app: add new GimpToolWidget subclass GimpToolRectangle

which is a replacement for GimpRectangleTool. It's a massive piece of
code and I'm not sure everyting works as it should, but it seems to do
crop stuff without any glitches.

app/display/Makefile.am

@@ -174,6 +174,8 @@ libappdisplay_a_sources = \
 	gimptoolpath.h				\
 	gimptoolpolygon.c			\
 	gimptoolpolygon.h			\
+	gimptoolrectangle.c			\
+	gimptoolrectangle.h			\
 	gimptoolrotategrid.c			\
 	gimptoolrotategrid.h			\
 	gimptoolsheargrid.c			\

app/display/gimptoolrectangle.h

@@ -0,0 +1,122 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptoolrectangle.h
+ * Copyright (C) 2017 Michael Natterer <mitch@gimp.org>
+ *
+ * Based on GimpRectangleTool
+ * Copyright (C) 2007 Martin Nordholts
+ *
+ * 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 3 of the License, 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TOOL_RECTANGLE_H__
+#define __GIMP_TOOL_RECTANGLE_H__
+
+
+#include "gimptoolwidget.h"
+
+
+typedef enum
+{
+  GIMP_TOOL_RECTANGLE_DEAD,
+  GIMP_TOOL_RECTANGLE_CREATING,
+  GIMP_TOOL_RECTANGLE_MOVING,
+  GIMP_TOOL_RECTANGLE_RESIZING_UPPER_LEFT,
+  GIMP_TOOL_RECTANGLE_RESIZING_UPPER_RIGHT,
+  GIMP_TOOL_RECTANGLE_RESIZING_LOWER_LEFT,
+  GIMP_TOOL_RECTANGLE_RESIZING_LOWER_RIGHT,
+  GIMP_TOOL_RECTANGLE_RESIZING_LEFT,
+  GIMP_TOOL_RECTANGLE_RESIZING_RIGHT,
+  GIMP_TOOL_RECTANGLE_RESIZING_TOP,
+  GIMP_TOOL_RECTANGLE_RESIZING_BOTTOM,
+  GIMP_TOOL_RECTANGLE_AUTO_SHRINK,
+  GIMP_TOOL_RECTANGLE_EXECUTING,
+  GIMP_N_TOOL_RECTANGLE_FUNCTIONS
+} GimpRectangleFunction;
+
+
+#define GIMP_TYPE_TOOL_RECTANGLE            (gimp_tool_rectangle_get_type ())
+#define GIMP_TOOL_RECTANGLE(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TOOL_RECTANGLE, GimpToolRectangle))
+#define GIMP_TOOL_RECTANGLE_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TOOL_RECTANGLE, GimpToolRectangleClass))
+#define GIMP_IS_TOOL_RECTANGLE(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TOOL_RECTANGLE))
+#define GIMP_IS_TOOL_RECTANGLE_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TOOL_RECTANGLE))
+#define GIMP_TOOL_RECTANGLE_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TOOL_RECTANGLE, GimpToolRectangleClass))
+
+
+typedef struct _GimpToolRectangle        GimpToolRectangle;
+typedef struct _GimpToolRectanglePrivate GimpToolRectanglePrivate;
+typedef struct _GimpToolRectangleClass   GimpToolRectangleClass;
+
+struct _GimpToolRectangle
+{
+  GimpToolWidget            parent_instance;
+
+  GimpToolRectanglePrivate *private;
+};
+
+struct _GimpToolRectangleClass
+{
+  GimpToolWidgetClass  parent_class;
+
+  /*  signals  */
+
+  gboolean (* change_complete) (GimpToolRectangle *rectangle);
+};
+
+
+GType    gimp_tool_rectangle_get_type         (void) G_GNUC_CONST;
+
+GimpToolWidget * gimp_tool_rectangle_new      (GimpDisplayShell       *shell);
+
+GimpRectangleFunction
+         gimp_tool_rectangle_get_function     (GimpToolRectangle      *rectangle);
+void     gimp_tool_rectangle_set_function     (GimpToolRectangle      *rectangle,
+                                               GimpRectangleFunction   function);
+
+void     gimp_tool_rectangle_set_constraint   (GimpToolRectangle      *rectangle,
+                                               GimpRectangleConstraint constraint);
+GimpRectangleConstraint
+         gimp_tool_rectangle_get_constraint   (GimpToolRectangle      *rectangle);
+
+void     gimp_tool_rectangle_get_public_rect  (GimpToolRectangle      *rectangle,
+                                               gdouble                *pub_x1,
+                                               gdouble                *pub_y1,
+                                               gdouble                *pub_x2,
+                                               gdouble                *pub_y2);
+
+void     gimp_tool_rectangle_pending_size_set (GimpToolRectangle      *rectangle,
+                                               GObject                *object,
+                                               const gchar            *width_property,
+                                               const gchar            *height_property);
+
+void     gimp_tool_rectangle_constraint_size_set
+                                              (GimpToolRectangle      *rectangle,
+                                               GObject                *object,
+                                               const gchar            *width_property,
+                                               const gchar            *height_property);
+
+gboolean gimp_tool_rectangle_rectangle_is_new (GimpToolRectangle      *rectangle);
+gboolean gimp_tool_rectangle_point_in_rectangle
+                                              (GimpToolRectangle      *rectangle,
+                                               gdouble                 x,
+                                               gdouble                 y);
+
+void     gimp_tool_rectangle_frame_item       (GimpToolRectangle      *rectangle,
+                                               GimpItem               *item);
+void     gimp_tool_rectangle_auto_shrink      (GimpToolRectangle      *rectrectangle,
+                                               gboolean                shrink_merged);
+
+
+#endif /* __GIMP_TOOL_RECTANGLE_H__ */

po/POTFILES.in

@@ -258,6 +258,7 @@ app/display/gimptoolcompass.c
 app/display/gimptoolhandlegrid.c
 app/display/gimptoolpath.c
 app/display/gimptoolpolygon.c
+app/display/gimptoolrectangle.c
 app/display/gimptooltransformgrid.c
 
 app/file/file-open.c