	demo->stop.y = CLAMP(demo->stop.y, 0, height);

	pgd_signature_viewer_queue_redraw(demo);

	return TRUE;
	}

	static void on_signing_done(GObject source, GAsyncResult result, gpointer user_data)
	{
	PopplerDocument *document = POPPLER_DOCUMENT(source);
	GError *error = NULL;
	gboolean ret = poppler_document_sign_finish(document, result, &error);

	g_print("%s: result %d\n", __FUNCTION__, ret);
	if (error) {
	g_print("Error: %s", error->message);
	g_error_free(error);
	}
	}

	static gboolean pgd_signature_drawing_area_button_release(GtkWidget area, GdkEventButton event, PgdSignatureDemo *demo)
	{
	if (!demo->page \|\| event->button != 1 \|\| !demo->started) {
	return FALSE;
	}

	demo->started = FALSE;
	pgd_signature_update_cursor(demo, GDK_LAST_CURSOR);

	/* poppler_certificate_set_nss_dir ("./glib/demo/cert"); */
	poppler_set_nss_password_callback(password_callback);
	GList *available_certificates = poppler_get_available_signing_certificates();

	if (available_certificates) {
	char *signature;
	char *signature_left;
	PopplerSigningData *data = poppler_signing_data_new();
	PopplerRectangle rect;
	PopplerCertificateInfo *certificate_info;
	time_t t;
	double width, height;

	certificate_info = available_certificates->data;
	time(&t);

	poppler_signing_data_set_certificate_info(data, certificate_info);
	poppler_signing_data_set_page(data, demo->num_page);
	poppler_signing_data_set_field_partial_name(data, g_uuid_string_random());
	poppler_signing_data_set_destination_filename(data, "test.pdf");
	poppler_signing_data_set_reason(data, "I'm the author");
	poppler_signing_data_set_location(data, "At my desk");

	poppler_page_get_size(demo->page, &width, &height);

	rect.x1 = demo->start.x > demo->stop.x ? demo->stop.x : demo->start.x;
	rect.y1 = demo->start.y > demo->stop.y ? demo->stop.y : demo->start.y;
	rect.x2 = demo->start.x > demo->stop.x ? demo->start.x : demo->stop.x;
	rect.y2 = demo->start.y > demo->stop.y ? demo->start.y : demo->stop.y;

	/* Adjust scale */
	rect.x1 /= demo->scale;
	rect.y1 /= demo->scale;
	rect.x2 /= demo->scale;
	rect.y2 /= demo->scale;

	rect.y1 = height - rect.y1;
	rect.y2 = height - rect.y2;

	poppler_signing_data_set_signature_rectangle(data, &rect);

	signature = g_strdup_printf("Digitally signed by %s\nDate: %s", poppler_certificate_info_get_subject_common_name(certificate_info), ctime(&t));
	poppler_signing_data_set_signature_text(data, signature);
	g_free(signature);

	signature_left = g_strdup_printf("%s", poppler_certificate_info_get_subject_common_name(certificate_info));
	poppler_signing_data_set_signature_text_left(data, signature_left);
	g_free(signature_left);

	poppler_document_sign(demo->doc, data, NULL, on_signing_done, NULL);
	}

	return TRUE;
	}

	static void pgd_signature_scale_selector_value_changed(GtkSpinButton spinbutton, PgdSignatureDemo demo)
	{
	demo->scale = gtk_spin_button_get_value(spinbutton);
	pgd_signature_viewer_queue_redraw(demo);
	}

