Develop Reference

Showing a text field in the app bar in Jetpack Compose with Material3

Many Android apps feature a search box in the app bar / toolbar, that looks somewhat like this screenshot:
How do I recreate something similar in Jetpack Compose + Material3? I would like the text field to have these features:
support showing a hint when the content string is empty (e.g. "Type your search...")
auto-focus on the first composition, so that the keyboard is opened
put the cursor at the end of the content string on the first composition
I tried to reproduce the same behavior in Jetpack Compose + Material3 by putting a TextField in the title of a CenterAlignedTopAppBar but the result does not look good. The text field uses the whole height of the app bar and has a grey background, and both of these things look odd.

I came up with a AppBarTextField after some engineering, see the code below. I had to use the lower-level BasicTextField since the normal TextField is not customizable enough. The code having to do with theming and color was copied directly from TextField's implementation, so that the theme's customizations apply normally to the components of the text field.
The parameters the AppBarTextField composable accepts are:
value: the content string to show in the text field
onValueChange: new values are passed here (remember to update value!)
hint: the hint to show when the text field is empty
modifier, keyboardOptions and keyboardActions: they are passed directly to BasicTextField and they behave the same as they would in a normal TextField. If you need to customize other TextField parameters just add them to the function signature and then pass them to BasicTextField.
The requested features are implemented:
the focus acquisition was achieved with a SideEffect, so that it would only happen on the first composition
putting the cursor at the end on the first composition required using a TextFieldValue
the strange-looking background is not present anymore, since no .background() modifier is present (while it is in the normal TextField)
the hint was added using by passing a placeholder to TextFieldDecorationBox in the decorationBox parameter (note that this was also possible with TextField)
TextFieldDecorationBox's padding is also now only 4dp. Padding was added here (and not with a modifier on BasicTextField) since otherwise the bottom line indicator (which is, instead, displayed using the .indicatorLine() modifier) would not be shown correctly.
#OptIn(ExperimentalMaterial3Api::class)
#Composable
fun AppBarTextField(
value: String,
onValueChange: (String) -> Unit,
hint: String,
modifier: Modifier = Modifier,
keyboardOptions: KeyboardOptions = KeyboardOptions.Default,
keyboardActions: KeyboardActions = KeyboardActions.Default,
) {
val interactionSource = remember { MutableInteractionSource() }
val textStyle = LocalTextStyle.current
// make sure there is no background color in the decoration box
val colors = TextFieldDefaults.textFieldColors(containerColor = Color.Unspecified)
// If color is not provided via the text style, use content color as a default
val textColor = textStyle.color.takeOrElse {
MaterialTheme.colorScheme.onSurface
}
val mergedTextStyle = textStyle.merge(TextStyle(color = textColor, lineHeight = 50.sp))
// request focus when this composable is first initialized
val focusRequester = FocusRequester()
SideEffect {
focusRequester.requestFocus()
}
// set the correct cursor position when this composable is first initialized
var textFieldValue by remember {
mutableStateOf(TextFieldValue(value, TextRange(value.length)))
}
textFieldValue = textFieldValue.copy(text = value) // make sure to keep the value updated
CompositionLocalProvider(
LocalTextSelectionColors provides LocalTextSelectionColors.current
) {
BasicTextField(
value = textFieldValue,
onValueChange = {
textFieldValue = it
// remove newlines to avoid strange layout issues, and also because singleLine=true
onValueChange(it.text.replace("\n", ""))
},
modifier = modifier
.fillMaxWidth()
.heightIn(32.dp)
.indicatorLine(
enabled = true,
isError = false,
interactionSource = interactionSource,
colors = colors
)
.focusRequester(focusRequester),
textStyle = mergedTextStyle,
cursorBrush = SolidColor(MaterialTheme.colorScheme.primary),
keyboardOptions = keyboardOptions,
keyboardActions = keyboardActions,
interactionSource = interactionSource,
singleLine = true,
decorationBox = { innerTextField ->
// places text field with placeholder and appropriate bottom padding
TextFieldDefaults.TextFieldDecorationBox(
value = value,
visualTransformation = VisualTransformation.None,
innerTextField = innerTextField,
placeholder = { Text(text = hint) },
singleLine = true,
enabled = true,
isError = false,
interactionSource = interactionSource,
colors = colors,
contentPadding = PaddingValues(bottom = 4.dp)
)
}
)
}
}
Here is an example usage:
var value by rememberSaveable { mutableStateOf("initial content") }
CenterAlignedTopAppBar(
title = {
AppBarTextField(
value = value,
onValueChange = { newValue -> value = newValue },
hint = "A hint..."
)
},
navigationIcon = /* the back icon */,
actions = /* the search icon */
)

