added API to register packages or folders where FlatLaf searches for application specific properties files with custom UI defaults

CHANGELOG.md

@@ -5,6 +5,9 @@ FlatLaf Change Log
 
 #### New features
 
+- Added API to register packages or folders where FlatLaf searches for
+  application specific properties files with custom UI defaults (see
+  `FlatLaf.registerCustomDefaultsSource(...)` methods).
 - Extras: `FlatSVGIcon` now allows specifying `ClassLoader` that is used to load
   SVG file. (issue #163)
 

flatlaf-core/src/main/java/com/formdev/flatlaf/FlatLaf.java

@@ -29,6 +29,7 @@ import java.awt.image.ImageFilter;
 import java.awt.image.ImageProducer;
 import java.beans.PropertyChangeEvent;
 import java.beans.PropertyChangeListener;
+import java.io.File;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
@@ -76,6 +77,8 @@ public abstract class FlatLaf
 	static final Logger LOG = Logger.getLogger( FlatLaf.class.getName() );
 	private static final String DESKTOPFONTHINTS = "awt.font.desktophints";
 
+	private static List<Object> customDefaultsSources;
+
 	private String desktopPropertyName;
 	private String desktopPropertyName2;
 	private PropertyChangeListener desktopPropertyListener;
@@ -552,6 +555,87 @@ public abstract class FlatLaf
 			defaults.put( key, value );
 	}
 
+	static List<Object> getCustomDefaultsSources() {
+		return customDefaultsSources;
+	}
+
+	/**
+	 * Registers a package where FlatLaf searches for properties files with custom UI defaults.
+	 * <p>
+	 * This can be used to specify application specific UI defaults that override UI values
+	 * of existing themes or to define own UI values used in custom controls.
+	 * <p>
+	 * There may be multiple properties files in that package for multiple themes.
+	 * The properties file name must match the used theme class names.
+	 * E.g. {@code FlatLightLaf.properties} for class {@link FlatLightLaf}
+	 * or {@code FlatDarkLaf.properties} for class {@link FlatDarkLaf}.
+	 * {@code FlatLaf.properties} is loaded first for all themes.
+	 * <p>
+	 * These properties files are loaded after theme and addon properties files
+	 * and can therefore override all UI defaults.
+	 * <p>
+	 * Invoke this method before setting the look and feel.
+	 *
+	 * @param packageName a package name (e.g. "com.myapp.resources")
+	 */
+	public static void registerCustomDefaultsSource( String packageName ) {
+		registerCustomDefaultsSource( packageName, null );
+	}
+
+	public static void unregisterCustomDefaultsSource( String packageName ) {
+		unregisterCustomDefaultsSource( packageName, null );
+	}
+
+	/**
+	 * Registers a package where FlatLaf searches for properties files with custom UI defaults.
+	 * <p>
+	 * See {@link #registerCustomDefaultsSource(String)} for details.
+	 *
+	 * @param packageName a package name (e.g. "com.myapp.resources")
+	 * @param classLoader a class loader used to find resources, or {@code null}
+	 */
+	public static void registerCustomDefaultsSource( String packageName, ClassLoader classLoader ) {
+		if( customDefaultsSources == null )
+			customDefaultsSources = new ArrayList<>();
+		customDefaultsSources.add( packageName );
+		customDefaultsSources.add( classLoader );
+	}
+
+	public static void unregisterCustomDefaultsSource( String packageName, ClassLoader classLoader ) {
+		if( customDefaultsSources == null )
+			return;
+
+		int size = customDefaultsSources.size();
+		for( int i = 0; i < size - 1; i++ ) {
+			Object source = customDefaultsSources.get( i );
+			if( packageName.equals( source ) && customDefaultsSources.get( i + 1 ) == classLoader ) {
+				customDefaultsSources.remove( i + 1 );
+				customDefaultsSources.remove( i );
+				break;
+			}
+		}
+	}
+
+	/**
+	 * Registers a folder where FlatLaf searches for properties files with custom UI defaults.
+	 * <p>
+	 * See {@link #registerCustomDefaultsSource(String)} for details.
+	 *
+	 * @param folder a folder
+	 */
+	public static void registerCustomDefaultsSource( File folder ) {
+		if( customDefaultsSources == null )
+			customDefaultsSources = new ArrayList<>();
+		customDefaultsSources.add( folder );
+	}
+
+	public static void unregisterCustomDefaultsSource( File folder ) {
+		if( customDefaultsSources == null )
+			return;
+
+		customDefaultsSources.remove( folder );
+	}
+
 	private static void reSetLookAndFeel() {
 		EventQueue.invokeLater( () -> {
 			LookAndFeel lookAndFeel = UIManager.getLookAndFeel();

flatlaf-core/src/main/java/com/formdev/flatlaf/UIDefaultsLoader.java

@@ -19,6 +19,8 @@ package com.formdev.flatlaf;
 import java.awt.Color;
 import java.awt.Dimension;
 import java.awt.Insets;
+import java.io.File;
+import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
@@ -107,6 +109,42 @@ class UIDefaultsLoader
 				}
 			}
 
+			// load custom properties files (usually provides by applications)
+			List<Object> customDefaultsSources = FlatLaf.getCustomDefaultsSources();
+			int size = (customDefaultsSources != null) ? customDefaultsSources.size() : 0;
+			for( int i = 0; i < size; i++ ) {
+				Object source = customDefaultsSources.get( i );
+				if( source instanceof String && i + 1 < size ) {
+					// load from package in classloader
+					String packageName = (String) source;
+					ClassLoader classLoader = (ClassLoader) customDefaultsSources.get( ++i );
+
+					packageName = packageName.replace( '.', '/' );
+					if( classLoader == null )
+						classLoader = FlatLaf.class.getClassLoader();
+
+					for( Class<?> lafClass : lafClasses ) {
+						String propertiesName = packageName + '/' + lafClass.getSimpleName() + ".properties";
+						try( InputStream in = classLoader.getResourceAsStream( propertiesName ) ) {
+							if( in != null )
+								properties.load( in );
+						}
+					}
+				} else if( source instanceof File ) {
+					// load from folder
+					File folder = (File) source;
+					for( Class<?> lafClass : lafClasses ) {
+						File propertiesFile = new File( folder, lafClass.getSimpleName() + ".properties" );
+						if( !propertiesFile.isFile() )
+							continue;
+
+						try( InputStream in = new FileInputStream( propertiesFile ) ) {
+							properties.load( in );
+						}
+					}
+				}
+			}
+
 			// collect addon class loaders
 			List<ClassLoader> addonClassLoaders = new ArrayList<>();
 			for( FlatDefaultsAddon addon : addons ) {

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatTestFrame.java

@@ -77,6 +77,9 @@ public class FlatTestFrame
 		// disable animated Laf change
 		System.setProperty( "flatlaf.animatedLafChange", "false" );
 
+		// test loading custom defaults from package
+		FlatLaf.registerCustomDefaultsSource( "com.formdev.flatlaf.testing.customdefaults" );
+
 		// set look and feel
 		DemoPrefs.initLaf( args );
 

flatlaf-testing/src/main/resources/com/formdev/flatlaf/testing/customdefaults/FlatDarkLaf.properties

@@ -0,0 +1 @@
+# @background=#000

flatlaf-testing/src/main/resources/com/formdev/flatlaf/testing/customdefaults/FlatLaf.properties

@@ -0,0 +1,2 @@
+# Component.arc=9999
+# TextComponent.arc=9999

flatlaf-testing/src/main/resources/com/formdev/flatlaf/testing/customdefaults/FlatLightLaf.properties

@@ -0,0 +1 @@
+# @background=#fff