InternalFrame: support draggable border for resizing frame inside of the visible frame border (issue #121)

2026-02-10 22:17:13 -06:00 · 2020-09-04 22:59:09 +02:00
parent 98b9df06fe
commit c44905ea5e
4 changed files with 319 additions and 97 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@ FlatLaf Change Log

 - Demo: Improved "SplitPane & Tabs" and "Data Components" tabs.
 - Menu items "File > Open" and "File > Save As" now show file choosers.
+- InternalFrame: Support draggable border for resizing frame inside of the
+  visible frame border. (issue #121)

 #### Fixed bugs

--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatInternalFrameUI.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatInternalFrameUI.java
@@ -84,6 +84,8 @@ import javax.swing.plaf.basic.BasicInternalFrameUI;
 public class FlatInternalFrameUI
 	extends BasicInternalFrameUI
 {
+	protected FlatWindowResizer windowResizer;
+
 	public static ComponentUI createUI( JComponent c ) {
 		return new FlatInternalFrameUI( (JInternalFrame) c );
 	}
@@ -97,6 +99,18 @@ public class FlatInternalFrameUI
 		super.installUI( c );

 		LookAndFeel.installProperty( frame, "opaque", false );
+
+		windowResizer = createWindowResizer();
+	}
+
+	@Override
+	public void uninstallUI( JComponent c ) {
+		super.uninstallUI( c );
+
+		if( windowResizer != null ) {
+			windowResizer.uninstall();
+			windowResizer = null;
+		}
 	}

 	@Override
@@ -104,6 +118,10 @@ public class FlatInternalFrameUI
 		return new FlatInternalFrameTitlePane( w );
 	}

+	protected FlatWindowResizer createWindowResizer() {
+		return new FlatWindowResizer.InternalFrameResizer( frame, this::getDesktopManager );
+	}
+
 	//---- class FlatInternalFrameBorder --------------------------------------

 	public static class FlatInternalFrameBorder
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatRootPaneUI.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatRootPaneUI.java
@@ -172,7 +172,7 @@ public class FlatRootPaneUI
 	}

 	protected FlatWindowResizer createWindowResizer() {
-		return new FlatWindowResizer( rootPane );
+		return new FlatWindowResizer.WindowResizer( rootPane );
 	}

 	protected FlatTitlePane createTitlePane() {
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatWindowResizer.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatWindowResizer.java
@@ -17,11 +17,13 @@
 package com.formdev.flatlaf.ui;

 import static java.awt.Cursor.*;
+import static javax.swing.SwingConstants.*;
 import java.awt.Container;
 import java.awt.Dialog;
 import java.awt.Dimension;
 import java.awt.Frame;
 import java.awt.Graphics;
+import java.awt.Insets;
 import java.awt.Rectangle;
 import java.awt.Toolkit;
 import java.awt.Window;
@@ -34,54 +36,59 @@ import java.awt.event.WindowEvent;
 import java.awt.event.WindowStateListener;
 import java.beans.PropertyChangeEvent;
 import java.beans.PropertyChangeListener;
+import java.util.function.Supplier;
+import javax.swing.DesktopManager;
 import javax.swing.JComponent;
+import javax.swing.JInternalFrame;
 import javax.swing.JLayeredPane;
 import javax.swing.JRootPane;
 import javax.swing.UIManager;
 import com.formdev.flatlaf.util.UIScale;

 /**
- * Resizes frames and dialogs.
+ * Resizes frames, dialogs or internal frames.
+ * <p>
+ * Could also be used to implement resize support for any Swing component
+ * by creating a new subclass.
 *
 * @author Karl Tauber
 */
-public class FlatWindowResizer
-	implements PropertyChangeListener, WindowStateListener, ComponentListener
+public abstract class FlatWindowResizer
+	implements PropertyChangeListener, ComponentListener
 {
 	protected final static Integer WINDOW_RESIZER_LAYER = JLayeredPane.DRAG_LAYER + 1;