	/* Main UI */
	GtkWidget pgd_signature_create_widget(PopplerDocument document)
	{
	PgdSignatureDemo *demo;
	GtkWidget *label;
	GtkWidget *vbox;
	GtkWidget *button;
	GtkWidget hbox, page_selector;
	GtkWidget scale_hbox, scale_selector;
	GtkWidget *swindow;
	gchar *str;
	gint n_pages;

	demo = g_new0(PgdSignatureDemo, 1);
	demo->cursor = GDK_LAST_CURSOR;
	demo->doc = g_object_ref(document);
	demo->scale = 1.0;

	n_pages = poppler_document_get_n_pages(document);

	vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 12);

	hbox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 6);

	label = gtk_label_new("Page:");
	gtk_box_pack_start(GTK_BOX(hbox), label, FALSE, TRUE, 0);
	gtk_widget_show(label);

	page_selector = gtk_spin_button_new_with_range(1, n_pages, 1);
	g_signal_connect(G_OBJECT(page_selector), "value-changed", G_CALLBACK(pgd_signature_page_selector_value_changed), (gpointer)demo);
	gtk_box_pack_start(GTK_BOX(hbox), page_selector, FALSE, TRUE, 0);
	gtk_widget_show(page_selector);

	str = g_strdup_printf("of %d", n_pages);
	label = gtk_label_new(str);
	gtk_box_pack_start(GTK_BOX(hbox), label, FALSE, TRUE, 0);
	gtk_widget_show(label);
	g_free(str);

	scale_hbox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 6);

	label = gtk_label_new("Scale:");
	gtk_box_pack_start(GTK_BOX(scale_hbox), label, TRUE, TRUE, 0);
	gtk_widget_show(label);

	scale_selector = gtk_spin_button_new_with_range(0, 10.0, 0.1);
	gtk_spin_button_set_value(GTK_SPIN_BUTTON(scale_selector), 1.0);
	g_signal_connect(G_OBJECT(scale_selector), "value-changed", G_CALLBACK(pgd_signature_scale_selector_value_changed), (gpointer)demo);
	gtk_box_pack_start(GTK_BOX(scale_hbox), scale_selector, TRUE, TRUE, 0);
	gtk_widget_show(scale_selector);

	gtk_box_pack_start(GTK_BOX(hbox), scale_hbox, FALSE, TRUE, 0);
	gtk_widget_show(scale_hbox);

	gtk_box_pack_start(GTK_BOX(vbox), hbox, FALSE, TRUE, 0);

	button = gtk_button_new_with_mnemonic("_Sign");
	g_signal_connect(G_OBJECT(button), "clicked", G_CALLBACK(pgd_signature_start_signing), (gpointer)demo);
	gtk_box_pack_end(GTK_BOX(hbox), button, FALSE, FALSE, 0);
	gtk_widget_show(button);

	gtk_widget_show(hbox);

	/* Demo Area (Render) */
	demo->darea = gtk_drawing_area_new();
	g_signal_connect(demo->darea, "draw", G_CALLBACK(pgd_signature_view_drawing_area_draw), demo);
	g_signal_connect(demo->darea, "realize", G_CALLBACK(pgd_signature_drawing_area_realize), (gpointer)demo);
	g_signal_connect(demo->darea, "button_press_event", G_CALLBACK(pgd_signature_drawing_area_button_press), (gpointer)demo);
	g_signal_connect(demo->darea, "motion_notify_event", G_CALLBACK(pgd_signature_drawing_area_motion_notify), (gpointer)demo);
	g_signal_connect(demo->darea, "button_release_event", G_CALLBACK(pgd_signature_drawing_area_button_release), (gpointer)demo);

	swindow = gtk_scrolled_window_new(NULL, NULL);
	#if GTK_CHECK_VERSION(3, 7, 8)
	gtk_container_add(GTK_CONTAINER(swindow), demo->darea);
	#else
	gtk_scrolled_window_add_with_viewport(GTK_SCROLLED_WINDOW(swindow), demo->darea);
	#endif
	gtk_widget_show(demo->darea);

	gtk_widget_show(swindow);

	gtk_box_pack_start(GTK_BOX(vbox), swindow, TRUE, TRUE, 0);

	demo->main_box = vbox;

	demo->num_page = 0;
	demo->page = poppler_document_get_page(demo->doc, demo->num_page);
	pgd_signature_viewer_queue_redraw(demo);

	return vbox;
	}