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.

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
funAlertDialogExample(
onDismissRequest:()->Unit,
onConfirmation:()->Unit,
dialogTitle:String,
dialogText:String,
icon:ImageVector,
){
AlertDialog(
icon={
Icon(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")
}
}
)
}Dialog.kt

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

@Composable
funDialogExamples(){
// ...
valopenAlertDialog=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=Icons.Default.Info
)
}
}
}
}Dialog.kt

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
funMinimalDialog(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,
)
}
}
}Dialog.kt

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 implemented of the Dialog composable. In this case, the component manually implements a similar interface to the AlertDialog example above.

@Composable
funDialogWithImage(
onDismissRequest:()->Unit,
onConfirmation:()->Unit,
painter:Painter,
imageDescription:String,
){
Dialog(onDismissRequest={onDismissRequest()}){
// Draw a rectangle shape with rounded corners inside the dialog
Card(
modifier=Modifier
.fillMaxWidth()
.height(375.dp)
.padding(16.dp),
shape=RoundedCornerShape(16.dp),
){
Column(
modifier=Modifier
.fillMaxSize(),
verticalArrangement=Arrangement.Center,
horizontalAlignment=Alignment.CenterHorizontally,
){
Image(
painter=painter,
contentDescription=imageDescription,
contentScale=ContentScale.Fit,
modifier=Modifier
.height(160.dp)
)
Text(
text="This is a dialog with buttons and an image.",
modifier=Modifier.padding(16.dp),
)
Row(
modifier=Modifier
.fillMaxWidth(),
horizontalArrangement=Arrangement.Center,
){
TextButton(
onClick={onDismissRequest()},
modifier=Modifier.padding(8.dp),
){
Text("Dismiss")
}
TextButton(
onClick={onConfirmation()},
modifier=Modifier.padding(8.dp),
){
Text("Confirm")
}
}
}
}
}
}Dialog.kt