FlatSVGIcon: getImage() now returns a multi-resolution image (on Java 9+) for HiDPI disabled icons in other LaFs that support multi-resolution images when producing disabled icons in LookAndFeel.getDisabledIcon() (e.g. Windows or Nimbus Laf) (issue #205)

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

@@ -16,11 +16,20 @@
 
 package com.formdev.flatlaf.util;
 
+import java.awt.Dimension;
 import java.awt.Image;
 import java.util.Collections;
 import java.util.List;
 import java.util.function.Function;
 
+//
+// NOTE:
+//     This implementation is for Java 8 only.
+//     There is also a variant for Java 9 and later.
+// 
+//     Make sure that the API is in sync.
+//
+
 /**
  * Support for multi-resolution images available since Java 9.
  *
@@ -28,26 +37,86 @@ import java.util.function.Function;
  */
 public class MultiResolutionImageSupport
 {
+	/**
+	 * Checks whether multi-resolution image support is available.
+	 * 
+	 * @return {@code true} when running on Java 9 or later; {@code false} on Java 8
+	 */
 	public static boolean isAvailable() {
 		return false;
 	}
 
+	/**
+	 * Checks whether the given image is a multi-resolution image that implements
+	 * the interface {@code java.awt.image.MultiResolutionImage}.
+	 */
 	public static boolean isMultiResolutionImage( Image image ) {
 		return false;
 	}
 
+	/**
+	 * Creates a multi-resolution image from the given resolution variants.
+	 * 
+	 * @param baseImageIndex index of the base image in the resolution variants array
+	 * @param resolutionVariants image resolution variants (sorted by size; smallest first)
+	 * @return a multi-resolution image on Java 9 or later; the base image on Java 8
+	 */
 	public static Image create( int baseImageIndex, Image... resolutionVariants ) {
 		return resolutionVariants[baseImageIndex];
 	}
 
+	/**
+	 * Creates a multi-resolution image for the given dimensions.
+	 * Initially the image does not contain any image data.
+	 * The real images are created (and cached) on demand by invoking the given producer function.
+	 * <p>
+	 * The given dimensions array is only used for {@link #getResolutionVariants(Image)}.
+	 * The producer function may be invoked with any dimension (that is not contained in 
+	 * dimensions array) and is expected to produce a image for the passed in dimension.
+	 * 
+	 * @param baseImageIndex index of the base image in the dimensions array
+	 * @param dimensions dimensions of resolution variants (sorted by size; smallest first)
+	 * @param producer producer function that creates a real image for the requested size
+	 * @return a multi-resolution image on Java 9 or later; the base image on Java 8
+	 */
+	public static Image create( int baseImageIndex, Dimension[] dimensions, Function<Dimension, Image> producer ) {
+		return producer.apply( dimensions[baseImageIndex] );
+	}
+
+	/**
+	 * Creates a multi-resolution image that maps images from another multi-resolution image
+	 * using the given mapper function.
+	 * <p>
+	 * Can be used to apply filter to multi-resolution images on demand.
+	 * E.g. passed in image is for "enabled" state and mapper function creates images
+	 * for "disabled" state.  
+	 * 
+	 * @param image a multi-resolution image that is mapped using the given mapper function
+	 * @param mapper mapper function that maps a single resolution variant to a new image (e.g. applying an filter)
+	 * @return a multi-resolution image on Java 9 or later; a mapped image on Java 8
+	 */
 	public static Image map( Image image, Function<Image, Image> mapper ) {
 		return mapper.apply( image );
 	}
 
+	/**
+	 * Get the image variant that best matches the given width and height.
+	 * <p>
+	 * If the given image is a multi-resolution image then invokes
+	 * {@code java.awt.image.MultiResolutionImage.getResolutionVariant(destImageWidth, destImageHeight)}.
+	 * Otherwise returns the given image.
+	 */
 	public static Image getResolutionVariant( Image image, int destImageWidth, int destImageHeight ) {
 		return image;
 	}
 
