TipUtil.java

/*
 * 08/13/2009
 *
 * TipUtil.java - Utility methods for homemade tool tips.
 * 
 * This library is distributed under a modified BSD license.  See the included
 * RSyntaxTextArea.License.txt file for details.
 */
package org.fife.ui.autocomplete;

import java.awt.Color;
import java.awt.Font;
import java.awt.SystemColor;
import java.net.URL;
import javax.swing.BorderFactory;
import javax.swing.JEditorPane;
import javax.swing.UIManager;
import javax.swing.border.Border;
import javax.swing.plaf.ColorUIResource;
import javax.swing.text.html.HTMLDocument;


/**
 * Static utility methods for homemade tool tips.<p>
 *
 * This is blatantly ripped off from RSyntaxTextArea's "FocusableTips" class
 * of the same name, but isn't re-used to prevent a hard dependency on the
 * RSTA library.
 *
 * @author Robert Futrell
 * @version 1.0
 */
class TipUtil {


	private TipUtil() {
	}


	/**
	 * Returns the default background color to use for tool tip windows.
	 *
	 * @return The default background color.
	 */
	public static Color getToolTipBackground() {

		Color c = UIManager.getColor("ToolTip.background");

		// Tooltip.background is wrong color on Nimbus (!)
		boolean isNimbus = isNimbusLookAndFeel();
		if (c==null || isNimbus) {
			c = UIManager.getColor("info"); // Used by Nimbus (and others)
			if (c==null || (isNimbus && isDerivedColor(c))) {
				c = SystemColor.info; // System default
			}
		}

		// Workaround for a bug (?) with Nimbus - calling JLabel.setBackground()
		// with a ColorUIResource does nothing, must be a normal Color
		if (c instanceof ColorUIResource) {
			c = new Color(c.getRGB());
		}

		return c;

	}


	/**
	 * Returns the border used by tool tips in this look and feel.
	 *
	 * @return The border.
	 */
	public static Border getToolTipBorder() {

		Border border = UIManager.getBorder("ToolTip.border");

		if (border==null || isNimbusLookAndFeel()) {
			border = UIManager.getBorder("nimbusBorder");
			if (border==null) {
				border = BorderFactory.createLineBorder(SystemColor.controlDkShadow);
			}
		}

		return border;

	}


	/**
	 * Returns whether a color is a Nimbus DerivedColor, which is troublesome
	 * in that it doesn't use its RGB values (uses HSB instead?) and so
	 * querying them is useless.
	 *
	 * @param c The color to check.
	 * @return Whether it is a DerivedColor
	 */
	private static final boolean isDerivedColor(Color c) {
		return c!=null && (c.getClass().getName().endsWith(".DerivedColor") ||
				c.getClass().getName().endsWith(".DerivedColor$UIResource"));
	}


	/**
	 * Returns whether the Nimbus Look and Feel is installed.
	 *
	 * @return Whether the current LAF is Nimbus.
	 */
	private static final boolean isNimbusLookAndFeel() {
		return UIManager.getLookAndFeel().getName().equals("Nimbus");
	}


	/**
	 * Tweaks a <code>JEditorPane</code> so it can be used to render the
	 * content in a focusable pseudo-tool tip.  It is assumed that the editor
	 * pane is using an <code>HTMLDocument</code>.
	 *
	 * @param textArea The editor pane to tweak.
	 */
	public static void tweakTipEditorPane(JEditorPane textArea) {

		// Jump through a few hoops to get things looking nice in Nimbus
		boolean isNimbus = isNimbusLookAndFeel();
		if (isNimbus) {
			Color selBG = textArea.getSelectionColor();
			Color selFG = textArea.getSelectedTextColor();
			textArea.setUI(new javax.swing.plaf.basic.BasicEditorPaneUI());
			textArea.setSelectedTextColor(selFG);
			textArea.setSelectionColor(selBG);
		}

		textArea.setEditable(false); // Required for links to work!
		textArea.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));

		// Make selection visible even though we are not (initially) focusable.
		textArea.getCaret().setSelectionVisible(true);

		// Set the foreground color.  Important because when rendering HTML,
		// default foreground becomes black, which may not match all LAF's
		// (e.g. Substance).
		Color fg = UIManager.getColor("Label.foreground");
		if (fg==null || (isNimbus && isDerivedColor(fg))) {
			fg = SystemColor.textText;
		}
		textArea.setForeground(fg);

		// Make it use the "tool tip" background color.
		textArea.setBackground(TipUtil.getToolTipBackground());

		// Force JEditorPane to use a certain font even in HTML.
		// All standard LookAndFeels, even Nimbus (!), define Label.font.
		Font font = UIManager.getFont("Label.font");
		if (font == null) { // Try to make a sensible default
			font = new Font("SansSerif", Font.PLAIN, 12);
		}
		HTMLDocument doc = (HTMLDocument) textArea.getDocument();
		doc.getStyleSheet().addRule(
				"body { font-family: " + font.getFamily() +
						"; font-size: " + font.getSize() + "pt" +
						"; color: " + Util.getHexString(fg) + "; }");

		// Always add link foreground rule.  Unfortunately these CSS rules
		// stack each time the LaF is changed (how can we overwrite them
		// without clearing out the important "standard" ones?).
		Color linkFG = Util.getHyperlinkForeground();
		doc.getStyleSheet().addRule(
				"a { color: " + Util.getHexString(linkFG) + "; }");

		URL url = TipUtil.class.getResource("bullet_black.png");
		if (url!=null) {
			doc.getStyleSheet().addRule(
				"ul { list-style-image: '" + url.toString() + "'; }");
		}

	}


}