CheckBox and RadioButton: do not fill background if used as cell renderer, except if cell is selected or has different background color (issue #311)

CHANGELOG.md

@@ -26,6 +26,8 @@ FlatLaf Change Log
 
 #### Fixed bugs
 
+- CheckBox and RadioButton: Do not fill background if used as cell renderer,
+  except if cell is selected or has different background color. (issue #311)
 - DesktopPane:
   - Fixed missing preview of iconified internal frames in dock when using a
     custom desktop manager. (PR #294)
@@ -202,7 +204,7 @@ FlatLaf Change Log
 - CheckBox and RadioButton: Fill component background as soon as background
   color is different to default background color, even if component is not
   opaque (which is the default). This paints selection if using the component as
-  cell renderer a Table, Tree or List.
+  cell renderer in Table, Tree or List.
 - TextComponents: Border of focused non-editable text components had wrong
   color.
 - Custom window decorations: Fixed top window border in dark themes when running

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

@@ -18,11 +18,14 @@ package com.formdev.flatlaf.ui;
 
 import static com.formdev.flatlaf.util.UIScale.scale;
 import java.awt.Color;
+import java.awt.Container;
 import java.awt.Dimension;
 import java.awt.Graphics;
 import java.awt.Insets;
 import java.awt.Rectangle;
+import java.util.Objects;
 import javax.swing.AbstractButton;
+import javax.swing.CellRendererPane;
 import javax.swing.JComponent;
 import javax.swing.LookAndFeel;
 import javax.swing.UIManager;
@@ -120,10 +123,11 @@ public class FlatRadioButtonUI
 	public void paint( Graphics g, JComponent c ) {
 		// fill background even if not opaque if
 		// - contentAreaFilled is true and
-		// - if background was explicitly set to a non-UIResource color
+		// - if background color is different to default background color
+		// (this paints selection if using the component as cell renderer)
 		if( !c.isOpaque() &&
 			((AbstractButton)c).isContentAreaFilled() &&
-			!defaultBackground.equals( c.getBackground() ) )
+			!Objects.equals( c.getBackground(), getDefaultBackground( c ) ) )
 		{
 			g.setColor( c.getBackground() );
 			g.fillRect( 0, 0, c.getWidth(), c.getHeight() );
@@ -160,6 +164,18 @@ public class FlatRadioButtonUI
 		FlatButtonUI.paintText( g, b, textRect, text, b.isEnabled() ? b.getForeground() : disabledText );
 	}
 
+	/**
+	 * Returns the default background color of the component.
+	 * If the component is used as cell renderer (e.g. in JTable),
+	 * then the background color of the renderer container is returned.
+	 */
+	private Color getDefaultBackground( JComponent c ) {
+		Container parent = c.getParent();
+		return (parent instanceof CellRendererPane && parent.getParent() != null)
+			? parent.getParent().getBackground()
+			: defaultBackground;
+	}
+
 	private int getIconFocusWidth( JComponent c ) {
 		AbstractButton b = (AbstractButton) c;
 		return (b.getIcon() == null && getDefaultIcon() instanceof FlatCheckBoxIcon)