InputText: numerical fields automatically accept full-width characters (U+FF01..U+FF5E) by converting them to half-width (U+0021..U+007E).

docs/CHANGELOG.txt

@@ -65,6 +65,8 @@ Other Changes:
 
 - InputText: added experimental io.ConfigInputTextEnterKeepActive feature to make pressing
   Enter keep the input active and select all text.
+- InputText: numerical fields automatically accept full-width characters (U+FF01..U+FF5E)
+  by converting them to half-width (U+0021..U+007E).
 - Tables,Columns: fixed a layout issue where SameLine() prior to a row change would set the
   next row in such state where subsequent SameLine() would move back to previous row.
 - Tabs: Fixed a crash when closing multiple windows (possible with docking only) with an

imgui_widgets.cpp

@@ -3923,6 +3923,13 @@ static bool InputTextFilterCharacter(unsigned int* p_char, ImGuiInputTextFlags f
         ImGuiContext& g = *GImGui;
         const unsigned c_decimal_point = (unsigned int)g.PlatformLocaleDecimalPoint;
 
+        // Full-width -> half-width conversion for numeric fields (https://en.wikipedia.org/wiki/Halfwidth_and_Fullwidth_Forms_(Unicode_block)
+        // While this is mostly convenient, this has the side-effect for uninformed users accidentally inputting full-width characters that they may
+        // scratch their head as to why it works in numerical fields vs in generic text fields it would require support in the font.
+        if (flags & (ImGuiInputTextFlags_CharsDecimal | ImGuiInputTextFlags_CharsScientific | ImGuiInputTextFlags_CharsHexadecimal))
+            if (c >= 0xFF01 && c <= 0xFF5E)
+                c = c - 0xFF01 + 0x21;
+
         // Allow 0-9 . - + * /
         if (flags & ImGuiInputTextFlags_CharsDecimal)
             if (!(c >= '0' && c <= '9') && (c != c_decimal_point) && (c != '-') && (c != '+') && (c != '*') && (c != '/'))
@@ -3941,11 +3948,13 @@ static bool InputTextFilterCharacter(unsigned int* p_char, ImGuiInputTextFlags f
         // Turn a-z into A-Z
         if (flags & ImGuiInputTextFlags_CharsUppercase)
             if (c >= 'a' && c <= 'z')
-                *p_char = (c += (unsigned int)('A' - 'a'));
+                c += (unsigned int)('A' - 'a');
 
         if (flags & ImGuiInputTextFlags_CharsNoBlank)
             if (ImCharIsBlankW(c))
                 return false;
+
+        *p_char = c;
     }
 
     // Custom callback filter