defaultwordrenderer.java

一套用于生成各种图形验证码的库(Java)

package nl.captcha.text.renderer;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.font.FontRenderContext;
import java.awt.font.GlyphVector;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

/**
 * Render a word using the given color and from a randomly selected font chosen from 
 * a list of fonts given in the constructor.
 * 
 * @author <a href="mailto:[e-mail]">James Childers</a>
 */
public class DefaultWordRenderer implements WordRenderer {

	private static final Color DEFAULT_COLOR = Color.BLACK;
	private static final List<Font> DEFAULT_FONTS = new ArrayList<Font>();
    
    private final Color _color;
    private final List<Font> _fonts;
    
    static {
    	DEFAULT_FONTS.add(new Font("Arial", Font.BOLD, 40));
        DEFAULT_FONTS.add(new Font("Courier", Font.BOLD, 40));	
    }
    
    /**
     * Will render the characters in black and in either 40pt Arial or Courier.
     */
    public DefaultWordRenderer() {
    	this(DEFAULT_COLOR, DEFAULT_FONTS);
    }
    
    public DefaultWordRenderer(Color color, List<Font> fonts) {
    	_color = color != null ? color : DEFAULT_COLOR;
    	_fonts = fonts != null ? fonts : DEFAULT_FONTS;
    }

    /**
     * Render a word onto a BufferedImage.
     * 
     * @param word The word to be rendered.
     * @param bi  The BufferedImage onto which the word will be painted on to
     */
    @Override
    public void render(String word, BufferedImage image) {
        Graphics2D g = image.createGraphics();

        RenderingHints hints = new RenderingHints(
                RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);
        hints.add(new RenderingHints(RenderingHints.KEY_RENDERING,
                RenderingHints.VALUE_RENDER_QUALITY));
        g.setRenderingHints(hints);

        g.setColor(_color);
        FontRenderContext frc = g.getFontRenderContext();
        int startPosX = 25;
        char[] wc = word.toCharArray();
        Random generator = new Random();
        for (char element : wc) {
            char[] itchar = new char[] { element };
            int choiceFont = generator.nextInt(_fonts.size());
            Font itFont = _fonts.get(choiceFont);
            g.setFont(itFont);

            GlyphVector gv = itFont.createGlyphVector(frc, itchar);
            double charWitdth = gv.getVisualBounds().getWidth();

            g.drawChars(itchar, 0, itchar.length, startPosX, 35);
            startPosX = startPosX + (int) charWitdth;
        }
    }
}