FlatLaf

https://www.formdev.com/flatlaf/
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FlatLaf is a modern open-source look and feel for Java Swing applications, providing a clean and...
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### Basic FlatLaf Customization Example

Source: https://www.formdev.com/flatlaf/how-to-customize

Example demonstrating basic FlatLaf customization by setting component arc and tabbed pane background color. Ensure UIManager.put() is called after FlatLightLaf.setup() and before component creation.

```java
FlatLightLaf.setup();

UIManager.put( "Component.arc", 0 );
UIManager.put( "ProgressBar.arc", 0 );
UIManager.put( "TabbedPane.selectedBackground", Color.white );
```

--------------------------------

### Setup FlatLightLaf

Source: https://www.formdev.com/flatlaf

Enable FlatLaf's light theme by calling FlatLightLaf.setup() before creating any Swing components. This is the recommended way to integrate FlatLaf.

```java
FlatLightLaf.setup();

// create UI here...
```

--------------------------------

### Basic Properties File Structure

Source: https://www.formdev.com/flatlaf/properties-files

Example of a simple properties file defining button colors. Lines starting with '#' are comments.

```properties
# button colors
Button.background = #ffffff
Button.focusedBackground = #e3f1fa
```

--------------------------------

### Setup FlatLaf with Custom Defaults

Source: https://www.formdev.com/flatlaf/how-to-customize

In your main method, register the custom defaults source and then set up the desired FlatLaf theme. This ensures your custom properties are loaded.

```java
FlatLaf.registerCustomDefaultsSource( "com.myapp.themes" );
FlatLightLaf.setup();
```

--------------------------------

### Apply Custom Theme in Main Method

Source: https://www.formdev.com/flatlaf/how-to-customize

In your application's main method, call the setup method of your custom theme class to apply it.

```java
MyDarkerLaf.setup();
```

--------------------------------

### Setup New Theme in Application

Source: https://www.formdev.com/flatlaf/theme-editor

Add this code to your main method to set up a newly created theme. Ensure it's called before setting the look and feel.

```java
MyAppTheme.setup();
```

--------------------------------

### Setup FlatLaf via UIManager

Source: https://www.formdev.com/flatlaf

Alternatively, set FlatLaf's look and feel using UIManager. This method allows for more explicit control and error handling during initialization.

```java
try {
    UIManager.setLookAndFeel( new FlatLightLaf() );
} catch( Exception ex ) {
    System.err.println( "Failed to initialize LaF" );
}

// create UI here...
```

--------------------------------

### Insets Properties

Source: https://www.formdev.com/flatlaf/properties-files

Example of defining insets for components like buttons and tabbed panes.

```properties
Button.margin = 2,14,2,14
TabbedPane.tabInsets = 0,12,0,12
```

--------------------------------

### Define Global Component Defaults

Source: https://www.formdev.com/flatlaf/how-to-customize

Create a properties file for global defaults that apply to all themes. This example sets the arc for components and progress bars to 0.

```properties
Component.arc = 0
ProgressBar.arc = 0
```

--------------------------------

### Assembly Descriptor for Packaging Dependencies

Source: https://www.formdev.com/flatlaf/native-libraries

Define the assembly descriptor file (e.g., zip.xml) to specify how dependencies, including native libraries, should be organized in the application distributable. This example places all dependencies into the 'lib' directory.

```xml
<assembly xmlns="http://maven.apache.org/ASSEMBLY/2.1.1"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/ASSEMBLY/2.1.1 https://maven.apache.org/xsd/assembly-2.1.1.xsd">
    <id>zip</id>
    <includeBaseDirectory>true</includeBaseDirectory>
    <formats>
        <format>zip</format>
        <format>dir</format>
    </formats>
    <dependencySets>
        <dependencySet>
            <outputDirectory>lib</outputDirectory>
        </dependencySet>
    </dependencySets>
</assembly>
```

--------------------------------

### Maven Assembly Plugin Configuration

Source: https://www.formdev.com/flatlaf/native-libraries

Configure the Maven Assembly Plugin to package your application distributable. This example shows how to set up the plugin to include all dependencies, including native libraries, into the 'lib' directory of the zip archive.

```xml
<project ...>
    ...

    <build>
        <plugins>
            <plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                        <configuration>
                            <appendAssemblyId>false</appendAssemblyId>
                            <descriptors>
                                <descriptor>src/main/assembly/zip.xml</descriptor>
                            </descriptors>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>
```

