waverenderer.java

一个J2ME平台上实现的水波倒影效果

package org.gameeden.micro.effect;

import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;

/**
 * 水波渲染。
 * @author Sol
 * @since CLDC 1.1
 */
public final class WaveRenderer
{
    private long time;
    
    /**
     * 绘制波动的图像。
     * @param g 指定的Graphics上下文
     * @param img 图像源
     * @param inverted 是否颠倒图像
     * @param power 波能(0.0-1.0)
     * @param x_src 图像拷贝起始象素X坐标
     * @param y_src 图像拷贝起始象素Y坐标
     * @param width 图像拷贝宽
     * @param height 图像拷贝高
     * @param x_dest 锚点的象素X坐标
     * @param y_dest 锚点的象素Y坐标
     * @param anchor 图像锚点
     * @throws IllegalArgumentException 如果参数错误则抛出此异常
     */
    public void drawImage(Graphics g,Image img,boolean inverted,double power,int x_src,int y_src,int width,int height,int x_dest,int y_dest,int anchor) throws IllegalArgumentException
    {
        switch(anchor)
        {
            case Graphics.TOP|Graphics.LEFT:
            case Graphics.TOP|Graphics.RIGHT:
            case Graphics.TOP|Graphics.HCENTER:
            case Graphics.BOTTOM|Graphics.LEFT:
            case Graphics.BOTTOM|Graphics.RIGHT:
            case Graphics.BOTTOM|Graphics.HCENTER:
            case Graphics.VCENTER|Graphics.LEFT:
            case Graphics.VCENTER|Graphics.RIGHT:
            case Graphics.VCENTER|Graphics.HCENTER:
                break;
            default:
                throw new IllegalArgumentException();
        }
        
        if(power<0||power>1)
        {
            throw new IllegalArgumentException();
        }

        int swing=height>>3;
        int offsetX=-((anchor&Graphics.RIGHT)!=0?width:(anchor&Graphics.HCENTER)!=0?width>>1:0);
        int offsetY=-((anchor&Graphics.BOTTOM)!=0?height:(anchor&Graphics.VCENTER)!=0?height>>1:0);
        
        if(x_src<0||y_src<0||width<0||height<0||x_src+width>img.getWidth()||y_src+height>img.getHeight())
        {
            throw new IllegalArgumentException();
        }
        
        time++;

        for(int n=0,offset;n<height;n++)
        {
            offset=(int)((swing*(n+20)*Math.sin((double)swing*(height-n)/(n+1)+time)/height)*power);
            
            if(n+offset<0)
            {
                offset=-n;
            }
            else if(n+offset>=height)
            {
                offset=height-n-1;
            }

            g.setClip(x_dest+offsetX,y_dest+offsetY+n,width,1);
            
            if(inverted)
            {
                g.drawImage(img,x_dest+offsetX-x_src,y_dest+offsetY-y_src-height+1+(n<<1)+offset,Graphics.LEFT|Graphics.TOP);
            }
            else
            {
                g.drawImage(img,x_dest+offsetX-x_src,y_dest+offsetY-y_src-offset,Graphics.LEFT|Graphics.TOP);
            }
        }
    }
}