app, cursors: add GimpToolTransform3DGrid tool widget

Add a new GimpToolTransform3DGrid tool widget, subclassed from
GimpToolTransformGrid, which can be used to perform 3D
transformations.

The widget can be in one of three modes:

  CAMERA - allows adjusting the primary vanishing point by moving a
  handle.

  MOVE   - allows moving the object through dragging.

  ROTATE - allows rotating the object through dragging.

By default, controlling the transformation through dragging applies
to the X and Y axes.  Holding Shift (or setting the "constrain-
axis" property) restricts the motion to only one of the axes.

For the MOVE and ROTATE mode, holding Ctrl (or setting the "z-axis"
property) allows controlling the Z axis instead.

For the same modes, holding Alt (or setting the "local-frame"
property), applies the adjustments in the object's local frame of
reference, instead of the display's global frame of reference.

app/display/Makefile.am

@@ -196,6 +196,8 @@ libappdisplay_a_sources = \
 	gimptoolrotategrid.h			\
 	gimptoolsheargrid.c			\
 	gimptoolsheargrid.h			\
+	gimptooltransform3dgrid.c		\
+	gimptooltransform3dgrid.h		\
 	gimptooltransformgrid.c			\
 	gimptooltransformgrid.h			\
 	gimptoolwidget.c			\

app/display/display-enums.c

@@ -389,6 +389,37 @@ gimp_rectangle_precision_get_type (void)
   return type;
 }
 
+GType
+gimp_transform_3d_mode_get_type (void)
+{
+  static const GEnumValue values[] =
+  {
+    { GIMP_TRANSFORM_3D_MODE_CAMERA, "GIMP_TRANSFORM_3D_MODE_CAMERA", "camera" },
+    { GIMP_TRANSFORM_3D_MODE_MOVE, "GIMP_TRANSFORM_3D_MODE_MOVE", "move" },
+    { GIMP_TRANSFORM_3D_MODE_ROTATE, "GIMP_TRANSFORM_3D_MODE_ROTATE", "rotate" },
+    { 0, NULL, NULL }
+  };
+
+  static const GimpEnumDesc descs[] =
+  {
+    { GIMP_TRANSFORM_3D_MODE_CAMERA, "GIMP_TRANSFORM_3D_MODE_CAMERA", NULL },
+    { GIMP_TRANSFORM_3D_MODE_MOVE, "GIMP_TRANSFORM_3D_MODE_MOVE", NULL },
+    { GIMP_TRANSFORM_3D_MODE_ROTATE, "GIMP_TRANSFORM_3D_MODE_ROTATE", NULL },
+    { 0, NULL, NULL }
+  };
+
+  static GType type = 0;
+
+  if (G_UNLIKELY (! type))
+    {
+      type = g_enum_register_static ("GimpTransform3DMode", values);
+      gimp_type_set_translation_context (type, "transform3-dmode");
+      gimp_enum_set_value_descriptions (type, descs);
+    }
+
+  return type;
+}
+
 GType
 gimp_transform_function_get_type (void)
 {

app/display/display-enums.h

@@ -171,6 +171,18 @@ typedef enum
 } GimpRectanglePrecision;
 
 
+#define GIMP_TYPE_TRANSFORM_3D_MODE (gimp_transform_3d_mode_get_type ())
+
+GType gimp_transform_3d_mode_get_type (void) G_GNUC_CONST;
+
+typedef enum /*< lowercase_name=gimp_transform_3d_mode >*/
+{
+  GIMP_TRANSFORM_3D_MODE_CAMERA,
+  GIMP_TRANSFORM_3D_MODE_MOVE,
+  GIMP_TRANSFORM_3D_MODE_ROTATE
+} GimpTransform3DMode;
+
+
 #define GIMP_TYPE_TRANSFORM_FUNCTION (gimp_transform_function_get_type ())
 
