FlatTitlePaneIcon: use getResolutionVariant(width, height) instead of getResolutionVariants() to allow creation of requested size on demand and to avoids creation of all resolution variants

Extras: `FlatSVGUtils.createWindowIconImages()` now returns a single multi-resolution image that creates requested image sizes on demand from SVG

(issue #323)

CHANGELOG.md

@@ -32,6 +32,9 @@ FlatLaf Change Log
   - Getters for icon name, classloader, etc.
 - Extras: UI Inspector: Show class hierarchies when pressing <kbd>Alt</kbd> key
   and prettified class names (dimmed package name).
+- Extras: `FlatSVGUtils.createWindowIconImages()` now returns a single
+  multi-resolution image that creates requested image sizes on demand from SVG
+  (Java 9+).
 
 #### Fixed bugs
 
@@ -58,6 +61,10 @@ FlatLaf Change Log
     dialogs. (issue #315)
   - Fixed broken maximizing window (under special conditions) when restoring
     frame state at startup.
+  - Title icon: For multi-resolution images now use `getResolutionVariant(width,
+    height)` (instead of `getResolutionVariants()`) to allow creation of
+    requested size on demand. This also avoids creation of all resolution
+    variants.
 - Linux: Fixed/improved detection of user font settings. (issue #309)
 
 

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

@@ -351,7 +351,7 @@ public class FlatTitlePane
 
 		// set icon
 		if( !images.isEmpty() )
-			iconLabel.setIcon( FlatTitlePaneIcon.create( images, iconSize ) );
+			iconLabel.setIcon( new FlatTitlePaneIcon( images, iconSize ) );
 		else {
 			// no icon set on window --> use default icon
 			Icon defaultIcon = UIManager.getIcon( "TitlePane.icon" );

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

@@ -20,8 +20,6 @@ import java.awt.Dimension;
 import java.awt.Image;
 import java.util.ArrayList;
 import java.util.List;
-import javax.swing.Icon;
-import javax.swing.ImageIcon;
 import com.formdev.flatlaf.util.MultiResolutionImageSupport;
 import com.formdev.flatlaf.util.ScaledImageIcon;
 
@@ -31,40 +29,43 @@ import com.formdev.flatlaf.util.ScaledImageIcon;
 public class FlatTitlePaneIcon
 	extends ScaledImageIcon
 {
-	public static Icon create( List<Image> images, Dimension size ) {
+	private final List<Image> images;
-		// collect all images including multi-resolution variants
+
+	/**
+	 * @since 1.2
+	 */
+	public FlatTitlePaneIcon( List<Image> images, Dimension size ) {
+		super( null, size.width, size.height );
+		this.images = images;
+	}
+
+	@Override
+	protected Image getResolutionVariant( int destImageWidth, int destImageHeight ) {
+		// collect all images including multi-resolution variants for requested size
 		List<Image> allImages = new ArrayList<>();
 		for( Image image : images ) {
 			if( MultiResolutionImageSupport.isMultiResolutionImage( image ) )
-				allImages.addAll( MultiResolutionImageSupport.getResolutionVariants( image ) );
+				allImages.add( MultiResolutionImageSupport.getResolutionVariant( image, destImageWidth, destImageHeight ) );
 			else
 				allImages.add( image );
 		}
 
+		if( allImages.size() == 1 )
+			return allImages.get( 0 );
+
 		// sort images by size
 		allImages.sort( (image1, image2) -> {
 			return image1.getWidth( null ) - image2.getWidth( null );
 		} );
 
-		// create icon
+		// search for optimal image size
-		return new FlatTitlePaneIcon( allImages, size );
+		for( Image image : allImages ) {
-	}
-
-	private final List<Image> images;
-
-	private FlatTitlePaneIcon( List<Image> images, Dimension size ) {
-		super( new ImageIcon( images.get( 0 ) ), size.width, size.height );
-		this.images = images;
-	}
-
-	@Override
-	protected Image getResolutionVariant( int destImageWidth, int destImageHeight ) {
-		for( Image image : images ) {
 			if( destImageWidth <= image.getWidth( null ) &&
 				destImageHeight <= image.getHeight( null ) )
 			  return image;
 		}
 
