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Transparent vs Translucent UI Components

In user interfaces, transparent elements are fully see-through (like clear glass), while translucent elements are semi-see-through (like frosted glass) that often blur or soften whatever is behind them. Both techniques let background content show through, but translucent layers typically add blur or tint to create depth. In code, transparency and translucency are controlled by opacity or alpha values and, for blurring effects, by special APIs (like backdrop filters or blur effects). We’ll explore how to make UI components transparent or translucent in HTML/CSS, Android (Jetpack Compose and XML), and iOS (SwiftUI and UIKit), with examples and technical details. Finally, we’ll look at iOS 26’s new Liquid Glass material – Apple’s latest adaptive translucency effect – and how it builds on these concepts.

Web (HTML/CSS)

On the web, CSS offers simple ways to make elements transparent or translucent:

  • Opacity and RGBA/HSLA: You can set an element’s opacity (0.0 = fully transparent, 1.0 = fully opaque) or use colors with alpha channels. For example, style="opacity: 0.5" makes an element 50% opaque. Similarly, an RGBA color like background-color: rgba(0, 0, 0, 0.5) uses an alpha channel (0.5 = 50% opacity) to let the background show through. A CSS color literal can also use the newer syntax: e.g. background-color: rgb(0 0 0 / 50%). In practice, you might write:

<div style="background-color: rgba(0,0,0,0.5); padding: 16px;">
  <p>This box has a semi-transparent black background.</p>
</div>

This makes the <div> background 50% opaque (semi-transparent) while its text remains fully opaque.

  • Backdrop Filters (Blur): To achieve a translucent glass effect (where background content is blurred), modern CSS provides the backdrop-filter property. For example, backdrop-filter: blur(10px) applies a Gaussian blur to whatever is behind the element. Because backdrop-filter affects the background, the element itself (or its background color) must be at least partially transparent to see the effect. In practice you might do:

.translucent-panel {
  background-color: rgba(255,255,255,0.3);
  backdrop-filter: blur(10px);
}

<div class="translucent-panel" style="padding: 16px;">
  This panel blurs the background behind it.
</div>

Here the panel has a semi-transparent white background plus a 10px blur behind it. This creates an “iOS-like” frosted glass look. (In WebKit-based browsers you may need the -webkit-backdrop-filter prefix.) Together, CSS opacity/alpha and backdrop-filter let you create both fully transparent overlays and frosted glass effects on web pages.

Android (Jetpack Compose)

In Jetpack Compose (Android’s modern UI toolkit), transparency and translucency are handled via modifiers and color alphas:

  • Opacity/Alpha: You can change a composable’s overall opacity using modifiers like Modifier.alpha(...) or Modifier.graphicsLayer { alpha = ... }. For example, Modifier.graphicsLayer { alpha = 0.5f } makes the entire composable 50% opaque. Similarly, Modifier.alpha(0.5f) draws its contents with 50% alpha. You can also give a background color a built-in alpha: e.g. background(Color.Red.copy(alpha = 0.5f)). For instance:

Box(
  modifier = Modifier
    .size(120.dp)
    .background(Color.Blue.copy(alpha = 0.7f))
) {
    Text("Hello", color = Color.White)
}

In this Compose Box, the blue background is 70% opaque (30% transparent) and the text is fully opaque. Setting alpha = 0.7f or graphicsLayer { alpha = 0.7f } would equivalently fade the entire Box to 70% opacity.

  • Blur Effects: Jetpack Compose now supports a blur modifier on Android 12+ (API level 31 and above). Using Modifier.blur(radius = 20.dp) will blur the content within the composable on Android 12 and later. For example:

Image(
  painter = painterResource(id = R.drawable.background),
  contentDescription = "Blurry",
  modifier = Modifier
    .size(200.dp)
    .blur(16.dp)   // only on Android 12+
)

This applies a 16dp Gaussian blur to the image itself. (On older Android versions this modifier is ignored.) The Compose blur modifier internally uses the new RenderEffect API. Together with alpha, these tools let you create frosted UI layers in Compose.

Android (XML Layouts)

In classic Android XML layouts (or Views), transparency is achieved through alpha attributes and ARGB colors:

  • View Alpha: Most View subclasses support an android:alpha attribute (API 11+) from 0 (transparent) to 1 (opaque). For example:

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Faded Button"
    android:alpha="0.5" />

This makes the button 50% opaque (semi-transparent). You can set android:alpha="0.0" for fully transparent or "1.0" for fully opaque. (This alpha applies to the View and all its contents.)

  • ARGB Colors: You can also give backgrounds or colors an explicit alpha in ARGB hex format. A color string #AARRGGBB uses the first two hex digits for alpha. For example, #80000000 is 50% opaque black (alpha = 0x80 = 128 out of 255). In XML you might write:

<View
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:background="#80FF0000" />

Here #80FF0000 is 50% opaque red (50% transparency). The table of alpha hex values shows that 0x80 corresponds to 50% (see source). Using transparent or translucent backgrounds in XML layouts is useful for overlays, dialog backgrounds, or custom drawable shapes.

Together, android:alpha and ARGB colors allow you to make Android Views transparent or tinted. For full-window translucency (e.g. dialogs with windowIsTranslucent), you would use themes or window flags, but for individual UI components these properties suffice.

iOS (SwiftUI)

SwiftUI makes transparency easy with its declarative modifiers, and introduces materials for frosted-glass effects:

  • Opacity and Color alpha: Every SwiftUI view has an .opacity() modifier. For example, .opacity(0.5) makes that view 50% opaque. Colors also have an opacity() method. A common pattern is Color.gray.opacity(0.5) to use a semi-transparent gray. As one guide notes: an opacity of 1.0 is fully opaque, 0.0 is fully clear. For instance:

Text("Hello, SwiftUI")
  .padding()
  .background(Color.red.opacity(0.3))

This text has a red background at 30% opacity. You can also write .opacity(0.3) on the Text itself. These modifiers let you fade any SwiftUI view.

