jetpack compose 学习

使用列表

fun ScrollingView()相当于recyclerview （原本是ScrollingList）
依赖：用于加载网络图片
implementation 'io.coil-kt:coil-compose:1.4.0'
painter = rememberImagePainter(
data = "https://tse4-mm.cn.bing.net/th/id/OIP-C.W_ojBE429JEt_UbsoDk6YQAAAA?pid=ImgDet&rs=1"),
使用前提是加载网络权限

@Preview
@Composable
fun ScrollingView(){
    val listSize = 100
    val scrollState = rememberLazyListState()
    //协程作用域，作用域消失，则作用域中的协程都会被取消
    val coroutineScope = rememberCoroutineScope()

    Column {

        Row {
            Button(
                modifier = Modifier.weight(1f),
                onClick = {
                    //animateScrollToItem为挂起函数suspend，只能在另一个挂起函数或协程内调用
                    coroutineScope.launch {//拿到协程作用域
                        scrollState.animateScrollToItem(0)
                    }
                }
            ) {
                Text(text = "Scroll to the top")
            }
            Button(
                modifier = Modifier.weight(1f),
                onClick = {
                    coroutineScope.launch {//拿到协程作用域
                        scrollState.animateScrollToItem(listSize-1)
                    }
                }
            ) {
                Text(text = "Scroll to the end")
            }

        }
        LazyColumn(state = scrollState){
            items(listSize){
                ImageListItem(index = it)
            }
        }

    }
}
@Composable
fun ImageListItem(index : Int){
    Row(verticalAlignment = Alignment.CenterVertically) {
        //coil加载网络图片，coil官网2022年12.30日显示的是AsyncImage
        //依赖最新版本2.2.2，但是会报错，和kotlin版本不兼容，调到了2.0.0运行
        AsyncImage(
            model = "https://developer.android.google.cn/images/brand/Android_Robot.png",
            contentDescription = null,
            modifier = Modifier.size(50.dp)
        )

        Spacer(modifier = Modifier.size(10.dp))
        Text(text = "Item # $index", style = MaterialTheme.typography.subtitle1)

    }
}