InternalFrame: added drop shadows (issue #94)

also made borders of internal frames in dark themes darker

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

@@ -0,0 +1,159 @@
+/*
+ * Copyright 2020 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
+ *
+ *     https://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.Color;
+import java.awt.Component;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Image;
+import java.awt.Insets;
+import java.awt.RadialGradientPaint;
+import java.awt.image.BufferedImage;
+import com.formdev.flatlaf.util.HiDPIUtils;
+import com.formdev.flatlaf.util.UIScale;
+
+/**
+ * Paints a drop shadow border around the component.
+ *
+ * @author Karl Tauber
+ */
+public class FlatDropShadowBorder
+	extends FlatEmptyBorder
+{
+	private final Color shadowColor;
+	private final int shadowSize;
+	private final int cornerInset;
+	private final int shadowAlpha;
+
+	private Image shadowImage;
+	private Color lastShadowColor;
+	private double lastSystemScaleFactor;
+	private float lastUserScaleFactor;
+
+	public FlatDropShadowBorder() {
+		this( null );
+	}
+
+	public FlatDropShadowBorder( Color shadowColor ) {
+		this( shadowColor, 4, 4, 128 );
+	}
+
+	public FlatDropShadowBorder( Color shadowColor, int shadowSize, int cornerInset, int shadowAlpha ) {
+		super( new Insets( 0, 0, shadowSize, shadowSize ) );
+		this.shadowColor = shadowColor;
+		this.shadowSize = shadowSize;
+		this.cornerInset = cornerInset;
+		this.shadowAlpha = shadowAlpha;
+	}
+
+	@Override
+	public void paintBorder( Component c, Graphics g, int x, int y, int width, int height ) {
+		HiDPIUtils.paintAtScale1x( (Graphics2D) g, x, y, width, height, this::paintImpl );
+	}
+
+	private void paintImpl( Graphics2D g, int x, int y, int width, int height, double scaleFactor ) {
+		Color shadowColor = (this.shadowColor != null) ? this.shadowColor : g.getColor();
+		int shadowSize = (int) Math.ceil( UIScale.scale( this.shadowSize ) * scaleFactor );
+		int cornerInset = (int) Math.ceil( UIScale.scale( this.cornerInset ) * scaleFactor );
+
+		// create and cache shadow image
+		float userScaleFactor = UIScale.getUserScaleFactor();
+		if( shadowImage == null ||
+			!shadowColor.equals( lastShadowColor ) ||
+			lastSystemScaleFactor != scaleFactor ||
+			lastUserScaleFactor != userScaleFactor )
+		{
+			shadowImage = createShadowImage( shadowColor, shadowSize, shadowAlpha,
+				(float) (scaleFactor * userScaleFactor) );
+			lastShadowColor = shadowColor;
+			lastSystemScaleFactor = scaleFactor;
+			lastUserScaleFactor = userScaleFactor;
+		}
+
+/*debug
+		int m = shadowImage.getWidth( null );
+		g.setColor( Color.lightGray );
+		g.drawRect( x - m - 1, y - m - 1, m + 1, m + 1 );
+		g.setColor( Color.white );
+		g.fillRect( x - m, y - m, m, m );
+		g.drawImage( shadowImage, x - m, y - m, null );
+debug*/
+
+		int x1c = x + cornerInset;
+		int y1c = y + cornerInset;
+		int x1cs = x1c + shadowSize;
+		int y1cs = y1c + shadowSize;
+
+		int x2s = x + width;
+		int y2s = y + height;
+		int x2 = x2s - shadowSize;
+		int y2 = y2s - shadowSize;
+
+		int wh = (shadowSize * 2) - 1;
+		int center = shadowSize - 1;
+
+		// left-bottom edge
+		g.drawImage( shadowImage, x1c, y2, x1cs, y2s,
+			0, center, shadowSize, wh, null );
+
+		// bottom shadow
+		g.drawImage( shadowImage, x1cs, y2, x2, y2s,
+			center, center, center + 1, wh, null );
+
+		// right-bottom edge
+		g.drawImage( shadowImage, x2, y2, x2s, y2s,
+			center, center, wh, wh, null );
+
+		// right shadow
+		g.drawImage( shadowImage, x2, y1cs, x2s, y2,
+			center, center, wh, center + 1, null );
+
+		// right-top edge
+		g.drawImage( shadowImage, x2, y1c, x2s, y1cs,
+			center, 0, wh, shadowSize, null );
+	}
+
+	private static BufferedImage createShadowImage( Color shadowColor, int shadowSize,
+		int shadowAlpha, float scaleFactor )
+	{
+		int shadowRGB = shadowColor.getRGB() & 0xffffff;
+		Color startColor = new Color( shadowRGB | ((shadowAlpha & 0xff) << 24), true );
+		Color midColor = new Color( shadowRGB | (((shadowAlpha / 2) & 0xff) << 24), true );
+		Color endColor = new Color( shadowRGB, true );
+
+		int wh = (shadowSize * 2) - 1;
+		int center = shadowSize - 1;
+
+		RadialGradientPaint p = new RadialGradientPaint( center, center,
+			shadowSize - (0.75f * scaleFactor),
+			new float[] { 0, 0.35f, 1 },
+			new Color[] { startColor, midColor, endColor } );
+
+		BufferedImage image = new BufferedImage( wh, wh, BufferedImage.TYPE_INT_ARGB );
+
+		Graphics2D g = image.createGraphics();
+		try {
+			g.setPaint( p );
+			g.fillRect( 0, 0, wh, wh );
+		} finally {
+			g.dispose();
+		}
+
+		return image;
+	}
+}

