ScrollPane: support rounded border

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

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2023 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.Insets;
+import javax.swing.UIManager;
+import com.formdev.flatlaf.ui.FlatStylingSupport.Styleable;
+import com.formdev.flatlaf.util.UIScale;
+
+/**
+ * Border for {@link javax.swing.JScrollPane}.
+ *
+ * @uiDefault ScrollPane.arc				int
+
+ * @author Karl Tauber
+ * @since 3.3
+ */
+public class FlatScrollPaneBorder
+	extends FlatBorder
+{
+	@Styleable protected int arc = UIManager.getInt( "ScrollPane.arc" );
+
+	@Override
+	public Insets getBorderInsets( Component c, Insets insets ) {
+		insets = super.getBorderInsets( c, insets );
+
+		// if view is rounded, increase left and right insets to avoid that the viewport
+		// is painted over the rounded border on the corners
+		int arc = getArc( c );
+		if( arc > 0 ) {
+			// increase insets by radius minus lineWidth because radius is measured
+			// from the outside of the line, but insets from super include lineWidth
+			int padding = UIScale.scale( (arc / 2) - getLineWidth( c ) );
+			insets.left += padding;
+			insets.right += padding;
+		}
+
+		return insets;
+	}
+
+	@Override
+	protected int getArc( Component c ) {
+		if( isCellEditor( c ) )
+			return 0;
+
+		return arc;
+	}
+}

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

@@ -17,9 +17,12 @@
 package com.formdev.flatlaf.ui;
 
 import java.awt.Component;
+import java.awt.Container;
 import java.awt.Graphics;
+import java.awt.Graphics2D;
 import java.awt.Insets;
 import java.awt.KeyboardFocusManager;
+import java.awt.LayoutManager;
 import java.awt.Rectangle;
 import java.awt.event.ContainerEvent;
 import java.awt.event.ContainerListener;
@@ -41,16 +44,19 @@ import javax.swing.JTree;
 import javax.swing.JViewport;
 import javax.swing.LookAndFeel;
 import javax.swing.ScrollPaneConstants;
+import javax.swing.ScrollPaneLayout;
 import javax.swing.Scrollable;
 import javax.swing.SwingConstants;
 import javax.swing.SwingUtilities;
 import javax.swing.UIManager;
+import javax.swing.border.Border;
 import javax.swing.plaf.ComponentUI;
 import javax.swing.plaf.basic.BasicScrollPaneUI;
 import com.formdev.flatlaf.FlatClientProperties;
 import com.formdev.flatlaf.ui.FlatStylingSupport.Styleable;
 import com.formdev.flatlaf.ui.FlatStylingSupport.StyleableUI;
 import com.formdev.flatlaf.util.LoggingFacade;
+import com.formdev.flatlaf.util.UIScale;
 
 /**
  * Provides the Flat LaF UI delegate for {@link javax.swing.JScrollPane}.
@@ -97,7 +103,13 @@ public class FlatScrollPaneUI
 		super.installUI( c );
 
 		int focusWidth = UIManager.getInt( "Component.focusWidth" );
-		LookAndFeel.installProperty( c, "opaque", focusWidth == 0 );
+		int arc = UIManager.getInt( "ScrollPane.arc" );
+		LookAndFeel.installProperty( c, "opaque", focusWidth == 0 && arc == 0 );
+
+		// install layout manager
+		LayoutManager layout = c.getLayout();
+		if( layout != null && layout.getClass() == ScrollPaneLayout.UIResource.class )
+			c.setLayout( createScrollPaneLayout() );
 
 		installStyle();
 
@@ -108,6 +120,10 @@ public class FlatScrollPaneUI
 	public void uninstallUI( JComponent c ) {
 		MigLayoutVisualPadding.uninstall( scrollpane );
 
+		// uninstall layout manager
+		if( c.getLayout() instanceof FlatScrollPaneLayout )
+			c.setLayout( new ScrollPaneLayout.UIResource() );
+
 		super.uninstallUI( c );
 
 		oldStyleValues = null;
@@ -130,6 +146,13 @@ public class FlatScrollPaneUI
 		handler = null;
 	}
 
+	/**
+	 * @since 3.3
+	 */
+	protected FlatScrollPaneLayout createScrollPaneLayout() {
+		return new FlatScrollPaneLayout();
+	}
+
 	@Override
 	protected MouseWheelListener createMouseWheelListener() {
 		MouseWheelListener superListener = super.createMouseWheelListener();
@@ -290,8 +313,7 @@ public class FlatScrollPaneUI
 					Object corner = e.getNewValue();
 					if( corner instanceof JButton &&
 						((JButton)corner).getBorder() instanceof FlatButtonBorder &&
-						scrollpane.getViewport() != null &&
-						scrollpane.getViewport().getView() instanceof JTable )
+						getView( scrollpane ) instanceof JTable )
 					{
 						((JButton)corner).setBorder( BorderFactory.createEmptyBorder() );
 						((JButton)corner).setFocusable( false );
@@ -334,9 +356,10 @@ public class FlatScrollPaneUI
 
