自己写的平面柱状图,有个小bug

这几天突然想自己写个柱状图,查了下API,就开始动手写了个,用JApplet做的视图,方便调试,但是发现一个bug,不知道怎么回事,知道的请回下,谢谢.

下面是例程:

package com.lazy.histogram;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;

import javax.swing.JApplet;

/**
 * 柱状图
 * 
 * @author lazy_p
 * @date 2010-3-20
 */
public class PlaneHistogram extends JApplet {

	private static final long serialVersionUID = 2322130592726740649L;
	private final int imageHeight = 400;// 柱状图的默认高度
	private final int histogramWidth = 15;// 柱形图的宽度
	private final int histogramPitch = 10;// 柱形图的间距
	private float scaling = 1f;// 缩放的比例
	private int maxStrWidth = 0; // 字符串需要的最大宽度

	@Override
	public void paint(Graphics g) {
		paintPlaneHistogram(g, "柱状图", new int[] { 100, 60, 80, 50, 90 },
				new String[] { "苹果", " 梨子", "香蕉", "菠萝蜜", "火腿肠" }, new Color[] {
						Color.RED, Color.GREEN, Color.BLUE, Color.cyan,
						Color.BLACK });
	}

	/**
	 * <pre>
	 *   参数b[i]和str[i]必须对应
	 * </pre>
	 * 
	 * @param g
	 * @param title
	 * @param b
	 * @param str
	 * @param color
	 *            可以为空
	 */
	private void paintPlaneHistogram(Graphics g, String title, int[] b,
			String[] str, Color[] color) {

		FontMetrics metrics = null;

		// 调用calculateImageSize()计算出图片的高度和宽度
		setSize(calculateImageSize(g.getFontMetrics(new Font(null, Font.PLAIN,
				12)), str, b));

		g.setFont(new Font(null, Font.BOLD, 18));
		g.setColor(Color.RED);

		g.drawString(title, (this.getWidth() - g.getFontMetrics().stringWidth(
				title)) >> 1, 30);// 画标题

		g.setFont(new Font(null, Font.PLAIN, 12));

		metrics = g.getFontMetrics();

		g.setColor(Color.BLACK);

		g.drawLine(10, 0, 10, this.getHeight() - 15); // 画Y坐标
		g.drawLine(10, this.getHeight() - 15, this.getWidth(),
				this.getHeight() - 15);// 画X坐标

		for (int i = 0; i < b.length; ++i) {

			if (color != null)
				g.setColor(color[i]);// 设置前景色
			else
				g.setColor(Color.RED);

			int x = 20 + i
					* (histogramPitch + histogramWidth + (maxStrWidth >> 1));// 计算出X坐标
			int y = this.getHeight() - 16 - (int) (b[i] * scaling); // 计算出Y坐标

			// 画占的比例
			g.drawString(b[i] + "", x
					- ((metrics.stringWidth(b[i] + "") - histogramWidth) >> 1),
					y);

			// 画平面的柱状图
			g.drawRect(x, y, histogramWidth, (int) (b[i] * scaling));
			g.fillRect(x, y, histogramWidth, (int) (b[i] * scaling));

			// 画每一项表示的东西
			g.drawString(str[i], x
					- ((metrics.stringWidth(str[i]) - histogramWidth) >> 1),
					this.getHeight() - 2);
		}
	}

	/**
	 * 计算实际需要显示的高度和宽度
	 * 
	 * @param metrics
	 * @param str
	 * @param b
	 * @return Dimension
	 */
	private Dimension calculateImageSize(FontMetrics metrics, String[] str,
			int[] b) {
		int len = str.length;
		maxStrWidth = -1; // 字符串需要的最大宽度

		for (int i = 0; i < len; ++i) {
			int strwidth = metrics.stringWidth(str[i]); // 计算出该字符串需要占据的宽度
			if (strwidth > maxStrWidth)
				maxStrWidth = strwidth;
		}

		int maxHeight = -1;
		for (int i = 0; i < len; ++i) {
			if (b[i] > maxHeight)
				maxHeight = b[i];
		}

		int width = ((maxStrWidth >> 1) + histogramPitch + histogramWidth)
				* len;// 算出需要的宽度

		int height = imageHeight;
		if (maxHeight > height) {
			scaling = (float) height / maxHeight; // 当给的最大的比例值大于了默认的高度就算个比例
			height += 30;
		} else
			height = maxHeight + 80;

		return new Dimension(width + 15, height);
	}

	public static void main(String[] args) {

	}

}

效果如图:

下一步:把平面的转化为立体效果的,赫赫!到时整理下代码打包.

评论

1 楼 wskiwwwx 2012-01-09  

你怎么盗用我的文章啊，两个转载都没标注？？？？http://blog.csdn.net/lazy_p/article/details/5400268