improved creation of disabled grayscale icons (issue #70)

CHANGELOG.md

@@ -1,6 +1,13 @@
 FlatLaf Change Log
 ==================
 
+## Unreleased
+
+- Improved creation of disabled grayscale icons used in disabled buttons, labels
+  and tabs. They now have more contrast and are lighter in light themes and
+  darker in dark themes. (issue #70)
+
+
 ## 0.30
 
 - Windows: Fixed rendering of Unicode characters. Previously not all Unicode

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

@@ -21,12 +21,16 @@ import java.awt.Component;
 import java.awt.Container;
 import java.awt.EventQueue;
 import java.awt.Font;
+import java.awt.Image;
 import java.awt.KeyEventPostProcessor;
 import java.awt.KeyboardFocusManager;
 import java.awt.RenderingHints;
 import java.awt.Toolkit;
 import java.awt.Window;
 import java.awt.event.KeyEvent;
+import java.awt.image.FilteredImageSource;
+import java.awt.image.ImageFilter;
+import java.awt.image.ImageProducer;
 import java.beans.PropertyChangeEvent;
 import java.beans.PropertyChangeListener;
 import java.lang.ref.WeakReference;
@@ -41,6 +45,7 @@ import java.util.logging.Level;
 import java.util.logging.Logger;
 import javax.swing.AbstractButton;
 import javax.swing.Icon;
+import javax.swing.ImageIcon;
 import javax.swing.JComponent;
 import javax.swing.JLabel;
 import javax.swing.JRootPane;
@@ -54,12 +59,11 @@ 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.GrayFilter;
 import com.formdev.flatlaf.util.SystemInfo;
 import com.formdev.flatlaf.util.UIScale;
 
@@ -123,7 +127,21 @@ public abstract class FlatLaf
 
 	@Override
 	public Icon getDisabledIcon( JComponent component, Icon icon ) {
-		return (icon == null) ? null : new IconUIResource( FlatUIUtils.getDisabledIcon( icon ) );
+		if( icon instanceof ImageIcon ) {
+			Object grayFilter = UIManager.get( "Component.grayFilter" );
+			if( !(grayFilter instanceof ImageFilter) ) {
+				// fallback
+				grayFilter = isDark()
+					? new GrayFilter( -20, -70, 100 )
+					: new GrayFilter(  25, -25, 100 );
+			}
+
+			Image image = ((ImageIcon)icon).getImage();
+			ImageProducer producer = new FilteredImageSource( image.getSource(), (ImageFilter) grayFilter );
+			return new ImageIconUIResource( Toolkit.getDefaultToolkit().createImage( producer ) );
+		}
+
+		return null;
 	}
 
 	@Override
@@ -629,4 +647,15 @@ public abstract class FlatLaf
 			return font;
 		}
 	}
+
+	//---- class ImageIconUIResource ------------------------------------------
+
+	private static class ImageIconUIResource
+		extends ImageIcon
+		implements UIResource
+	{
+		ImageIconUIResource( Image image ) {
+			super( image );
+		}
+	}
 }

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

@@ -41,6 +41,7 @@ import com.formdev.flatlaf.ui.FlatEmptyBorder;
 import com.formdev.flatlaf.ui.FlatLineBorder;
 import com.formdev.flatlaf.util.ColorFunctions;
 import com.formdev.flatlaf.util.DerivedColor;
+import com.formdev.flatlaf.util.GrayFilter;
 import com.formdev.flatlaf.util.HSLColor;
 import com.formdev.flatlaf.util.StringUtils;
 import com.formdev.flatlaf.util.SystemInfo;
@@ -222,7 +223,7 @@ class UIDefaultsLoader
 	}
 
 	private enum ValueType { UNKNOWN, STRING, CHARACTER, INTEGER, FLOAT, BORDER, ICON, INSETS, DIMENSION, COLOR,
-		SCALEDINTEGER, SCALEDFLOAT, SCALEDINSETS, SCALEDDIMENSION, INSTANCE, CLASS }
+		SCALEDINTEGER, SCALEDFLOAT, SCALEDINSETS, SCALEDDIMENSION, INSTANCE, CLASS, GRAYFILTER }
 
 	static Object parseValue( String key, String value ) {
 		return parseValue( key, value, v -> v, Collections.emptyList() );
@@ -289,6 +290,8 @@ class UIDefaultsLoader
 				valueType = ValueType.CHARACTER;
 			else if( key.endsWith( "UI" ) )
 				valueType = ValueType.STRING;
+			else if( key.endsWith( "grayFilter" ) )
+				valueType = ValueType.GRAYFILTER;
 		}
 
 		// parse value
@@ -308,6 +311,7 @@ class UIDefaultsLoader
 			case SCALEDDIMENSION:return parseScaledDimension( value );
 			case INSTANCE:		return parseInstance( value, addonClassLoaders );
 			case CLASS:			return parseClass( value, addonClassLoaders );
+			case GRAYFILTER:	return parseGrayFilter( value );
 			case UNKNOWN:
 			default:
 				// colors
@@ -664,6 +668,21 @@ class UIDefaultsLoader
 		};
 	}
 
