FileChooser: scale file icons (issue #100)

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

@@ -19,11 +19,13 @@ package com.formdev.flatlaf.ui;
 import java.awt.Dimension;
 import java.io.File;
 import javax.swing.Icon;
+import javax.swing.ImageIcon;
 import javax.swing.JComponent;
 import javax.swing.JFileChooser;
 import javax.swing.filechooser.FileView;
 import javax.swing.plaf.ComponentUI;
 import javax.swing.plaf.metal.MetalFileChooserUI;
+import com.formdev.flatlaf.util.ScaledImageIcon;
 import com.formdev.flatlaf.util.UIScale;
 
 /**
@@ -157,19 +159,32 @@ public class FlatFileChooserUI
 	{
 		@Override
 		public Icon getIcon( File f ) {
+			// get cached icon
 			Icon icon = getCachedIcon( f );
 			if( icon != null )
 				return icon;
 
+			// get system icon
 			if( f != null ) {
 				icon = getFileChooser().getFileSystemView().getSystemIcon( f );
+
 				if( icon != null ) {
+					if( icon instanceof ImageIcon )
+						icon = new ScaledImageIcon( (ImageIcon) icon );
 					cacheIcon( f, icon );
 					return icon;
 				}
 			}
 
-			return super.getIcon( f );
+			// get default icon
+			icon = super.getIcon( f );
+
+			if( icon instanceof ImageIcon ) {
+				icon = new ScaledImageIcon( (ImageIcon) icon );
+				cacheIcon( f, icon );
+			}
+
+			return icon;
 		}
 	}
 }

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

@@ -17,6 +17,8 @@
 package com.formdev.flatlaf.util;
 
 import java.awt.Image;
+import java.util.Collections;
+import java.util.List;
 import java.util.function.Function;
 
 /**
@@ -41,4 +43,12 @@ public class MultiResolutionImageSupport
 	public static Image map( Image image, Function<Image, Image> mapper ) {
 		return mapper.apply( image );
 	}
+
+	public static Image getResolutionVariant( Image image, int destImageWidth, int destImageHeight ) {
+		return image;
+	}
+
+	public static List<Image> getResolutionVariants( Image image ) {
+		return Collections.singletonList( image );
+	}
 }

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

@@ -0,0 +1,172 @@
+/*
+ * Copyright 2020 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf.util;
+
+import java.awt.Component;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Image;
+import java.awt.RenderingHints;
+import java.awt.image.BufferedImage;
+import javax.swing.Icon;
+import javax.swing.ImageIcon;
+
+/**
+ * Scales the given image icon using the system and user scale factors and
+ * paints the icon at system scale factor 1x. This gives best scaling quality.
+ * If the given image icon supports multiple resolutions, the best resolution
+ * variant is used. The last scaled image is cached for faster repainting.
+ *
+ * @author Karl Tauber
+ */
+public class ScaledImageIcon
+	implements Icon
+{
+	private final ImageIcon imageIcon;
+
+	private double lastSystemScaleFactor;
+	private float lastUserScaleFactor;
+	private Image lastImage;
+
+	public ScaledImageIcon( ImageIcon imageIcon ) {
+		this.imageIcon = imageIcon;
+	}
+
+	@Override
+	public int getIconWidth() {
+		return UIScale.scale( imageIcon.getIconWidth() );
+	}
+
+	@Override
+	public int getIconHeight() {
+		return UIScale.scale( imageIcon.getIconHeight() );
+	}
+
+	@Override
+	public void paintIcon( Component c, Graphics g, int x, int y ) {
+/*debug
+		g.setColor( Color.red );
+		g.drawRect( x, y, getIconWidth(), getIconHeight() );
+debug*/
+
+		// scale factor
+		double systemScaleFactor = UIScale.getSystemScaleFactor( (Graphics2D) g );
+		float userScaleFactor = UIScale.getUserScaleFactor();
+		double scaleFactor = systemScaleFactor * userScaleFactor;
+
+		// paint input image icon if not necessary to scale
+		if( scaleFactor == 1 ) {
+			imageIcon.paintIcon( c, g, x, y );
+			return;
+		}
+
+		// paint cached scaled icon
+		if( systemScaleFactor == lastSystemScaleFactor &&
+			userScaleFactor == lastUserScaleFactor &&
+			lastImage != null )
+		{
+			paintLastImage( g, x, y );
+			return;
+		}
+
+		// destination image size
+		int destImageWidth = (int) Math.round( imageIcon.getIconWidth() * scaleFactor );
+		int destImageHeight = (int) Math.round( imageIcon.getIconHeight() * scaleFactor );
+
+		// get resolution variant of image if it is a multi-resolution image
+		Image image = MultiResolutionImageSupport.getResolutionVariant(
+			imageIcon.getImage(), destImageWidth, destImageHeight );
+
+		// size of image
+		int imageWidth = image.getWidth( null );
+		int imageHeight = image.getHeight( null );
+
+		// scale image if necessary to destination size
+		if( imageWidth != destImageWidth || imageHeight != destImageHeight ) {
+			// determine scaling method; default is "quality"
+			Object scalingInterpolation = RenderingHints.VALUE_INTERPOLATION_BICUBIC;
+			float imageScaleFactor = (float) destImageWidth / (float) imageWidth;
+			if( ((int) imageScaleFactor) == imageScaleFactor &&
+				imageScaleFactor > 1f &&
+				imageWidth <= 16 &&
+				imageHeight <= 16 )
+			{
+				// use "speed" scaling for small icons if the scale factor is an integer
+				// to avoid blurred icons
+				scalingInterpolation = RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR;
+			}
+
+			// scale image
+			BufferedImage bufferedImage = image2bufferedImage( image );
+			image = scaleImage( bufferedImage, destImageWidth, destImageHeight, scalingInterpolation );
+		}
+
+		// cache image
+		lastSystemScaleFactor = systemScaleFactor;
+		lastUserScaleFactor = userScaleFactor;
+		lastImage = image;
+
+		// paint image
+		paintLastImage( g, x, y );
+	}
+
+	private void paintLastImage( Graphics g, int x, int y ) {
+		if( lastSystemScaleFactor > 1 ) {
+			HiDPIUtils.paintAtScale1x( (Graphics2D) g, x, y, 100, 100, // width and height are not used
+				(g2, x2, y2, width2, height2, scaleFactor2) -> {
+					g2.drawImage( lastImage, x2, y2, null );
+				} );
+		} else
+			g.drawImage( lastImage, x, y, null );
+	}
+
+	/**
+	 * Scales the given image to the target dimensions.
+	 *
+	 * This is the same what imgscalr library (https://github.com/rkalla/imgscalr)
+	 * would do when invoking Scalr.resize().
+	 */
+	private BufferedImage scaleImage( BufferedImage image, int targetWidth, int targetHeight,
+		Object scalingInterpolation )
+	{
+		BufferedImage bufferedImage = new BufferedImage( targetWidth, targetHeight, BufferedImage.TYPE_INT_ARGB );
+		Graphics2D g = bufferedImage.createGraphics();
+		try {
+			g.setRenderingHint( RenderingHints.KEY_INTERPOLATION, scalingInterpolation );
+			g.drawImage( image, 0, 0, targetWidth, targetHeight, null );
+		} finally {
+			g.dispose();
+		}
+		return bufferedImage;
+
+	}
+
+	private BufferedImage image2bufferedImage( Image image ) {
+		if( image instanceof BufferedImage )
+			return (BufferedImage) image;
+
+		BufferedImage bufferedImage = new BufferedImage( image.getWidth( null ),
+			image.getHeight( null ), BufferedImage.TYPE_INT_ARGB );
+		Graphics2D g = bufferedImage.createGraphics();
+		try {
+			g.drawImage( image, 0, 0, null );
+		} finally {
+			g.dispose();
+		}
+		return bufferedImage;
+	}
+}

