FastTheme — Native Windows Theme, Titlebar Styling & Display API for Java [ALPHA]

Lightweight alternative to FlatLAF when you only need real OS theme events, titlebar styling, opacity, and display metrics.

FastTheme brings real Windows theming to Java applications: Dark/Light Mode, Titlebar Styling, Window Opacity, and Display DPI — all native, without replacing your Look-and-Feel.

// Quick Start — Window Styling with FastTheme API
import fasttheme.FastTheme;
import javax.swing.*;

public class StyledWindow {
    public static void main(String[] args) {
        JFrame frame = new JFrame("FastTheme Window");
        frame.setSize(800, 600);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true); // Must be visible first!
        
        // Apply native styling
        long hwnd = FastTheme.getWindowHandle(frame);
        if (hwnd != 0) {
            FastTheme.setTitleBarColor(hwnd, 12, 12, 12);    // Dark gray
            FastTheme.setTitleBarDarkMode(hwnd, true);       // Dark mode
            FastTheme.setWindowTransparency(hwnd, 230);      // 90% opacity
        }
    }
}

// Or: Monitor display changes
FastTheme theme = new FastTheme();
theme.setListener(new FastTheme.ThemeListener() {
    @Override
    public void onInitialState(int width, int height, int dpi, int refreshRate, 
                               FastTheme.Orientation orientation, boolean isDarkTheme) {
        System.out.println("Display: " + width + "x" + height + " @ " + dpi + "DPI, " + 
                          refreshRate + "Hz, " + (isDarkTheme ? "DARK" : "LIGHT"));
    }
    
    @Override
    public void onResolutionChanged(int width, int height, int dpi, int refreshRate) {
        System.out.println("Resolution changed: " + width + "x" + height);
    }
    
    @Override
    public void onOrientationChanged(FastTheme.Orientation o) {}
    
    @Override
    public void onThemeChanged(boolean dark) {
        System.out.println("Theme: " + (dark ? "DARK" : "LIGHT"));
    }
});
theme.startMonitoring();

FastTheme is a minimal, native, fast library that provides:

🎨 Native Window Styling — Custom titlebar colors, transparency, and icons via DWM APIs
📊 Display Monitoring — Real-time notifications for resolution, DPI, orientation, refresh rate changes
🌓 Theme Detection — Windows dark/light mode detection

Unlike Swing Look & Feels that replace rendering, FastTheme controls the native Windows chrome — giving you true OS integration without sacrificing Swing's capabilities.

Keywords: java display monitor, screen resolution detection, dpi scaling detection, windows theme detection, dark mode detection java, display orientation monitor, refresh rate detection, jni native windows

Installation

Maven (JitPack)

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

<dependency>
    <groupId>io.github.andrestubbe</groupId>
    <artifactId>fasttheme</artifactId>
    <version>v1.3.0</version>
</dependency>

FastCore is automatically included as a transitive dependency.

Gradle (JitPack)

repositories {
    maven { url 'https://jitpack.io' }
}

dependencies {
    implementation 'io.github.andrestubbe:fasttheme:v1.3.0'
}

Direct Download (Both JARs Required)

fasttheme-1.3.0.jar — Main library with DLL
fastcore-1.0.0.jar — JNI loader

java -cp "fasttheme-1.3.0.jar:fastcore-1.0.0.jar:." YourApp

Why FastTheme?

When searching for Java Theme, Java Dark Mode, Java Windows Theme, Java Titlebar Styling, or FlatLAF alternatives, you usually need one of two things:

1. A complete UI framework (FlatLAF) — replaces Swing's Look-and-Feel entirely

2. Just real Windows theme info for your own UI — without replacing anything

FastTheme is Option 2:

Minimal — no UI framework, no overhead
Native — real Windows API via JNI
Fast — direct access to OS events
Non-intrusive — works with your existing Swing/AWT code

Use FastTheme when you want:

Native Dark/Light mode detection without changing your LAF
Custom titlebar colors while keeping standard Swing components
Real-time display metrics (DPI, resolution, refresh rate)
Window transparency without complex workarounds

Use FlatLAF when you want:

A complete, polished cross-platform Look-and-Feel
Consistent UI across Windows, macOS, and Linux
Pre-built themes and component styling

Key Features

🎨 Native Window Styling (v1.1)

Titlebar Color — Set any RGB color, seamless with content
Window Opacity — 0-100% transparency via SetLayeredWindowAttributes
Dark Mode — Native Windows dark/light titlebar
Custom Icons — Programmatic icon generation

📊 Display Monitoring

Real-time detection — Resolution, DPI, orientation, refresh rate
Instant callbacks — WM_DISPLAYCHANGE, WM_DPICHANGED events
Complete metrics — Scale %, DPI, orientation, refresh rate

🌓 Theme Detection

Dark/Light mode — Windows theme detection via Registry
System colors — Access to Windows accent colors (planned)

⚡ Technical

Zero dependencies — Java 17+ and Windows only
Lightweight — Minimal CPU/memory overhead
MIT licensed — free for commercial use
Cross-platform Ready — Windows implementation, extensible for Linux/macOS