--------------------------------

### Wildcard Replacements for Component Defaults

Source: https://www.formdev.com/flatlaf/properties-files

Uses keys starting with '*.' to replace matching keys in `BasicLookAndFeel.getDefaults()` and `FlatLaf.getDefaults()`. This is commonly used for initializing basic component colors.

```properties
*.background = #f2f2f2
*.foreground = #000
```

--------------------------------

### Maven Central Native Libraries

Source: https://www.formdev.com/flatlaf/native-libraries

Example of FlatLaf native libraries available on Maven Central for version 3.4. These are typically bundled with the main JAR or can be downloaded separately.

```text
https://repo1.maven.org/maven2/com/formdev/flatlaf/3.4/
    flatlaf-3.4.jar
    flatlaf-3.4-no-natives.jar
    flatlaf-3.4-sources.jar
    flatlaf-3.4-javadoc.jar
    flatlaf-3.4-linux-x86_64.so
    flatlaf-3.4-macos-arm64.dylib
    flatlaf-3.4-macos-x86_64.dylib
    flatlaf-3.4-windows-x86_64.dll
    flatlaf-3.4-windows-x86.dll
    flatlaf-3.4-windows-arm64.dll
```

--------------------------------

### Define Light Theme Specific Defaults

Source: https://www.formdev.com/flatlaf/how-to-customize

Create a properties file for light themes to override specific component appearances and define application-specific colors. This example customizes the selected tab background and sidebar background for light themes.

```properties
TabbedPane.selectedBackground = #fff

# define application specific UI values
MyApp.SideBar.background = darken(@background,10%)
MyApp.someColor = #f00
MyApp.anotherColor = #645554
```

--------------------------------

### Create a New Custom Theme Class

Source: https://www.formdev.com/flatlaf/how-to-customize

Subclass FlatDarkLaf to create a new theme. Provide a setup method and override the getName method to define your custom theme's identity.

```java
package com.myapp.themes;

import com.formdev.flatlaf.FlatDarkLaf;

public class MyDarkerLaf extends FlatDarkLaf {
    public static boolean setup() {
        return setup( new MyDarkerLaf() );
    }

    @Override
    public String getName() {
        return "MyDarkerLaf";
    }
}
```

--------------------------------

### Define Style Classes in FlatLaf.properties

Source: https://www.formdev.com/flatlaf/typography

Example of defining style classes that reference font properties. Used for applying specific font styles to components.

```properties
...
[style].h0 = font: $h0.font
...
```

--------------------------------

### Define Dark Theme Specific Defaults

Source: https://www.formdev.com/flatlaf/how-to-customize

Create a properties file for dark themes to override specific component appearances and define application-specific colors. This example customizes the selected tab background and sidebar background for dark themes.

```properties
TabbedPane.selectedBackground = darken($TabbedPane.background,5%)

# define application specific UI values
MyApp.SideBar.background = lighten(@background,10%)
MyApp.someColor = #00f
MyApp.anotherColor = #278354
```

--------------------------------

### JPanel as Placeholder for Full Window Buttons (macOS) in Tabbed Pane

Source: https://www.formdev.com/flatlaf/client-properties

This example shows how to add a JPanel as a placeholder for macOS window buttons as the leading component of a JTabbedPane when in full window content mode.

```java
JPanel placeholder = new JPanel();
placeholder.putClientProperty( FlatClientProperties.FULL_WINDOW_CONTENT_BUTTONS_PLACEHOLDER, "mac" );

tabbedPane.putClientProperty( FlatClientProperties.TABBED_PANE_LEADING_COMPONENT, placeholder );
```

--------------------------------

### Set JButton Button Type

Source: https://www.formdev.com/flatlaf/client-properties

Use client properties to change the visual style of a JButton. This example sets the button to have round rectangle edges.

```Java
myButton.putClientProperty( "JButton.buttonType", "roundRect" );
```

--------------------------------

### Applying System Theme to FlatLaf

Source: https://www.formdev.com/flatlaf/sponsor

This Java code demonstrates how to set up FlatLaf's look and feel based on the system's dark mode preference and how to update the UI when the system theme changes.

```java
// setup application look and feel
if( SystemTheming.isDarkMode() )
    FlatDarkLaf.setup();
else
    FlatLightLaf.setup();

// update application look and feel on OS changes 
SystemTheming.addListener( e -> {
    if( e.isDarkMode() )
        FlatDarkLaf.setup();
    else
        FlatLightLaf.setup();
    FlatLaf.updateUI();
} );

// create UI ...
```

--------------------------------

### Run Theme Editor

Source: https://www.formdev.com/flatlaf/theme-editor

Execute the FlatLaf theme editor JAR file. Requires Java 8 or newer.

```bash
java -jar flatlaf-theme-editor-<version>.jar
```

--------------------------------

### JTextField.clearCallback with Consumer

Source: https://www.formdev.com/flatlaf/client-properties

Example of setting a clear callback for a JTextField using a Consumer. The Consumer receives the text field as a parameter, allowing for custom clearing logic.

```java
myTextField.putClientProperty( "JTextField.clearCallback",
    (Consumer<JTextComponent>) textField -> {
        // clear field here or cancel search
    } );
```

--------------------------------

### SystemTheming

Source: https://www.formdev.com/flatlaf/sponsor

Provides access to system theme information (light/dark, accent color, etc) and allows listening to changes.

```APIDOC
## Class SystemTheming

### Description
Provides access to system theme information (light/dark, accent color, etc) and allows listening to changes.

### Methods

#### `isSupportedPlatform()`
Returns whether supported on current operating system and CPU architecture.

#### `isDarkMode()`
Returns whether the operating system theme is dark.

#### `getAccentColor()`
Returns the operating system theme accent color, or null.

#### `getHighlightColor()`
Returns the macOS operating system theme highlight color, or null.

#### `addListener(Listener l)`
Adds a listener. Will be invoked on AWT thread.

#### `removeListener(Listener l)`
Removes the listener.

### Inner Interfaces

#### `interface Listener`

##### Description
The listener interface for receiving system theme change events.

##### Methods

###### `systemThemeChanged(Event e)`
Called when the system theme has changed.

### Inner Classes

#### `class Event`

##### Description
A event that indicates that the system theme has changed.

##### Methods

###### `isDarkMode()`
Returns whether the system theme is dark.

###### `getAccentColor()`
Returns the system theme accent color.
```

--------------------------------

### JTextField.clearCallback with Runnable

Source: https://www.formdev.com/flatlaf/client-properties

Example of setting a clear callback for a JTextField using a Runnable. This callback is invoked when the clear button is clicked and is responsible for clearing the text field.

```java
myTextField.putClientProperty( "JTextField.clearCallback",
    (Runnable) () -> {
        // clear field here or cancel search
    } );
```

--------------------------------

### Primitive Type Properties

Source: https://www.formdev.com/flatlaf/properties-files

Demonstrates the syntax for boolean, integer, float, and null values in properties files.

```properties
# boolean
Menu.opaque = false
MenuItem.borderPainted = true

# integer
Button.borderWidth = 1

# float
Popup.dropShadowOpacity = 0.15

# null
Menu.checkIcon = null
```

--------------------------------

### Lib/Bin Directory Native Library Layout

Source: https://www.formdev.com/flatlaf/native-libraries

This layout demonstrates how to organize the FlatLaf JAR in a 'lib' directory and native libraries in a 'bin' directory.

```text
lib/flatlaf-3.4.jar
bin/flatlaf-3.4-linux-x86_64.so
bin/flatlaf-3.4-macos-arm64.dylib
bin/flatlaf-3.4-macos-x86_64.dylib
bin/flatlaf-3.4-windows-x86_64.dll
bin/flatlaf-3.4-windows-x86.dll
bin/flatlaf-3.4-windows-arm64.dll
```

--------------------------------

### Integrate with macOS Application Menu (Java 9+)

Source: https://www.formdev.com/flatlaf/macos

Use `java.awt.Desktop` to set handlers for the About, Preferences, and Quit menu items. Ensure the respective actions are supported before setting the handlers.

```java
Desktop desktop = Desktop.getDesktop();
if( desktop.isSupported( Desktop.Action.APP_ABOUT ) ) {
    desktop.setAboutHandler( e -> {
        // show about dialog
    } );
}
if( desktop.isSupported( Desktop.Action.APP_PREFERENCES ) ) {
    desktop.setPreferencesHandler( e -> {
        // show preferences dialog
    } );
}
if( desktop.isSupported( Desktop.Action.APP_QUIT_HANDLER ) ) {
    desktop.setQuitHandler( (e, response) -> {
        boolean canQuit = // TODO
        if( canQuit )
            response.performQuit();
        else
            response.cancelQuit();
    } );
}
```

--------------------------------

### Select Folder

Source: https://www.formdev.com/flatlaf/system-file-chooser

Opens a dialog to select a directory. The selected directory path is printed to the console.

```Java
SystemFileChooser fc = new SystemFileChooser();
fc.setFileSelectionMode( SystemFileChooser.DIRECTORIES_ONLY );
if( fc.showOpenDialog( this ) == SystemFileChooser.APPROVE_OPTION ) {
    File directory = fc.getSelectedFile();
    System.out.println( directory );
}
```

--------------------------------

### Set UI Defaults in Properties Files

Source: https://www.formdev.com/flatlaf/customizing

Set UI defaults in FlatLaf properties files using key-value pairs.

```properties
someKey = someValue
```

--------------------------------

### Color Properties

Source: https://www.formdev.com/flatlaf/properties-files

Shows how to define colors using hexadecimal formats and color functions.

```properties
Button.background = #fff
Button.focusedBackground = #e3f1fa
PasswordField.capsLockIconColor = #00000064
```

```properties
TableHeader.separatorColor = darken($TableHeader.background,10%)
```

--------------------------------

### Use FlatClientProperties Constants for JButton

Source: https://www.formdev.com/flatlaf/client-properties

Leverage constants from FlatClientProperties for setting button types, ensuring type safety and code readability. This example configures a round rectangle button.

```Java
myButton.putClientProperty( FlatClientProperties.BUTTON_TYPE, FlatClientProperties.BUTTON_TYPE_ROUND_RECT );
```

--------------------------------

### Check Modifier Key Press on Tab Close

Source: https://www.formdev.com/flatlaf/client-properties

This example shows how to check if a modifier key like Shift was pressed when a tab close button was clicked, by accessing the current AWTEvent.

```java
AWTEvent e = EventQueue.getCurrentEvent();
boolean shift = (e instanceof MouseEvent) ? ((MouseEvent)e).isShiftDown() : false;
```

--------------------------------

### Implement and Set State Store

Source: https://www.formdev.com/flatlaf/system-file-chooser

Implements the SystemFileChooser.StateStore interface to persist the last visited folder and sets it for the file chooser.

```Java
SystemFileChooser.setStateStore( new SystemFileChooser.StateStore() {
    private static final String KEY_PREFIX = "fileChooser.";

    private final Preferences state = Preferences.userRoot().node( "my-application" );

    @Override
    public String get( String key, String def ) {
        return state.get( KEY_PREFIX + key, def );
    }

    @Override
    public void put( String key, String value ) {
        if( value != null )
            state.put( KEY_PREFIX + key, value );
        else
            state.remove( KEY_PREFIX + key );
    }
} );
```

--------------------------------

### Load Custom IntelliJ Theme

Source: https://www.formdev.com/flatlaf/themes

Use this code to load and initialize a custom IntelliJ theme from a .theme.json file within your application's resources. Ensure the file path is correct.

```java
IntelliJTheme.setup( MyApp.class.getResourceAsStream(
    "/com/myapp/themes/arc-theme-orange.theme.json" ) );

// create UI here...
```

--------------------------------

### Using Variables in Property Values

Source: https://www.formdev.com/flatlaf/properties-files

Demonstrates how to reference previously defined variables using the '@' prefix within property values.

```properties
Table.background = @background
Table.foreground = @foreground
MenuBar.hoverBackground = @menuHoverBackground
MenuItem.acceleratorForeground = lighten(@foreground,30%)
```

--------------------------------

### Dimension Properties

Source: https://www.formdev.com/flatlaf/properties-files

Shows how to define dimensions for components like desktop icons and progress bars.

```properties
DesktopIcon.iconSize = 64,64
ProgressBar.horizontalSize = 146,4
```

--------------------------------

### Activate Editor Shortcut

Source: https://www.formdev.com/flatlaf/theme-editor

Use this shortcut to activate the editor.

```text
F12
```

--------------------------------

### Open Multiple Files

Source: https://www.formdev.com/flatlaf/system-file-chooser

Opens a dialog to select multiple files. The selected files are printed to the console, with each file on a new line.

```Java
SystemFileChooser fc = new SystemFileChooser();
fc.setMultiSelectionEnabled( true );
if( fc.showOpenDialog( this ) == SystemFileChooser.APPROVE_OPTION ) {
    File[] files = chooser.getSelectedFiles();
    System.out.println( Arrays.toString( files ).replace( ",", "\n" ) );
}
```

--------------------------------

### Integrate with macOS Application Menu (Java 8)

Source: https://www.formdev.com/flatlaf/macos

Use `com.formdev.flatlaf.extras.FlatDesktop` from the flatlaf-extras library to set handlers for About, Preferences, and Quit menu items. This is an alternative for applications using Java 8.

```java
FlatDesktop.setAboutHandler( () -> {
    // show about dialog
} );
FlatDesktop.setPreferencesHandler( () -> {
    // show preferences dialog
} );
FlatDesktop.setQuitHandler( response -> {
    boolean canQuit = // TODO
    if( canQuit )
        response.performQuit();
    else
        response.cancelQuit();
} );
```

--------------------------------

### Fat JAR Lib/Bin Directory Native Library Layout

Source: https://www.formdev.com/flatlaf/native-libraries

This layout illustrates organizing a fat JAR in 'lib' and its native libraries in 'bin'.

```text
lib/myapp-1.0.jar
bin/myapp-1.0-flatlaf-linux-x86_64.so
bin/myapp-1.0-flatlaf-macos-arm64.dylib
bin/myapp-1.0-flatlaf-macos-x86_64.dylib
bin/myapp-1.0-flatlaf-windows-x86_64.dll
bin/myapp-1.0-flatlaf-windows-x86.dll
bin/myapp-1.0-flatlaf-windows-arm64.dll
```

--------------------------------

### SystemTheming API Definition

Source: https://www.formdev.com/flatlaf/sponsor

This Java class provides methods to query system theme properties like dark mode and accent color, and to register listeners for theme changes.

```java
/**
 * Gives access to system theme information (light/dark, accent color, etc)
 * and allows listening to changes.
 */
public class SystemTheming
{
    /** Returns whether supported on current operating system and CPU architecture. */
    public static boolean isSupportedPlatform()

    /** Returns whether the operating system theme is dark. */
    public static boolean isDarkMode()

    /** Returns the operating system theme accent color, or null. */
    public static Color getAccentColor()

    /** Returns the macOS operating system theme highlight color, or null. */
    public static Color getHighlightColor()

    /** Adds a listener. Will be invoked on AWT thread. */
    public static void addListener( Listener l )

    /** Removes the listener. */
    public static void removeListener( Listener l )

    /** The listener interface for receiving system theme change events. */
    public interface Listener {
        public void systemThemeChanged( Event e );
    }

    /** A event that indicates that the system theme has changed. */
    public static class Event {
        public boolean isDarkMode()
        public Color getAccentColor()
    }
}
```

--------------------------------

### Standard Native Library Layout

Source: https://www.formdev.com/flatlaf/native-libraries

This layout shows the standard naming convention for FlatLaf JAR and its associated native libraries.

```text
flatlaf-3.4.jar
flatlaf-3.4-linux-x86_64.so
flatlaf-3.4-macos-arm64.dylib
flatlaf-3.4-macos-x86_64.dylib
flatlaf-3.4-windows-x86_64.dll
flatlaf-3.4-windows-x86.dll
flatlaf-3.4-windows-arm64.dll
```

--------------------------------

### Define Custom Theme Properties

Source: https://www.formdev.com/flatlaf/how-to-customize

Create a properties file with the same basename as your custom theme class to define theme-specific properties like background, foreground, and accent colors.

```properties
@background = #111
@foreground = #ddd
@accentColor = #f57900
```

--------------------------------

### Fat JAR with Native Library Naming

Source: https://www.formdev.com/flatlaf/native-libraries

This layout shows the naming convention when FlatLaf is repackaged into a fat/uber application JAR.

```text
myapp-1.0.jar
myapp-1.0-flatlaf-linux-x86_64.so
myapp-1.0-flatlaf-macos-arm64.dylib
myapp-1.0-flatlaf-macos-x86_64.dylib
myapp-1.0-flatlaf-windows-x86_64.dll
myapp-1.0-flatlaf-windows-x86.dll
myapp-1.0-flatlaf-windows-arm64.dll
```

--------------------------------

### Applying FlatLaf Styles with CSS Syntax

Source: https://www.formdev.com/flatlaf/client-properties

Use `FlatLaf.style` to apply styles to a JComponent using CSS-like syntax. This allows for granular control over component appearance.

```Java
myComponent.putClientProperty( "FlatLaf.style", "arc: 10;" );
```

--------------------------------

### Approve Callback with Message Dialog

Source: https://www.formdev.com/flatlaf/system-file-chooser

Demonstrates using ApproveContext.showMessageDialog within a callback to display a system message dialog. Avoid showing Swing dialogs directly from the callback.

```Java
fc.setApproveCallback( (selectedFiles, context) -> {
    if( !selectedFiles[0].getName().startsWith( "blabla" ) ) {
        context.showMessageDialog( JOptionPane.WARNING_MESSAGE,
            "File name must start with 'blabla' :)", null, 0 );
        return SystemFileChooser.CANCEL_OPTION;
    }
    return SystemFileChooser.APPROVE_OPTION;
} );
```

