field/me.tbsten.compose.preview.lab.field/NullableField

NullableField

class NullableField<Value : Any> : MutablePreviewLabField<Value?>

Create a PreviewLabField that makes the receiver's PreviewLabField nullable.

Usage

// Basic nullable string field
@Preview
@Composable
fun AvatarPreview() = PreviewLab {
    val avatarUrl: String? = fieldValue {
        StringField("Avatar URL", "https://example.com/avatar.jpg")
            .nullable(initialValue = null)
    }
    UserProfile(avatarUrl = avatarUrl) // Show placeholder if null
}

// Combining nullable with EnumField
enum class IconType { HOME, SEARCH, SETTINGS }
@Preview
@Composable
fun IconPreview() = PreviewLab {

    val icon: IconType? = fieldValue {
        EnumField("Icon", IconType.HOME)
            .nullable()
    }
    MyButton(icon = icon) // Button without icon if null
}

Properties

coroutineScope

open override val coroutineScope: CoroutineScope

initialValue

open override val initialValue: Value?

Default value for this field.

label

open override val label: String

The label for this field. This is not used in any of the program logic, but only for display purposes, so it is best to set it in a language that is easy for your team members to read.

value

open override var value: Value?

Current value of this PreviewLabField.

valueFlow

open override val valueFlow: Flow<Value?>

Functions

component1

open operator override fun component1(): Value?

component2

open operator override fun component2(): (Value?) -> Unit

Content

@Composable

open override fun Content()

Composable, which displays the main UI for this Field. If you want to customize the UI, you can override this method in your PreviewLabField to customize the UI.

DefaultFieldView

@Composable

fun <Value> PreviewLabField<Value>.DefaultFieldView(modifier: Modifier = Modifier, menuItems: List<PreviewLabField.ViewMenuItem<Value>> = ViewMenuItem.defaults<Value>(this), content: @Composable () -> Unit = { Content() })

Default UI implementation of me.tbsten.compose.preview.lab.PreviewLabField.View. Display a label and draw the content below it.

FieldLabelHeader

@Composable

fun <Value> PreviewLabField<Value>.FieldLabelHeader(menuItems: List<PreviewLabField.ViewMenuItem<Value>> = ViewMenuItem.defaults<Value>(this))

Display the label of PreviewLabField.

nullable

fun <Value : Any> PreviewLabField<Value>.nullable(initialValue: Value? = this.initialValue): NullableField<Value>

Create a PreviewLabField that makes the receiver's PreviewLabField nullable.

onCleared

open fun onCleared()

serializer

open override fun serializer(): KSerializer<Value?>?

Returns a KSerializer for this field's value type, or null if serialization is not supported.

testValues

open override fun testValues(): List<Value?>

Returns a list of representative values for this field to be used in automated testing.

TextFieldContent

@Composable

fun <Value> MutablePreviewLabField<Value>.TextFieldContent(toString: (Value) -> String, toValue: (String) -> Result<Value>, modifier: Modifier = Modifier, prefix: @Composable () -> Unit? = null, suffix: @Composable () -> Unit? = null, placeholder: @Composable () -> Unit? = null)

Helper for UI of Fields that can be input with TextField.

transform

fun <BaseValue, TransformedValue> MutablePreviewLabField<BaseValue>.transform(transform: (BaseValue) -> TransformedValue, reverse: (TransformedValue) -> BaseValue, label: String = this.label, initialValue: TransformedValue = transform(this.value)): TransformField<BaseValue, TransformedValue>

Transforms a MutablePreviewLabField to work with a different value type.

valueCode

open override fun valueCode(): String

Returns a Kotlin code string representing the current value of this field.

View

@Composable

open fun View(menuItems: List<PreviewLabField.ViewMenuItem<Value?>>)

Composable, which displays the entire UI for this Field. If you want to customize the UI, you can override this method in your PreviewLabField to customize the UI. However, in many cases where the UI is customized, overriding the content method is more appropriate.

withHint

fun <Value> MutablePreviewLabField<Value>.withHint(vararg choices: Pair<String, Value>): MutablePreviewLabField<Value>

Adds hint choices to a MutablePreviewLabField, allowing users to quickly select from predefined values.

withImageUrlHint

fun MutablePreviewLabField<String>.withImageUrlHint(includeDummyImages: Boolean = true, includeInvalidImages: Boolean = true): MutablePreviewLabField<String>

withPredefinedColorHint

fun MutablePreviewLabField<Color>.withPredefinedColorHint(): MutablePreviewLabField<Color>

Adds predefined color hints to a Color field for quick selection.

withSerializer

fun <Value> MutablePreviewLabField<Value>.withSerializer(serializer: KSerializer<Value>): MutablePreviewLabField<Value>

Wraps this field with a custom me.tbsten.compose.preview.lab.PreviewLabField.serializer implementation.

withTestValues

fun <Value> MutablePreviewLabField<Value>.withTestValues(vararg additionalTestValues: Value): MutableWithTestValuesField<Value>

fun <Value> PreviewLabField<Value>.withTestValues(vararg additionalTestValues: Value): WithTestValuesField<Value>

withTextHint

fun MutablePreviewLabField<String>.withTextHint(): MutablePreviewLabField<String>

withValueCode

fun <Value> MutablePreviewLabField<Value>.withValueCode(valueCode: (Value) -> String): WithValueCodeField<Value>

Wraps this field with a custom me.tbsten.compose.preview.lab.PreviewLabField.valueCode implementation.

wrap

fun <Value> MutablePreviewLabField<Value>.wrap(wrapRange: WrapRange = WrapRange.OnlyContent, content: @Composable (@Composable () -> Unit) -> Unit): WrapField<Value>

Wraps this field with additional composable content.

NullableField

Usage

See also

Properties

Functions