path-tool: Add a restrict command

This lets you subset a path between two given lengths.

tools/gtk-path-tool-restrict.c

@@ -0,0 +1,97 @@
+/*  Copyright 2023 Red Hat, Inc.
+ *
+ * GTK+ 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 of the
+ * License, or (at your option) any later version.
+ *
+ * GLib 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 GTK+; see the file COPYING.  If not,
+ * see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Matthias Clasen
+ */
+
+#include "config.h"
+
+#include <gtk/gtk.h>
+#include "gtk-path-tool.h"
+
+#include <glib/gi18n-lib.h>
+
+void
+do_restrict (int *argc, const char ***argv)
+{
+  GError *error = NULL;
+  double start = G_MAXDOUBLE;
+  double end = G_MAXDOUBLE;
+  char **args = NULL;
+  GOptionContext *context;
+  GOptionEntry entries[] = {
+    { "start", 0, 0, G_OPTION_ARG_DOUBLE, &start, N_("Beginning of segment"), N_("LENGTH") },
+    { "end", 0, 0, G_OPTION_ARG_DOUBLE, &start, N_("End of segment"), N_("LENGTH") },
+    { G_OPTION_REMAINING, 0, 0, G_OPTION_ARG_FILENAME_ARRAY, &args, NULL, N_("PATH") },
+    { NULL, },
+  };
+  GskPath *path, *result;
+  GskPathMeasure *measure;
+  GskPathBuilder *builder;
+  GskPathPoint start_point, end_point;
+
+  g_set_prgname ("gtk4-path-tool restrict");
+
+  context = g_option_context_new (NULL);
+  g_option_context_set_translation_domain (context, GETTEXT_PACKAGE);
+  g_option_context_add_main_entries (context, entries, NULL);
+  g_option_context_set_summary (context, _("Restrict a path to a segment."));
+
+  if (!g_option_context_parse (context, argc, (char ***)argv, &error))
+    {
+      g_printerr ("%s\n", error->message);
+      g_error_free (error);
+      exit (1);
+    }
+
+  g_option_context_free (context);
+
+  if (args == NULL)
+    {
+      g_printerr ("%s\n", _("No paths given."));
+      exit (1);
+    }
+
+  path = get_path (args[0]);
+  measure = gsk_path_measure_new (path);
+
+  if (start == G_MAXDOUBLE)
+    start = 0;
+
+  if (end == G_MAXDOUBLE)
+    end = gsk_path_measure_get_length (measure);
+
+  builder = gsk_path_builder_new ();
+
+  gsk_path_measure_get_point (measure, start, &start_point);
+  gsk_path_measure_get_point (measure, end, &end_point);
+
+  gsk_path_builder_add_segment (builder, path, &start_point, &end_point);
+
+  result = gsk_path_builder_free_to_path (builder);
+
+  if (result)
+    {
+      char *str = gsk_path_to_string (result);
+      g_print ("%s\n", str);
+      g_free (str);
+    }
+  else
+    {
+      g_printerr ("%s\n", _("That didn't work out."));
+      exit (1);
+    }
+}

tools/gtk-path-tool.c

@@ -39,6 +39,7 @@ usage (void)
              "\n"
              "Commands:\n"
              "  decompose    Decompose the path\n"
+             "  restrict     Restrict the path to a segment\n"
              "  show         Display the path in a window\n"
              "  render       Render the path as an image\n"
              "  info         Print information about the path\n"
@@ -130,6 +131,8 @@ main (int argc, const char *argv[])
     do_info (&argc, &argv);
   else if (strcmp (argv[0], "render") == 0)
     do_render (&argc, &argv);
+  else if (strcmp (argv[0], "restrict") == 0)
+    do_restrict (&argc, &argv);
   else if (strcmp (argv[0], "show") == 0)
     do_show (&argc, &argv);
   else

tools/gtk-path-tool.h

@@ -2,6 +2,7 @@
 
 void do_info      (int *argc, const char ***argv);
 void do_decompose (int *argc, const char ***argv);
+void do_restrict  (int *argc, const char ***argv);
 void do_render    (int *argc, const char ***argv);
 void do_show      (int *argc, const char ***argv);
 

tools/meson.build

@@ -27,6 +27,7 @@ gtk_tools = [
                       'gtk-path-tool-decompose.c',
                       'gtk-path-tool-info.c',
                       'gtk-path-tool-render.c',
+                      'gtk-path-tool-restrict.c',
                       'gtk-path-tool-show.c',
                       'gtk-path-tool-utils.c',
                       'path-view.c'], [libgtk_dep]],