+	/**
+	 * Get a list of all resolution variants.
+	 * <p>
+	 * If the given image is a multi-resolution image then invokes
+	 * {@code java.awt.image.MultiResolutionImage.getResolutionVariants()}.
+	 * Otherwise returns a list containing only the given image.
+	 */
 	public static List<Image> getResolutionVariants( Image image ) {
 		return Collections.singletonList( image );
 	}

flatlaf-core/src/main/java9/com/formdev/flatlaf/util/MultiResolutionImageSupport.java

@@ -16,6 +16,7 @@
 
 package com.formdev.flatlaf.util;
 
+import java.awt.Dimension;
 import java.awt.Image;
 import java.awt.image.AbstractMultiResolutionImage;
 import java.awt.image.BaseMultiResolutionImage;
@@ -27,6 +28,14 @@ import java.util.List;
 import java.util.function.Function;
 import javax.swing.ImageIcon;
 
+//
+// NOTE:
+//     This implementation is for Java 9 and later.
+//     There is also a variant for Java 8.
+//
+//     Make sure that the API is in sync.
+//
+
 /**
  * Support for multi-resolution images available since Java 9.
  *
@@ -46,6 +55,10 @@ public class MultiResolutionImageSupport
 		return new BaseMultiResolutionImage( baseImageIndex, resolutionVariants );
 	}
 
+	public static Image create( int baseImageIndex, Dimension[] dimensions, Function<Dimension, Image> producer ) {
+		return new ProducerMultiResolutionImage( dimensions, producer );
+	}
+
 	public static Image map( Image image, Function<Image, Image> mapper ) {
 		return image instanceof MultiResolutionImage
 			? new MappedMultiResolutionImage( image, mapper )
@@ -66,6 +79,9 @@ public class MultiResolutionImageSupport
 
 	//---- class MappedMultiResolutionImage -----------------------------------
 
+	/**
+	 * A multi-resolution image implementation that maps images on demand for requested sizes.
+	 */
 	private static class MappedMultiResolutionImage
 		extends AbstractMultiResolutionImage
 	{
@@ -102,8 +118,52 @@ public class MultiResolutionImageSupport
 
 		private Image mapAndCacheImage( Image image ) {
 			return cache.computeIfAbsent( image, img -> {
+				// using ImageIcon here makes sure that the image is loaded
 				return new ImageIcon( mapper.apply( img ) ).getImage();
 			} );
 		}
 	}
+
+	//---- class ProducerMultiResolutionImage ---------------------------------
+
+	/**
+	 * A multi-resolution image implementation that produces images on demand for requested sizes.
+	 */
+	private static class ProducerMultiResolutionImage
+		extends AbstractMultiResolutionImage
+	{
+		private final Dimension[] dimensions;
+		private final Function<Dimension, Image> producer;
+		private final IdentityHashMap<Dimension, Image> cache = new IdentityHashMap<>();
+
+		ProducerMultiResolutionImage( Dimension[] dimensions, Function<Dimension, Image> producer ) {
+			this.dimensions = dimensions;
+			this.producer = producer;
+		}
+
+		@Override
+		public Image getResolutionVariant( double destImageWidth, double destImageHeight ) {
+			return produceAndCacheImage( new Dimension( (int) destImageWidth, (int) destImageHeight ) );
+		}
+
+		@Override
+		public List<Image> getResolutionVariants() {
+			List<Image> mappedVariants = new ArrayList<>();
+			for( Dimension size : dimensions )
+				mappedVariants.add( produceAndCacheImage( size ) );
+			return mappedVariants;
+		}
+
+		@Override
+		protected Image getBaseImage() {
+			return produceAndCacheImage( dimensions[0] );
+		}
+
+		private Image produceAndCacheImage( Dimension size ) {
+			return cache.computeIfAbsent( size, size2 -> {
+				// using ImageIcon here makes sure that the image is loaded
+				return new ImageIcon( producer.apply( size2 ) ).getImage();
+			} );
+		}
+	}
 }