android - 在 Jetpack Compose 中动态更改图标

Question

我有两个“赞”按钮图标 - ic_thumb_up和 ic_thumb_up_selected图标的类型应该取决于 offer.likedByUser范围。

var thumbIcon by remember {
    mutableStateOf(if (offer.likedByUser) R.drawable.ic_thumb_up_selected else R.drawable.ic_thumb_up)
}

IconButton(
    onClick = {
        offer.likedByUser = !offer.likedByUser
    } 
) {
    Image(painter = painterResource(id = thumbIcon) )
}

为什么它不起作用？

Answer 1

这段代码

var thumbIcon by remember {
   mutableStateOf(if (offer.likedByUser) R.drawable.ic_thumb_up_selected else R.drawable.ic_thumb_up)
}

只运行一次，并将值设置为 thumbs_up_selected或 thumbs_up .您没有更改 mutableStateOf在您的 onClick处理程序，所以什么也没有发生。
你需要像这样改变它

var thumbIconLiked by remember {
   mutableStateOf(offer.likedByUser)
}

IconButton(
    onClick = {
        thumbIconLiked = !thumbIconLiked
    } 
) {
    Image(
        painter = painterResource(
            id = if (thumbIconLIked) { 
                R.drawable.ic_thumb_up_selected 
            } else { 
                R.drawable.ic_thumb_up 
            }
        )
    )
}