DualLineFill.kt

private class DualLineFill(
    private val fillBefore: Fill,
    private val fillAfter: Fill,
) : LineCartesianLayer.LineFill {
    private val paintBefore = Paint().apply { color = fillBefore.color }
    private val paintAfter = Paint().apply { color = fillAfter.color }

    private var markerX: Float? = null

    fun updateMarkerX(x: Float?) {
        markerX = x
    }

    override fun draw(
        context: CartesianDrawingContext,
        halfLineThickness: Float,
        verticalAxisPosition: Axis.Position.Vertical?,
    ) {
        with(context) {
            fillBefore.brush?.applyTo(size = layerBounds.size, p = paintBefore, alpha = 1f)
            fillAfter.brush?.applyTo(size = layerBounds.size, p = paintAfter, alpha = 1f)

            canvas.withSave {
                canvas.translate(layerBounds.left, layerBounds.top)

                canvas.drawRect(0f, 0f, layerBounds.width, layerBounds.height, paintBefore)

                markerX?.let { x ->
                    canvas.drawRect(x, 0f, layerBounds.width, layerBounds.bottom, paintAfter)
                }
            }
        }
    }

}