Question

我正在尝试使用IndexColorModel在Java中创建一个2位/ 4色位图。但是，当我运行代码时，我似乎遇到了错误。

import java.awt.Color;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import java.awt.image.IndexColorModel;

public class bitmaptest {

    public static void main(String[] args) {
        String text = "اردو لکھیئے";

        BufferedImage img = new BufferedImage(1, 1, BufferedImage.TYPE_BYTE_BINARY);

        Graphics2D g2d = img.createGraphics();
        Font font = new Font("Arabic Typesetting", Font.PLAIN, 48);
        g2d.setFont(font);
        FontMetrics fm = g2d.getFontMetrics();
        int width = fm.stringWidth(text);
        int height = fm.getHeight();
        g2d.dispose();

        Color[] colors = {Color.red, Color.green, Color.yellow,  
                Color.black};  
        byte[] reds = new byte[4];  
        byte[] greens = new byte[4];  
        byte[] blues = new byte[4];  
        for (int i = 0; i < colors.length; i++) {  
             reds[i] = (byte) colors[i].getRed();  
             greens[i] = (byte) colors[i].getGreen();  
             blues[i] = (byte) colors[i].getBlue();  
        }  
        IndexColorModel cm = new IndexColorModel(2, 4, reds, greens, blues); 

        BufferedImage img2 = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_BINARY, cm);
        g2d = img2.createGraphics();
        g2d.setFont(font);
        fm = g2d.getFontMetrics();
        g2d.setColor(Color.red);
        g2d.drawString(text, 0, fm.getAscent());
        g2d.dispose();
        try {
            ImageIO.write(img2, "BMP", new File("Text.bmp"));
            System.out.println(img2);
        } catch (IOException ex) {
            ex.printStackTrace();
        }

    }

}

我得到的错误是：

Exception in thread "main" java.lang.IndexOutOfBoundsException
    at java.io.RandomAccessFile.writeBytes0(Native Method)
    at java.io.RandomAccessFile.writeBytes(Unknown Source)
    at java.io.RandomAccessFile.write(Unknown Source)
    at javax.imageio.stream.FileImageOutputStream.write(Unknown Source)
    at com.sun.imageio.plugins.bmp.BMPImageWriter.write(Unknown Source)
    at javax.imageio.ImageWriter.write(Unknown Source)
    at javax.imageio.ImageIO.doWrite(Unknown Source)
    at javax.imageio.ImageIO.write(Unknown Source)
    at bitmaptest.main(bitmaptest.java:51)

我非常感谢任何帮助。谢谢。

Answer 1

将IndexColorModel颜色分量数组的大小更改为2或更小

IndexColorModel cm = new IndexColorModel(4, 2, reds, greens, blues);

或将Image类型从BufferedImage第三个参数构造函数调用更改为：

new BufferedImage(width, height, BufferedImage.TYPE_BYTE_INDEXED, cm);

文档提供了这些参数说明，可以让您更清楚地了解正在发生的事情：

public IndexColorModel（int bits， int size， byte [] cmap， int start， boolean hasalpha）
bits - the number of bits each pixel occupies
size - the size of the color component arrays
cmap - the array of color components
start - the starting offset of the first color component
hasalpha - indicates whether alpha values are contained in the cmap array

使用IndexColorModel在Java中创建2位/ 4色位图

1 个答案: