Fix #459: Add API to hide expanded folds except on hover, and do so w…

…hen the fold style is 'modern'

RSyntaxTextArea/src/main/java/org/fife/ui/rtextarea/AbstractGutterComponent.java

@@ -11,8 +11,10 @@
 import java.awt.Container;
 import java.awt.Rectangle;
 import java.awt.Shape;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
 
-import javax.swing.JPanel;
+import javax.swing.*;
 import javax.swing.event.DocumentEvent;
 import javax.swing.text.View;
 
@@ -35,6 +37,8 @@ abstract class AbstractGutterComponent extends JPanel {
 	 */
 	protected int currentLineCount;
 
+	private static Listener listener;
+
 
 	/**
 	 * Constructor.
@@ -47,6 +51,13 @@ abstract class AbstractGutterComponent extends JPanel {
 	}
 
 
+	@Override
+	public void addNotify() {
+		super.addNotify();
+		getListener().install(this);
+	}
+
+
 	/**
 	 * Returns the bounds of a child view as a rectangle, since
 	 * <code>View</code>s tend to use <code>Shape</code>.
@@ -81,6 +92,19 @@ protected Gutter getGutter() {
 	}
 
 
+	/**
+	 * Returns the singleton instance of the listener for all gutter components.
+	 *
+	 * @return The singleton instance.
+	 */
+	private static Listener getListener() {
+		if (listener == null) {
+			listener = new Listener();
+		}
+		return listener;
+	}
+
+
 	/**
 	 * Called when text is inserted to or removed from the text area.
 	 * Implementations can take this opportunity to repaint, revalidate, etc.
@@ -106,6 +130,13 @@ protected void init() {
 	abstract void lineHeightsChanged();
 
 
+	@Override
+	public void removeNotify() {
+		getListener().uninstall(this);
+		super.removeNotify();
+	}
+
+
 	/**
 	 * Sets the text area being displayed.  Subclasses can override, but
 	 * should call the super implementation.
@@ -122,4 +153,35 @@ public void setTextArea(RTextArea textArea) {
 	}
 
 
+	static class Listener extends MouseAdapter {
+
+		private boolean newArmed;
+
+		void install(AbstractGutterComponent component) {
+			component.addMouseListener(this);
+			component.addMouseMotionListener(this);
+		}
+
+		public void mouseExited(MouseEvent e) {
+			setArmed((AbstractGutterComponent)e.getComponent(), false);
+		}
+
+		public void mouseMoved(MouseEvent e) {
+			setArmed((AbstractGutterComponent)e.getComponent(), true);
+		}
+
+		private void setArmed(AbstractGutterComponent component, boolean armed) {
+			newArmed = armed;
+			SwingUtilities.invokeLater(() -> {
+				if (component.getGutter() != null && newArmed != component.getGutter().isArmed()) {
+					component.getGutter().setArmed(newArmed);
+				}
+			});
+		}
+
+		void uninstall(AbstractGutterComponent component) {
+			component.removeMouseListener(this);
+			component.removeMouseMotionListener(this);
+		}
+	}
 }

RSyntaxTextArea/src/main/java/org/fife/ui/rtextarea/ExpandedFoldRenderStrategy.java

@@ -0,0 +1,25 @@
+/*
+ * This library is distributed under a modified BSD license.  See the included
+ * LICENSE file for details.
+ */
+package org.fife.ui.rtextarea;
+
+
+/**
+ * The strategy to use when rendering expanded folds in the gutter.
+ *
+ * @author Robert Futrell
+ * @version 1.0
+ */
+public enum ExpandedFoldRenderStrategy {
+
+	/**
+	 * Always render expanded folds.
+	 */
+	ALWAYS,
+
+	/**
+	 * Only render expanded folds when the mouse is hovered over the gutter.
+	 */
+	ON_HOVER
+}

RSyntaxTextArea/src/main/java/org/fife/ui/rtextarea/FoldIndicator.java

@@ -106,6 +106,11 @@ public class FoldIndicator extends AbstractGutterComponent {
 	 */
 	private int additionalLeftMargin;
 
+	/**
+	 * The strategy to use when rendering expanded folds.
+	 */
+	private ExpandedFoldRenderStrategy expandedFoldRenderStrategy;
+
 	/**
 	 * The color used to paint fold outlines.
 	 */
@@ -187,6 +192,17 @@ private Fold findOpenFoldClosestTo(Point p) {
 	}
 
