examples: add img-capture example

This one can be useful in scripts, e.g. for building fingerprint
dataset.

examples/img-capture.c

+/*
+ * Example fingerprint verification program, which verifies the
+ * finger which has been previously enrolled to disk.
+ * Copyright (C) 2007 Daniel Drake <dsd@gentoo.org>
+ * Copyright (C) 2019 Marco Trevisan <marco.trevisan@canonical.com>
+ * Copyright (C) 2020 Vasily Khoruzhick <anarsoul@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#define FP_COMPONENT "example-capture"
+
+#include <stdio.h>
+#include <libfprint/fprint.h>
+#include <glib-unix.h>
+
+#include "storage.h"
+#include "utilities.h"
+
+typedef struct CaptureData
+{
+  GMainLoop    *loop;
+  GCancellable *cancellable;
+  unsigned int  sigint_handler;
+  int           ret_value;
+  const char   *filename;
+} CaptureData;
+
+static void
+capture_data_free (CaptureData *capture_data)
+{
+  g_clear_handle_id (&capture_data->sigint_handler, g_source_remove);
+  g_clear_object (&capture_data->cancellable);
+  g_main_loop_unref (capture_data->loop);
+  g_free (capture_data);
+}
+G_DEFINE_AUTOPTR_CLEANUP_FUNC (CaptureData, capture_data_free)
+
+static void
+on_device_closed (FpDevice *dev, GAsyncResult *res, void *user_data)
+{
+  CaptureData *capture_data = user_data;
+
+  g_autoptr(GError) error = NULL;
+
+  fp_device_close_finish (dev, res, &error);
+
+  if (error)
+    g_warning ("Failed closing device %s\n", error->message);
+
+  g_main_loop_quit (capture_data->loop);
+}
+
+static void
+capture_quit (FpDevice    *dev,
+              CaptureData *capture_data)
+{
+  if (!fp_device_is_open (dev))
+    {
+      g_main_loop_quit (capture_data->loop);
+      return;
+    }
+
+  fp_device_close (dev, NULL, (GAsyncReadyCallback) on_device_closed, capture_data);
+}
+
+static void
+dev_capture_cb (FpDevice     *dev,
+                GAsyncResult *res,
+                void         *user_data)
+{
+  g_autoptr(GError) error = NULL;
+  CaptureData *capture_data = user_data;
+  FpImage *image = NULL;
+
+  g_clear_object (&capture_data->cancellable);
+
+  image = fp_device_capture_finish (dev, res, &error);
+  if (!image)
+    {
+      g_warning ("Error capturing data: %s", error->message);
+      capture_quit (dev, capture_data);
+      return;
+    }
+
+  save_image_to_pgm (image, capture_data->filename);
+
+  capture_quit (dev, capture_data);
+}
+
+static void
+start_capture (FpDevice *dev, CaptureData *capture_data)
+{
+  fp_device_capture (dev, TRUE, capture_data->cancellable, (GAsyncReadyCallback) dev_capture_cb, capture_data);
+}
+
+static void
+on_device_opened (FpDevice *dev, GAsyncResult *res, void *user_data)
+{
+  CaptureData *capture_data = user_data;
+
+  g_autoptr(GError) error = NULL;
+
+  if (!fp_device_open_finish (dev, res, &error))
+    {
+      g_warning ("Failed to open device: %s", error->message);
+      capture_quit (dev, capture_data);
+      return;
+    }
+
+  g_print ("Opened device. ");
+
+  start_capture (dev, capture_data);
+}
+
+static gboolean
+sigint_cb (void *user_data)
+{
+  CaptureData *capture_data = user_data;
+
+  g_cancellable_cancel (capture_data->cancellable);
+
+  return G_SOURCE_CONTINUE;
+}
+
+int
+main (int argc, const char *argv[])
+{
+  g_autoptr(FpContext) ctx = NULL;
+  g_autoptr(CaptureData) capture_data = NULL;
+  GPtrArray *devices;
+  FpDevice *dev;
+
+  setenv ("G_MESSAGES_DEBUG", "all", 0);
+  setenv ("LIBUSB_DEBUG", "3", 0);
+
+  ctx = fp_context_new ();
+
+  devices = fp_context_get_devices (ctx);
+  if (!devices)
+    {
+      g_warning ("Impossible to get devices");
+      return EXIT_FAILURE;
+    }
+
+  dev = discover_device (devices);
+  if (!dev)
+    {
+      g_warning ("No devices detected.");
+      return EXIT_FAILURE;
+    }
+
+  capture_data = g_new0 (CaptureData, 1);
+  capture_data->ret_value = EXIT_FAILURE;
+  capture_data->loop = g_main_loop_new (NULL, FALSE);
+  capture_data->cancellable = g_cancellable_new ();
+  capture_data->sigint_handler = g_unix_signal_add_full (G_PRIORITY_HIGH,
+                                                         SIGINT,
+                                                         sigint_cb,
+                                                         capture_data,
+                                                         NULL);
+  if (argc == 2)
+    capture_data->filename = argv[1];
+  else
+    capture_data->filename = "finger.pgm";
+  fp_device_open (dev, capture_data->cancellable,
+                  (GAsyncReadyCallback) on_device_opened,
+                  capture_data);
+
+  g_main_loop_run (capture_data->loop);
+
+  return capture_data->ret_value;
+}

examples/meson.build

 
-examples = [ 'enroll', 'verify', 'manage-prints' ]
+examples = [ 'enroll', 'verify', 'manage-prints', 'img-capture' ]
 foreach example: examples
     executable(example,
         [ example + '.c', 'storage.c', 'utilities.c' ],

examples/storage.c

@@ -180,7 +180,7 @@ print_create_template (FpDevice *dev, FpFinger finger)
 }
 
 
-static gboolean
+gboolean
 save_image_to_pgm (FpImage *img, const char *path)
 {
   FILE *fd = fopen (path, "w");

examples/storage.h

@@ -28,3 +28,5 @@ FpPrint * print_create_template (FpDevice *dev,
                                  FpFinger  finger);
 gboolean print_image_save (FpPrint    *print,
                            const char *path);
+gboolean save_image_to_pgm (FpImage    *img,
+                            const char *path);