--------------------------------

### Change Color Components (Hue, Saturation, Lightness, Alpha)

Source: https://www.formdev.com/flatlaf/properties-files

Use `changeHue`, `changeSaturation`, `changeLightness`, or `changeAlpha` to set specific color components to a new value. Hue is in degrees, while saturation, lightness, and alpha are percentages.

```java
changeHue(#80e619,70)
```

```java
changeSaturation(#80e619,60%)
```

```java
changeLightness(#80e619,70%)
```

```java
Button.focusedBackground = changeLightness($Component.focusColor,95%)
```

--------------------------------

### Set System Property via Command Line

Source: https://www.formdev.com/flatlaf/system-properties

Pass system properties directly when launching an application from the command line. This is useful for quick configuration changes without modifying code.

```bash
$ myapp -Dflatlaf.animation=false
```

--------------------------------

### Referencing Other Properties

Source: https://www.formdev.com/flatlaf/properties-files

Shows how to reference other property values using the '$' prefix followed by the key. This allows for value reuse and dynamic updates.

```properties
Table.background = $List.background
Tree.background = $List.background
Button.hoverBackground = darken($Button.background,3%,derived)
```

--------------------------------

### Open Single File

Source: https://www.formdev.com/flatlaf/system-file-chooser

Opens a dialog to select a single file. The selected file is printed to the console.

```Java
SystemFileChooser fc = new SystemFileChooser();
if( fc.showOpenDialog( this ) == SystemFileChooser.APPROVE_OPTION ) {
    File file = fc.getSelectedFile();
    System.out.println( file );
}
```

--------------------------------

### Enable Full Screen Mode on macOS (Pre Java 11)

Source: https://www.formdev.com/flatlaf/macos

Allows applications to support macOS full screen mode by setting a client property. Holding Alt while clicking the green button still maximizes the window.

```java
frame.getRootPane().putClientProperty( "apple.awt.fullscreenable", true );
```

--------------------------------

### Enable FlatLaf Window Decorations on Linux

Source: https://www.formdev.com/flatlaf/window-decorations

Enable custom window decorations for JFrame and JDialog on Linux systems before creating any UI. This should not be used if your application supports switching Look and Feels dynamically.

```java
if( SystemInfo.isLinux ) {
    // enable custom window decorations
    JFrame.setDefaultLookAndFeelDecorated( true );
    JDialog.setDefaultLookAndFeelDecorated( true );
}
```

--------------------------------

### Approve Callback with Method Reference

Source: https://www.formdev.com/flatlaf/system-file-chooser

Sets an approval callback using a method reference. The callback method must return APPROVE_OPTION or CANCEL_OPTION.

```Java
fc.setApproveCallback( this::approveCallback );

private boolean approveCallback( File[] selectedFiles, ApproveContext context ) {
    // do something
    return SystemFileChooser.APPROVE_OPTION; // or SystemFileChooser.CANCEL_OPTION
}
```

--------------------------------

### Select Contrasting Color

Source: https://www.formdev.com/flatlaf/properties-files

Use `contrast` to choose between a dark and light color based on their contrast with a given color. A threshold can be specified to adjust the transition point.

```java
contrast(#bbb, #00f, #0f0)
```

```java
contrast(#444, #00f, #0f0)
```

```java
@selectionForeground = contrast(@selectionBackground, @foreground, #fff)
```

--------------------------------

### Applying FlatLaf Styles with a Map

Source: https://www.formdev.com/flatlaf/client-properties

Use `FlatLaf.style` with a `Map<String, Object>` for applying styles programmatically. Values in the map must be binary.

```Java
Map<String, Object> styles = new HashMap<>();
styles.put( "arc", 10 );
myComponent.putClientProperty( "FlatLaf.style", styles );
```