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

@@ -113,6 +113,8 @@ public class FlatInternalFrameUI
 		private final Color inactiveBorderColor = UIManager.getColor( "InternalFrame.inactiveBorderColor" );
 		private final int borderLineWidth = FlatUIUtils.getUIInt( "InternalFrame.borderLineWidth", 1 );
 
+		private final FlatDropShadowBorder dropShadowBorder = new FlatDropShadowBorder();
+
 		public FlatInternalFrameBorder() {
 			super( UIManager.getInsets( "InternalFrame.borderMargins" ) );
 		}
@@ -137,16 +139,24 @@ public class FlatInternalFrameUI
 			Insets insets = getBorderInsets( c );
 			float lineWidth = scale( (float) borderLineWidth );
 
+			float rx = x + insets.left - lineWidth;
+			float ry = y + insets.top - lineWidth;
+			float rwidth = width - insets.left - insets.right + (lineWidth * 2);
+			float rheight = height - insets.top - insets.bottom + (lineWidth * 2);
+
 			Graphics2D g2 = (Graphics2D) g.create();
 			try {
 				FlatUIUtils.setRenderingHints( g2 );
 				g2.setColor( f.isSelected() ? activeBorderColor : inactiveBorderColor );
-				g2.fill( FlatUIUtils.createRectangle(
-					x + insets.left - lineWidth,
-					y + insets.top - lineWidth,
-					width - insets.left - insets.right + (lineWidth * 2),
-					height - insets.top - insets.bottom + (lineWidth * 2),
-					lineWidth ) );
+
+				// paint drop shadow
+				Insets dropShadowInsets = dropShadowBorder.getBorderInsets();
+				dropShadowBorder.paintBorder( c, g2, (int) rx, (int) ry,
+					(int) rwidth + dropShadowInsets.right,
+					(int) rheight + dropShadowInsets.bottom );
+
+				// paint border
+				g2.fill( FlatUIUtils.createRectangle( rx, ry, rwidth, rheight, lineWidth ) );
 			} finally {
 				g2.dispose();
 			}

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

@@ -148,8 +148,8 @@ InternalFrame.activeTitleForeground=@foreground
 InternalFrame.inactiveTitleBackground=darken(@background,5%)
 InternalFrame.inactiveTitleForeground=@disabledText
 
