/**
 * @(#)VerticalLabelUI.java	1.0 02/18/09
 */
package net.sf.jabref.gui;

import java.awt.Component;
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.Icon;
import javax.swing.JComponent;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
import javax.swing.plaf.ComponentUI;
import javax.swing.plaf.basic.BasicLabelUI;

/**
 * A UI delegate for JLabel that rotates the label 90�
 * <P>
 * Extends {@link BasicLabelUI}.
 * <P>
 * The only difference between the appearance of labels in the Basic and Metal
 * L&Fs is the manner in which diabled text is painted.  As VerticalLabelUI
 * does not override the method paintDisabledText, this class can be adapted
 * for Metal L&F by extending MetalLabelUI instead of BasicLabelUI.
 * <P>
 * No other changes are required.
 * 
 * @author Darryl
 */
public class VerticalLabelUI extends BasicLabelUI {

   private boolean clockwise = false;
   // see comment in BasicLabelUI
   Rectangle verticalViewR = new Rectangle();
   Rectangle verticalIconR = new Rectangle();
   Rectangle verticalTextR = new Rectangle();
   protected static VerticalLabelUI verticalLabelUI =
         new VerticalLabelUI();
   private final static VerticalLabelUI SAFE_VERTICAL_LABEL_UI =
         new VerticalLabelUI();

   /**
    * Constructs a <code>VerticalLabelUI</code> with the default anticlockwise
    * rotation
    */
   public VerticalLabelUI() {
   }

   /**
    * Constructs a <code>VerticalLabelUI</code> with the desired rotation.
    * <P>
    * @param clockwise true to rotate clockwise, false for anticlockwise
    */
   public VerticalLabelUI(boolean clockwise) {
      this.clockwise = clockwise;
   }

   /**
    * @see ComponentUI#createUI(javax.swing.JComponent) 
    */
   public static ComponentUI createUI(JComponent c) {
      if (System.getSecurityManager() != null) {
         return SAFE_VERTICAL_LABEL_UI;
      } else {
         return verticalLabelUI;
      }
   }

   /**
    * Overridden to always return -1, since a vertical label does not have a
    * meaningful baseline.
    * 
    * @see ComponentUI#getBaseline(JComponent, int, int)
    */
   @Override
   public int getBaseline(JComponent c, int width, int height) {
      super.getBaseline(c, width, height);
      return -1;
   }

   /**
    * Overridden to always return Component.BaselineResizeBehavior.OTHER,
    * since a vertical label does not have a meaningful baseline 
    * 
    * @see ComponentUI#getBaselineResizeBehavior(javax.swing.JComponent)
    */
   @Override
   public Component.BaselineResizeBehavior getBaselineResizeBehavior(
         JComponent c) {
      super.getBaselineResizeBehavior(c);
      return Component.BaselineResizeBehavior.OTHER;
   }

   /**
    * Transposes the view rectangles as appropriate for a vertical view
    * before invoking the super method and copies them after they have been
    * altered by {@link SwingUtilities#layoutCompoundLabel(FontMetrics, String,
    * Icon, int, int, int, int, Rectangle, Rectangle, Rectangle, int)}
    */
   @Override
   protected String layoutCL(JLabel label, FontMetrics fontMetrics,
         String text, Icon icon, Rectangle viewR, Rectangle iconR,
         Rectangle textR) {

      verticalViewR = transposeRectangle(viewR, verticalViewR);
      verticalIconR = transposeRectangle(iconR, verticalIconR);
      verticalTextR = transposeRectangle(textR, verticalTextR);

      text = super.layoutCL(label, fontMetrics, text, icon,
            verticalViewR, verticalIconR, verticalTextR);

      viewR = copyRectangle(verticalViewR, viewR);
      iconR = copyRectangle(verticalIconR, iconR);
      textR = copyRectangle(verticalTextR, textR);
      return text;
   }

   /**
    * Transforms the Graphics for vertical rendering and invokes the
    * super method.
    */
   @Override
   public void paint(Graphics g, JComponent c) {
      Graphics2D g2 = (Graphics2D) g.create();
      if (clockwise) {
         g2.rotate(Math.PI / 2, c.getSize().width / 2, c.getSize().width / 2);
      } else {
         g2.rotate(-Math.PI / 2, c.getSize().height / 2, c.getSize().height / 2);
      }
      super.paint(g2, c);
   }

   /**
    * Returns a Dimension appropriate for vertical rendering
    * 
    * @see ComponentUI#getPreferredSize(javax.swing.JComponent)
    */
   @Override
   public Dimension getPreferredSize(JComponent c) {
      return transposeDimension(super.getPreferredSize(c));
   }

   /**
    * Returns a Dimension appropriate for vertical rendering
    * 
    * @see ComponentUI#getMaximumSize(javax.swing.JComponent)
    */
   @Override
   public Dimension getMaximumSize(JComponent c) {
      return transposeDimension(super.getMaximumSize(c));
   }

   /**
    * Returns a Dimension appropriate for vertical rendering
    * 
    * @see ComponentUI#getMinimumSize(javax.swing.JComponent)
    */
   @Override
   public Dimension getMinimumSize(JComponent c) {
      return transposeDimension(super.getMinimumSize(c));
   }

   private Dimension transposeDimension(Dimension from) {
      return new Dimension(from.height, from.width + 2);
   }

   private Rectangle transposeRectangle(Rectangle from, Rectangle to) {
      if (to == null) {
         to = new Rectangle();
      }
      to.x = from.y;
      to.y = from.x;
      to.width = from.height;
      to.height = from.width;
      return to;
   }

   private Rectangle copyRectangle(Rectangle from, Rectangle to) {
      if (to == null) {
         to = new Rectangle();
      }
      to.x = from.x;
      to.y = from.y;
      to.width = from.width;
      to.height = from.height;
      return to;
   }
}