I'm making a simple TextField `VisualTransformatio...

# compose

[Jorge Domínguez]

I'm making a simple TextField VisualTransformation to ignore blank spaces, but when I tap the space bar multiple times and then I try to undo the typing it's counting all the blank spaces that were ignored, as seen in the video. Also, when I type two blank spaces it transforms them into a "." character. Any idea what I might be doing wrong?

val ignoreBlanksVisualTransformation = VisualTransformation { text ->
    val blanksCount = text.text.count { it.toString().isBlank() }
    val transformedText = text.text.filterNot { it.toString().isBlank() }

    TransformedText(AnnotatedString(transformedText), object : OffsetMapping {
        override fun originalToTransformed(offset: Int) = offset - blanksCount
        override fun transformedToOriginal(offset: Int) = offset + blanksCount
    })
}

Screen Recording 2022-06-09 at 3.19.17 PM.mov

[ephemient]

.-insertion is the behavior of many keyboards. "Gboard settings » Text correction » Double-space period" for example

[ephemient]

what is your goal here?
if it's to keep but hide all spaces, then the most straightforward thing to do would be to replace them with WJ or ZWS, e.g.

val visualTransformation = VisualTransform { text ->
    TransformedText(
         AnnotatedString(text.text.replace("""\s""".toRegex(), "\u200B")),
        OffsetMapping.Identity
    )
}

if it's to prevent the user for inserting spaces, you can do that directly,

private fun TextFieldValue.filtered(predicate: (Char) -> Boolean): TextFieldValue = copy(
    text = text.filter(predicate),
    selection = selection.adjustForFilter(text, predicate),
    composition = composition?.adjustForFilter(text, predicate),
)

private fun TextRange.adjustForFilter(text: String, predicate: (Char) -> Boolean): TextRange =
    TextRange(
        start = text.subSequence(0, start).count(predicate),
        end = text.subSequence(0, end).count(predicate),
    )

var textValue by remember { mutableStateOf(TextFieldValue()) }
TextField(
    value = textValue,
    onValueChange = { text -> textValue = text.filtered { !it.isWhitespace()} },
)

[Jorge Domínguez]

That's so much simpler, I haven't used the TextFieldValue override so it didn't cross my mind. Yeah I just want the user to not be able to type spaces