UI: support drawing booleans with icons as check-boxes

Previously, if a boolean happened to use an icon there was no way
to make it display as a check-box from Python scripts.

The previous logic meant we ended up having to edit the RNA.
Since booleans with icons don't work well with the split-property layout
(now used for most of the interface).
Icons were being removed from RNA then added back using awkward Python
ternary expressions in the interface scripts.

The toggle argument now has an unset state (-1).

- toggle=True: no checkbox (emboss).
- toggle=False: always use a checkbox (no icon).
- toggle=(unset/-1): depends on the icon status, default as before.

Since toggle=False was default, this isn't used in existing UI logic.

1 files changed, 10 insertions, 0 deletions

diff --git a/source/blender/editors/interface/interface.c b/source/blender/editors/interface/interface.c
index 8ff270bb622..931a4faa1c0 100644
--- a/source/blender/editors/interface/interface.c
+++ b/source/blender/editors/interface/interface.c
@@ -3738,6 +3738,16 @@ void ui_def_but_icon(uiBut *but, const int icon, const int flag)
   }
 }
 
+/**
+ * Avoid using this where possible since it's better not to ask for an icon in the first place.
+ */
+void ui_def_but_icon_clear(uiBut *but)
+{
+  but->icon = ICON_NONE;
+  but->flag &= ~UI_HAS_ICON;
+  but->drawflag &= ~UI_BUT_ICON_LEFT;
+}
+
 static void ui_def_but_rna__disable(uiBut *but, const char *info)
 {
   but->flag |= UI_BUT_DISABLED;