Dialog

The Dialog component displays dialog messages or requests user input on a layer above the main app content. It creates an interruptive UI experience to capture user attention.

Among the use cases for a dialog are the following:

  • Confirming user action, such as when deleting a file.
  • Requesting user input, such as in a to-do list app.
  • Presenting a list of options for user selection, like choosing a country in a profile setup.
A dialog populated with text and icons.
Figure 1. An example of a dialog populated with text and icons.

Alert dialog

The AlertDialog composable provides a convenient API for creating a Material Design themed dialog. AlertDialog has specific parameters for handling particular elements of the dialog. Among them are the following:

  • title: The text that appears along the top of the dialog.
  • text: The text that appears centered within the dialog.
  • icon: The graphic that appears at the top of the dialog.
  • onDismissRequest: The function called when the user dismisses the dialog, such as by tapping outside of it.
  • dismissButton: A composable that serves as the dismiss button.
  • confirmButton: A composable that serves as the confirm button.

The following example implements two buttons in an alert dialog, one that dismisses the dialog, and another that confirms its request.

@Composable
fun AlertDialogExample(
    onDismissRequest: () -> Unit,
    onConfirmation: () -> Unit,
    dialogTitle: String,
    dialogText: String,
    icon: ImageVector,
) {
    AlertDialog(
        icon = {
            Icon(painter = rememberVectorPainter(icon), contentDescription = "Example Icon")
        },
        title = {
            Text(text = dialogTitle)
        },
        text = {
            Text(text = dialogText)
        },
        onDismissRequest = {
            onDismissRequest()
        },
        confirmButton = {
            TextButton(
                onClick = {
                    onConfirmation()
                }
            ) {
                Text("Confirm")
            }
        },
        dismissButton = {
            TextButton(
                onClick = {
                    onDismissRequest()
                }
            ) {
                Text("Dismiss")
            }
        }
    )
}

This implementation implies a parent composable that passes arguments to the child composable in this way:

@Composable
fun DialogExamples() {
    // ...
    val openAlertDialog = remember { mutableStateOf(false) }

    // ...
        when {
            // ...
            openAlertDialog.value -> {
                AlertDialogExample(
                    onDismissRequest = { openAlertDialog.value = false },
                    onConfirmation = {
                        openAlertDialog.value = false
                        println("Confirmation registered") // Add logic here to handle confirmation.
                    },
                    dialogTitle = "Alert dialog example",
                    dialogText = "This is an example of an alert dialog with buttons.",
                    icon = AppIcons.Info
                )
            }
        }
    }
}

This implementation appears as follows:

Figure 2. An alert dialog with buttons.

Dialog composable

Dialog is a basic composable that doesn't provide any styling or predefined slots for content. It is a relatively straightforward container that you should populate with a container such as Card. The following are some of the key parameters of a dialog:

  • onDismissRequest: The lambda called when the user closes the dialog.
  • properties: An instance of DialogProperties that provides some additional scope for customization.

Basic example

The following example is a basic implementation of the Dialog composable. Note that it uses a Card as the secondary container. Without the Card, the Text component would appear alone above the main app content.

@Composable
fun MinimalDialog(onDismissRequest: () -> Unit) {
    Dialog(onDismissRequest = { onDismissRequest() }) {
        Card(
            modifier = Modifier
                .fillMaxWidth()
                .height(200.dp)
                .padding(16.dp),
            shape = RoundedCornerShape(16.dp),
        ) {
            Text(
                text = "This is a minimal dialog",
                modifier = Modifier
                    .fillMaxSize()
                    .wrapContentSize(Alignment.Center),
                textAlign = TextAlign.Center,
            )
        }
    }
}

This implementation appears as follows. Note that when the dialog is open, the main app content beneath it appears darkened and grayed out:

Figure 3. Minimal dialog.

Advanced example

The following is a more advanced implementation of the Dialog composable. In this case, the component manually implements a similar interface to the preceding AlertDialog example.

@Composable
fun DialogWithImage(
    onDismissRequest: () -> Unit,
    onConfirmation: () -> Unit,
    painter: Painter,
    imageDescription: String,
) {
    Dialog(onDismissRequest = { onDismissRequest() }) {
        // Use the Material dialog shape and color. The Card clips the image to its rounded corners.
        Card(
            modifier = Modifier
                .fillMaxWidth()
                .padding(16.dp),
            shape = MaterialTheme.shapes.extraLarge,
            colors = CardDefaults.cardColors(
                containerColor = MaterialTheme.colorScheme.surfaceContainerHigh,
            ),
        ) {
            Column {
                // The image fills the full width of the dialog.
                Image(
                    painter = painter,
                    contentDescription = imageDescription,
                    contentScale = ContentScale.Crop,
                    modifier = Modifier
                        .fillMaxWidth()
                        .height(160.dp)
                )
                Text(
                    text = "This is a dialog with buttons and an image.",
                    style = MaterialTheme.typography.bodyMedium,
                    color = MaterialTheme.colorScheme.onSurfaceVariant,
                    modifier = Modifier.padding(start = 24.dp, top = 24.dp, end = 24.dp),
                )
                // Material dialogs align their actions to the end, 8.dp apart.
                Row(
                    modifier = Modifier
                        .fillMaxWidth()
                        .padding(24.dp),
                    horizontalArrangement = Arrangement.spacedBy(8.dp, Alignment.End),
                ) {
                    TextButton(onClick = { onDismissRequest() }) {
                        Text("Dismiss")
                    }
                    TextButton(onClick = { onConfirmation() }) {
                        Text("Confirm")
                    }
                }
            }
        }
    }
}

This implementation appears as follows:

Figure 4. A dialog that includes an image.

Additional resources