Merge pull request #72 from basix86:disabledIcon into branch disabled-icons

Improve disabled button rendering #70

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

@@ -40,6 +40,8 @@ import java.util.function.Consumer;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import javax.swing.AbstractButton;
+import javax.swing.Icon;
+import javax.swing.JComponent;
 import javax.swing.JLabel;
 import javax.swing.JRootPane;
 import javax.swing.JTabbedPane;
@@ -52,10 +54,12 @@ import javax.swing.UnsupportedLookAndFeelException;
 import javax.swing.UIDefaults.ActiveValue;
 import javax.swing.plaf.ColorUIResource;
 import javax.swing.plaf.FontUIResource;
+import javax.swing.plaf.IconUIResource;
 import javax.swing.plaf.UIResource;
 import javax.swing.plaf.basic.BasicLookAndFeel;
 import javax.swing.text.StyleContext;
 import javax.swing.text.html.HTMLEditorKit;
+import com.formdev.flatlaf.ui.FlatUIUtils;
 import com.formdev.flatlaf.util.SystemInfo;
 import com.formdev.flatlaf.util.UIScale;
 
@@ -117,6 +121,11 @@ public abstract class FlatLaf
 		return true;
 	}
 
+	@Override
+	public Icon getDisabledIcon( JComponent component, Icon icon ) {
+		return (icon == null) ? null : new IconUIResource( FlatUIUtils.getDisabledIcon( icon ) );
+	}
+
 	@Override
 	public void initialize() {
 		if( SystemInfo.IS_MAC )

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatUIUtils.java

@@ -23,10 +23,15 @@ import java.awt.Dimension;
 import java.awt.Font;
 import java.awt.Graphics;
 import java.awt.Graphics2D;
+import java.awt.GraphicsConfiguration;
+import java.awt.GraphicsDevice;
+import java.awt.GraphicsEnvironment;
+import java.awt.Image;
 import java.awt.Insets;
 import java.awt.Rectangle;
 import java.awt.RenderingHints;
 import java.awt.Shape;
+import java.awt.Toolkit;
 import java.awt.event.FocusEvent;
 import java.awt.event.FocusListener;
 import java.awt.event.MouseAdapter;
@@ -34,7 +39,13 @@ import java.awt.event.MouseEvent;
 import java.awt.geom.Path2D;
 import java.awt.geom.Rectangle2D;
 import java.awt.geom.RoundRectangle2D;
+import java.awt.image.BufferedImage;
+import java.awt.image.FilteredImageSource;
+import java.awt.image.ImageProducer;
+import java.awt.image.RGBImageFilter;
 import java.util.function.Consumer;
+import javax.swing.Icon;
+import javax.swing.ImageIcon;
 import javax.swing.JComponent;
 import javax.swing.LookAndFeel;
 import javax.swing.UIManager;
@@ -433,6 +444,59 @@ public class FlatUIUtils
 		return explicitlySet;
 	}
 
+	public static Icon getDisabledIcon( Icon icon ) {
+		Image image = safeGetImage( icon );
+		int grayMinValue = FlatUIUtils.getUIInt( "Button.disabledGrayMinValue", 180 );
+		int grayMaxValue = FlatUIUtils.getUIInt( "Button.disabledGrayMaxValue", 215 );
+		DisabledImageFilter imageFilter = new DisabledImageFilter( grayMinValue, grayMaxValue );
+		ImageProducer producer = new FilteredImageSource( image.getSource(), imageFilter );
+		return new ImageIcon( Toolkit.getDefaultToolkit().createImage( producer ) );
+	}
+
+	private static Image safeGetImage( Icon icon ) {
+		if( icon instanceof ImageIcon ) {
+			return ((ImageIcon)icon).getImage();
+		} else {
+			int width = icon.getIconWidth();
+			int height = icon.getIconHeight();
+			GraphicsEnvironment environment = GraphicsEnvironment.getLocalGraphicsEnvironment();
+			GraphicsDevice device = environment.getDefaultScreenDevice();
+			GraphicsConfiguration configuration = device.getDefaultConfiguration();
+			BufferedImage image = configuration.createCompatibleImage( width, height );
+			Graphics2D g = image.createGraphics();
+			icon.paintIcon( null, g, 0, 0 );
+			g.dispose();
+			return image;
+		}
+	}
+
+	//---- class DisabledImageFilter ------------------------------------------
+
+	private static class DisabledImageFilter
+		extends RGBImageFilter
+	{
+		private final float min;
+		private final float factor;
+
+		DisabledImageFilter( int min, int max ) {
+			this.min = min;
+			this.factor = (max - min) / 255f;
+
+			canFilterIndexColorModel = true;
+		}
+
+		@Override
+		public int filterRGB( int x, int y, int rgb ) {
+			// https://en.wikipedia.org/wiki/Grayscale
+			float linearLuminance =
+				(0.2126f * ((rgb >> 16) & 0xff)) +
+				(0.7152f * ((rgb >> 8) & 0xff)) +
+				(0.0722f * (rgb & 0xff));
+			int gray = Math.min( (int) ((linearLuminance + .5f) * factor + min), 255 );
+			return (rgb & 0xff000000) | (gray << 16) | (gray << 8) | gray;
+		}
+	}
+
 	//---- class HoverListener ------------------------------------------------
 
 	public static class HoverListener