Is there any way to measure a Composable before dr...

# compose

[TheMrCodes]

Is there any way to measure a Composable before drawing without getting the siize aferward with .onSizeChanged?

[Vitor Prado]

you can use BoxWithConstraints

[Vitor Prado]

inside this composable you have access to :

/**
     * The constraints given by the parent layout in pixels.
     *
     * Use [minWidth], [maxWidth], [minHeight] or [maxHeight] if you need value in [Dp].
     */
    val constraints: Constraints
    /**
     * The minimum width in [Dp].
     *
     * @see constraints for the values in pixels.
     */
    val minWidth: Dp
    /**
     * The maximum width in [Dp].
     *
     * @see constraints for the values in pixels.
     */
    val maxWidth: Dp
    /**
     * The minimum height in [Dp].
     *
     * @see constraints for the values in pixels.
     */
    val minHeight: Dp
    /**
     * The minimum height in [Dp].
     *
     * @see constraints for the values in pixels.
     */
    val maxHeight: Dp

[TheMrCodes]

the problem is there is no actuall width and height they are only the constraints of the composable

[Tash]

Depending on what you want to do with the resulting width / height you can intercept with Modifier.layout

Modifier.layout { measurable, constraints ->
    val placeable = measurable.measure(constraints)
    val width = placeable.width
    val height = placeable.height
    ...
}

[Nader Jawad]

Do you have an example of the use case? We introduced Modifier.drawWithCache to give an opportunity to allocate graphics objects when sizing information is known and re-use those objects within the corresponding onDraw block wihin the implementation. This is useful to create gradients with sizing information known upfront or Paths and re-use he result across draw calls as long as the size has not changed or state parameters being read do not change.