-	protected final JRootPane rootPane;
+	protected final JComponent resizeComp;

 	protected final int borderDragThickness = FlatUIUtils.getUIInt( "RootPane.borderDragThickness", 5 );
 	protected final int cornerDragWidth = FlatUIUtils.getUIInt( "RootPane.cornerDragWidth", 16 );
 	protected final boolean honorFrameMinimumSizeOnResize = UIManager.getBoolean( "RootPane.honorFrameMinimumSizeOnResize" );
 	protected final boolean honorDialogMinimumSizeOnResize = UIManager.getBoolean( "RootPane.honorDialogMinimumSizeOnResize" );

-	protected final JComponent north;
-	protected final JComponent south;
-	protected final JComponent west;
-	protected final JComponent east;
+	protected final DragBorderComponent topDragComp;
+	protected final DragBorderComponent bottomDragComp;
+	protected final DragBorderComponent leftDragComp;
+	protected final DragBorderComponent rightDragComp;

-	protected Window window;
+	protected FlatWindowResizer( JComponent resizeComp ) {
+		this.resizeComp = resizeComp;

-	public FlatWindowResizer( JRootPane rootPane ) {
-		this.rootPane = rootPane;
+		topDragComp = createDragBorderComponent( NW_RESIZE_CURSOR, N_RESIZE_CURSOR, NE_RESIZE_CURSOR );
+		bottomDragComp = createDragBorderComponent( SW_RESIZE_CURSOR, S_RESIZE_CURSOR, SE_RESIZE_CURSOR );
+		leftDragComp = createDragBorderComponent( NW_RESIZE_CURSOR, W_RESIZE_CURSOR, SW_RESIZE_CURSOR );
+		rightDragComp = createDragBorderComponent( NE_RESIZE_CURSOR, E_RESIZE_CURSOR, SE_RESIZE_CURSOR );

-		north = createDragBorderComponent( NW_RESIZE_CURSOR, N_RESIZE_CURSOR, NE_RESIZE_CURSOR );
-		south = createDragBorderComponent( SW_RESIZE_CURSOR, S_RESIZE_CURSOR, SE_RESIZE_CURSOR );
-		west = createDragBorderComponent( NW_RESIZE_CURSOR, W_RESIZE_CURSOR, SW_RESIZE_CURSOR );
-		east = createDragBorderComponent( NE_RESIZE_CURSOR, E_RESIZE_CURSOR, SE_RESIZE_CURSOR );
+		Container cont = (resizeComp instanceof JRootPane) ? ((JRootPane)resizeComp).getLayeredPane() : resizeComp;
+		Object cons = (cont instanceof JLayeredPane) ? WINDOW_RESIZER_LAYER : null;
+		cont.add( topDragComp, cons, 0 );
+		cont.add( bottomDragComp, cons, 1 );
+		cont.add( leftDragComp, cons, 2 );
+		cont.add( rightDragComp, cons, 3 );

-		JLayeredPane layeredPane = rootPane.getLayeredPane();
-		layeredPane.add( north, WINDOW_RESIZER_LAYER );
-		layeredPane.add( south, WINDOW_RESIZER_LAYER );
-		layeredPane.add( west, WINDOW_RESIZER_LAYER );
-		layeredPane.add( east, WINDOW_RESIZER_LAYER );
+		resizeComp.addComponentListener( this );
+		resizeComp.addPropertyChangeListener( "ancestor", this );

-		rootPane.addComponentListener( this );
-		rootPane.addPropertyChangeListener( "ancestor", this );
-
-		if( rootPane.isDisplayable() )
+		if( resizeComp.isDisplayable() )
 			addNotify();
 	}

@@ -92,85 +99,96 @@ public class FlatWindowResizer
 	public void uninstall() {
 		removeNotify();

-		rootPane.removeComponentListener( this );
-		rootPane.removePropertyChangeListener( "ancestor", this );
+		resizeComp.removeComponentListener( this );
+		resizeComp.removePropertyChangeListener( "ancestor", this );

