Scrollpane rounded border

CHANGELOG.md

@@ -1,6 +1,14 @@
 FlatLaf Change Log
 ==================
 
+## 3.3-SNAPSHOT
+
+#### Fixed bugs
+
+- ScrollPane: Styling ScrollPane border properties did not work if view
+  component is a Table.
+
+
 ## 3.2
 
 #### New features and improvements

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

@@ -28,7 +28,6 @@
 import javax.swing.JComponent;
 import javax.swing.JScrollPane;
 import javax.swing.JSpinner;
-import javax.swing.JViewport;
 import javax.swing.UIManager;
 import javax.swing.plaf.basic.BasicBorders;
 import com.formdev.flatlaf.FlatClientProperties;
@@ -195,8 +194,7 @@ protected Paint getBorderColor( Component c ) {
 	protected boolean isEnabled( Component c ) {
 		if( c instanceof JScrollPane ) {
 			// check whether view component is disabled
-			JViewport viewport = ((JScrollPane)c).getViewport();
-			Component view = (viewport != null) ? viewport.getView() : null;
+			Component view = FlatScrollPaneUI.getView( (JScrollPane) c );
 			if( view != null && !isEnabled( view ) )
 				return false;
 		}

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

@@ -0,0 +1,118 @@
+/*
+ * 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.JList;
+import javax.swing.JScrollPane;
+import javax.swing.JTable;
+import javax.swing.JTree;
+import javax.swing.UIManager;
+import javax.swing.text.JTextComponent;
+import com.formdev.flatlaf.ui.FlatStylingSupport.Styleable;
+import com.formdev.flatlaf.util.UIScale;
+
+/**
+ * Border for {@link javax.swing.JScrollPane}.
+ *
+ * @uiDefault ScrollPane.arc				int
+ * @uiDefault ScrollPane.List.arc			int
+ * @uiDefault ScrollPane.Table.arc			int
+ * @uiDefault ScrollPane.TextComponent.arc	int
+ * @uiDefault ScrollPane.Tree.arc			int
+
+ * @author Karl Tauber
+ * @since 3.3
+ */
+public class FlatScrollPaneBorder
+	extends FlatBorder
+{
+	@Styleable protected int arc = UIManager.getInt( "ScrollPane.arc" );
+
+	private boolean isArcStyled;
+	private final int listArc = FlatUIUtils.getUIInt( "ScrollPane.List.arc", -1 );
+	private final int tableArc = FlatUIUtils.getUIInt( "ScrollPane.Table.arc", -1 );
+	private final int textComponentArc = FlatUIUtils.getUIInt( "ScrollPane.TextComponent.arc", -1 );
+	private final int treeArc = FlatUIUtils.getUIInt( "ScrollPane.Tree.arc", -1 );
+
+	@Override
+	public Object applyStyleProperty( String key, Object value ) {
+		Object oldValue = super.applyStyleProperty( key, value );
+
+		if( "arc".equals( key ) )
+			isArcStyled = true;
+
+		return oldValue;
+	}
+
+	@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 padding = getLeftRightPadding( c );
+		if( padding > 0 ) {
+			insets.left += padding;
+			insets.right += padding;
+		}
+
+		return insets;
+	}
+
+	@Override
+	protected int getArc( Component c ) {
+		if( isCellEditor( c ) )
+			return 0;
+
+		if( isArcStyled )
+			return arc;
+
+		if( c instanceof JScrollPane ) {
+			Component view = FlatScrollPaneUI.getView( (JScrollPane) c );
+			if( listArc >= 0 && view instanceof JList )
+				return listArc;
+			if( tableArc >= 0 && view instanceof JTable )
+				return tableArc;
+			if( textComponentArc >= 0&& view instanceof JTextComponent )
+				return textComponentArc;
+			if( treeArc >= 0 && view instanceof JTree )
+				return treeArc;
+		}
+
+		return arc;
+	}
+
+	/**
+	 * Returns the scaled left/right padding used when arc is larger than zero.
+	 * <p>
+	 * This is the distance from the inside of the left border to the left side of the view component.
+	 * On the right side, this is the distance between the right side of the view component and
+	 * the vertical scrollbar. Or the inside of the right border if the scrollbar is hidden.
+	 */
+	public int getLeftRightPadding( Component c ) {
+		// Subtract lineWidth from radius because radius is given for the outside
+		// of the painted line, but insets from super already include lineWidth.
+		// Reduce padding by 10% to make padding slightly smaller because it is not recognizable
+		// when the view is minimally painted over the beginning of the border curve.
+		int arc = getArc( c );
+		return (arc > 0)
+			? Math.max( Math.round( UIScale.scale( ((arc / 2f) - getLineWidth( c )) * 0.9f ) ), 0 )
+			: 0;
+	}
+}