Jetpack Compose TextField cuts text on scroll

I have a TextField with a fixed height. When the user enters a longer text it will scroll. It will cut off any text within the padding when scrolling:
Basically something like this:
var text by remember { mutableStateOf("") }
TextField(
value = text,
onValueChange = { value -> text = value },
modifier = modifier
.fillMaxWidth()
.height(100.dp),
colors = TextFieldDefaults.textFieldColors(
focusedIndicatorColor = Color.Transparent,
unfocusedIndicatorColor = Color.Transparent,
backgroundColor = Color.Transparent
)
)
It is possible to adjust/remove the padding for a TextField, by using BasicTextField directly, e.g. see this stack overflow question.
However I want to keep the padding, but without the clipping of the text when the user scrolls. A simple Text Composable has this behavior.

You can use BasicTextField and modify its decorationBox parameter.
Simply put innerTextField() inside a scrollable Column and add Spacers at the top and the bottom of it.
var text by remember {
mutableStateOf("Hello Stackoverflow")
}
val paddingSize = remember { 16.dp }
BasicTextField(
modifier = Modifier
.height(100.dp),
value = text,
onValueChange = { text = it },
decorationBox = { innerTextField ->
Column(
modifier = Modifier
.fillMaxWidth()
.verticalScroll(state = rememberScrollState())
) {
Spacer(modifier = Modifier.height(paddingSize))
innerTextField()
Spacer(modifier = Modifier.height(paddingSize))
}
}
)

Just use the maxLines parameter of the TextField to avoid clipping. Set it to 1 or 2, per your case, then adjust the height/font-size so the max lines you specify are accomodated correctly. It will likely start to snap to the visible portion, cutting the extra stuff entirely.

Jetpack Compose Material Design TextField WrapContentWidth [duplicate]

I'm trying to make an OutlinedTextField (see below image) act as "wrap-content". It would be ideal for it to be just big enough to fit the inside text 500g and expand and contract if user edits the field.
If I remember correctly this was possible to do with the old views with the (non-Compose) ConstraintLayout but in Compose this isn't working.
So far I have tried adjusting various modifiers, (each separately):
.defaultMinSize(minWidth = 10.dp)
.width(IntrinsicSize.Min)
.widthIn(1.dp, Dp.Infinity)
.requiredWidth(IntrinsicSize.Min)
I also tried putting the Row into a Compose ConstraintLayout, but nothing seems to work
If I set the size modifier to a small width it does reduce the width but it no longer expands...
Anyone was able to achieve this?

The OutlinedTextField has default min size.
You can achieve it using a OutlinedTextFieldDecorationBox together with BasicTextField, applying the modifier width(IntrinsicSize.Min).
Something like:
var text by remember { mutableStateOf("500") }
val interactionSource = remember { MutableInteractionSource() }
val enabled = true
val singleLine = true
BasicTextField(
value = text,
onValueChange = {text = it},
interactionSource = interactionSource,
enabled = enabled,
singleLine = singleLine,
modifier = Modifier.width(IntrinsicSize.Min)
) {
TextFieldDefaults.OutlinedTextFieldDecorationBox(
value = text,
visualTransformation = VisualTransformation.None,
innerTextField = it,
singleLine = singleLine,
enabled = enabled,
interactionSource = interactionSource,
// keep vertical paddings but change the horizontal
contentPadding = TextFieldDefaults.textFieldWithoutLabelPadding(
start = 8.dp, end = 8.dp
),
colors = TextFieldDefaults.outlinedTextFieldColors()
)
}
Note: it requires at least the compose version 1.2.0

How to know when a Composable like TextField gains focus?

I want to trigger a function upon my TextField's focus-gain, but I am unable to find something like a listener.

You can use the onFocusChanged modifier
TextField(
value = text,
onValueChange = { text = it},
modifier = Modifier.onFocusChanged {
if (it.isFocused){
//...
}
}
)

Disable upward movement animation of label in TextField (Jetpack compose)

On tapping a TextField, created with Jetpack compose, the label of TextField moves upward. How do we disable this?
Or is there any other way the TexField would work like an EditText in View system where we have hint which disappears on tapping the EditText?

Jetpack compose version - 1.0.3
placeholder attribute might be what you are looking for.
But, the text doesn't disappear on clicking the TextField.
It disappears only when the user enters some input text.
Default state
Focused state
After entering input
Code
TextField(
placeholder = { Text(text = "Label") },
// Other attributes
)

UPDATE
You can use placeholder with state.
var focusState by remember { mutableStateOf(false) }
placeholder = {
Text(
text = if (focusState) "" else "label",
)
}
and focusState you take from onFocusChanged
TextField(
modifier = Modifier
.onFocusChanged { focus ->
focusState = focus.isFocused
}