ScrollPane implemented (with focused border)

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

@@ -22,6 +22,8 @@ import java.awt.Graphics;
 import java.awt.Graphics2D;
 import java.awt.Insets;
 import java.awt.Paint;
+import javax.swing.JScrollPane;
+import javax.swing.JViewport;
 import javax.swing.UIManager;
 import javax.swing.plaf.basic.BasicBorders;
 import javax.swing.text.JTextComponent;
@@ -43,7 +45,7 @@ public class FlatBorder
 			float focusWidth = getFocusWidth();
 			float lineWidth = getLineWidth();
 
-			if( c.hasFocus() ) {
+			if( isFocused( c ) ) {
 				g2.setColor( UIManager.getColor( "Component.focusColor" ) );
 				FlatUIUtils.paintOutlineBorder( g2, x, y, width, height, focusWidth, lineWidth, 0 );
 			}
@@ -58,21 +60,30 @@ public class FlatBorder
 	private Paint getBorderColor( Component c ) {
 		boolean editable = !(c instanceof JTextComponent) || ((JTextComponent)c).isEditable();
 		return UIManager.getColor( c.isEnabled() && editable
-			? (c.hasFocus()
+			? (isFocused( c )
 				? "Component.focusedBorderColor"
 				: "Component.borderColor")
 			: "Component.disabledBorderColor" );
 	}
 
+	private boolean isFocused( Component c ) {
+		if( c instanceof JScrollPane ) {
+			JViewport viewport = ((JScrollPane)c).getViewport();
+			Component view = (viewport != null) ? viewport.getView() : null;
+			return (view != null) ? view.hasFocus() : false;
+		} else
+			return c.hasFocus();
+	}
+
 	@Override
 	public Insets getBorderInsets( Component c, Insets insets ) {
 		float ow = getFocusWidth() + getLineWidth();
 
 		insets = super.getBorderInsets( c, insets );
-		insets.top = round( scale( (float) insets.top ) + ow );
-		insets.left = round( scale( (float) insets.left ) + ow );
-		insets.bottom = round( scale( (float) insets.bottom ) + ow );
-		insets.right = round( scale( (float) insets.right ) + ow );
+		insets.top = Math.round( scale( (float) insets.top ) + ow );
+		insets.left = Math.round( scale( (float) insets.left ) + ow );
+		insets.bottom = Math.round( scale( (float) insets.bottom ) + ow );
+		insets.right = Math.round( scale( (float) insets.right ) + ow );
 		return insets;
 	}
 

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

@@ -82,10 +82,10 @@ public class FlatButtonBorder
 		float ow = getFocusWidth() + getLineWidth();
 
 		insets = super.getBorderInsets( c, insets );
-		insets.top = round( scale( (float) insets.top ) + ow );
-		insets.left = round( scale( (float) insets.left ) + ow );
-		insets.bottom = round( scale( (float) insets.bottom ) + ow );
-		insets.right = round( scale( (float) insets.right ) + ow );
+		insets.top = Math.round( scale( (float) insets.top ) + ow );
+		insets.left = Math.round( scale( (float) insets.left ) + ow );
+		insets.bottom = Math.round( scale( (float) insets.bottom ) + ow );
+		insets.right = Math.round( scale( (float) insets.right ) + ow );
 		return insets;
 	}
 

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

@@ -104,13 +104,11 @@ public class FlatCheckBoxIcon
 
 	@Override
 	public int getIconWidth() {
-		// use Math.round(), instead of UIScale.round(), because this gives same
-		// icon size as scaled graphics used in paintIcon()
-		return Math.round( scale( 19f ) );
+		return scale( 19 );
 	}
 
 	@Override
 	public int getIconHeight() {
-		return Math.round( scale( 19f ) );
+		return scale( 19 );
 	}
 }

