[gimp/gimp-2-10] app: add "Constrain handles", "Around center" options to the perspective tool

[Ell <ell src gnome org>]

commit 5a62d61885b718c1a97eff18c3e24291a9a2035a
Author: Ell <ell_se yahoo com>
Date:   Thu Feb 28 15:43:05 2019 -0500

    app: add "Constrain handles", "Around center" options to the perspective tool
    
    Add "Constrain handles" and "Around center" options to the
    perspective-transform tool's GUI, which are similar to the
    corresponding options of the unified-transform tool.  Both of these
    options can already be controlled using Shift and Ctrl,
    respectively, through the transform-grid widget, so we might as
    well provide GUI toggles for them.
    
    (cherry picked from commit ac4b0fe9f18cb3c59d6b46f788aed849b8f9a65f)

 app/tools/gimptransformgridoptions.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
---
diff --git a/app/tools/gimptransformgridoptions.c b/app/tools/gimptransformgridoptions.c
index 631bbe7b12..ee8dddb109 100644
--- a/app/tools/gimptransformgridoptions.c
+++ b/app/tools/gimptransformgridoptions.c
@@ -32,6 +32,7 @@
 #include "widgets/gimpspinscale.h"
 #include "widgets/gimpwidgets-utils.h"
 
+#include "gimpperspectivetool.h"
 #include "gimprotatetool.h"
 #include "gimpscaletool.h"
 #include "gimpunifiedtransformtool.h"
@@ -472,6 +473,37 @@ gimp_transform_grid_options_gui (GimpToolOptions *tool_options)
       gimp_help_set_help_data (button, _("Scale around the center point"),
                                NULL);
 
+      g_free (label);
+    }
+  else if (tool_options->tool_info->tool_type == GIMP_TYPE_PERSPECTIVE_TOOL)
+    {
+      GtkWidget *button;
+      gchar     *label;
+
+      label = g_strdup_printf (_("Constrain handles (%s)"),
+                               gimp_get_mod_string (extend_mask));
+
+      button = gimp_prop_check_button_new (config, "constrain-perspective", label);
+      gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
+      gtk_widget_show (button);
+
+      gimp_help_set_help_data (
+        button, _("Constrain handles to move along edges and diagonal (%s)"),
+        NULL);
+
+      g_free (label);
+
+      label = g_strdup_printf (_("Around center (%s)"),
+                               gimp_get_mod_string (constrain_mask));
+
+      button = gimp_prop_check_button_new (config, "frompivot-perspective", label);
+      gtk_box_pack_start (GTK_BOX (vbox), button, FALSE, FALSE, 0);
+      gtk_widget_show (button);
+
+      gimp_help_set_help_data (
+        button, _("Transform around the center point"),
+        NULL);
+
       g_free (label);
     }
   else if (tool_options->tool_info->tool_type == GIMP_TYPE_UNIFIED_TRANSFORM_TOOL)