 	/** @since 2 */
 	protected Object applyStyleProperty( String key, Object value ) {
-		if( key.equals( "focusWidth" ) ) {
+		if( key.equals( "focusWidth" ) || key.equals( "arc" ) ) {
 			int focusWidth = (value instanceof Integer) ? (int) value : UIManager.getInt( "Component.focusWidth" );
-			LookAndFeel.installProperty( scrollpane, "opaque", focusWidth == 0 );
+			int arc = (value instanceof Integer) ? (int) value : UIManager.getInt( "ScrollPane.arc" );
+			LookAndFeel.installProperty( scrollpane, "opaque", focusWidth == 0 && arc == 0 );
 		}
 
 		if( borderShared == null )
@@ -402,13 +425,26 @@ public class FlatScrollPaneUI
 				c.getHeight() - insets.top - insets.bottom );
 		}
 
+		// if view is rounded, paint rounded background with view background color
+		// to ensure that free areas at left and right have same color as view
+		Component view;
+		float arc = getBorderArc( scrollpane );
+		if( arc > 0 && (view = getView( scrollpane )) != null ) {
+			float focusWidth = FlatUIUtils.getBorderFocusWidth( c );
+
+			g.setColor( view.getBackground() );
+
+			Object[] oldRenderingHints = FlatUIUtils.setRenderingHints( g );
+			FlatUIUtils.paintComponentBackground( (Graphics2D) g, 0, 0, c.getWidth(), c.getHeight(), focusWidth, arc );
+			FlatUIUtils.resetRenderingHints( g, oldRenderingHints );
+		}
+
 		paint( g, c );
 	}
 
 	/** @since 1.3 */
 	public static boolean isPermanentFocusOwner( JScrollPane scrollPane ) {
-		JViewport viewport = scrollPane.getViewport();
-		Component view = (viewport != null) ? viewport.getView() : null;
+		Component view = getView( scrollPane );
 		if( view == null )
 			return false;
 
@@ -428,6 +464,18 @@ public class FlatScrollPaneUI
 		return false;
 	}
 
+	private static Component getView( JScrollPane scrollPane ) {
+		JViewport viewport = scrollPane.getViewport();
+		return (viewport != null) ? viewport.getView() : null;
+	}
+
+	private static float getBorderArc( JScrollPane scrollPane ) {
+		Border border = scrollPane.getBorder();
+		return (border instanceof FlatScrollPaneBorder)
+			? UIScale.scale( (float) ((FlatScrollPaneBorder)border).getArc( scrollPane ) )
+			: 0;
+	}
+
 	//---- class Handler ------------------------------------------------------
 
 	/**
@@ -459,4 +507,35 @@ public class FlatScrollPaneUI
 			scrollpane.repaint();
 		}
 	}
+
+	//---- class FlatScrollPaneLayout -----------------------------------------
+
+	/**
+	 * @since 3.3
+	 */
+	protected static class FlatScrollPaneLayout
+		extends ScrollPaneLayout.UIResource
+	{
+		@Override
+		public void layoutContainer( Container parent ) {
+			super.layoutContainer( parent );
+
+			JScrollPane scrollPane = (JScrollPane) parent;
+			float arc = getBorderArc( scrollPane );
+			if( arc > 0 ) {
+				JScrollBar vsb = getVerticalScrollBar();
+				if( vsb != null && vsb.isVisible() ) {
+					// move vertical scrollbar to trailing edge
+					int padding = Math.round( (arc / 2) - FlatUIUtils.getBorderLineWidth( scrollPane ) );
+					Insets insets = parent.getInsets();
+					Rectangle r = vsb.getBounds();
+					int y = Math.max( r.y, insets.top + padding );
+					int y2 = Math.min( r.y + r.height, parent.getHeight() - insets.bottom - padding );
+					boolean ltr = parent.getComponentOrientation().isLeftToRight();
+
+					vsb.setBounds( r.x + (ltr ? padding : -padding), y, r.width, y2 - y );
+				}
+			}
+		}
+	}
 }

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

@@ -597,10 +597,11 @@ ScrollBar.allowsAbsolutePositioning = true
 
 #---- ScrollPane ----
 
-ScrollPane.border = com.formdev.flatlaf.ui.FlatBorder
+ScrollPane.border = com.formdev.flatlaf.ui.FlatScrollPaneBorder
 ScrollPane.background = $ScrollBar.track
 ScrollPane.fillUpperCorner = true
 ScrollPane.smoothScrolling = true
+ScrollPane.arc = 0
 