--------------------------------

### Configure Global macOS Settings for FlatLaf

Source: https://www.formdev.com/flatlaf/macos

Use this snippet to enable the screen menu bar, set the application name, and configure the appearance of window title bars for all windows in a macOS application using FlatLaf.

```java
public static void main( String[] args ) {
    // macOS  (see https://www.formdev.com/flatlaf/macos/)
    if( SystemInfo.isMacOS ) {
        // enable screen menu bar
        // (moves menu bar from JFrame window to top of screen)
        System.setProperty( "apple.laf.useScreenMenuBar", "true" );

        // application name used in screen menu bar
        // (in first menu after the "apple" menu)
        System.setProperty( "apple.awt.application.name", "My Application" );

        // appearance of window title bars
        // possible values:
        //   - "system": use current macOS appearance (light or dark)
        //   - "NSAppearanceNameAqua": use light appearance
        //   - "NSAppearanceNameDarkAqua": use dark appearance
        // (must be set on main thread and before AWT/Swing is initialized;
        //  setting it on AWT thread does not work)
        System.setProperty( "apple.awt.application.appearance", "system" );
    }

    SwingUtilities.invokeLater( () -> {
        FlatLightLaf.setup();

        // create and show UI
    } );
}
```

--------------------------------

### Font Properties

Source: https://www.formdev.com/flatlaf/properties-files

Illustrates various ways to define fonts, including size, style, family, and derivation from base fonts.

```properties
defaultFont = 13 "Open Sans", "Noto Sans", Roboto, Arial
Label.font = +italic
h1.font = +12
xxxl.font = bold +36
lightTitle.font = 200% $light.font
```

--------------------------------

### Always Show Mnemonics using Properties

Source: https://www.formdev.com/flatlaf/customizing

Set 'Component.hideMnemonics' to false in properties files to make mnemonics always visible, instead of appearing only when Alt is pressed.

```properties
Component.hideMnemonics = false
```

--------------------------------

### Pick Color from Screen Shortcut

Source: https://www.formdev.com/flatlaf/theme-editor

Use this shortcut to pick a color from anywhere on the screen and insert its value into the editor. Press Esc to cancel.

```text
Ctrl+Shift+G
```

--------------------------------

### Set Platform Specific Properties

Source: https://www.formdev.com/flatlaf/system-file-chooser

Sets platform-specific properties for the file chooser, such as custom labels or directory handling.

```Java
fc.putPlatformProperty( SystemFileChooser.WINDOWS_FILE_NAME_LABEL, "My filename label:" );
fc.putPlatformProperty( SystemFileChooser.MAC_TREATS_FILE_PACKAGES_AS_DIRECTORIES, true );
```

--------------------------------

### Custom Icon in Properties Files

Source: https://www.formdev.com/flatlaf/properties-files

Defines an icon using its fully qualified class name. The class must be public and have a zero-argument public constructor.

```properties
CheckBox.icon = com.formdev.flatlaf.icons.FlatCheckBoxIcon
```

--------------------------------

### Setting Minimum Height for Buttons

Source: https://www.formdev.com/flatlaf/client-properties

Use `JComponent.minimumHeight` to specify the minimum height for buttons and toggle buttons.

```Java
myToggleButton.putClientProperty( "JComponent.minimumHeight", 40 );
```

--------------------------------

### System File Chooser API

Source: https://www.formdev.com/flatlaf/sponsor

Provides access to the system file chooser. Includes a method to check platform support.

```java
/**
 * Gives access to system file chooser.
 */
public class SystemFileChooser
{
    /** Returns whether supported on current operating system and CPU architecture. */
    public static boolean isSupportedPlatform()

    TBD
}
```

--------------------------------

### Save File

Source: https://www.formdev.com/flatlaf/system-file-chooser

Opens a dialog to select a file for saving. The selected file path is printed to the console.

```Java
SystemFileChooser fc = new SystemFileChooser();
if( fc.showSaveDialog( this ) == SystemFileChooser.APPROVE_OPTION ) {
    File file = fc.getSelectedFile();
    System.out.println( file );
}
```

--------------------------------

### Configure Main Frame for macOS Specifics

Source: https://www.formdev.com/flatlaf/macos

Customize the main frame on macOS to hide redundant menu items, handle HTML text in menus, and enable advanced window features like full-window content and transparent title bars.

```java
// macOS  (see https://www.formdev.com/flatlaf/macos/)
if( SystemInfo.isMacOS ) {
    // hide menu items that are in macOS application menu
    aboutMenuItem.setVisible( false );
    preferencesMenuItem.setVisible( false );
    exitMenuItem.setVisible( false );

    // do not use HTML text in menu items because this is not supported in macOS screen menu
    htmlMenuItem.setText( "some text" );

    if( SystemInfo.isMacFullWindowContentSupported ) {
        // expand window content into window title bar and make title bar transparent
        frame.getRootPane().putClientProperty( "apple.awt.fullWindowContent", true );
        frame.getRootPane().putClientProperty( "apple.awt.transparentTitleBar", true );

        // hide window title
        if( SystemInfo.isJava_17_orLater )
            frame.getRootPane().putClientProperty( "apple.awt.windowTitleVisible", false );
        else
            frame.setTitle( null );

        // add gap to left side of toolbar
        toolBar.add( Box.createHorizontalStrut( 70 ), 0 );
    }

    // enable full screen mode for this window (for Java 8 - 10; not necessary for Java 11+)
    if( !SystemInfo.isJava_11_orLater )
        frame.getRootPane().putClientProperty( "apple.awt.fullscreenable", true );
}
```

