/* BevelBorder.java -- 
   Copyright (C) 2003 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
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GNU Classpath is distributed in the hope that it will be useful, but
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02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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package javax.swing.border;

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Insets;


/**
 * A rectangular, two pixel thick border that causes the enclosed area
 * to appear as if it was raising out of or lowered into the screen. Some
 * LookAndFeels use this kind of border for rectangular buttons.
 *
 * <p>A BevelBorder has a highlight and a shadow color. In the raised
 * variant, the highlight color is used for the top and left edges,
 * and the shadow color is used for the bottom and right edge. For an
 * image, see the documentation of the individual constructors.
 *
 * @author Sascha Brawer (brawer@dandelis.ch)
 */
public class BevelBorder
  extends AbstractBorder
{
  /**
   * Determined using the <code>serialver</code> tool
   * of Apple/Sun JDK 1.3.1 on MacOS X 10.1.5.
   */
  static final long serialVersionUID = -1034942243356299676L;


  /**
   * Indicates that the BevelBorder looks like if the enclosed area was
   * raising out of the screen.
   */
  public static final int RAISED = 0;


  /**
   * Indicates that the BevelBorder looks like if the enclosed area was
   * pressed into the screen.
   */
  public static final int LOWERED = 1;
  

  /**
   * The type of this BevelBorder, which is either {@link #RAISED}
   * or {@link #LOWERED}.
   */  
  protected int bevelType;


  /**
   * The outer highlight color, or <code>null</code> to indicate that
   * the color shall be derived from the background of the component
   * whose border is being painted.
   */
  protected Color highlightOuter;


  /**
   * The inner highlight color, or <code>null</code> to indicate that
   * the color shall be derived from the background of the component
   * whose border is being painted.
   */
  protected Color highlightInner;


  /**
   * The outer shadow color, or <code>null</code> to indicate that the
   * color shall be derived from the background of the component whose
   * border is being painted.
   */
  protected Color shadowOuter;


  /**
   * The inner shadow color, or <code>null</code> to indicate that the
   * color shall be derived from the background of the component whose
   * border is being painted.
   */
  protected Color shadowInner;


  /**
   * Constructs a BevelBorder whose colors will be derived from the
   * background of the enclosed component. The background color is
   * retrieved each time the border is painted, so a BevelBorder
   * constructed by this method will automatically reflect a change
   * to the component&#x2019;s background color.
   *
   * <p><img src="doc-files/BevelBorder-1.png" width="500" height="150"
   * alt="[An illustration showing raised and lowered BevelBorders]" />
   *
   * @param bevelType the desired appearance of the border. The value
   *        must be either {@link #RAISED} or {@link #LOWERED}.
   *
   * @throws IllegalArgumentException if <code>bevelType</code> has
   *         an unsupported value.
   */
  public BevelBorder(int bevelType)
  {
    if ((bevelType != RAISED) && (bevelType != LOWERED))
      throw new IllegalArgumentException();

    this.bevelType = bevelType;
  }


  /**
   * Constructs a BevelBorder given its appearance type and two colors
   * for its highlight and shadow.
   *
   * <p><img src="doc-files/BevelBorder-2.png" width="500" height="150"
   * alt="[An illustration showing BevelBorders that were constructed
   * with this method]" />
   *
   * @param bevelType the desired appearance of the border. The value
   *        must be either {@link #RAISED} or {@link #LOWERED}.
   *
   * @param highlight the color that will be used for the inner
   *        side of the highlighted edges (top and left if
   *        if <code>bevelType</code> is {@link #RAISED}; bottom
   *        and right otherwise). The color for the outer side
   *        is a brightened version of this color.
   *
   * @param shadow the color that will be used for the outer
   *        side of the shadowed edges (bottom and right
   *        if <code>bevelType</code> is {@link #RAISED}; top
   *        and left otherwise). The color for the inner side
   *        is a brightened version of this color.
   *
   * @throws IllegalArgumentException if <code>bevelType</code> has
   *         an unsupported value.
   *
   * @throws NullPointerException if <code>highlight</code> or
   *         <code>shadow</code> is <code>null</code>.
   *
   * @see java.awt.Color.brighter()
   */
  public BevelBorder(int bevelType, Color highlight, Color shadow)
  {
    this(bevelType,
         /* highlightOuter */ highlight.brighter(),
         /* highlightInner */ highlight,
         /* shadowOuter */    shadow,
         /* shadowInner */    shadow.brighter());
  }