 
 #---- SearchField ----
@@ -731,7 +732,7 @@ Table.showVerticalLines = false
 Table.showTrailingVerticalLine = false
 Table.consistentHomeEndKeyBehavior = true
 Table.intercellSpacing = 0,0
-Table.scrollPaneBorder = com.formdev.flatlaf.ui.FlatBorder
+Table.scrollPaneBorder = com.formdev.flatlaf.ui.FlatScrollPaneBorder
 Table.ascendingSortIcon = com.formdev.flatlaf.icons.FlatAscendingSortIcon
 Table.descendingSortIcon = com.formdev.flatlaf.icons.FlatDescendingSortIcon
 Table.sortIconColor = @icon

flatlaf-core/src/test/java/com/formdev/flatlaf/ui/TestFlatStyleableInfo.java

@@ -601,7 +601,7 @@ public class TestFlatStyleableInfo
 		);
 
 		// border
-		flatBorder( expected );
+		flatScrollPaneBorder( expected );
 
 		assertMapEquals( expected, ui.getStyleableInfos( c ) );
 	}
@@ -1005,17 +1005,23 @@ public class TestFlatStyleableInfo
 
 		expectedMap( expected,
 			"arc", int.class,
-
 			"roundRect", Boolean.class
 		);
 	}
 
+	private void flatScrollPaneBorder( Map<String, Class<?>> expected ) {
+		flatBorder( expected );
+
+		expectedMap( expected,
+			"arc", int.class
+		);
+	}
+
 	private void flatTextBorder( Map<String, Class<?>> expected ) {
 		flatBorder( expected );
 
 		expectedMap( expected,
 			"arc", int.class,
-
 			"roundRect", Boolean.class
 		);
 	}

flatlaf-core/src/test/java/com/formdev/flatlaf/ui/TestFlatStyleableValue.java

@@ -625,7 +625,7 @@ public class TestFlatStyleableValue
 		FlatScrollPaneUI ui = (FlatScrollPaneUI) c.getUI();
 
 		// border
-		flatBorder( c, ui );
+		flatScrollPaneBorder( c, ui );
 
 		testBoolean( c, ui, "showButtons", true );
 	}
@@ -965,15 +965,19 @@ public class TestFlatStyleableValue
 		flatBorder( c, ui );
 
 		testInteger( c, ui, "arc", 123 );
-
 		testBoolean( c, ui, "roundRect", true );
 	}
 
+	private void flatScrollPaneBorder( JComponent c, StyleableUI ui ) {
+		flatBorder( c, ui );
+
+		testInteger( c, ui, "arc", 123 );
+	}
+
 	private void flatTextBorder( JComponent c, StyleableUI ui ) {
 		flatBorder( c, ui );
 
 		testInteger( c, ui, "arc", 123 );
-
 		testBoolean( c, ui, "roundRect", true );
 	}
 
@@ -1034,6 +1038,17 @@ public class TestFlatStyleableValue
 		// FlatRoundBorder extends FlatBorder
 		flatBorder( border );
 
+		testValue( border, "arc", 6 );
+		testValue( border, "roundRect", true );
+	}
+
+	@Test
+	void flatScrollPaneBorder() {
+		FlatScrollPaneBorder border = new FlatScrollPaneBorder();
+
+		// FlatScrollPaneBorder extends FlatBorder
+		flatBorder( border );
+
 		testValue( border, "arc", 6 );
 	}
 
@@ -1045,6 +1060,7 @@ public class TestFlatStyleableValue
 		flatBorder( border );
 
 		testValue( border, "arc", 6 );
+		testValue( border, "roundRect", true );
 	}
 
 	@Test

flatlaf-core/src/test/java/com/formdev/flatlaf/ui/TestFlatStyling.java

@@ -760,7 +760,7 @@ public class TestFlatStyling
 		FlatScrollPaneUI ui = (FlatScrollPaneUI) c.getUI();
 
 		// border
-		flatBorder( style -> ui.applyStyle( style ) );
+		flatScrollPaneBorder( style -> ui.applyStyle( style ) );
 
 		ui.applyStyle( "showButtons: true" );
 
@@ -1234,15 +1234,19 @@ public class TestFlatStyling
 		flatBorder( applyStyle );
 
 		applyStyle.accept( "arc: 6" );
-
 		applyStyle.accept( "roundRect: true" );
 	}
 
+	private void flatScrollPaneBorder( Consumer<String> applyStyle ) {
+		flatBorder( applyStyle );
+
+		applyStyle.accept( "arc: 6" );
+	}
+
 	private void flatTextBorder( Consumer<String> applyStyle ) {
 		flatBorder( applyStyle );
 
 		applyStyle.accept( "arc: 6" );
-
 		applyStyle.accept( "roundRect: true" );
 	}