patch [#23758] Better handling of UTF chars in UNITS fields (lengths, angles, etc.)

from Lorenzo Tozzi (oni_niubbo) with minor edits.

--- from the tracker
The present situation is this: due to bug#22274, during editing, UTF chars are stripped from buttons with a unit associated
(length, angles, etc.).
Example: if the button displays '90°' and you click on it with LMB, the editing string will become '90'.

The problem arises if you use microns: '34µm' becomes '34' that blender interprets as 34 meters. So clicking on a button
and hitting enter won't confirm the previous value, but will change it (very badly also).

Of course nobody is using microns in blender, but the problem will arise when we will implement areas and option 'Separate
Units' will be enabled. The value '2m² 3cm²' will become '2m' during editing.

This patch solves the problem rewriting the string in a smarter way than just stripping the UTF chars: the unit is translated
from unit->name_short ('µm') to unit->name_alt ('um'). So clicking on '34µm' the editing string will become
'34um'.
--- end

note: rather then allowing empty strings in name_alt field I made it so if the unit system was the default one a NULL name_alt will just strip the string, since its the default its not needed.

1 files changed, 3 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_unit.h b/source/blender/blenkernel/BKE_unit.h
index 36ccc1f1497..65bdea8095a 100644
--- a/source/blender/blenkernel/BKE_unit.h
+++ b/source/blender/blenkernel/BKE_unit.h
@@ -36,6 +36,9 @@ void	bUnit_AsString(char *str, int len_max, double value, int prec, int system,
 /* replace units with values, used before python button evaluation */
 int		bUnit_ReplaceString(char *str, int len_max, char *str_prev, double scale_pref, int system, int type);
 
+/* make string keyboard-friendly: 10µm --> 10um */
+void bUnit_ToUnitAltName(char *str, int len_max, char *orig_str, int system, int type);
+
 /* the size of the unit used for this value (used for calculating the ckickstep) */
 double bUnit_ClosestScalar(double value, int system, int type);