  /**
   * Constructs a BevelBorder given its appearance type and all
   * colors.
   *
   * <p><img src="doc-files/BevelBorder-3.png" width="500" height="150"
   * alt="[An illustration showing BevelBorders that were constructed
   * with this method]" />
   *
   * @param bevelType the desired appearance of the border. The value
   *        must be either {@link #RAISED} or {@link #LOWERED}.
   *
   * @param highlightOuter the color that will be used for the outer
   *        side of the highlighted edges (top and left if
   *        <code>bevelType</code> is {@link #RAISED}; bottom and
   *        right otherwise).
   *
   * @param highlightInner the color that will be used for the inner
   *        side of the highlighted edges.
   *
   * @param shadowOuter the color that will be used for the outer
   *        side of the shadowed edges (bottom and right
   *        if <code>bevelType</code> is {@link #RAISED}; top
   *        and left otherwise).
   *
   * @param shadowInner the color that will be used for the inner
   *        side of the shadowed edges.
   *
   * @throws IllegalArgumentException if <code>bevelType</code> has
   *         an unsupported value.
   *
   * @throws NullPointerException if one of the passed colors
   *         is <code>null</code>.
   */
  public BevelBorder(int bevelType,
                     Color highlightOuter, Color highlightInner,
                     Color shadowOuter, Color shadowInner)
  {
    this(bevelType); // checks the validity of bevelType

    if ((highlightOuter == null) || (highlightInner == null)
        || (shadowOuter == null) || (shadowInner == null))
      throw new NullPointerException();

    this.highlightOuter = highlightOuter;
    this.highlightInner = highlightInner;
    this.shadowOuter = shadowOuter;
    this.shadowInner = shadowInner;
  }


  /**
   * Paints the border for a given component.
   *
   * @param c the component whose border is to be painted.
   * @param g the graphics for painting.
   * @param x the horizontal position for painting the border.
   * @param y the vertical position for painting the border.
   * @param width the width of the available area for painting the border.
   * @param height the height of the available area for painting the border.
   */
  public void paintBorder(Component c, Graphics  g,
                          int x, int y, int width, int height)
  {
    switch (bevelType)
    {
    case RAISED:
      paintRaisedBevel(c, g, x, y, width, height);
      break;

    case LOWERED:
      paintLoweredBevel(c, g, x, y, width, height);
      break;
    }
  }


  /**
   * Measures the width of this border.
   *
   * @param c the component whose border is to be measured.
   *
   * @return an Insets object whose <code>left</code>, <code>right</code>,
   *         <code>top</code> and <code>bottom</code> fields indicate the
   *         width of the border at the respective edge.
   *
   * @see #getBorderInsets(java.awt.Component, java.awt.Insets)
   */
  public Insets getBorderInsets(Component c)
  {
    return new Insets(2, 2, 2, 2);
  }


  /**
   * Measures the width of this border, storing the results into a
   * pre-existing Insets object.
   *
   * @param insets an Insets object for holding the result values.
   *        After invoking this method, the <code>left</code>,
   *        <code>right</code>, <code>top</code> and
   *        <code>bottom</code> fields indicate the width of the
   *        border at the respective edge.
   *
   * @return the same object that was passed for <code>insets</code>.
   *
   * @see #getBorderInsets()
   */
  public Insets getBorderInsets(Component c, Insets insets)
  {
    insets.left = insets.right = insets.top = insets.bottom = 2;
    return insets;
  }

