UI: Grease Pencil Modifier Drag and Drop, Layout Changes

This patch implements the list panel system D7490 for grease pencil
modifiers. It also moves their drawing to a callback in
GpencilModifierTypeInfo in line with the extensible architecture
refactoring goal T75724.

This also adds the "set_error" function for grease pencil modifiers,
which hadn't been copied from mesh modifiers yet.

The implementation is basically exactly the same as for the modifier
patch (9b099c86123fc82).

Thanks to Matias Mendiola (mendio) for providing mockups for many
of the layout changes.

Differential Revision: https://developer.blender.org/D7978

2 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/editors/include/ED_object.h b/source/blender/editors/include/ED_object.h
index ebd7321a46d..0cc926987b2 100644
--- a/source/blender/editors/include/ED_object.h
+++ b/source/blender/editors/include/ED_object.h
@@ -421,6 +421,10 @@ int ED_object_gpencil_modifier_move_down(struct ReportList *reports,
 int ED_object_gpencil_modifier_move_up(struct ReportList *reports,
                                        struct Object *ob,
                                        struct GpencilModifierData *md);
+bool ED_object_gpencil_modifier_move_to_index(struct ReportList *reports,
+                                              struct Object *ob,
+                                              struct GpencilModifierData *md,
+                                              const int index);
 int ED_object_gpencil_modifier_apply(struct Main *bmain,
                                      struct ReportList *reports,
                                      struct Depsgraph *depsgraph,
diff --git a/source/blender/editors/include/UI_interface.h b/source/blender/editors/include/UI_interface.h
index d89e590122c..8e9591c1963 100644
--- a/source/blender/editors/include/UI_interface.h
+++ b/source/blender/editors/include/UI_interface.h
@@ -2004,6 +2004,7 @@ void uiTemplatePathBuilder(uiLayout *layout,
                            struct PointerRNA *root_ptr,
                            const char *text);
 void uiTemplateModifiers(uiLayout *layout, struct bContext *C);
+void uiTemplateGpencilModifiers(uiLayout *layout, struct bContext *C);
 void uiTemplateConstraints(uiLayout *layout, struct bContext *C, bool use_bone_constraints);
 
 uiLayout *uiTemplateGpencilModifier(uiLayout *layout, struct bContext *C, struct PointerRNA *ptr);