Custom Composer

The message composer allows users to participate in a conversation by sending messages and attachments.

The name of the standard Compose UI component is MessageComposer and, by default, it looks like below:

After we'll finish our customization, it will look like this:

We'll customize:

• The input field's size and hint message
• The position and icon of the Add Attachments and Send buttons

State Handling

Let's define a new composable, CustomMessageComposer, that takes two view models as parameters, needed for state handling.

Inside it, we'll use the standard MessageComposer component and customize it as we need.

@Composable
private fun CustomMessageComposer(
    composerViewModel: MessageComposerViewModel,
    attachmentsPickerViewModel: AttachmentsPickerViewModel,
) {
    MessageComposer(
        viewModel = composerViewModel,
        modifier = Modifier
            .fillMaxWidth()
            .wrapContentHeight(),
        input = {
            // ... See below
        },
        onAttachmentsClick = { attachmentsPickerViewModel.changeAttachmentState(showAttachments = true) },
        integrations = {} // Important for hiding the default Add Attachments button
    )
}

Input Field Customization

We have access to the input field through the input parameter of MessageComposer. We'll pass a custom version of the MessageInput SDK component.

MessageComposer(
    // ... See above
    input = { composerState ->
        // Standard component that we can customize
        MessageInput(
            messageComposerState = composerState,
            onValueChange = { composerViewModel.setMessageInput(it) },
            onAttachmentRemoved = { composerViewModel.removeSelectedAttachment(it) },
            modifier = Modifier
                .padding(horizontal = 10.dp)
                .align(Alignment.CenterVertically),
            // ... See below
        )
    },
    onAttachmentsClick = { attachmentsPickerViewModel.changeAttachmentState(showAttachments = true) },
    integrations = {} // Important for hiding the default Add Attachments button
)

Custom Hint

In order to customize the hint message, we'll use the MessageInput label parameter and pass a Text composable to it.

MessageInput(
    // ... See above
    label = {
        Text(
            modifier = Modifier.padding(start = 4.dp),
            text = "Type a message",
            color = ChatTheme.colors.textLowEmphasis
        )
    },
)

Custom Buttons

To customize the Add Attachments and Send buttons, we'll use the innerTrailingContent slot. We'll pass a Row that contains two IconButton composables, each with a different icon.

For the button click handlers, we use methods from the attachments and composer view models.

MessageInput(
    // ... See above
    innerTrailingContent = {
        Row {
            IconButton(
                modifier = Modifier.size(24.dp),
                onClick = {
                    attachmentsPickerViewModel.changeAttachmentState(showAttachments = true)
                },
                content = {
                    Icon(
                        imageVector = Icons.Outlined.AddCircle,
                        contentDescription = null,
                        tint = Color.DarkGray
                    )
                }
            )
            Spacer(modifier = Modifier.width(20.dp))
            IconButton(
                modifier = Modifier.size(24.dp),
                onClick = {
                    composerViewModel.sendMessage(
                        composerViewModel.buildNewMessage(
                            composerState.inputValue,
                            composerState.attachments
                        )
                    )
                },
                content = {
                    Icon(
                        imageVector = Icons.Outlined.Send,
                        contentDescription = null,
                        tint = Color.DarkGray
                    )
                }
            )
        }
    }
)

In order to hide the default buttons, we need to pass an empty composable to the MessageComposer integrations parameter (see section above).

Usage

We'll use our custom message composer in a screen that contains other components, like a header, a messages list and an attachments picker. We'll also use the BackHandler standard component.

fun CustomScreen(cid: String, onBackClick: () -> Unit = {}) {
    val viewModelFactory = MessagesViewModelFactory(LocalContext.current, channelId = cid)
    val listViewModel = viewModel(modelClass = MessageListViewModel::class.java, factory = viewModelFactory)
    val composerViewModel = viewModel(modelClass = MessageComposerViewModel::class.java, factory = viewModelFactory)
    val attachmentsPickerViewModel = viewModel(modelClass = AttachmentsPickerViewModel::class.java, factory = viewModelFactory)
    
    val isShowingAttachments = attachmentsPickerViewModel.isShowingAttachments

    val backAction = remember(composerViewModel, attachmentsPickerViewModel) {
        {
            // First close the attachments picker, if visible, then call onBackClick
            when {
                attachmentsPickerViewModel.isShowingAttachments -> {
                    attachmentsPickerViewModel.changeAttachmentState(false)
                }
                else -> onBackClick()
            }
        }
    }
    BackHandler(enabled = true, onBack = backAction) // Standard SDK component

    Box(modifier = Modifier.fillMaxSize(), contentAlignment = Alignment.BottomCenter) {
        // Screen content
        Scaffold(
            topBar = { 
                // MessageListHeader,
            },
            bottomBar = {
                CustomMessageComposer(
                    composerViewModel = composerViewModel,
                    attachmentsPickerViewModel = attachmentsPickerViewModel
                )
            },
            content = { 
                // MessageList
            }
        )

        if (isShowingAttachments) {
            // AttachmentsPicker
        }
    }
}

More Resources

If you want to learn how to use our Compose UI Components, read this page.

Also, check the other pages in this Cookbook to find out how to create custom versions of our components.