  
  /**
   * Determines the color that will be used for the outer side of
   * highlighted edges when painting the border.  If a highlight color
   * has been specified upon constructing the border, that color is
   * returned. Otherwise, the inner highlight color is brightened.
   *
   * @param c the component enclosed by this border.
   *
   * @see #getHighlightInnerColor(java.awt.Component)
   * @see java.awt.Color#brighter()
   */
  public Color getHighlightOuterColor(Component c)
  {
    if (highlightOuter != null)
      return highlightOuter;
    else
      return getHighlightInnerColor(c).brighter();
  }


  /**
   * Determines the color that will be used for the inner side of
   * highlighted edges when painting the border. If a highlight color
   * has been specified upon constructing the border, that color is
   * returned. Otherwise, the background color of the enclosed
   * component is brightened.
   *
   * @param c the component enclosed by this border.
   *
   * @see java.awt.Component#getBackground()
   * @see java.awt.Color#brighter()
   */
  public Color getHighlightInnerColor(Component c)
  {
    if (highlightInner != null)
      return highlightInner;
    else
      return c.getBackground().brighter();
  }


  /**
   * Determines the color that will be used for the inner side of
   * shadowed edges when painting the border. If a shadow color has
   * been specified upon constructing the border, that color is
   * returned. Otherwise, the background color of the enclosed
   * component is darkened.
   *
   * @param c the component enclosed by this border.
   *
   * @see java.awt.Component#getBackground()
   * @see java.awt.Color#darker()
   */
  public Color getShadowInnerColor(Component c)
  {
    if (shadowInner != null)
      return shadowInner;
    else
      return c.getBackground().darker();
  }


  /**
   * Determines the color that will be used for the outer side of
   * shadowed edges when painting the border.  If a shadow color
   * has been specified upon constructing the border, that color is
   * returned. Otherwise, the inner shadow color is darkened.
   *
   * @param c the component enclosed by this border.
   *
   * @see #getShadowInnerColor(java.awt.Component)
   * @see java.awt.Color#darker()
   */
  public Color getShadowOuterColor(Component c)
  {
    if (shadowOuter != null)
      return shadowOuter;
    else
      return getShadowInnerColor(c).darker();
  }


  /**
   * Returns the color that will be used for the outer side of
   * highlighted edges when painting the border, or <code>null</code>
   * if that color will be derived from the background of the enclosed
   * Component.
   */
  public Color getHighlightOuterColor()
  {
    return highlightOuter;
  }


  /**
   * Returns the color that will be used for the inner side of
   * highlighted edges when painting the border, or <code>null</code>
   * if that color will be derived from the background of the enclosed
   * Component.
   */
  public Color getHighlightInnerColor()
  {
    return highlightInner;
  }


  /**
   * Returns the color that will be used for the inner side of
   * shadowed edges when painting the border, or <code>null</code> if
   * that color will be derived from the background of the enclosed
   * Component.
   */
  public Color getShadowInnerColor()
  {
    return shadowInner;
  }


  /**
   * Returns the color that will be used for the outer side of
   * shadowed edges when painting the border, or <code>null</code> if
   * that color will be derived from the background of the enclosed
   * Component.
   */
  public Color getShadowOuterColor()
  {
    return shadowOuter;
  }
  
  
  /**
   * Returns the appearance of this border, which is either {@link
   * #RAISED} or {@link #LOWERED}.
   */
  public int getBevelType()
  {
    return bevelType;
  }


