Implement string composition for CGUIEditBox

irr/src/CGUIEditBox.cpp

@@ -234,6 +234,10 @@ bool CGUIEditBox::OnEvent(const SEvent &event)
 			inputString(*event.StringInput.Str);
 			return true;
 			break;
+		case EET_STRING_COMPOSITION_EVENT:
+			composeString(*event.StringComposition.Str);
+			return true;
+			break;
 		default:
 			break;
 		}
@@ -1262,10 +1266,10 @@ void CGUIEditBox::inputChar(wchar_t c)
 	inputString(s);
 }
 
-void CGUIEditBox::inputString(const core::stringw &str)
+bool CGUIEditBox::insertString(const core::stringw &str)
 {
 	if (!isEnabled())
-		return;
+		return false;
 
 	core::stringw s;
 	u32 len = str.size();
@@ -1324,6 +1328,13 @@ void CGUIEditBox::inputString(const core::stringw &str)
 	}
 
 	BlinkStartTime = os::Timer::getTime();
+	return true;
+}
+
+void CGUIEditBox::inputString(const core::stringw &str)
+{
+	if (!insertString(str))
+		return;
 	setTextMarkers(0, 0);
 
 	breakText();
@@ -1331,6 +1342,17 @@ void CGUIEditBox::inputString(const core::stringw &str)
 	sendGuiEvent(EGET_EDITBOX_CHANGED);
 }
 
+void CGUIEditBox::composeString(const core::stringw &str)
+{
+	if (!insertString(str))
+		return;
+	setTextMarkers(CursorPos-str.size(), CursorPos);
+
+	breakText();
+	calculateScrollPos();
+	sendGuiEvent(EGET_EDITBOX_CHANGED);
+}
+
 // calculate autoscroll
 void CGUIEditBox::calculateScrollPos()
 {

irr/src/CGUIEditBox.h

@@ -144,10 +144,14 @@ protected:
 	void setTextRect(s32 line);
 	//! returns the line number that the cursor is on
 	s32 getLineFromPos(s32 pos);
+	//! inserts a string to the edit box; used by inputString and composeString
+	bool insertString(const core::stringw &str);
 	//! adds a letter to the edit box
 	void inputChar(wchar_t c);
 	//! adds a string to the edit box
 	void inputString(const core::stringw &str);
+	//! compose a string before it is added
+	void composeString(const core::stringw &str);
 	//! calculates the current scroll position
 	void calculateScrollPos();
 	//! calculated the FrameRect

irr/src/CGUIEnvironment.cpp

@@ -552,6 +552,7 @@ bool CGUIEnvironment::postEventFromUser(const SEvent &event)
 			}
 		}
 	} break;
+	case EET_STRING_COMPOSITION_EVENT: [[fallthrough]];
 	case EET_STRING_INPUT_EVENT:
 		if (Focus && Focus->OnEvent(event))
 			return true;