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

@@ -0,0 +1,115 @@
+/*
+ * Copyright 2019 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
+ *
+ *     http://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.ui;
+
+import java.awt.Component;
+import java.awt.event.ContainerEvent;
+import java.awt.event.ContainerListener;
+import java.awt.event.FocusEvent;
+import java.awt.event.FocusListener;
+import java.beans.PropertyChangeEvent;
+import javax.swing.JComponent;
+import javax.swing.JScrollPane;
+import javax.swing.JViewport;
+import javax.swing.plaf.ComponentUI;
+import javax.swing.plaf.basic.BasicScrollPaneUI;
+
+/**
+ * Provides the Flat LaF UI delegate for {@link javax.swing.JScrollPane}.
+ *
+ * @author Karl Tauber
+ */
+public class FlatScrollPaneUI
+	extends BasicScrollPaneUI
+{
+	private final Handler handler = new Handler();
+
+	public static ComponentUI createUI( JComponent c ) {
+		return new FlatScrollPaneUI();
+	}
+
+	@Override
+	protected void installListeners( JScrollPane c ) {
+		super.installListeners( c );
+
+		JViewport viewport = scrollpane.getViewport();
+		if( viewport != null )
+			viewport.addContainerListener( handler );
+	}
+
+	@Override
+	protected void uninstallListeners( JComponent c ) {
+		super.uninstallListeners( c );
+
+		JViewport viewport = scrollpane.getViewport();
+		if( viewport != null )
+			viewport.removeContainerListener( handler );
+	}
+
+	@Override
+	protected void updateViewport( PropertyChangeEvent e ) {
+		super.updateViewport( e );
+
+		JViewport oldViewport = (JViewport) (e.getOldValue());
+		JViewport newViewport = (JViewport) (e.getNewValue());
+
+		if( oldViewport != null ) {
+			oldViewport.removeContainerListener( handler );
+
+			Component oldView = oldViewport.getView();
+			if( oldView != null )
+				oldView.removeFocusListener( handler );
+		}
+		if( newViewport != null ) {
+			newViewport.addContainerListener( handler );
+
+			Component newView = newViewport.getView();
+			if( newView != null )
+				newView.addFocusListener( handler );
+		}
+	}
+
+	//---- class Handler ------------------------------------------------------
+
+	/**
+	 * ContainerListener is added to JViewport to keep focus listener on view up-to-date.
+	 * FocusListener is added to view for repainting when view gets focused.
+	 */
+	private class Handler
+		implements ContainerListener, FocusListener
+	{
+		@Override
+		public void componentAdded( ContainerEvent e ) {
+			e.getChild().addFocusListener( this );
+		}
+
+		@Override
+		public void componentRemoved( ContainerEvent e ) {
+			e.getChild().removeFocusListener( this );
+		}
+
+		@Override
+		public void focusGained( FocusEvent e ) {
+			scrollpane.repaint();
+		}
+
+		@Override
+		public void focusLost( FocusEvent e ) {
+			scrollpane.repaint();
+		}
+	}
+}

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

@@ -169,7 +169,7 @@ public class UIScale
 	}
 
 	public static int scale( int value ) {
-		return (scaleFactor == 1) ? value : round( value * scaleFactor );
+		return (scaleFactor == 1) ? value : Math.round( value * scaleFactor );
 	}
 
 	public static float unscale( float value ) {
@@ -177,14 +177,7 @@ public class UIScale
 	}
 
 	public static int unscale( int value ) {
-		return (scaleFactor == 1f) ? value : round( value / scaleFactor );
-	}
-
-	public static int round( float value ) {
-		// subtracting 0.01 gives "better" results in some cases
-		//   e.g. 2px * 125% = 2px instead of 3px
-		//     or 1px * 150% = 1px instead of 2px
-		return Math.round( value - 0.01f );
+		return (scaleFactor == 1f) ? value : Math.round( value / scaleFactor );
 	}
 
 	public static void scaleGraphics( Graphics2D g ) {

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

@@ -22,6 +22,7 @@ FormattedTextFieldUI=com.formdev.flatlaf.ui.FlatFormattedTextFieldUI
 LabelUI=com.formdev.flatlaf.ui.FlatLabelUI
 PasswordFieldUI=com.formdev.flatlaf.ui.FlatPasswordFieldUI
 RadioButtonUI=com.formdev.flatlaf.ui.FlatRadioButtonUI
+ScrollPaneUI=com.formdev.flatlaf.ui.FlatScrollPaneUI
 TextFieldUI=com.formdev.flatlaf.ui.FlatTextFieldUI
 
 
@@ -63,6 +64,11 @@ RadioButton.border=com.formdev.flatlaf.ui.FlatMarginBorder
 RadioButton.icon=com.formdev.flatlaf.ui.FlatRadioButtonIcon
 
 
+#---- ScrollPane ----
+
+ScrollPane.border=com.formdev.flatlaf.ui.FlatBorder
+
+
 #---- TextField ----
 
 TextField.border=com.formdev.flatlaf.ui.FlatBorder