  • Blur and Materials: SwiftUI also offers blur and built-in “material” effects for translucency. You can add a blur with .blur(radius: 10, opaque: false) on any view. More powerfully, SwiftUI provides system materials (introduced in iOS 15) like .ultraThinMaterial, .regularMaterial, etc., that apply adaptive blur layers. For example:

ZStack {
    Image("backgroundImage")
        .resizable().scaledToFill()
        .ignoresSafeArea()
    Text("Translucent Text")
        .padding()
        .background(.regularMaterial, in: RoundedRectangle(cornerRadius: 8))
}

In this code, .regularMaterial creates a translucent backdrop behind the text. As Majid’s blog explains, “Material is ready to use translucent blur effect” and automatically blurs the view’s background without blurring the foreground content. Materials adapt to light/dark mode and the content behind the app. The blurring from a Material “isn’t simple transparency” – it’s computed to match the look of real glass. In other words, SwiftUI’s materials insert a frosted-glass layer between your view and its background, automatically adjusting contrast and color. This makes it very convenient to create “glassmorphic” UI.

SwiftUI Code Example

VStack {
    Text("Semi-Transparent Button")
        .padding()
        .background(Color.blue.opacity(0.5))  // 50% opaque background
        .cornerRadius(8)
    Spacer().frame(height: 20)
    Text("Frosted Glass Card")
        .padding()
        .background(.ultraThickMaterial, in: RoundedRectangle(cornerRadius: 12))
}
.padding()

Here the first text has a semi-transparent background (using Color.opacity), while the second uses .ultraThickMaterial for a strongly translucent card. Both achieve see-through visuals in SwiftUI.

iOS (UIKit)

In UIKit (the older iOS UI framework), you manage transparency via view alphas and colors, and translucency via UIVisualEffectView:

  • View Alpha and Background Alpha: Any UIView has an alpha property (0.0–1.0) controlling its transparency. For example:

    let box = UIView(frame: CGRect(x: 50, y: 50, width: 100, height: 100))
box.backgroundColor = UIColor.green.withAlphaComponent(0.5)  // green at 50% opacity
box.alpha = 0.8  // entire view at 80% opacity

    This makes the box partially see-through. Setting box.alpha = 0.8 would also apply a semi-transparent effect (20% transparent). Views also support fully transparent colors, e.g. UIColor.red.withAlphaComponent(0.3) or the special UIColor.clear. These are standard UIKit techniques for transparency.

  • Blur and Frosted Glass: For true translucency (blurring what's behind), UIKit provides UIBlurEffect with UIVisualEffectView. A UIVisualEffectView displays a blur or vibrancy effect over its content. For example, you can do:

    let blurEffect = UIBlurEffect(style: .light)
let blurView = UIVisualEffectView(effect: blurEffect)
blurView.frame = view.bounds
blurView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
view.addSubview(blurView)

    This overlays the entire view with a light blur effect. As one tutorial notes, UIVisualEffectView has been around for a while now and comes in handy to blur a UIView. You choose styles like .light, .dark, .regular, .prominent, etc. (or the new material styles in iOS 13+). The blur view itself is typically transparent (you should set no background), and it blurs whatever is underneath it on screen. This is how iOS creates the frosted glass look in navigation bars, action sheets, and dynamic backgrounds. For example, a partially transparent blur effect on iOS might combine a UIVisualEffectView and a tint UIView behind it (since setting the blur view’s alpha directly is not recommended).

Together, UIKit’s alpha and UIVisualEffectView let you compose opaque, transparent, and glassy layers. You can put UI elements on top of a blurred background view to create the classic translucent iOS panel appearance.

iOS 26 Liquid Glass

Apple’s upcoming iOS 26 introduces a new design material called Liquid Glass. Liquid Glass is essentially an advanced adaptive translucency effect that builds on the concepts above. As Apple describes it, Liquid Glass is a “brand new, adaptive material for controls and navigational elements” inspired by “the optical properties of glass and the fluidity of liquid”. In practice, UI components like toolbars, toggles, sliders, and even search fields will be rendered as if made from a dynamic, partially transparent glass. The system automatically adjusts the appearance: for example, as content scrolls underneath, the glass “adapts to the content, changing from light to dark”. Controls “transform into liquid glass during interaction,” giving a shimmering, fluid feel.

In other words, Liquid Glass is Apple’s next-level “frosted glass” effect. It goes beyond a fixed blur or opacity – it’s an environment-aware material that blends translucency, blur, and animation. For developers, this means any standard control or container will inherit this look by default on iOS 26, and new APIs let you apply Liquid Glass styling to custom views. In relation to the topics above, Liquid Glass is simply the new way iOS handles translucency: think of it as a smart, animated blur layer that adapts like water pouring over your interface.

In summary, transparency (opacity) and translucency (blur/material) are fundamental to modern UI design. HTML/CSS uses opacity and backdrop-filter, Android uses alpha and blur modifiers, and iOS uses view alpha and visual effects. The new Liquid Glass material in iOS 26 is Apple’s evolution of these ideas – an automatic, dynamic translucent material that makes interfaces feel more layered and alive.

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