-		return images.get( images.size() - 1 );
+		// use largest image
+		return allImages.get( allImages.size() - 1 );
 	}
 }

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

@@ -77,7 +77,7 @@ debug*/
 		double scaleFactor = systemScaleFactor * userScaleFactor;
 
 		// paint input image icon if not necessary to scale
-		if( scaleFactor == 1 && iconWidth == imageIcon.getIconWidth() && iconHeight == imageIcon.getIconHeight() ) {
+		if( scaleFactor == 1 && imageIcon != null && iconWidth == imageIcon.getIconWidth() && iconHeight == imageIcon.getIconHeight() ) {
 			imageIcon.paintIcon( c, g, x, y );
 			return;
 		}

flatlaf-extras/src/main/java/com/formdev/flatlaf/extras/FlatSVGUtils.java

@@ -16,6 +16,7 @@
 
 package com.formdev.flatlaf.extras;
 
+import java.awt.Dimension;
 import java.awt.Graphics2D;
 import java.awt.Image;
 import java.awt.RenderingHints;
@@ -23,8 +24,10 @@ import java.awt.image.BufferedImage;
 import java.net.URISyntaxException;
 import java.net.URL;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import javax.swing.JWindow;
+import com.formdev.flatlaf.util.MultiResolutionImageSupport;
 import com.kitfox.svg.SVGCache;
 import com.kitfox.svg.SVGDiagram;
 import com.kitfox.svg.SVGException;
@@ -40,22 +43,51 @@ public class FlatSVGUtils
 	 * Creates from the given SVG a list of icon images with different sizes that
 	 * can be used for windows headers. The SVG should have a size of 16x16,
 	 * otherwise it is scaled.
+	 * <p>
+	 * If running on Java 9 or later and multi-resolution image support is available,
+	 * then a single multi-resolution image is returned that creates images on demand
+	 * for requested sizes from SVG.
+	 * This has the advantage that only images for used sizes are created.
+	 * Also if unusual sizes are requested (e.g. 18x18), then they are created from SVG.
 	 *
 	 * @param svgName the name of the SVG resource (a '/'-separated path)
-	 * @return list of icon images with different sizes (16x16, 24x24, 32x32, 48x48 and 64x64)
+	 * @return list of icon images with different sizes (16x16, 20x20, 24x24, 28x28, 32x32, 48x48 and 64x64)
 	 * @throws RuntimeException if failed to load or render SVG file
 	 * @see JWindow#setIconImages(List)
 	 */
 	public static List<Image> createWindowIconImages( String svgName ) {
 		SVGDiagram diagram = loadSVG( svgName );
 
-		return Arrays.asList(
+		if( MultiResolutionImageSupport.isAvailable() ) {
-			svg2image( diagram, 16, 16 ),
+			// use a multi-resolution image that creates images on demand for requested sizes
-			svg2image( diagram, 24, 24 ),
+			return Collections.singletonList( MultiResolutionImageSupport.create( 0,
-			svg2image( diagram, 32, 32 ),
+				new Dimension[] {
-			svg2image( diagram, 48, 48 ),
+					// Listing all these sizes here is actually not necessary because
-			svg2image( diagram, 64, 64 )
+					// any size is created on demand when
-		);
+					// MultiResolutionImage.getResolutionVariant(double destImageWidth, double destImageHeight)
+					// is invoked.
+					// This sizes are only used by MultiResolutionImage.getResolutionVariants().
+					new Dimension( 16, 16 ),	// 100%
+					new Dimension( 20, 20 ),	// 125%
+					new Dimension( 24, 24 ),	// 150%
+					new Dimension( 28, 28 ),	// 175%
+					new Dimension( 32, 32 ),	// 200%
+					new Dimension( 48, 48 ),	// 300%
+					new Dimension( 64, 64 ),	// 400%
+			}, dim -> {
+				return svg2image( diagram, dim.width, dim.height );
+			} ) );
+		} else {
+			return Arrays.asList(
+				svg2image( diagram, 16, 16 ),	// 100%
+				svg2image( diagram, 20, 20 ),	// 125%
+				svg2image( diagram, 24, 24 ),	// 150%
+				svg2image( diagram, 28, 28 ),	// 175%
+				svg2image( diagram, 32, 32 ),	// 200%
+				svg2image( diagram, 48, 48 ),	// 300%
+				svg2image( diagram, 64, 64 )	// 400%
+			);
+		}
 	}
 
