multilinelabel.java

经典的货郎担问题解决办法

//
// Label ueber mehrere Zeilen
//
// Java in a Nutshell, p. 120
//
// From the VoroGlide distribution, which is marked
// Copyright 1996-1997 Praktische Informatik VI, FernUniversit鋞 Hagen
// Christian Icking, Rolf Klein, Peter K鰈lner, Lihong Ma

package com.well.www.user.xanthian.java.tools;

import java.awt.*;
import java.util.*;

public class MultiLineLabel extends Canvas
{
  public static final int LEFT = 0;
  public static final int CENTER = 1;
  public static final int RIGHT = 2;

  protected String[] lines;
  protected int num_lines;
  protected int margin_width;
  protected int margin_height;
  protected int line_height;
  protected int line_ascent;
  protected int[] line_widths;
  protected int max_width;
  protected int alignment = LEFT;

  protected void newLabel(String label)
  {
    StringTokenizer t = new StringTokenizer(label, "\n");
    num_lines = t.countTokens();
    lines = new String[num_lines];
    line_widths = new int[num_lines];
    for(int i = 0; i<num_lines; i++)
      lines[i] = t.nextToken();
  }

  protected void measure()
  {
    FontMetrics fm = this.getFontMetrics(this.getFont());

    if(fm == null) return;

    line_height = fm.getHeight();
    line_ascent = fm.getAscent();
    max_width = 0;
    for(int i = 0; i < num_lines; i++)
    {
      line_widths[i] = fm.stringWidth(lines[i]);
      if(line_widths[i] > max_width)
        max_width = line_widths[i];
    }
  }

  public MultiLineLabel
  (
    String label,
    int margin_width,
    int margin_height,
    int alignment
  )
  {
    newLabel(label);
    this.margin_width = margin_width;
    this.margin_height = margin_height;
    this.alignment = alignment;
  }

  public MultiLineLabel(String label, int margin_width, int margin_height)
  {
    this(label, margin_width, margin_height, LEFT);
  }

   public MultiLineLabel(String label, int alignment)
   {
     this(label, 10, 10, alignment);
  }

   public MultiLineLabel(String label)
   {
     this(label, 10, 10, LEFT);
  }

  public void setLabel(String label)
  {
    newLabel(label);
    measure();
    repaint();
  }

  public void setFont(Font f)
  {
    super.setFont(f);
    measure();
    repaint();
  }

  public void setForeground(Color c)
  {
    super.setForeground(c);
    repaint();
  }

  public void setAlignment(int a)
  {
    alignment = a;
    repaint();
  }

  public void setMarginWidth(int mw)
  {
    margin_width = mw;
    repaint();
  }

  public void setMarginHeight(int mh)
  {
    margin_height = mh;
    repaint();
  }

  public int getAlignment()
  {
    return(alignment);
  }

  public int getMarginWidth()
  {
    return(margin_width);
  }

  public int getMarginHeight()
  {
    return(margin_height);
  }

  public void addNotify()
  {
    super.addNotify();
    measure();
  }

  public Dimension getPreferredSize()
  {
    return new
    Dimension
    (
      max_width + 2 * margin_width,
      num_lines * line_height + 2 * margin_height
    );
  }

  public Dimension getMinimumSize()
  {
    return new Dimension(max_width, num_lines * line_height);
  }

  public void paint(Graphics g)
  {
    int x, y;

    Dimension d = this.getSize();
    y = line_ascent + (d.height - num_lines * line_height)/2;

    for(int i = 0; i < num_lines; i++, y += line_height)
    {
      switch(alignment) {
        case LEFT:
          x = margin_width;
          break;
        case CENTER:
        default:
          x = (d.width - line_widths[i])/2;
          break;
        case RIGHT:
          x = d.width - margin_width - line_widths[i];
          break;
      }
      g.drawString(lines[i], x, y);
    }
  }
}