  /**
   * Determines whether this border fills every pixel in its area
   * when painting.
   *
   * <p>If the border colors are derived from the background color of
   * the enclosed component, the result is <code>true</code> because
   * the derivation method always returns opaque colors. Otherwise,
   * the result depends on the opacity of the individual colors.
   *
   * @return <code>true</code> if the border is fully opaque, or
   *         <code>false</code> if some pixels of the background
   *         can shine through the border.
   */
  public boolean isBorderOpaque()
  {
    /* If the colors are to be drived from the enclosed Component's
     * background color, the border is guaranteed to be fully opaque
     * because Color.brighten() and Color.darken() always return an
     * opaque color.
     */
    return 
      ((highlightOuter == null) || (highlightOuter.getAlpha() == 255))
      && ((highlightInner == null) || (highlightInner.getAlpha() == 255))
      && ((shadowInner == null) || (shadowInner.getAlpha() == 255))
      && ((shadowOuter == null) ||(shadowOuter.getAlpha() == 255));
  }


  /**
   * Paints a raised bevel border around a component.
   *
   * @param c the component whose border is to be painted.
   * @param g the graphics for painting.
   * @param x the horizontal position for painting the border.
   * @param y the vertical position for painting the border.
   * @param width the width of the available area for painting the border.
   * @param height the height of the available area for painting the border.
   */
  protected void paintRaisedBevel(Component c, Graphics g,
                                  int x, int y, int width, int height)
  {
    paintBevel(g, x, y, width, height,
               getHighlightOuterColor(c), getHighlightInnerColor(c),
               getShadowInnerColor(c), getShadowOuterColor(c));
  }


  /**
   * Paints a lowered bevel border around a component.
   *
   * @param c the component whose border is to be painted.
   * @param g the graphics for painting.
   * @param x the horizontal position for painting the border.
   * @param y the vertical position for painting the border.
   * @param width the width of the available area for painting the border.
   * @param height the height of the available area for painting the border.
   */
  protected void paintLoweredBevel(Component c, Graphics g,
                                   int x, int y, int width, int height)
  {
    paintBevel(g, x, y, width, height,
               getShadowInnerColor(c), getShadowOuterColor(c),
               getHighlightInnerColor(c), getHighlightOuterColor(c));
  }


  /**
   * Paints a two-pixel bevel in four colors.
   * 
   * <pre>
   * @@@@@@@@@@@@
   * @..........#    @ = color a
   * @.        X#    . = color b
   * @.        X#    X = color c
   * @.XXXXXXXXX#    # = color d
   * ############</pre>
   *
   * @param g the graphics for painting.
   * @param x the horizontal position for painting the border.
   * @param y the vertical position for painting the border.
   * @param width the width of the available area for painting the border.
   * @param height the height of the available area for painting the border.
   * @param a the color for the outer side of the top and left edges.
   * @param b the color for the inner side of the top and left edges.
   * @param c the color for the inner side of the bottom and right edges.
   * @param d the color for the outer side of the bottom and right edges.
   */
  private static void paintBevel(Graphics g,
                                 int x, int y, int width, int height,
                                 Color a, Color b, Color c, Color d)
  {
    Color oldColor;

    oldColor = g.getColor();
    g.translate(x, y);
    width = width - 1;
    height = height - 1;

    try
    {
      /* To understand this code, it might be helpful to look at the
       * images that are included with the JavaDoc. They are located
       * in the "doc-files" subdirectory.
       */
      g.setColor(a);
      g.drawLine(0, 0, width, 0);                       // a, horizontal
      g.drawLine(0, 1, 0, height);                      // a, vertical

      g.setColor(b);
      g.drawLine(1, 1, width - 1, 1);                   // b, horizontal
      g.drawLine(1, 2, 1, height - 1);                  // b, vertical

      g.setColor(c);
      g.drawLine(2, height - 1, width - 1, height - 1); // c, horizontal
      g.drawLine(width - 1, 2, width - 1, height - 2);  // c, vertical

      g.setColor(d);
      g.drawLine(1, height, width, height);             // d, horizontal
      g.drawLine(width, 1, width, height - 1);          // d, vertical
    }
    finally
    {
      g.translate(-x, -y);
      g.setColor(oldColor);
    }
  }
}