Quick Start

import fasttheme.FastTheme;

public class Main {
    public static void main(String[] args) throws Exception {
        FastTheme theme = new FastTheme();
        
        theme.setListener(new FastTheme.ThemeListener() {
            @Override
            public void onInitialState(int width, int height, int dpi, int refreshRate,
                                       FastTheme.Orientation orientation, boolean isDarkTheme) {
                int scalePercent = (dpi * 100) / 96;
                System.out.println("INIT: " + width + "x" + height + 
                                 " | Scale: " + scalePercent + "% (DPI: " + dpi + ")" +
                                 " | " + refreshRate + "Hz" +
                                 " | " + orientation +
                                 " | Theme: " + (isDarkTheme ? "DARK" : "LIGHT"));
            }
            
            @Override
            public void onResolutionChanged(int width, int height, int dpi, int refreshRate) {
                int scalePercent = (dpi * 100) / 96;
                String orientation = (width > height) ? "LANDSCAPE" : "PORTRAIT";
                System.out.println("EVENT: Resolution changed to " + width + "x" + height + 
                                 " | Scale: " + scalePercent + "% (DPI: " + dpi + ")" +
                                 " | " + refreshRate + "Hz" +
                                 " | " + orientation);
            }
            
            @Override
            public void onOrientationChanged(FastTheme.Orientation orientation) {
                // Orientation changes included in resolution event
            }
            
            @Override
            public void onThemeChanged(boolean isDarkTheme) {
                System.out.println("EVENT: Theme changed to " + (isDarkTheme ? "DARK" : "LIGHT") + " mode");
            }
        });

        if (theme.startMonitoring()) {
            System.out.println("Monitoring started...");
            System.in.read(); // Press Enter to stop
            theme.stopMonitoring();
        }
    }
}

Window Styling API

FastTheme v1.3.0 provides a generic window styling API via static native methods. Works with any Swing/AWT window.

Basic Window Styling

import fasttheme.FastTheme;
import javax.swing.*;
import java.awt.*;

public class StyledWindow {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Styled Window");
        frame.setSize(800, 600);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        // Content color (dark gray)
        JPanel content = new JPanel();
        content.setBackground(new Color(12, 12, 12));
        frame.setContentPane(content);
        
        frame.setVisible(true); // Must be visible first!
        
        // Apply native styling
        long hwnd = FastTheme.getWindowHandle(frame);
        if (hwnd != 0) {
            FastTheme.setTitleBarColor(hwnd, 12, 12, 12);      // Match content
            FastTheme.setTitleBarTextColor(hwnd, 255, 255, 255); // White text
            FastTheme.setTitleBarDarkMode(hwnd, true);         // Dark mode
            FastTheme.setWindowTransparency(hwnd, 204);        // 80% opacity
        }
    }
}

System Information

// Get real system values
String resolution = FastTheme.getSystemResolution();  // "1920x1080"
int dpi = FastTheme.getSystemDPI();                   // 96, 120, 144...
int refresh = FastTheme.getSystemRefreshRate();       // 60, 120, 144...
boolean dark = FastTheme.isSystemDarkMode();          // true/false

Window Styling Features:

🎨 Titlebar Color — RGB background color for seamless design
✏️ Titlebar Text — RGB text color for the window title
🌙 Dark Mode — Native Windows dark/light titlebar
🔲 Transparency — 0-100% window opacity

System Detection Features:

📊 Resolution — Current screen resolution
🔍 DPI Scaling — System DPI value (96 = 100%)
🔄 Refresh Rate — Display refresh rate in Hz
� Theme Detection — Windows dark/light mode

Native APIs Used:

DwmSetWindowAttribute (DWMWA_CAPTION_COLOR, DWMWA_TEXT_COLOR, DWMWA_USE_IMMERSIVE_DARK_MODE)
SetLayeredWindowAttributes (WS_EX_LAYERED)
GetDeviceCaps / EnumDisplaySettings (DPI, Resolution, Refresh Rate)
RegQueryValueEx (Theme detection)

API Reference

Display Monitoring

Method	Description
`void setListener(ThemeListener listener)`	Set the event listener for display/theme changes
`boolean startMonitoring()`	Start monitoring (creates background thread)
`void stopMonitoring()`	Stop monitoring and release resources

Window Styling (Static Methods)

All window styling methods are public static native and can be called from any thread:

Method	Parameters	Returns	Description
`getWindowHandle`	`Component component`	`long`	Extract native HWND from Swing window
`setWindowTransparency`	`long hwnd, int alpha`	`boolean`	Set window opacity (0-255)
`setTitleBarColor`	`long hwnd, int r, int g, int b`	`boolean`	Set titlebar background color
`setTitleBarTextColor`	`long hwnd, int r, int g, int b`	`boolean`	Set titlebar text color
`setTitleBarDarkMode`	`long hwnd, boolean enabled`	`boolean`	Enable/disable dark mode
`getSystemResolution`	—	`String`	Current resolution (e.g., "1920x1080")
`getSystemDPI`	—	`int`	System DPI (96 = 100% scaling)
`getSystemRefreshRate`	—	`int`	Display refresh rate in Hz
`isSystemDarkMode`	—	`boolean`	Windows dark mode status

