PyAPI: support Operator.poll functions 'disabled' hint

Python scripts can now define the reason it's poll function fails using:

`Operator.poll_message_set(message, ...)`

This supports both regular text as well as delaying message creation
using a callback which should be used in situations where constructing
detailed messages is too much overhead for a poll function.

Ref D11001

1 files changed, 17 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_context.h b/source/blender/blenkernel/BKE_context.h
index cbc5ea818ea..cbebd1dfe0e 100644
--- a/source/blender/blenkernel/BKE_context.h
+++ b/source/blender/blenkernel/BKE_context.h
@@ -206,8 +206,24 @@ void CTX_wm_area_set(bContext *C, struct ScrArea *area);
 void CTX_wm_region_set(bContext *C, struct ARegion *region);
 void CTX_wm_menu_set(bContext *C, struct ARegion *menu);
 void CTX_wm_gizmo_group_set(bContext *C, struct wmGizmoGroup *gzgroup);
-const char *CTX_wm_operator_poll_msg_get(struct bContext *C);
+
+/**
+ * Values to create the message that describes the reason poll failed.
+ *
+ * \note This must be called in the same context as the poll function that created it.
+ */
+struct bContextPollMsgDyn_Params {
+  /** The result is allocated . */
+  char *(*get_fn)(bContext *C, void *user_data);
+  /** Optionally free the user-data. */
+  void (*free_fn)(bContext *C, void *user_data);
+  void *user_data;
+};
+
+const char *CTX_wm_operator_poll_msg_get(struct bContext *C, bool *r_free);
 void CTX_wm_operator_poll_msg_set(struct bContext *C, const char *msg);
+void CTX_wm_operator_poll_msg_set_dynamic(bContext *C,
+                                          const struct bContextPollMsgDyn_Params *parms);
 void CTX_wm_operator_poll_msg_clear(struct bContext *C);
 
 /* Data Context