 GType gimp_transform_function_get_type (void) G_GNUC_CONST;

app/display/gimptooltransform3dgrid.h

@@ -0,0 +1,65 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * gimptool3dtransformgrid.h
+ * Copyright (C) 2019 Ell
+ *
+ * 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 <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GIMP_TOOL_TRANSFORM_3D_GRID_H__
+#define __GIMP_TOOL_TRANSFORM_3D_GRID_H__
+
+
+#include "gimptooltransformgrid.h"
+
+
+#define GIMP_TYPE_TOOL_TRANSFORM_3D_GRID            (gimp_tool_transform_3d_grid_get_type ())
+#define GIMP_TOOL_TRANSFORM_3D_GRID(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), GIMP_TYPE_TOOL_TRANSFORM_3D_GRID, GimpToolTransform3DGrid))
+#define GIMP_TOOL_TRANSFORM_3D_GRID_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass), GIMP_TYPE_TOOL_TRANSFORM_3D_GRID, GimpToolTransform3DGridClass))
+#define GIMP_IS_TOOL_TRANSFORM_3D_GRID(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GIMP_TYPE_TOOL_TRANSFORM_3D_GRID))
+#define GIMP_IS_TOOL_TRANSFORM_3D_GRID_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), GIMP_TYPE_TOOL_TRANSFORM_3D_GRID))
+#define GIMP_TOOL_TRANSFORM_3D_GRID_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj), GIMP_TYPE_TOOL_TRANSFORM_3D_GRID, GimpToolTransform3DGridClass))
+
+
+typedef struct _GimpToolTransform3DGrid        GimpToolTransform3DGrid;
+typedef struct _GimpToolTransform3DGridPrivate GimpToolTransform3DGridPrivate;
+typedef struct _GimpToolTransform3DGridClass   GimpToolTransform3DGridClass;
+
+struct _GimpToolTransform3DGrid
+{
+  GimpToolTransformGrid     parent_instance;
+
+  GimpToolTransform3DGridPrivate *priv;
+};
+
+struct _GimpToolTransform3DGridClass
+{
+  GimpToolTransformGridClass  parent_class;
+};
+
+
+GType            gimp_tool_transform_3d_grid_get_type (void) G_GNUC_CONST;
+
+GimpToolWidget * gimp_tool_transform_3d_grid_new      (GimpDisplayShell    *shell,
+                                                       gdouble              x1,
+                                                       gdouble              y1,
+                                                       gdouble              x2,
+                                                       gdouble              y2,
+                                                       gdouble              camera_x,
+                                                       gdouble              camera_y,
+                                                       gdouble              camera_z);
+
+
+#endif /* __GIMP_TOOL_TRANSFORM_3D_GRID_H__ */

app/widgets/gimpcursor.c

@@ -177,6 +177,7 @@ static GimpCursor gimp_tool_cursors[] =
   { "tool-rotate" },
   { "tool-shear" },
   { "tool-perspective" },
+  { "tool-transform-3d-camera" },
   { "tool-flip-horizontal" },
   { "tool-flip-vertical" },
   { "tool-text" },

app/widgets/widgets-enums.h

@@ -228,6 +228,7 @@ typedef enum  /*< skip >*/
   GIMP_TOOL_CURSOR_ROTATE,
   GIMP_TOOL_CURSOR_SHEAR,
   GIMP_TOOL_CURSOR_PERSPECTIVE,
+  GIMP_TOOL_CURSOR_TRANSFORM_3D_CAMERA,
   GIMP_TOOL_CURSOR_FLIP_HORIZONTAL,
   GIMP_TOOL_CURSOR_FLIP_VERTICAL,
   GIMP_TOOL_CURSOR_TEXT,

cursors/Makefile.am

@@ -151,6 +151,8 @@ CURSOR_IMAGES = \
 	tool-smudge-x2.png			\
 	tool-text.png				\
 	tool-text-x2.png			\
+	tool-transform-3d-camera.png		\
+	tool-transform-3d-camera-x2.png		\
 	tool-warp.png				\
 	tool-warp-x2.png			\
 	tool-zoom.png				\

po/POTFILES.in

@@ -267,6 +267,7 @@ app/display/gimptoolline.c
 app/display/gimptoolpath.c
 app/display/gimptoolpolygon.c
 app/display/gimptoolrectangle.c
+app/display/gimptooltransform3dgrid.c
 app/display/gimptooltransformgrid.c
 
 app/file/file-open.c