Internals: Added ImTextCountUtf8BytesFromChar() helper.

imgui.cpp

@@ -1479,6 +1479,13 @@ static inline int ImTextCharToUtf8(char* buf, int buf_size, unsigned int c)
     }
 }
 
+// Not optimal but we very rarely use this function.
+int ImTextCountUtf8BytesFromChar(const char* in_text, const char* in_text_end)
+{
+    unsigned int dummy = 0;
+    return ImTextCharFromUtf8(&dummy, in_text, in_text_end);
+}
+
 static inline int ImTextCountUtf8BytesFromChar(unsigned int c)
 {
     if (c < 0x80) return 1;

imgui_internal.h

@@ -107,10 +107,11 @@ extern IMGUI_API ImGuiContext* GImGui;  // Current implicit ImGui context pointe
 
 // Helpers: UTF-8 <> wchar
 IMGUI_API int           ImTextStrToUtf8(char* buf, int buf_size, const ImWchar* in_text, const ImWchar* in_text_end);      // return output UTF-8 bytes count
-IMGUI_API int           ImTextCharFromUtf8(unsigned int* out_char, const char* in_text, const char* in_text_end);          // return input UTF-8 bytes count
+IMGUI_API int           ImTextCharFromUtf8(unsigned int* out_char, const char* in_text, const char* in_text_end);          // read one character. return input UTF-8 bytes count
 IMGUI_API int           ImTextStrFromUtf8(ImWchar* buf, int buf_size, const char* in_text, const char* in_text_end, const char** in_remaining = NULL);   // return input UTF-8 bytes count
 IMGUI_API int           ImTextCountCharsFromUtf8(const char* in_text, const char* in_text_end);                            // return number of UTF-8 code-points (NOT bytes count)
-IMGUI_API int           ImTextCountUtf8BytesFromStr(const ImWchar* in_text, const ImWchar* in_text_end);                   // return number of bytes to express string as UTF-8 code-points
+IMGUI_API int           ImTextCountUtf8BytesFromChar(const char* in_text, const char* in_text_end);                        // return number of bytes to express one char in UTF-8
+IMGUI_API int           ImTextCountUtf8BytesFromStr(const ImWchar* in_text, const ImWchar* in_text_end);                   // return number of bytes to express string in UTF-8
 
 // Helpers: Misc
 IMGUI_API ImU32         ImHash(const void* data, int data_size, ImU32 seed = 0);    // Pass data_size==0 for zero-terminated strings