Android动态壁纸-为什么这么慢-如何提高速度？

Question

I'm attempting to create my first Live Wallpaper. It works and everything would be just fine except of the speed problem. It slows down desktop - widgets and icons are scrolling noticeably slower than when using pro live wallpapers (I'm testing it on Samsung note so there shouldn't be a speed problem). I start thinking that I do it all wrong way- so take a look at my code please:

public class DemoWallpaperService extends WallpaperService {


@Override
public Engine onCreateEngine() {
    return new DemoWallpaperEngine();

}

private class DemoWallpaperEngine extends Engine {
    private boolean mVisible = false;
    private final Handler mHandler = new Handler();

     int x=0,y=0,a=255,i=-1, a1=255, i1=-1;
     float r=0,rs=1;
     float rx1=10, rxs=-1;

     private Matrix mMatrix = new Matrix();
     private Matrix mMatrix1 = new Matrix();
     private Matrix mMatrixRotate1 = new Matrix();
     private Matrix mMatrixRotate2 = new Matrix();

     public Bitmap spaceShip = BitmapFactory.decodeResource(getResources(), R.drawable.spaceship);
     public Bitmap background= BitmapFactory.decodeResource(getResources(), R.drawable.back2short2j);
     public Bitmap wyspa= BitmapFactory.decodeResource(getResources(), R.drawable.wyspa22g);
     public Bitmap ksiezyc = BitmapFactory.decodeResource(getResources(), R.drawable.ksiezyc);
     public Bitmap reflektorfront= BitmapFactory.decodeResource(getResources(), R.drawable.reflektorwyspa);

     private float mPixels;
     private float mPixels1;



    private final Runnable mUpdateDisplay = new Runnable() {
    @Override
    public void run() {
        draw();
    }};



    private void draw() {
       SurfaceHolder holder = getSurfaceHolder();
       Canvas c = null;

       Display d = ((WindowManager)getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
       int wx= d.getWidth();
       int wy= d.getHeight();


       try {
           Runtime.getRuntime().gc();
          c = holder.lockCanvas();
          c.save();

          if (c != null) {

              Paint paintMoon = new Paint();

              if(a1<=15){
                  i1=1;
              }
              else if(a1>=255){
                  i1=-1;
              }
              a1+=5*i1;
              paintMoon.setAlpha(a1);

              c.translate((float)mPixels, 0f);
              c.drawBitmap(background, mMatrix, null);
              c.drawBitmap(ksiezyc, 1027*wx/480,15*wy/800, paintMoon);

              if(rx1<=-15){
                  rxs=1;
              }
              else if(rx1>=15){
                  rxs=-1;
              }
              rx1+=rxs*0.7;

              c.translate((float)mPixels1, 0f);
              //reflektor wyspa back
              mMatrixRotate2.setTranslate(340*wx/480,300*wy/800);
              mMatrixRotate2.preRotate(rx1,reflektorfront.getWidth()/2,20);
              c.drawBitmap(reflektorfront, mMatrixRotate2, null);


              c.drawBitmap(wyspa, mMatrix1, null);

              if(r<=-15){
                  rs=1;
              }
              else if(r>=15){
                  rs=-1;
              }
              r+=rs*0.5;


              mMatrixRotate1.setTranslate(160*wx/480,380*wy/800);

              mMatrixRotate1.preRotate(r,reflektorfront.getWidth()/2,20);

              c.drawBitmap(reflektorfront, mMatrixRotate1, null);


              if(x<c.getWidth()){
              x+=3;}
              else{x=0;}
              if(y<c.getHeight()){
              y+=3;}
              else{y=0;}
              Paint paint = new Paint();


              if(a<=5){
                  i=1;
              }
              else if(a>=255){
                  i=-1;
              }
              a+=10*i;
              paint.setAlpha(a);

              c.drawBitmap(spaceShip,x,y,paint);


                 c.restore();

          }
       } finally {
          if (c != null)
             holder.unlockCanvasAndPost(c);
       }
       mHandler.removeCallbacks(mUpdateDisplay);
       if (mVisible) {
           mHandler.postDelayed(mUpdateDisplay, 10);
       }
    }
    @Override
    public void onOffsetsChanged(float xOffset, float yOffset,
             float xStep, float yStep, int xPixels, int yPixels){

        super.onOffsetsChanged(xOffset, yOffset, xStep, yStep, xPixels, yPixels);                   
         mPixels = xPixels*7/4;

         mPixels1 = 500+xPixels;

            draw();
    }



    @Override
    public void onVisibilityChanged(boolean visible) {
        mVisible = visible;
        if (visible) {
            draw();
        } else {
            mHandler.removeCallbacks(mUpdateDisplay);
        }
    }

     @Override
      public void onSurfaceChanged(SurfaceHolder holder, int format, int width, int height) {

         super.onSurfaceChanged(holder, format, width, height);

         float w = background.getWidth();
         float h = background.getHeight();
         float s = height / (float)h;
         float z = height / (float)h;
         mMatrix.reset();
         mMatrix1.reset();
         mMatrixRotate1.reset();
         mMatrixRotate2.reset();

         mMatrix.setScale(s, s);
         mMatrix1.setScale(z, z);
         mMatrixRotate1.setScale(s, s);

         draw();
      }

    @Override
    public void onSurfaceDestroyed(SurfaceHolder holder) {
        super.onSurfaceDestroyed(holder);
        mVisible = false;
        mHandler.removeCallbacks(mUpdateDisplay);
    }


    @Override
     public void onCreate(SurfaceHolder surfaceHolder) {
         super.onCreate(surfaceHolder);

         setTouchEventsEnabled(false);
     }

    @Override
    public void onDestroy() {
         super.onDestroy();
         mVisible = false;
         mHandler.removeCallbacks(mUpdateDisplay);
    }
}    

Basically its a bitmap at background (850x480jpg 70kb), that scrolls slower, bitmap at front (350x400 transparent gif 100 kb) that scrolls faster (to achieve parallax effect) and some smaller png bitmaps (3x 10-20 kb 50x50) that are rotating and moving at the foreground (lights and space ships).

My question is - am I missing the point - I'm animating it by refreshing draw() function with a delay set to 10. (that's the only way I know - should I animate it some other way? Are the bitmaps too big? Or why is it so slow? Should I use sprites to animate front small effects to make it faster? Are there other ways of animating life wallpaper? I went through many tutorials and I've come so far but now I have to ask for help.

Answer 1

I'm not sure it is the complete answer... But it is worth attempting this. Rather than referencing the bitmap using Bitmap.decodeResources() method, try this:

pic1 = Bitmap.createScaledBitmap(background, (int)background.getWidth(), (int)background.getHeight(), true);

I've been building parallax wallpapers for a while and have found that the slowness normally is due to how many bitmaps are drawn on the screen.