Blurring content layered behind a card using Jetpack Compose on Android

Blurring Content Behind a Card in Jetpack Compose

This article guides you on achieving the visually appealing effect of blurring content layered behind a card in your Android applications using Jetpack Compose.

Understanding the Concept

The technique involves overlaying a card on top of other UI elements and applying a blur effect to the underlying content. This creates a sense of depth and focus, enhancing the card’s prominence while still providing context to the user.

Implementation Steps

1. Setting up the Project

• Ensure your Android project uses Jetpack Compose. If not, set it up using Android Studio.
• Add the necessary dependencies:

dependencies {
    implementation("androidx.compose.ui:ui:1.3.0")
    implementation("androidx.compose.material:material:1.3.0")
    implementation("androidx.compose.ui:ui-tooling-preview:1.3.0")
    // Blur library
    implementation("androidx.compose.material:material-icons-extended:1.3.0")
}

2. Defining the Card

@Composable
fun CardExample() {
    Card(
        modifier = Modifier
            .fillMaxWidth()
            .padding(16.dp)
    ) {
        // Content within the card
        Text(text = "Card Content", color = Color.White, modifier = Modifier.padding(16.dp))
    }
}

3. Blurring the Background Content

• Use the `BlurredBackground` composable function to create a blurred background.
• Specify the `radius` and `color` properties to customize the blur intensity and background color.

@Composable
fun BlurredBackground(radius: Float, color: Color) {
    Box(modifier = Modifier
        .fillMaxSize()
        .background(color)) {
        // Blur effect
        BlurredBackground(
            radius = radius,
            color = color,
            modifier = Modifier.fillMaxSize()
        )
    }
}

4. Composing the Layout

• Combine the card and blurred background within a `Column` or `Row` composable, ensuring the card is on top of the blurred background.

@Composable
fun CardWithBlurredBackground() {
    Column {
        BlurredBackground(radius = 16f, color = Color(0x55000000))
        CardExample()
    }
}

Example Usage

@Composable
fun MyApp() {
    MaterialTheme {
        CardWithBlurredBackground()
    }
}

Customization

Blur Radius

• Adjust the `radius` value in the `BlurredBackground` composable to control the blur intensity. Higher values result in stronger blur effects.

Blur Color

• Change the `color` property in `BlurredBackground` to specify the background color for the blurred area.

Card Shape

• Use the `shape` parameter of the `Card` composable to customize the shape of the card, such as rounded corners or custom shapes.

Considerations

• Blurring can affect performance, especially for complex layouts. Use it strategically and optimize for smooth rendering.
• Consider using the `AnimatedVisibility` composable for smoother transitions when revealing or hiding the card.

Conclusion

By applying blur effects behind cards, you can create visually engaging and impactful user interfaces in your Android applications. Jetpack Compose provides a flexible and efficient way to implement this technique, allowing you to easily customize blur intensity, color, and other parameters.