-		JLayeredPane layeredPane = rootPane.getLayeredPane();
-		layeredPane.remove( north );
-		layeredPane.remove( south );
-		layeredPane.remove( west );
-		layeredPane.remove( east );
+		Container cont = topDragComp.getParent();
+		cont.remove( topDragComp );
+		cont.remove( bottomDragComp );
+		cont.remove( leftDragComp );
+		cont.remove( rightDragComp );
 	}

 	public void doLayout() {
-		if( !north.isVisible() )
+		if( !topDragComp.isVisible() )
 			return;

 		int x = 0;
 		int y = 0;
-		int width = rootPane.getWidth();
-		int height = rootPane.getHeight();
+		int width = resizeComp.getWidth();
+		int height = resizeComp.getHeight();
 		if( width == 0 || height == 0 )
 			return;

+		Insets resizeInsets = getResizeInsets();
 		int thickness = UIScale.scale( borderDragThickness );
-		int y2 = y + thickness;
-		int height2 = height - (thickness * 2);
+		int topThickness = Math.max( resizeInsets.top, thickness );
+		int bottomThickness = Math.max( resizeInsets.bottom, thickness );
+		int leftThickness = Math.max( resizeInsets.left, thickness );
+		int rightThickness = Math.max( resizeInsets.right, thickness );
+		int y2 = y + topThickness;
+		int height2 = height - topThickness - bottomThickness;

-		north.setBounds( x, y, width, thickness );
-		south.setBounds( x, y + height - thickness, width, thickness );
-		west.setBounds( x, y2, thickness, height2 );
-		east.setBounds( x + width - thickness, y2, thickness, height2 );
+		// set bounds of drag components
+		topDragComp.setBounds( x, y, width, topThickness );
+		bottomDragComp.setBounds( x, y + height - bottomThickness, width, bottomThickness );
+		leftDragComp.setBounds( x, y2, leftThickness, height2 );
+		rightDragComp.setBounds( x + width - rightThickness, y2, rightThickness, height2 );
+
+		// set corner drag widths
+		int cornerDelta = UIScale.scale( cornerDragWidth - borderDragThickness );
+		topDragComp.setCornerDragWidths( leftThickness + cornerDelta, rightThickness + cornerDelta );
+		bottomDragComp.setCornerDragWidths( leftThickness + cornerDelta, rightThickness + cornerDelta );
+		leftDragComp.setCornerDragWidths( cornerDelta, cornerDelta );
+		rightDragComp.setCornerDragWidths( cornerDelta, cornerDelta );
+	}
+
+	protected Insets getResizeInsets() {
+		return new Insets( 0, 0, 0, 0 );
 	}

 	protected void addNotify() {
-		Container parent = rootPane.getParent();
-		window = (parent instanceof Window) ? (Window) parent : null;
-		if( window instanceof Frame ) {
-			window.addPropertyChangeListener( "resizable", this );
-			window.addWindowStateListener( this );
-		}
-
 		updateVisibility();
 	}

 	protected void removeNotify() {
-		if( window instanceof Frame ) {
-			window.removePropertyChangeListener( "resizable", this );
-			window.removeWindowStateListener( this );
-		}
-		window = null;
-
 		updateVisibility();
 	}

 	protected void updateVisibility() {
 		boolean visible = isWindowResizable();
-		if( visible == north.isVisible() )
+		if( visible == topDragComp.isVisible() )
 			return;

-		north.setVisible( visible );
-		south.setVisible( visible );
-		west.setVisible( visible );
+		topDragComp.setVisible( visible );
+		bottomDragComp.setVisible( visible );
+		leftDragComp.setVisible( visible );

 		// The east component is not hidden, instead its bounds are set to 0,0,1,1 and
 		// it is disabled. This is necessary so that DragBorderComponent.paintComponent() is invoked.
-		east.setEnabled( visible );
+		rightDragComp.setEnabled( visible );
 		if( visible ) {
-			east.setVisible( true ); // necessary because it is initially invisible
+			rightDragComp.setVisible( true ); // necessary because it is initially invisible
 			doLayout();
 		} else
-			east.setBounds( 0, 0, 1, 1 );
+			rightDragComp.setBounds( 0, 0, 1, 1 );
 	}