 
+	/**
+	 * Returns the strategy to use for rendering expanded folds.
+	 *
+	 * @return The strategy to use for rendering expanded folds.
+	 * @see #setExpandedFoldRenderStrategy(ExpandedFoldRenderStrategy)
+	 */
+	public ExpandedFoldRenderStrategy getExpandedFoldRenderStrategy() {
+		return expandedFoldRenderStrategy;
+	}
+
+
 	/**
 	 * Returns the color to use for the "background" of armed fold icons.  This
 	 * is ignored if custom icons are used.
@@ -214,6 +230,16 @@ public Color getFoldIconBackground() {
 	}
 
 
+	/**
+	 * Returns whether to paint expanded folds.
+	 *
+	 * @return Whether to paint expanded folds.
+	 */
+	private boolean getPaintExpandedFolds() {
+		return expandedFoldRenderStrategy == ExpandedFoldRenderStrategy.ALWAYS || getGutter().isArmed();
+	}
+
+
 	@Override
 	public Dimension getPreferredSize() {
 		int iconWidth = Math.max(expandedFoldIcon.getIconWidth(), collapsedFoldIcon.getIconWidth());
@@ -350,6 +376,7 @@ protected void init() {
 		listener = new Listener(this);
 		visibleRect = new Rectangle();
 		setShowCollapsedRegionToolTips(true);
+		setExpandedFoldRenderStrategy(ExpandedFoldRenderStrategy.ALWAYS);
 	}
 
 
@@ -464,7 +491,7 @@ protected void paintComponent(Graphics g) {
 						fold = fm.getFoldForLine(line);
 					} while (fold!=null && fold.isCollapsed());
 				}
-				else {
+				else if (getPaintExpandedFolds()) {
 					int x = (width - expandedFoldIcon.getIconWidth()) / 2;
 					paintIcon(expandedFoldIcon, g, x, y);
 				}
@@ -585,8 +612,10 @@ private void paintComponentWrapped(Graphics g) {
 					line += fold.getLineCount() + 1;
 				}
 				else {
-					int x = (width - expandedFoldIcon.getIconWidth()) / 2;
-					paintIcon(expandedFoldIcon, g, x, y);
+					if (getPaintExpandedFolds()) {
+						int x = (width - expandedFoldIcon.getIconWidth()) / 2;
+						paintIcon(expandedFoldIcon, g, x, y);
+					}
 					y += curLineH;
 					line++;
 				}
@@ -645,6 +674,20 @@ public void setAdditionalLeftMargin(int leftMargin) {
 	}
 
 
+	/**
+	 * Sets the strategy to use for rendering expanded folds.
+	 *
+	 * @param strategy The strategy to use. This cannot be {@code null}.
+	 * @see #getExpandedFoldRenderStrategy()
+	 */
+	public void setExpandedFoldRenderStrategy(ExpandedFoldRenderStrategy strategy) {
+		if (strategy == null) {
+			throw new NullPointerException("strategy cannot be null");
+		}
+		expandedFoldRenderStrategy = strategy;
+	}
+
+
 	/**
 	 * Sets the color to use for the "background" of armed fold icons.  This
 	 * will be ignored if custom icons are used.
@@ -742,11 +785,13 @@ void setStyle(FoldIndicatorStyle style) {
 			case CLASSIC:
 				setFoldIcons(new PlusMinusFoldIcon(true), new PlusMinusFoldIcon(false));
 				setShowArmedFoldRange(true);
+				setExpandedFoldRenderStrategy(ExpandedFoldRenderStrategy.ALWAYS);
 				break;
 
 			case MODERN:
 				setFoldIcons(new ChevronFoldIcon(true), new ChevronFoldIcon(false));
 				setShowArmedFoldRange(false);
+				setExpandedFoldRenderStrategy(ExpandedFoldRenderStrategy.ON_HOVER);
 				break;
 		}
 	}

RSyntaxTextArea/src/main/java/org/fife/ui/rtextarea/Gutter.java

@@ -171,6 +171,22 @@ public Gutter(RTextArea textArea) {
 	}
 
 
+	private boolean armed;
+	public boolean isArmed() {
+		return armed;
+	}
+
+	public void setArmed(boolean armed) {
+		if (armed != this.armed) {
+			this.armed = armed;
+			if (foldIndicator != null) {
+				foldIndicator.repaint();
+			}
+		}
+	}
+
+
+
 	/**
 	 * Adds an icon that tracks an offset in the document, and is displayed
 	 * adjacent to the line numbers.  This is useful for marking things such
@@ -341,6 +357,17 @@ public Color getCurrentLineNumberColor() {
 	}
 
