本文讲述如何在游戏开发中实现类似于打字的功能,其实原理和前面讲述的文字滚屏差别不大,主要还是利用Timer和Canvas提供的函数。

    我们的目的是把几个字按照顺序和一定的时间间隔打印在屏幕上,这就要求我们计算好文字的宽度和具体打印的位置。例如这样一个数组
    private final String[] content = { "hello ", "world ", "who ", "are ","you ", "?" };
我使用的办法是计算它们的相对距离,这样我用一个int类型的数组来存储这些数值。
    private int[] slen = new int[content.length];
slen[0]存储字开始打印的位置,这里我设置为10,slen[1]则存储开始位置与hello这个字的长度之和作为下个单词world的开始位置,依次类推。
    private void initSlen()
    {

        int temp = 10;

        for (int i = 0; i < content.length; i++)
        {
            slen[i] = temp;
            temp = temp + font.stringWidth(content[i]);

        }
    }
注意这里并没有考虑屏幕宽度的因素,如果你要显示多行的话应该考虑到屏幕的宽度,调整你的算法。

    在paint()方法里面我们就按照得到的坐标位置进行绘画
    protected void paint(Graphics arg0)
    {
        if (first)
        {
            arg0.setColor(128, 0, 128);
            arg0.fillRect(0, 0, getWidth(), height);
            first = false;

        }
        arg0.setColor(255, 255, 255);

        arg0.setFont(font);
        arg0.drawString(content[i], slen[i], height / 2, Graphics.LEFT
                | Graphics.TOP);
    }
程序并不复杂,下面给出源代码。

import javax.microedition.lcdui.Display;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

public class TypeMIDlet extends MIDlet
{

    private Display display;
    private TypeCanvas typeCanvas;

    protected void startApp() throws MIDletStateChangeException
    {

        display = Display.getDisplay(this);
        typeCanvas = new TypeCanvas();
        display.setCurrent(typeCanvas);

    }

    protected void pauseApp()
    {

    }

    protected void destroyApp(boolean arg0) throws MIDletStateChangeException
    {

    }

}

import java.util.Timer;
import java.util.TimerTask;

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;

public class TypeCanvas extends Canvas
{
    private Timer timer = new Timer();
    private int i = 0;
    private boolean first = true;
    private int height = getHeight();
    Font font = Font.getFont(Font.FACE_SYSTEM, Font.STYLE_BOLD,
            Font.SIZE_MEDIUM);
    private final String[] content = { "hello ", "world ", "who ", "are ",
            "you ", "?" };
    private int[] slen = new int[content.length];

    public TypeCanvas()
    {
        super();
        initSlen();
        TypeTask tt = new TypeTask();
        timer.schedule(tt, 300, 300);

    }

    protected void paint(Graphics arg0)
    {
        if (first)
        {
            arg0.setColor(128, 0, 128);
            arg0.fillRect(0, 0, getWidth(), height);
            first = false;

        }
        arg0.setColor(255, 255, 255);

        arg0.setFont(font);
        arg0.drawString(content[i], slen[i], height / 2, Graphics.LEFT
                | Graphics.TOP);
    }

    private void initSlen()
    {

        int temp = 10;

        for (int i = 0; i < content.length; i++)
        {
            slen[i] = temp;
            temp = temp + font.stringWidth(content[i]);

        }
    }

    private class TypeTask extends TimerTask
    {
        public void run()
        {

            if (i < content.length - 1)
            {
                repaint();
                i++;
            } else
            {
                timer.cancel();
            }

        }
    }
}