easydev991/loading-overlay

Content Blocking During Loading (Loading Overlay)

When to Use

• Use this skill when developing a screen with loading data from server
• Use this skill when implementing CRUD operations (create, update, delete)
• Use this skill when you need to block buttons and interactive elements during processing
• Use this skill when user should see operation progress
• This skill is useful for preventing repeated user actions during waiting
• This skill provides consistent UX during data loading

Core Approach

Step 1: ViewModel - add loading state

In ViewModel, add StateFlow<Boolean> for tracking loading state:

private val _isProcessing = MutableStateFlow(false)
val isProcessing: StateFlow<Boolean> = _isProcessing.asStateFlow()

In operation methods, set _isProcessing.value = true at the beginning and _isProcessing.value = false in the finally block.

Step 2: UI - pass loading state

In Composable screen, collect state via collectAsState() and pass to the stateless component:

val isProcessing by viewModel.isProcessing.collectAsState()

MyFriendsScreenContent(
    // other parameters...
    isProcessing = isProcessing
)

Step 3: Stateless component - blocking and indicator

In stateless component:

1. Pass enabled = !isProcessing to content components
2. Use LoadingOverlayView from design system over content during loading

Box(modifier = Modifier.fillMaxSize()) {
    Content(enabled = !isProcessing)

    if (isProcessing) {
        LoadingOverlayView()
    }
}

Note: LoadingOverlayView automatically occupies the entire size of the parent Box and blocks all gestures. The component is located in com.swparks.ui.ds.

Step 4: List components - enabled parameter

In list components, pass enabled to interactive elements:

Box(
    modifier = Modifier.clickable(enabled = enabled) { onClick() }
) {
    UserRowView(/* parameters */)
}

Typical Usage Scenarios

Scenario 1: Loading list from server

• User opens screen
• Show indicator in center (UiState.Loading)
• After successful loading show data (UiState.Success)

Scenario 2: User action on list item

• User clicks button in list (accept, decline, delete)
• Block all list items (enabled = false)
• Show indicator over content (isProcessing = true)
• After successful execution update data and unblock (isProcessing = false)

Scenario 3: Combining multiple loading states

• Initial data loading (isLoading)
• Executing asynchronous action (isProcessing)
• Combine both states via combine or in UI (!isLoading && !isProcessing)

When to Use Different Indicator Variants

1. Initial Data Loading

Use regular CircularProgressIndicator or LoadingIndicator in the center of the screen in the when block for UiState.Loading.

2. Data Update or User Actions

Use LoadingOverlayView from design system over content in Box with isProcessing. This component automatically blocks all gestures and occupies the entire size of the parent container.

3. Indicator Inside Button

For buttons with CRUD operations, use built-in CircularProgressIndicator or enabled parameter.

Key Implementation Points

1. Box with fillMaxSize for content

Always use Box with Modifier.fillMaxSize() for content so LoadingOverlayView can display over and correctly block all gestures.

2. LoadingOverlayView automatically occupies parent size

LoadingOverlayView from design system automatically occupies the parent Box size and blocks all gestures. No need to use matchParentSize() or fillMaxSize().

3. try-finally for reliable blocking

Always use try-finally for guaranteed unlocking on successful execution or error.

4. Passing enabled to all interactive elements

Don't forget to pass enabled to all clickable elements: buttons, clickable Box/Row/Surface.

Implementation Checklist

• [ ] Added StateFlow<Boolean> for loading state in ViewModel
• [ ] Wrapped asynchronous operations in try-finally for reliable blocking
• [ ] Collected loading state in Composable screen via collectAsState()
• [ ] Passed enabled = !isProcessing to stateless component
• [ ] Added LoadingOverlayView() from design system over content during loading
• [ ] Passed enabled to interactive list elements (buttons, clickable areas)
• [ ] Checked that overlay displays over content during loading
• [ ] Checked that buttons are blocked and not clickable during processing
• [ ] Tested error handling (user sees error, overlay hides)