+	private static Object parseGrayFilter( String value ) {
+		List<String> numbers = split( value, ',' );
+		try {
+			int brightness = Integer.parseInt( numbers.get( 0 ) );
+			int contrast = Integer.parseInt( numbers.get( 1 ) );
+			int alpha = Integer.parseInt( numbers.get( 2 ) );
+
+			return (LazyValue) t -> {
+				return new GrayFilter( brightness, contrast, alpha );
+			};
+		} catch( NumberFormatException ex ) {
+			throw new IllegalArgumentException( "invalid gray filter '" + value + "'" );
+		}
+	}
+
 	/**
 	 * Split string and trim parts.
 	 */

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

@@ -23,15 +23,10 @@ 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;
@@ -39,13 +34,7 @@ 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;
@@ -444,59 +433,6 @@ 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

flatlaf-core/src/main/java/com/formdev/flatlaf/util/GrayFilter.java

@@ -0,0 +1,81 @@
+// Copyright 2000-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.formdev.flatlaf.util;
+
+import java.awt.image.RGBImageFilter;
+
+// based on https://github.com/JetBrains/intellij-community/blob/3840eab54746f5c4f301bb3ac78f00a980b5fd6e/platform/util/ui/src/com/intellij/util/ui/UIUtil.java#L253-L347
+
+/**
+ * An image filter that turns an image into a grayscale image.
+ * Used for icons in disabled buttons and labels.
+ */
+public class GrayFilter
+	extends RGBImageFilter
+{
+	private final float brightness;
+	private final float contrast;
+	private final int alpha;
+
+	private final int origContrast;
+	private final int origBrightness;
+
+	/**
+	 * @param brightness in range [-100..100] where 0 has no effect
+	 * @param contrast in range [-100..100] where 0 has no effect
+	 * @param alpha in range [0..100] where 0 is transparent, 100 has no effect
+	 */
+	public GrayFilter( int brightness, int contrast, int alpha ) {
+		this.origBrightness = Math.max( -100, Math.min( 100, brightness ) );
+		this.origContrast = Math.max( -100, Math.min( 100, contrast ) );
+		this.alpha = Math.max( 0, Math.min( 100, alpha ) );
+
+		this.brightness = (float) (Math.pow( origBrightness, 3 ) / (100f * 100f)); // cubic in [0..100]
+		this.contrast = origContrast / 100f;
+
+		canFilterIndexColorModel = true;
+	}
+
+	public GrayFilter() {
+		this( 0, 0, 100 );
+	}
+
+	public int getBrightness() {
+		return origBrightness;
+	}
+
+	public int getContrast() {
+		return origContrast;
+	}
+
+	public int getAlpha() {
+		return alpha;
+	}
+
+	@Override
+	public int filterRGB( int x, int y, int rgb ) {
+		// use NTSC conversion formula
+		int gray = (int)(
+			0.30 * (rgb >> 16 & 0xff) +
+			0.59 * (rgb >> 8 & 0xff) +
+			0.11 * (rgb & 0xff));
+
+		if( brightness >= 0 )
+			gray = (int) ((gray + brightness * 255) / (1 + brightness));
+		else
+			gray = (int) (gray / (1 - brightness));
+
+		if( contrast >= 0 ) {
+			if( gray >= 127 )
+				gray = (int) (gray + (255 - gray) * contrast);
+			else
+				gray = (int) (gray - gray * contrast);
+		} else
+			gray = (int) (127 + (gray - 127) * (contrast + 1));
+
+		int a = (alpha != 100)
+			? (((rgb >> 24) & 0xff) * alpha / 100) << 24
+			: (rgb & 0xff000000);
+
+		return a | (gray << 16) | (gray << 8) | gray;
+	}
+}

flatlaf-core/src/main/resources/com/formdev/flatlaf/FlatDarkLaf.properties

@@ -129,6 +129,7 @@ Component.disabledBorderColor=#646464
 Component.focusedBorderColor=#466d94
 Component.focusColor=#3d6185
 Component.linkColor=#589df6
+Component.grayFilter=-20,-70,100
 
 
 #---- Desktop ----

flatlaf-core/src/main/resources/com/formdev/flatlaf/FlatLightLaf.properties

@@ -131,6 +131,7 @@ Component.disabledBorderColor=#cfcfcf
 Component.focusedBorderColor=#87afda
 Component.focusColor=#97c3f3
 Component.linkColor=#2470B3
+Component.grayFilter=25,-25,100
 
 
 #---- Desktop ----

flatlaf-testing/src/main/resources/com/formdev/flatlaf/testing/FlatTestLaf.properties

@@ -128,6 +128,7 @@ Component.focusedBorderColor=#466d94
 Component.focusColor=#97c3f3
 #Component.focusWidth=5
 #Component.arc=8
+Component.grayFilter=25,25,100
 
 
 #---- Desktop ----