-	protected boolean isWindowResizable() {
-		if( window instanceof Frame )
-			return ((Frame)window).isResizable() && (((Frame)window).getExtendedState() & Frame.MAXIMIZED_BOTH) == 0;
-		if( window instanceof Dialog )
-			return ((Dialog)window).isResizable();
+	boolean isDialog() {
 		return false;
 	}

+	protected abstract boolean isWindowResizable();
+	protected abstract Rectangle getWindowBounds();
+	protected abstract void setWindowBounds( Rectangle r );
+	protected abstract boolean honorMinimumSizeOnResize();
+	protected abstract Dimension getWindowMinimumSize();
+
+	protected void beginResizing( int direction ) {}
+	protected void endResizing() {}
+
+	//---- interface PropertyChangeListener ----
+
 	@Override
 	public void propertyChange( PropertyChangeEvent e ) {
 		switch( e.getPropertyName() ) {
@@ -187,10 +205,7 @@ public class FlatWindowResizer
 		}
 	}

-	@Override
-	public void windowStateChanged( WindowEvent e ) {
-		updateVisibility();
-	}
+	//---- interface ComponentListener ----

 	@Override
 	public void componentResized( ComponentEvent e ) {
@@ -201,6 +216,163 @@ public class FlatWindowResizer
 	@Override public void componentShown( ComponentEvent e ) {}
 	@Override public void componentHidden( ComponentEvent e ) {}

+	//---- class WindowResizer ------------------------------------------------
+
+	/**
+	 * Resizes frames and dialogs.
+	 */
+	public static class WindowResizer
+		extends FlatWindowResizer
+		implements WindowStateListener
+	{
+		protected Window window;
+
+		public WindowResizer( JRootPane rootPane ) {
+			super( rootPane );
+		}
+
+		@Override
+		protected void addNotify() {
+			Container parent = resizeComp.getParent();
+			window = (parent instanceof Window) ? (Window) parent : null;
+			if( window instanceof Frame ) {
+				window.addPropertyChangeListener( "resizable", this );
+				window.addWindowStateListener( this );
+			}
+
+			super.addNotify();
+		}
+
+		@Override
+		protected void removeNotify() {
+			if( window instanceof Frame ) {
+				window.removePropertyChangeListener( "resizable", this );
+				window.removeWindowStateListener( this );
+			}
+			window = null;
+
+			super.removeNotify();
+		}
+
+		@Override
+		protected boolean isWindowResizable() {
+			if( window instanceof Frame )
+				return ((Frame)window).isResizable() && (((Frame)window).getExtendedState() & Frame.MAXIMIZED_BOTH) == 0;
+			if( window instanceof Dialog )
+				return ((Dialog)window).isResizable();
+			return false;
+		}
+
+		@Override
+		protected Rectangle getWindowBounds() {
+			return window.getBounds();
+		}
+
+		@Override
+		protected void setWindowBounds( Rectangle r ) {
+			window.setBounds( r );
+
+			// immediately layout drag border components
+			doLayout();
+
+			if( Toolkit.getDefaultToolkit().isDynamicLayoutActive() ) {
+				window.validate();
+				resizeComp.repaint();
+			}
+		}
+
+		@Override
+		protected boolean honorMinimumSizeOnResize() {
+			return
+				(honorFrameMinimumSizeOnResize && window instanceof Frame) ||
+				(honorDialogMinimumSizeOnResize && window instanceof Dialog);
+		}
+
+		@Override
+		protected Dimension getWindowMinimumSize() {
+			return window.getMinimumSize();
+		}
+
+		@Override
+		boolean isDialog() {
+			return window instanceof Dialog;
+		}
+
+		@Override
+		public void windowStateChanged( WindowEvent e ) {
+			updateVisibility();
+		}
+	}
+
+	//---- class InternalFrameResizer -----------------------------------------
+
+	/**
+	 * Resizes internal frames.
+	 */
+	public static class InternalFrameResizer
+		extends FlatWindowResizer
+	{
+		protected final Supplier<DesktopManager> desktopManager;
+
+		public InternalFrameResizer( JInternalFrame frame, Supplier<DesktopManager> desktopManager ) {
+			super( frame );
+			this.desktopManager = desktopManager;
+
+			frame.addPropertyChangeListener( "resizable", this );
+		}
+
+		@Override
+		public void uninstall() {
+			getFrame().removePropertyChangeListener( "resizable", this );
+
+			super.uninstall();
+		}
+
+		private JInternalFrame getFrame() {
+			return (JInternalFrame) resizeComp;
+		}
+
+		@Override
+		protected Insets getResizeInsets() {
+			return getFrame().getInsets();
+		}
+
+		@Override
+		protected boolean isWindowResizable() {
+			return getFrame().isResizable();
+		}
+
+		@Override
+		protected Rectangle getWindowBounds() {
+			return getFrame().getBounds();
+		}
+
+		@Override
+		protected void setWindowBounds( Rectangle r ) {
+			desktopManager.get().resizeFrame( getFrame(), r.x, r.y, r.width, r.height );
+		}
+
+		@Override
+		protected boolean honorMinimumSizeOnResize() {
+			return true;
+		}
+
+		@Override
+		protected Dimension getWindowMinimumSize() {
+			return getFrame().getMinimumSize();
+		}
+
+		@Override
+		protected void beginResizing( int direction ) {
+			desktopManager.get().beginResizingFrame( getFrame(), direction );
+		}
+
+		@Override
+		protected void endResizing() {
+			desktopManager.get().endResizingFrame( getFrame() );
+		}
+	}
+
 	//---- class DragBorderComponent ------------------------------------------

