Variable ImagePainter on Jetpack Compose

Question

I'm working on an Android app using Jetpack Compose 1.0.0 and I'm trying to make a composable that uses a nullable image URL string and, if it's null, it will show a placeholder with painterResource and, if it's not null, it will display the actual image using rememberImagePainter.

The way I was doing that was:

@Composable
fun VariableImagePainterExample (
    imageURL: String?
) {
    val painter = rememberCoilPainter(
        null,
        previewPlaceholder = R.drawable.ic_placeholder_user,
        fadeIn = true,
    )

    LaunchedEffect(imageURL) {
        painter.request = imageURL
    }

    Image(painter = painter, contentDescription = null)
}

Unfortunately, the rememberCoilPainter became deprecated from accompanist-coil and it's suggested now to use the rememberImagePainter. However, the ImagePainter.request can't be changed like above. I then tried the following code:

@Composable
fun VariableImagePainterExample (
    imageURL: String?
) {
    val painter = remember {
        mutableStateOf<ImagePainter>(painterResource(id = R.drawable.ic_placeholder_user))
    }

    LaunchedEffect(imageURL) {
        painter.value = rememberImagePainter(imageURL)
    }

    Image(painter = painter.value, contentDescription = null)
}

But this doesn't work because painterResource and rememberImagePainter must be used on the @Composable function. How can i achieve the same effect as before?

Answer 1

In Coil 2.0.0 both AsyncImage and rememberAsyncImagePainter have placeholder parameter that takes any other painter:

AsyncImage(
    model = imageURL,
    placeholder = painterResource(R.drawable.placeholder),
    contentDescription = null,
)

---

In Coil 1.4.0 you can use builder like this:

Image(
    rememberImagePainter(
        imageURL,
        builder = {
            placeholder(R.drawable.placeholder)
        }
    ),
    contentDescription = null,
)