-InternalFrame.activeBorderColor=lighten($Component.borderColor,10%)
-InternalFrame.inactiveBorderColor=$Component.borderColor
+InternalFrame.activeBorderColor=darken(@background,7%)
+InternalFrame.inactiveBorderColor=darken(@background,3%)
 
 InternalFrame.buttonHoverBackground=lighten($InternalFrame.activeTitleBackground,10%,derived autoInverse)
 InternalFrame.buttonPressedBackground=lighten($InternalFrame.activeTitleBackground,20%,derived autoInverse)

flatlaf-testing/src/main/resources/com/formdev/flatlaf/testing/uidefaults/FlatDarkLaf_1.8.0_202-mac.txt

@@ -327,7 +327,7 @@ HyperlinkUI                    com.formdev.flatlaf.swingx.ui.FlatHyperlinkUI
 
 #---- InternalFrame ----
 
-InternalFrame.activeBorderColor #7e7e7e    javax.swing.plaf.ColorUIResource [UI]
+InternalFrame.activeBorderColor #2b2d2e    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.activeTitleBackground #242526    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.activeTitleForeground #bbbbbb    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.border           [lazy] 6,6,6,6  false    com.formdev.flatlaf.ui.FlatInternalFrameUI$FlatInternalFrameBorder [UI]
@@ -348,7 +348,7 @@ InternalFrame.closePressedBackground [lazy] #ad3b37    javax.swing.plaf.ColorUIR
 InternalFrame.closePressedForeground #ffffff    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.icon             [lazy] 16,16    sun.swing.ImageIconUIResource [UI]  (sun.awt.image.ToolkitImage)
 InternalFrame.iconifyIcon      [lazy] 24,24    com.formdev.flatlaf.icons.FlatInternalFrameIconifyIcon [UI]
-InternalFrame.inactiveBorderColor #646464    javax.swing.plaf.ColorUIResource [UI]
+InternalFrame.inactiveBorderColor #353739    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.inactiveTitleBackground #303234    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.inactiveTitleForeground #777777    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.maximizeIcon     [lazy] 24,24    com.formdev.flatlaf.icons.FlatInternalFrameMaximizeIcon [UI]

flatlaf-testing/src/main/resources/com/formdev/flatlaf/testing/uidefaults/FlatDarkLaf_1.8.0_202.txt

@@ -326,7 +326,7 @@ HyperlinkUI                    com.formdev.flatlaf.swingx.ui.FlatHyperlinkUI
 
 #---- InternalFrame ----
 
-InternalFrame.activeBorderColor #7e7e7e    javax.swing.plaf.ColorUIResource [UI]
+InternalFrame.activeBorderColor #2b2d2e    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.activeTitleBackground #242526    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.activeTitleForeground #bbbbbb    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.border           [lazy] 6,6,6,6  false    com.formdev.flatlaf.ui.FlatInternalFrameUI$FlatInternalFrameBorder [UI]
@@ -347,7 +347,7 @@ InternalFrame.closePressedBackground [lazy] #ad3b37    javax.swing.plaf.ColorUIR
 InternalFrame.closePressedForeground #ffffff    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.icon             [lazy] 16,16    sun.swing.ImageIconUIResource [UI]  (sun.awt.image.ToolkitImage)
 InternalFrame.iconifyIcon      [lazy] 24,24    com.formdev.flatlaf.icons.FlatInternalFrameIconifyIcon [UI]
-InternalFrame.inactiveBorderColor #646464    javax.swing.plaf.ColorUIResource [UI]
+InternalFrame.inactiveBorderColor #353739    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.inactiveTitleBackground #303234    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.inactiveTitleForeground #777777    javax.swing.plaf.ColorUIResource [UI]
 InternalFrame.maximizeIcon     [lazy] 24,24    com.formdev.flatlaf.icons.FlatInternalFrameMaximizeIcon [UI]