DesktopIcon: use derived color for icon background, based on background color of JDesktopPane

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

@@ -16,10 +16,12 @@
 
 package com.formdev.flatlaf.ui;
 
+import java.awt.Color;
 import java.awt.Component;
 import java.awt.Container;
 import java.awt.Dimension;
 import java.awt.EventQueue;
+import java.awt.Graphics;
 import java.awt.Graphics2D;
 import java.awt.Image;
 import java.awt.Insets;
@@ -33,6 +35,7 @@ import javax.swing.BorderFactory;
 import javax.swing.ImageIcon;
 import javax.swing.JButton;
 import javax.swing.JComponent;
+import javax.swing.JDesktopPane;
 import javax.swing.event.MouseInputAdapter;
 import javax.swing.event.MouseInputListener;
 import javax.swing.JLabel;
@@ -229,6 +232,21 @@ public class FlatDesktopIconUI
 		return getPreferredSize( c );
 	}
 
+	@Override
+	public void update( Graphics g, JComponent c ) {
+		if( c.isOpaque() ) {
+			// fill background with color derived from desktop pane
+			Color background = c.getBackground();
+			JDesktopPane desktopPane = desktopIcon.getDesktopPane();
+			g.setColor( (desktopPane != null)
+				? FlatUIUtils.deriveColor( background, desktopPane.getBackground() )
+				: background );
+			g.fillRect( 0, 0, c.getWidth(), c.getHeight() );
+		}
+
+		paint( g, c );
+	}
+
 	void updateDockIcon() {
 		// use invoke later to make sure that components are updated when switching LaF
 		EventQueue.invokeLater( () -> {

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

@@ -166,7 +166,7 @@ Desktop.background = #3E434C
 
 #---- DesktopIcon ----
 
-DesktopIcon.background = lighten($Desktop.background,10%)
+DesktopIcon.background = lighten($Desktop.background,10%,derived)
 
 
 #---- InternalFrame ----

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

@@ -172,7 +172,7 @@ Desktop.background = #E6EBF0
 
 #---- DesktopIcon ----
 
-DesktopIcon.background = darken($Desktop.background,10%)
+DesktopIcon.background = darken($Desktop.background,10%,derived)
 
 
 #---- HelpButton ----

flatlaf-extras/src/main/resources/com/formdev/flatlaf/extras/resources/DerivedColorKeys.properties

@@ -88,6 +88,11 @@ ComboBox.buttonPressedArrowColor = ComboBox.buttonArrowColor
 Component.custom.borderColor = null
 
 
+#---- HelpButton ----
+
+DesktopIcon.background = Desktop.background
+
+
 #---- HelpButton ----
 
 HelpButton.disabledBackground = HelpButton.background

flatlaf-testing/dumps/uidefaults/FlatDarkLaf_1.8.0_202.txt

@@ -249,7 +249,7 @@ Desktop.minOnScreenInsets      3,3,3,3    javax.swing.plaf.InsetsUIResource [UI]
 
 #---- DesktopIcon ----
 
-DesktopIcon.background         #555c68    javax.swing.plaf.ColorUIResource [UI]
+DesktopIcon.background         #555c68    com.formdev.flatlaf.util.DerivedColor [UI]    lighten(10% autoInverse)
 DesktopIcon.border             [lazy] 4,4,4,4  false    com.formdev.flatlaf.ui.FlatEmptyBorder [UI]
 DesktopIcon.closeIcon          [lazy] 24,24    com.formdev.flatlaf.icons.FlatInternalFrameCloseIcon [UI]
 DesktopIcon.closeSize          20,20    javax.swing.plaf.DimensionUIResource [UI]

flatlaf-testing/dumps/uidefaults/FlatLightLaf_1.8.0_202.txt

@@ -253,7 +253,7 @@ Desktop.minOnScreenInsets      3,3,3,3    javax.swing.plaf.InsetsUIResource [UI]
 
 #---- DesktopIcon ----
 
-DesktopIcon.background         #c6d2dd    javax.swing.plaf.ColorUIResource [UI]
+DesktopIcon.background         #c6d2dd    com.formdev.flatlaf.util.DerivedColor [UI]    darken(10% autoInverse)
 DesktopIcon.border             [lazy] 4,4,4,4  false    com.formdev.flatlaf.ui.FlatEmptyBorder [UI]
 DesktopIcon.closeIcon          [lazy] 24,24    com.formdev.flatlaf.icons.FlatInternalFrameCloseIcon [UI]
 DesktopIcon.closeSize          20,20    javax.swing.plaf.DimensionUIResource [UI]

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

@@ -446,7 +446,9 @@ public class FlatTestFrame
 			Color green = dark ? Color.green.darker() : Color.green;
 
 			updateComponentsRecur( content, (c, type) -> {
-				if( type == "view" || type == "tab" || c instanceof JSlider ) {
+				if( type == "view" || type == "tab" || c instanceof JSlider || c instanceof JInternalFrame ) {
+					if( c instanceof JInternalFrame )
+						c = ((JInternalFrame)c).getContentPane();
 					c.setForeground( explicit ? magenta : restoreColor );
 					c.setBackground( explicit ? orange : restoreColor );
 				} else {
@@ -620,7 +622,7 @@ public class FlatTestFrame
 
 	public static void updateComponentsRecur( Container container, BiConsumer<Component, String> action ) {
 		for( Component c : container.getComponents() ) {
-			if( c instanceof JPanel || c instanceof JDesktopPane ) {
+			if( c instanceof JPanel ) {
 				updateComponentsRecur( (Container) c, action );
 				continue;
 			}
@@ -639,6 +641,9 @@ public class FlatTestFrame
 					if( tab != null )
 						action.accept( tab, "tab" );
 				}
+			} else if( c instanceof JDesktopPane ) {
+				for( JInternalFrame f : ((JDesktopPane)c).getAllFrames() )
+					action.accept( f, null );
 			}
 
 			if( c instanceof JToolBar )