 	/**

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

@@ -19,12 +19,16 @@ package com.formdev.flatlaf.testing;
 import java.awt.*;
 import java.awt.Dialog.ModalityType;
 import java.awt.event.*;
+import java.awt.image.BufferedImage;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.Random;
 import javax.swing.*;
 import com.formdev.flatlaf.FlatClientProperties;
+import com.formdev.flatlaf.ui.FlatUIUtils;
+import com.formdev.flatlaf.util.MultiResolutionImageSupport;
 import net.miginfocom.swing.*;
 
 /**
@@ -355,6 +359,32 @@ public class FlatWindowDecorationsTest
 			window.setIconImages( images );
 		else if( iconTestRandomRadioButton.isSelected() )
 			window.setIconImage( images.get( (int) (Math.random() * images.size()) ) );
+		else if( iconTestMRIRadioButton.isSelected() ) {
+			ArrayList<Image> sortedImages = new ArrayList<>( images );
+			sortedImages.sort( (image1, image2) -> {
+				return image1.getWidth( null ) - image2.getWidth( null );
+			} );
+			window.setIconImage( MultiResolutionImageSupport.create( 0, sortedImages.toArray( new Image[sortedImages.size()] ) ) );
+		} else if( iconTestDynMRIRadioButton.isSelected() ) {
+			window.setIconImage( MultiResolutionImageSupport.create( 0,
+				new Dimension[] {
+					new Dimension( 16, 16 ),
+			}, dim -> {
+				BufferedImage image = new BufferedImage( dim.width, dim.height, BufferedImage.TYPE_INT_ARGB );
+				Graphics2D g = image.createGraphics();
+				try {
+					g.setColor( Color.getHSBColor( (dim.width - 16) / 64f, 1, 0.8f ) );
+					g.fillRect( 0, 0, dim.width, dim.height );
+
+					g.setColor( Color.white );
+					g.setFont( new Font( "Dialog", Font.PLAIN, (int) (dim.width * 0.8) ) );
+					FlatUIUtils.drawString( this, g, String.valueOf( dim.width ), 0, dim.height - 2 );
+				} finally {
+					g.dispose();
+				}
+				return image;
+			} ) );
+		}
 	}
 
 	private JRootPane getWindowRootPane() {
@@ -403,6 +433,8 @@ public class FlatWindowDecorationsTest
 		iconNoneRadioButton = new JRadioButton();
 		iconTestAllRadioButton = new JRadioButton();
 		iconTestRandomRadioButton = new JRadioButton();
+		iconTestMRIRadioButton = new JRadioButton();
+		iconTestDynMRIRadioButton = new JRadioButton();
 		JButton openDialogButton = new JButton();
 		JButton openFrameButton = new JButton();
 		menuBar = new JMenuBar();
@@ -642,6 +674,8 @@ public class FlatWindowDecorationsTest
 				// rows
 				"[]" +
 				"[]" +
+				"[]" +
+				"[]" +
 				"[]"));
 
 			//---- iconNoneRadioButton ----
@@ -659,6 +693,16 @@ public class FlatWindowDecorationsTest
 			iconTestRandomRadioButton.setText("test random");
 			iconTestRandomRadioButton.addActionListener(e -> iconChanged());
 			panel2.add(iconTestRandomRadioButton, "cell 0 2");
+
+			//---- iconTestMRIRadioButton ----
+			iconTestMRIRadioButton.setText("test multi-resolution (Java 9+)");
+			iconTestMRIRadioButton.addActionListener(e -> iconChanged());
+			panel2.add(iconTestMRIRadioButton, "cell 0 3");
+
+			//---- iconTestDynMRIRadioButton ----
+			iconTestDynMRIRadioButton.setText("test dynamic multi-resolution (Java 9+)");
+			iconTestDynMRIRadioButton.addActionListener(e -> iconChanged());
+			panel2.add(iconTestDynMRIRadioButton, "cell 0 4");
 		}
 		add(panel2, "cell 1 8");
 