 
+	/**
+	 * Returns the strategy to use for rendering expanded folds.
+	 *
+	 * @return The strategy to use for rendering expanded folds.
+	 * @see #setExpandedFoldRenderStrategy(ExpandedFoldRenderStrategy)
+	 */
+	public ExpandedFoldRenderStrategy getExpandedFoldRenderStrategy() {
+		return foldIndicator.getExpandedFoldRenderStrategy();
+	}
+
+
 	/**
 	 * Returns the background color used by the (default) fold icons.
 	 *
@@ -653,6 +680,17 @@ public void setCurrentLineNumberColor(Color color) {
 	}
 
 
+	/**
+	 * Sets the strategy to use for rendering expanded folds.
+	 *
+	 * @param strategy The strategy to use. This cannot be {@code null}.
+	 * @see #getExpandedFoldRenderStrategy()
+	 */
+	public void setExpandedFoldRenderStrategy(ExpandedFoldRenderStrategy strategy) {
+		foldIndicator.setExpandedFoldRenderStrategy(strategy);
+	}
+
+
 	/**
 	 * Sets the icons to use to represent collapsed and expanded folds.
 	 * This method can be used for further customization after setting this

RSyntaxTextArea/src/test/java/org/fife/ui/rtextarea/FoldIndicatorTest.java

@@ -91,6 +91,16 @@ void testGetSetAdditionalLeftMargin_error_negativeValue() {
 	}
 
 
+	@Test
+	void testGetSetExpandedFoldRenderStrategy() {
+		RSyntaxTextArea textArea = createTextArea();
+		FoldIndicator fi = new FoldIndicator(textArea);
+		Assertions.assertEquals(ExpandedFoldRenderStrategy.ALWAYS, fi.getExpandedFoldRenderStrategy());
+		fi.setExpandedFoldRenderStrategy(ExpandedFoldRenderStrategy.ON_HOVER);
+		Assertions.assertEquals(ExpandedFoldRenderStrategy.ON_HOVER, fi.getExpandedFoldRenderStrategy());
+	}
+
+
 	@Test
 	void testGetSetShowCollapsedRegionToolTips() {
 		RSyntaxTextArea textArea = createTextArea();
@@ -134,7 +144,7 @@ void testGetToolTipLocation_codeFoldingEnabledAndHoverOverCollapsedFold() {
 		hackyGutter.add(fi);
 
 		// Collapse the top-level fold, and create a synthetic mouse-over
-		// event over its fold indicataor.
+		// event over its fold indicator.
 		textArea.getFoldManager().getFold(0).setCollapsed(true);
 		MouseEvent e = new MouseEvent(textArea, 0, 0, 0, 3, 3, 0, false);
 
@@ -227,9 +237,17 @@ void testPaintComponent_noLineWrap() {
 
 	@Test
 	void testPaintComponent_modernLook() {
+
 		RSyntaxTextArea textArea = createTextArea();
+
+		// FoldIndicator needs a parent Gutter to calculate where to display
+		// the tool tip, but Gutter doesn't expose its child FoldIndicator
+		// via its API.  So here we really hack things to get around this.
 		FoldIndicator fi = new FoldIndicator(textArea);
 		fi.setStyle(FoldIndicatorStyle.MODERN);
+		Gutter hackyGutter = new Gutter(textArea);
+		hackyGutter.add(fi);
+
 		fi.paintComponent(createTestGraphics());
 	}
 

RSyntaxTextArea/src/test/java/org/fife/ui/rtextarea/GutterTest.java

@@ -283,6 +283,16 @@ void testGetSetCurrentLineNumberColor() {
 	}
 
 
+	@Test
+	void testGetSetExpandedFoldRenderStrategy() {
+		RTextArea textArea = new RTextArea(PLAIN_TEXT);
+		Gutter gutter = new Gutter(textArea);
+		Assertions.assertEquals(ExpandedFoldRenderStrategy.ALWAYS, gutter.getExpandedFoldRenderStrategy());
+		gutter.setExpandedFoldRenderStrategy(ExpandedFoldRenderStrategy.ON_HOVER);
+		Assertions.assertEquals(ExpandedFoldRenderStrategy.ON_HOVER, gutter.getExpandedFoldRenderStrategy());
+	}
+
+
 	@Test
 	void testGetSetFoldBackground() {