Multi style text editing for TextField composable in android jetpack compose - android-jetpack-compose

Question

I want to change the text style (fontSize , color , fontWeight , ...) of a selected text in a TextFiled() composable , with a button in android jetpack compose.
(The main problem is, when i change the text style of a selected text ,the TextField can not save it , or when i add/remove a letter in TextField , the TextField deletes the previous text style.)
In other words, when the recomposition process occurs, the text styles disappears in the TextField()
my code is :
#Composable
fun Show() {
val inputText = remember{ mutableStateOf(TextFieldValue("This is a annotated text text"))}
Column(
modifier = Modifier.fillMaxSize().padding(5.dp) ,
horizontalAlignment = Alignment.CenterHorizontally
) {
//=================== TextField
CustomTextField(textInput = inputText)
//==================== Button
Button(onClick = {
inputText.value = changeSegmentColor(inputText.value)
}) {
Text(text = "Change the text style of selected text")
}
//======================
}
}
#Composable
fun CustomTextField (
textInput:MutableState<TextFieldValue>
) {
TextField(
value = textInput.value , onValueChange = {
textInput.value = it
},
modifier = Modifier.fillMaxWidth().heightIn(min = 200.dp) ,
)
}
private fun changeSegmentColor(textFVal: TextFieldValue):TextFieldValue{
val txtAnnotatedBuilder = AnnotatedString.Builder()
val realStartIndex = textFVal.getTextBeforeSelection(textFVal.text.length).length
val endIndex = realStartIndex + textFVal.getSelectedText().length
txtAnnotatedBuilder.append(textFVal.annotatedString)
val myStyle = SpanStyle(
color = Color.Red ,
fontSize = 16.sp ,
background = Color.Green
)
txtAnnotatedBuilder.addStyle(myStyle ,realStartIndex ,endIndex)
return textFVal.copy(annotatedString = txtAnnotatedBuilder.toAnnotatedString())
}