@@ -858,6 +902,8 @@ public class FlatWindowDecorationsTest
 		iconButtonGroup.add(iconNoneRadioButton);
 		iconButtonGroup.add(iconTestAllRadioButton);
 		iconButtonGroup.add(iconTestRandomRadioButton);
+		iconButtonGroup.add(iconTestMRIRadioButton);
+		iconButtonGroup.add(iconTestDynMRIRadioButton);
 		// JFormDesigner - End of component initialization  //GEN-END:initComponents
 	}
 
@@ -892,6 +938,8 @@ public class FlatWindowDecorationsTest
 	private JRadioButton iconNoneRadioButton;
 	private JRadioButton iconTestAllRadioButton;
 	private JRadioButton iconTestRandomRadioButton;
+	private JRadioButton iconTestMRIRadioButton;
+	private JRadioButton iconTestDynMRIRadioButton;
 	private JMenuBar menuBar;
 	// JFormDesigner - End of variables declaration  //GEN-END:variables
 }

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

@@ -328,7 +328,7 @@ new FormModel {
 			} )
 			add( new FormContainer( "javax.swing.JPanel", new FormLayoutManager( class net.miginfocom.swing.MigLayout ) {
 				"$columnConstraints": "[fill]"
-				"$rowConstraints": "[][][]"
+				"$rowConstraints": "[][][][][]"
 				"$layoutConstraints": "ltr,insets 0,hidemode 3,gap 0 0"
 			} ) {
 				name: "panel2"
@@ -366,6 +366,28 @@ new FormModel {
 				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 					"value": "cell 0 2"
 				} )
+				add( new FormComponent( "javax.swing.JRadioButton" ) {
+					name: "iconTestMRIRadioButton"
+					"text": "test multi-resolution (Java 9+)"
+					"$buttonGroup": new FormReference( "iconButtonGroup" )
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
+					addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "iconChanged", false ) )
+				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+					"value": "cell 0 3"
+				} )
+				add( new FormComponent( "javax.swing.JRadioButton" ) {
+					name: "iconTestDynMRIRadioButton"
+					"text": "test dynamic multi-resolution (Java 9+)"
+					"$buttonGroup": new FormReference( "iconButtonGroup" )
+					auxiliary() {
+						"JavaCodeGenerator.variableLocal": false
+					}
+					addEvent( new FormEvent( "java.awt.event.ActionListener", "actionPerformed", "iconChanged", false ) )
+				}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+					"value": "cell 0 4"
+				} )
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 				"value": "cell 1 8"
 			} )
@@ -386,7 +408,7 @@ new FormModel {
 			} )
 		}, new FormLayoutConstraints( null ) {
 			"location": new java.awt.Point( 0, 0 )
-			"size": new java.awt.Dimension( 690, 440 )
+			"size": new java.awt.Dimension( 690, 495 )
 		} )
 		add( new FormContainer( "javax.swing.JMenuBar", new FormLayoutManager( class javax.swing.JMenuBar ) ) {
 			name: "menuBar"
@@ -552,18 +574,18 @@ new FormModel {
 				} )
 			} )
 		}, new FormLayoutConstraints( null ) {
-			"location": new java.awt.Point( 0, 470 )
+			"location": new java.awt.Point( 0, 515 )
 			"size": new java.awt.Dimension( 255, 30 )
 		} )
 		add( new FormNonVisual( "javax.swing.ButtonGroup" ) {
 			name: "styleButtonGroup"
 		}, new FormLayoutConstraints( null ) {
-			"location": new java.awt.Point( 0, 520 )
+			"location": new java.awt.Point( 0, 565 )
 		} )
 		add( new FormNonVisual( "javax.swing.ButtonGroup" ) {
 			name: "iconButtonGroup"
 		}, new FormLayoutConstraints( null ) {
-			"location": new java.awt.Point( 0, 570 )
+			"location": new java.awt.Point( 0, 615 )
 		} )
 	}
 }