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

@@ -21,6 +21,7 @@ import java.awt.image.AbstractMultiResolutionImage;
 import java.awt.image.BaseMultiResolutionImage;
 import java.awt.image.MultiResolutionImage;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.IdentityHashMap;
 import java.util.List;
 import java.util.function.Function;
@@ -51,6 +52,18 @@ public class MultiResolutionImageSupport
 			: mapper.apply( image );
 	}
 
+	public static Image getResolutionVariant( Image image, int destImageWidth, int destImageHeight ) {
+		return (image instanceof MultiResolutionImage)
+			? ((MultiResolutionImage)image).getResolutionVariant( destImageWidth, destImageHeight )
+			: image;
+	}
+
+	public static List<Image> getResolutionVariants( Image image ) {
+		return (image instanceof MultiResolutionImage)
+			? ((MultiResolutionImage)image).getResolutionVariants()
+			: Collections.singletonList( image );
+	}
+
 	//---- class MappedMultiResolutionImage -----------------------------------
 
 	private static class MappedMultiResolutionImage

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

@@ -62,7 +62,7 @@ public class FlatChooserTest
 			"[]",
 			// rows
 			"[top]" +
-			"[top]" +
+			"[grow,top]" +
 			"[]"));
 
 		//---- colorChooserLabel ----
@@ -73,7 +73,7 @@ public class FlatChooserTest
 		//---- fileChooserLabel ----
 		fileChooserLabel.setText("JFileChooser:");
 		add(fileChooserLabel, "cell 0 1");
-		add(fileChooser1, "cell 1 1");
+		add(fileChooser1, "cell 1 1,growy");
 
 		//---- label1 ----
 		label1.setText("icons:");

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatChooserTest.jfd

@@ -1,4 +1,4 @@
-JFDML JFormDesigner: "7.0.0.0.194" Java: "11.0.2" encoding: "UTF-8"
+JFDML JFormDesigner: "7.0.1.0.272" Java: "13.0.2" encoding: "UTF-8"
 
 new FormModel {
 	contentType: "form/swing"
@@ -9,7 +9,7 @@ new FormModel {
 		add( new FormContainer( "com.formdev.flatlaf.testing.FlatTestPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
 			"$layoutConstraints": "ltr,insets dialog,hidemode 3"
 			"$columnConstraints": "[][]"
-			"$rowConstraints": "[top][top][]"
+			"$rowConstraints": "[top][grow,top][]"
 		} ) {
 			name: "this"
 			add( new FormComponent( "javax.swing.JLabel" ) {
@@ -32,7 +32,7 @@ new FormModel {
 			add( new FormComponent( "javax.swing.JFileChooser" ) {
 				name: "fileChooser1"
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
-				"value": "cell 1 1"
+				"value": "cell 1 1,growy"
 			} )
 			add( new FormComponent( "javax.swing.JLabel" ) {
 				name: "label1"