Forked from colinrtwhite/complex_forwarding_painter.kt
Created
November 13, 2023 13:41
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A painter that wraps another painter to overwrite its color filter, alpha, and/or onDraw.
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/** | |
* Create and return a new [Painter] that wraps [painter] with its [alpha], [colorFilter], or [onDraw] overwritten. | |
*/ | |
fun forwardingPainter( | |
painter: Painter, | |
alpha: Float = DefaultAlpha, | |
colorFilter: ColorFilter? = null, | |
onDraw: DrawScope.(ForwardingDrawInfo) -> Unit = DefaultOnDraw, | |
): Painter = ForwardingPainter(painter, alpha, colorFilter, onDraw) | |
data class ForwardingDrawInfo( | |
val painter: Painter, | |
val alpha: Float, | |
val colorFilter: ColorFilter?, | |
) | |
private class ForwardingPainter( | |
private val painter: Painter, | |
private var alpha: Float, | |
private var colorFilter: ColorFilter?, | |
private val onDraw: DrawScope.(ForwardingDrawInfo) -> Unit, | |
) : Painter() { | |
private var info = newInfo() | |
override val intrinsicSize get() = painter.intrinsicSize | |
override fun applyAlpha(alpha: Float): Boolean { | |
if (alpha != DefaultAlpha) { | |
this.alpha = alpha | |
this.info = newInfo() | |
} | |
return true | |
} | |
override fun applyColorFilter(colorFilter: ColorFilter?): Boolean { | |
if (colorFilter != null) { | |
this.colorFilter = colorFilter | |
this.info = newInfo() | |
} | |
return true | |
} | |
override fun DrawScope.onDraw() = onDraw(info) | |
private fun newInfo() = ForwardingDrawInfo(painter, alpha, colorFilter) | |
} | |
private val DefaultOnDraw: DrawScope.(ForwardingDrawInfo) -> Unit = { info -> | |
with(info.painter) { | |
draw(size, info.alpha, info.colorFilter) | |
} | |
} |
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