--------------------------------

### JPanel as Placeholder for Full Window Buttons (macOS) in ToolBar

Source: https://www.formdev.com/flatlaf/client-properties

This snippet demonstrates adding a JPanel as a placeholder for macOS window buttons directly into a JToolBar. FlatLaf will automatically position it correctly.

```java
JPanel placeholder = new JPanel();
placeholder.putClientProperty( FlatClientProperties.FULL_WINDOW_CONTENT_BUTTONS_PLACEHOLDER, "mac" );

JToolBar toolBar = new JToolBar();
toolBar.add( placeholder );
// add tool bar items

frame.getContentPane().add( toolBar, BorderLayout.NORTH );
```

--------------------------------

### Scaled Values for HiDPI Screens

Source: https://www.formdev.com/flatlaf/properties-files

Specifies values that should be automatically scaled for HiDPI screens. Prefixes include `{scaledInteger}`, `{scaledFloat}`, `{scaledInsets}`, and `{scaledDimension}`.

```properties
Caret.width = {scaledInteger}1
Component.innerFocusWidth = {scaledFloat}0.5
TabbedPane.tabInsets = {scaledInsets}0,12,0,12
ColorChooser.swatchesSwatchSize = {scaledDimension}16,16
```

--------------------------------

### Create HSL/HSLA Colors

Source: https://www.formdev.com/flatlaf/properties-files

Use `hsl` for hue, saturation, and lightness, or `hsla` to include an alpha channel. Hue is in degrees (0-360), while saturation, lightness, and alpha are percentages.

```java
hsl(90, 100%, 50%)
```

```java
List.selectionBackground = hsl(209,66%,44%)
```

```java
List.selectionForeground = hsla(0,0%,100%,50%)
```

--------------------------------

### Approve Callback with Lambda

Source: https://www.formdev.com/flatlaf/system-file-chooser

Sets an approval callback using a lambda expression. The callback is invoked when the user presses 'OK'. It can return CANCEL_OPTION to keep the dialog open.

```Java
fc.setApproveCallback( (selectedFiles, context) -> {
    // do something
    return SystemFileChooser.APPROVE_OPTION; // or SystemFileChooser.CANCEL_OPTION
} );
```

--------------------------------

### Create RGB/RGBA Colors

Source: https://www.formdev.com/flatlaf/properties-files

Use `rgb` for red, green, and blue values, or `rgba` to include an alpha channel. Values can be integers (0-255) or percentages (0-100%).

```java
rgb(90, 129, 32)
```

```java
Button.focusedBackground = rgb(227,241,250)
```

```java
PasswordField.capsLockIconColor = rgba(0,0,0,120)
```

--------------------------------

### Move Lines Shortcut

Source: https://www.formdev.com/flatlaf/theme-editor

Use these shortcuts to move the current line up or down in the editor.

```text
Alt+Up / Alt+Down
```

--------------------------------

### Custom Borders in Properties Files

Source: https://www.formdev.com/flatlaf/properties-files

Defines borders using comma-separated values for top, left, bottom, right insets, optionally including line color and thickness. An empty border is created if no lineColor is specified. A line border is created if lineColor is specified.

```properties
OptionPane.border = 12,12,12,12
ToolTip.border = 4,6,4,6,#000
```

--------------------------------

### Define Font Sizes in FlatLaf.properties

Source: https://www.formdev.com/flatlaf/typography

Defines various heading and text font sizes relative to the default font. Use $semibold.font for bold variants.

```properties
# headings
h00.font = +24
h0.font = +18
h1.font = +12 $semibold.font
h2.font = +6 $semibold.font
h3.font = +3 $semibold.font
h4.font = bold

h1.regular.font = +12
h2.regular.font = +6
h3.regular.font = +3

# text
large.font = +2
medium.font = -1
small.font = -2
mini.font = -3
```
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