diaphanous-swing is a Java library to apply native translucency/backdrop and window decoration styles to Swing/AWT windows.

This project was created under two drivers:

• weisJ/darklaf#351 [Feature Request] Frosted / Blurry background window support (Windows Acrylic / macOs: Vibrant)
• 8375578: Enable translucent window backdrops by beldenfox · Pull Request #2048 · openjdk/jfx
• Windows and Linux aren’t supported (yet).

import io.github.bric3.diaphanous.backdrop.MacosBackdropEffectSpec;
import io.github.bric3.diaphanous.backdrop.MacosBackdropEffectSpec.MacosBackdropMaterial;
import io.github.bric3.diaphanous.backdrop.WindowBackgroundEffectSpec;
import io.github.bric3.diaphanous.backdrop.WindowBackdrop;
import io.github.bric3.diaphanous.decorations.MacosWindowAppearanceSpec;
import io.github.bric3.diaphanous.decorations.MacosWindowDecorationsSpec;
import io.github.bric3.diaphanous.decorations.WindowPresentations;

MacosWindowDecorationsSpec style = MacosWindowDecorationsSpec.builder()
    .transparentTitleBar(true)
    .fullSizeContentView(true)
    .titleVisible(false)
    .build();
WindowPresentations.applyDecorations(frame, style);

WindowBackgroundEffectSpec vibrancy = MacosBackdropEffectSpec.builder()
    .material(MacosBackdropMaterial.UNDER_WINDOW_BACKGROUND)
    .build();
WindowBackdrop.apply(frame, vibrancy);

WindowPresentations.applyAppearance(frame, MacosWindowAppearanceSpec.SYSTEM);

At a high level, this library does two things for Swing windows on macOS:

1. It updates NSWindow style/appearance flags (title bar, full-size content, appearance).
2. It installs/removes an NSVisualEffectView-based backdrop behind the AWT host view.

On the Swing side, content still needs to cooperate (setOpaque(false) and transparent content pane) so the native backdrop can actually be visible.

flowchart TD
    A[Swing code] --> B[WindowPresentations / WindowBackdrop APIs]
    B --> C[diaphanous-core facade]
    C --> D[Library acquires native OS window pointer]
    D --> E[Native macOS operations]
    E --> G[NSWindow style updates]
    E --> H[Install/update/remove NSVisualEffectView]
    H --> I[Backdrop visible through non-opaque Swing content]

What gets changed natively:

• Window decorations:
  • Transparent title bar (setTitlebarAppearsTransparent:)
  • Full-size content view (setStyleMask: + NSWindowStyleMaskFullSizeContentView)
  • Title visibility (setTitleVisibility:)
  • Appearance (setAppearance:)
• Window backdrop:
  • NSVisualEffectView install/update/remove
  • Material/state/alpha configuration (or default install via WindowBackdrop.install(...))

• diaphanous-core: library module.
• diaphanous-core-macos-native: macOS native bridge (NSView wrapper + effect view management).
• demo-swing: sample Swing app using the library.

Decorated mode:

./gradlew :demo-swing:run

The demo is preconfigured with this JVM argument:

• --enable-native-access=ALL-UNNAMED

diaphanous-core bundles a simple macOS native library that is loaded it from classpath by default. For local override/debug, set -Ddiaphanous.macos.nativeLib=/absolute/path/to/libdiaphanous-core-macos-native.dylib.

Robot smoke test:

./gradlew :demo-swing:robotTest

• https://github.com/weisJ/darklaf
• https://lukakerr.github.io/swift/nswindow-styles
• https://github.com/macosui/macos_window_utils.dart
• https://github.com/dukke/FXThemes
• openjdk/jfx#2048

Mozilla Public License 2.0 (MPL-2.0). See LICENSE.