litho-widget-kotlin/com.facebook.litho.kotlin.widget/RenderWithConstraints

RenderWithConstraints

fun ResourcesScope.RenderWithConstraints(style: Style? = null, content: ComponentScope.(SizeConstraints) -> Component): Component

Utility for creating a layout tree that depends on its own and/or its children's size.

For example, Component A is returned if it fits within the specified width otherwise Component B is returned.

Example:

RenderWithConstraints { sizeConstraints ->
    val textComponent = Text(textSize = 16.sp, text = "Some text to measure")

    val textOutputSize = Size()

    textComponent.measure(
    context,
    SizeSpec.makeSizeSpec(0, UNSPECIFIED),
    SizeSpec.makeSizeSpec(0, UNSPECIFIED),
    textOutputSize)

    // Small component to use in case textComponent doesn't fit within
    // the current layout.
    val imageComponent = Image(drawable = drawableRes(R.drawable.ic_launcher))

    // Assuming sizeConstraints.hasBoundedWidth == true
    val doesTextFit = textOutputSize.width <= sizeConstraints.maxWidth

    if (doesTextFit) textComponent else imageComponent
}