 	protected class DragBorderComponent
@@ -213,6 +385,9 @@ public class FlatWindowResizer

 		private int resizeDir = -1;

+		private int leadingCornerDragWidth;
+		private int trailingCornerDragWidth;
+
 		// offsets of mouse position to window edges
 		private int dragLeftOffset;
 		private int dragRightOffset;
@@ -231,6 +406,11 @@ public class FlatWindowResizer
 			addMouseMotionListener( this );
 		}

+		void setCornerDragWidths( int leading, int trailing ) {
+			leadingCornerDragWidth = leading;
+			trailingCornerDragWidth = trailing;
+		}
+
 		protected void setResizeDir( int resizeDir ) {
 			if( this.resizeDir == resizeDir )
 				return;
@@ -250,12 +430,25 @@ public class FlatWindowResizer
 			super.paintChildren( g );

 			// this is necessary because Dialog.setResizable() does not fire events
-			if( window instanceof Dialog )
+			if( isDialog() )
 				updateVisibility();

 /*debug
+			int width = getWidth();
+			int height = getHeight();
+
+			g.setColor( java.awt.Color.blue );
+			boolean topOrBottom = (centerResizeDir == N_RESIZE_CURSOR || centerResizeDir == S_RESIZE_CURSOR);
+			if( topOrBottom ) {
+				g.drawLine( leadingCornerDragWidth, 0, leadingCornerDragWidth, height );
+				g.drawLine( width - trailingCornerDragWidth, 0, width - trailingCornerDragWidth, height );
+			} else {
+				g.drawLine( 0, leadingCornerDragWidth, width, leadingCornerDragWidth );
+				g.drawLine( 0, height - trailingCornerDragWidth, width, height - trailingCornerDragWidth );
+			}
+
 			g.setColor( java.awt.Color.red );
-			g.drawRect( 0, 0, getWidth() - 1, getHeight() - 1 );
+			g.drawRect( 0, 0, width - 1, height - 1 );
 debug*/
 		}

@@ -265,34 +458,55 @@ debug*/

 		@Override
 		public void mousePressed( MouseEvent e ) {
-			if( window == null )
+			if( !isWindowResizable() )
 				return;

 			int xOnScreen = e.getXOnScreen();
 			int yOnScreen = e.getYOnScreen();
-			Rectangle windowBounds = window.getBounds();
+			Rectangle windowBounds = getWindowBounds();

