2013.1.9

package com.kerwin.livewallpaper;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.os.Handler;
import android.service.wallpaper.WallpaperService;
import android.view.SurfaceHolder;

public class LiveWallpaperService extends WallpaperService {

    private int width,height,xPixelOffset;    
    
    private Bitmap bg;
    protected float bgOffsetStep;
    
    private boolean visible;
    private Engine eigine;
    private final Handler HANDLER = new Handler();
    private final Runnable DRAWTHREAD = new Runnable(){
        @Override
        public void run(){
            LiveWallpaperService.this.draw();
        }
    };    
    
    private synchronized void draw(){
        SurfaceHolder holder = this.eigine.getSurfaceHolder();
        Canvas canvas = holder.lockCanvas(null);
        if(canvas != null){
            if(Float.isNaN(bgOffsetStep)){
                canvas.drawBitmap(bg, null, new Rect(-this.bg.getWidth() / 3,0,this.bg.getWidth()+width-this.bg.getWidth() / 3,this.height), null);
            }else{
                canvas.drawBitmap(bg, null, new Rect(xPixelOffset,0,(int)(this.bg.getWidth()+width+xPixelOffset*bgOffsetStep),this.height), null);
            }
            holder.unlockCanvasAndPost(canvas);
        }
        if(this.visible){
            this.HANDLER.post(DRAWTHREAD);
        }
    }
    
    private void stop(){
        this.HANDLER.removeCallbacks(DRAWTHREAD);
    }
    
    private void loadBitmap(){
        this.bg = BitmapFactory.decodeStream(getResources().openRawResource(R.drawable.wallpaper));
    }
    
    @Override
    public Engine onCreateEngine() {
        return eigine = new MyEngine();
    }
    
    class MyEngine extends Engine{
        
        public MyEngine(){
            super();
            loadBitmap();
        }
        
        @Override
        public void onSurfaceChanged(SurfaceHolder holder, int format, int width, int height){
            super.onSurfaceChanged(holder, format, width, height);
            LiveWallpaperService.this.width = width;
            LiveWallpaperService.this.height = height;
        }
        
        @Override
        public void onVisibilityChanged(boolean visible){
            super.onVisibilityChanged(visible);
            LiveWallpaperService.this.visible = visible;
            if(visible){
                LiveWallpaperService.this.draw();
            }else{
                LiveWallpaperService.this.stop();
            }
        }
        
        @Override
        public void onOffsetsChanged(float xOffset, float yOffset, float xOffsetStep, float yOffsetStep, int xPixelOffset, int yPixelOffset){
            super.onOffsetsChanged(xOffset, yOffset, xOffsetStep, yOffsetStep, xPixelOffset, yPixelOffset);
            LiveWallpaperService.this.xPixelOffset = xPixelOffset;
            LiveWallpaperService.this.bgOffsetStep = ((float)(bg.getWidth()/Math.ceil((width/(width*xOffsetStep))+1))/(float)width)/xOffsetStep;
        }
    }

}