ThemeListener Interface

Method	Description
`void onInitialState(int w, int h, int dpi, int refresh, Orientation o, boolean dark)`	Called once on startup
`void onResolutionChanged(int w, int h, int dpi, int refresh)`	Resolution or DPI changed
`void onOrientationChanged(Orientation o)`	Display orientation changed
`void onThemeChanged(boolean dark)`	Windows theme changed

Orientation Enum

Value	Description
`LANDSCAPE`	Normal landscape (0°)
`PORTRAIT`	Portrait (90° clockwise)
`LANDSCAPE_FLIPPED`	Flipped landscape (180°)
`PORTRAIT_FLIPPED`	Flipped portrait (270°)

Use Cases

Adaptive UI Applications — Automatically adjust layouts when DPI or resolution changes
Multi-Monitor Apps — Detect display configuration changes
Tablet/Convertible Apps — Handle orientation switches (landscape ↔ portrait)
Gaming Overlays — Match refresh rate for smooth rendering
Theme-Aware Apps — Apply dark/light theme based on OS preference
System Monitoring Tools — Track display configuration over time

Platform Support

Platform	Status	Notes
Windows 10/11	✅ Supported	Full feature set via JNI
Linux	🚧 Planned	X11/Wayland implementation
macOS	🚧 Planned	macOS display API implementation

Build from Source

Prerequisites

Java 17+ JDK
Visual Studio 2022 (or Build Tools)
Maven 3.8+

Windows Build

# Using the provided batch file (compiles Java + native DLL)
compile.bat

# Or with Maven
mvn clean package

Project Structure

FastTheme/
├── src/main/
│   └── java/fasttheme/
│       └── FastTheme.java           # Main API class
│   └── resources/native/
│       └── fasttheme.dll            # Native JNI library
├── native/
│   ├── FastTheme.cpp                # JNI implementation
│   ├── FastTheme.h                  # JNI header
│   └── FastTheme.def                # DLL exports
├── examples/
│   └── 00-basic-usage/
│       └── src/main/java/fasttheme/
│           ├── WindowDemo.java    # Window styling demo
│           └── ConsoleDemo.java   # Display monitoring demo
├── compile.bat                      # Windows build script
├── pom.xml                          # Maven configuration
└── README.md                        # This file

Changelog

v1.3.0 — Generic Window Styling API

✨ Generic JNI API — Renamed JNI methods to FastTheme_*
✨ Static Native Methods — All window styling via FastTheme.* static methods
✨ Doxygen Documentation — Complete C++ API documentation
✨ Java Documentation — Comprehensive Javadoc for all classes

v1.2.0 — Initial Window Styling

✨ TitleBar Color — Custom RGB titlebar colors
✨ TitleBar Text — Custom titlebar text color
✨ Dark Mode — Native Windows dark/light mode toggle
✨ Transparency — Window opacity control
✨ System Detection — Resolution, DPI, refresh rate, theme detection

v1.0.0 — Display Monitoring

✨ Display Monitoring — Real-time resolution, DPI, orientation changes
✨ Theme Detection — Windows dark/light mode detection

Roadmap

Real-time Theme Change Events — Runtime dark/light mode switching detection
Button Colors — Control Windows caption button colors
Multi-Monitor Support — Per-display settings detection
Linux Support — X11/Wayland display monitoring
macOS Support — macOS display configuration monitoring

License

MIT License — See LICENSE file for details.

Related Projects

FastRobot — High-performance Java automation & screen capture

Made with ⚡ by the FastJava Team

Name		Name	Last commit message	Last commit date
Latest commit History 23 Commits
docs		docs
examples/00-basic-usage		examples/00-basic-usage
native		native
src/main/java/fasttheme		src/main/java/fasttheme
.gitattributes		.gitattributes
.gitignore		.gitignore
LICENSE		LICENSE
README.md		README.md
compile.bat		compile.bat
pom.xml		pom.xml

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FastTheme — Native Windows Theme, Titlebar Styling & Display API for Java [ALPHA]

Table of Contents

Installation

Maven (JitPack)

Gradle (JitPack)

Direct Download (Both JARs Required)

Why FastTheme?

Key Features

🎨 Native Window Styling (v1.1)

📊 Display Monitoring

🌓 Theme Detection

⚡ Technical

Quick Start

Window Styling API

Basic Window Styling

System Information

API Reference

Display Monitoring

Window Styling (Static Methods)

ThemeListener Interface

Orientation Enum

Use Cases

Platform Support

Build from Source

Prerequisites

Windows Build

Project Structure

Changelog

v1.3.0 — Generic Window Styling API

v1.2.0 — Initial Window Styling

v1.0.0 — Display Monitoring

Roadmap

License

Related Projects

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