 			// compute offsets of mouse position to window edges
 			dragLeftOffset = xOnScreen - windowBounds.x;
 			dragTopOffset = yOnScreen - windowBounds.y;
 			dragRightOffset = windowBounds.x + windowBounds.width - xOnScreen;
 			dragBottomOffset = windowBounds.y + windowBounds.height - yOnScreen;
+
+			int direction = 0;
+			switch( resizeDir ) {
+				case N_RESIZE_CURSOR:	direction = NORTH; break;
+				case S_RESIZE_CURSOR:	direction = SOUTH; break;
+				case W_RESIZE_CURSOR:	direction = WEST; break;
+				case E_RESIZE_CURSOR:	direction = EAST; break;
+				case NW_RESIZE_CURSOR:	direction = NORTH_WEST; break;
+				case NE_RESIZE_CURSOR:	direction = NORTH_EAST; break;
+				case SW_RESIZE_CURSOR:	direction = SOUTH_WEST; break;
+				case SE_RESIZE_CURSOR:	direction = SOUTH_EAST; break;
+			}
+			beginResizing( direction );
+		}
+
+		@Override
+		public void mouseReleased( MouseEvent e ) {
+			if( !isWindowResizable() )
+				return;
+
+			dragLeftOffset = dragRightOffset = dragTopOffset = dragBottomOffset = 0;
+
+			endResizing();
 		}

-		@Override public void mouseReleased( MouseEvent e ) {}
 		@Override public void mouseEntered( MouseEvent e ) {}
 		@Override public void mouseExited( MouseEvent e ) {}

 		@Override
 		public void mouseMoved( MouseEvent e ) {
-			boolean topBottom = (centerResizeDir == N_RESIZE_CURSOR || centerResizeDir == S_RESIZE_CURSOR);
-			int xy = topBottom ? e.getX() : e.getY();
-			int wh = topBottom ? getWidth() : getHeight();
-			int cornerWH = UIScale.scale( cornerDragWidth - (topBottom ? 0 : borderDragThickness) );
+			boolean topOrBottom = (centerResizeDir == N_RESIZE_CURSOR || centerResizeDir == S_RESIZE_CURSOR);
+			int xy = topOrBottom ? e.getX() : e.getY();
+			int wh = topOrBottom ? getWidth() : getHeight();

-			setResizeDir( xy <= cornerWH
+			setResizeDir( xy <= leadingCornerDragWidth
 				? leadingResizeDir
-				: (xy >= wh - cornerWH
+				: (xy >= wh - trailingCornerDragWidth
 					? trailingResizeDir
 					: centerResizeDir) );
 		}
@@ -311,7 +525,7 @@ debug*/
 			// a window on first screen to the second screen, then the window manager may
 			// decide at some point that the window should be only on second screen
 			// and adjusts its bounds.
-			Rectangle oldBounds = window.getBounds();
+			Rectangle oldBounds = getWindowBounds();
 			Rectangle newBounds = new Rectangle( oldBounds );

 			// compute new window bounds
@@ -337,10 +551,7 @@ debug*/
 				newBounds.width = (xOnScreen + dragRightOffset) - newBounds.x;

 			// apply minimum window size
-			boolean honorMinimumSizeOnResize =
-				(honorFrameMinimumSizeOnResize && window instanceof Frame) ||
-				(honorDialogMinimumSizeOnResize && window instanceof Dialog);
-			Dimension minimumSize = honorMinimumSizeOnResize ? window.getMinimumSize() : null;
+			Dimension minimumSize = honorMinimumSizeOnResize() ? getWindowMinimumSize() : null;
 			if( minimumSize == null )
 				minimumSize = UIScale.scale( new Dimension( 150, 50 ) );
 			if( newBounds.width < minimumSize.width ) {
@@ -355,17 +566,8 @@ debug*/
 			}

 			// set window bounds
-			if( !newBounds.equals( oldBounds ) ) {
-				window.setBounds( newBounds );
-
-				// immediately layout drag border components
-				FlatWindowResizer.this.doLayout();
-
-				if( Toolkit.getDefaultToolkit().isDynamicLayoutActive() ) {
-					window.validate();
-					rootPane.repaint();
-				}
-			}
+			if( !newBounds.equals( oldBounds ) )
+				setWindowBounds( newBounds );
 		}
 	}
 }