Android: make animation from still images

问题:

I've a series of still images and total of more than 500 images presented in drawable directory. I need to make an animation (load about 20 images per second). I want it to run smoothly and with no Out Of Memory Exception.

I've idea to do this that images for 2 to 3 seconds (40 to 60 images) should load in memory and displayed and then they should disposed off (release the memory) and then images for next 2 to 3 seconds should load. This technique can prevent Out Of Memory Exception. Its just an idea, I dont know whether its a good idea or not. Please guide me some better idea with some code to go with... If my idea is much better and can work then please tell me some helping code to do that.

After reading replies and doing as you suggest, I've written some code like this:

  <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/llMain">

<ViewFlipper android:id="@+id/imageflipper"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
<ImageView android:id="@+id/ImageView01"
        android:layout_width="fill_parent" 
        android:layout_height="fill_parent"        
        android:scaleType="centerInside"        
        android:layout_gravity="center" />
    </ViewFlipper>
    </LinearLayout>

and here is my code for doing animation:

public class Animation extends Activity {
ViewFlipper flipper;
int myIndex = 216;
private final Handler handler = new Handler();
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    flipper=(ViewFlipper)findViewById(R.id.imageflipper); 
    doTheAutoRefresh();
        //displayData();
}

private void doTheAutoRefresh() {
    handler.postDelayed(new Runnable() {
        public void run(){
            displayData(); // this is where you put your refresh code
            doTheAutoRefresh();
             }
         }, 30);

}

private void displayData()
{
    Resources r = getResources();
    if(myIndex > 230){
        myIndex = 216;
        ImageView myImg = (ImageView)findViewById(R.id.ImageView01);
        myImg.setImageResource(r.getIdentifier("drum0" + myIndex, "drawable", "com.vt.animation"));

        myIndex += 1;
        flipper.showNext();
    }
    else{
        ImageView myImg = (ImageView)findViewById(R.id.ImageView01);

        myImg.setImageResource(r.getIdentifier("drum0" + myIndex, "drawable", "com.vt.animation"));

        myIndex += 1;
        flipper.showNext();
    }
}

}

but its very slow. I've set up the refresh time to 30 milliseconds but actually its not refreshing too fast rather its refresh time is about 1 second. Any suggestion to make it fast to feel like real animation?

Thanks,

回答1:

Use a FrameAnimation, eg in res/drawable/movie.xml:

<?xml version="1.0" encoding="utf-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android"
    android:oneshot="true">
    <item android:drawable="@drawable/frame1" android:duration="50" />
    <item android:drawable="@drawable/frame2" android:duration="50" />
    <item android:drawable="@drawable/frame3" android:duration="50" />
    etc...
</animation-list>

And then in Java:

imageView.setBackgroundResource(R.drawable.movie);
AnimationDrawable anim = (AnimationDrawable) imageView.getBackground();
anim.start();

回答2:

OK. The biggest problem and the easiest solution I got to go with after so many days. I would never expect that it would be so easy to do... :D

I've used both handler and timer to achieve with just an image view, no flipper, no animator nothing else at all... Here is my solution:

----- main.xml file -----

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@drawable/background">

<ImageView 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:id="@+id/imageView1">
</ImageView>

And here is the way I have done it:

public class MainActivity extends Activity {
private ImageView _imagView;
private Timer _timer;
private int _index;
private MyHandler handler;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    handler= new MyHandler();
    _imagView=(ImageView) findViewById(R.id.imageView1);

    _index=0;
    _timer= new Timer();
    _timer.schedule(new TickClass(), 500, 200);
}

private class TickClass extends TimerTask
{
    @Override
    public void run() {
        // TODO Auto-generated method stub
        handler.sendEmptyMessage(_index);
        _index++;
    }
}

private class MyHandler extends Handler
{
    @Override
    public void handleMessage(Message msg) {
        // TODO Auto-generated method stub
        super.handleMessage(msg);

        try {
                Bitmap bmp= BitmapFactory.decodeStream(MainActivity.this.getAssets().open("drum_"+_index+".png"));
                _imagView.setImageBitmap(bmp);

                Log.v("Loaing Image: ",_index+"");
        } catch (IOException e) {
            // TODO Auto-generated catch block
            Log.v("Exception in Handler ",e.getMessage());
        }
    }
}

}

Note: I've placed all my images to asset directory.

Its so simple as it can, nothing big to do...

I hope it'll be helpful for someone looking to go like this :)

回答3:

Loading several images is very expensive.

I think it's better to load a single image containing all the movements of that certain animation. An animation strip.

private Bitmap animation = BitmapFactory.decodeResource(getResources(), R.drawable.myPng);

The idea is to traverse the bitmap.

回答4:

Well, I'm using viewFlipper, switching between views. Good thing about this one is that u can see previous picture sliding out while the new one slides in.

Inside image displaying method:

    if (direction == NEXT) {
        viewFlipper.setInAnimation(slideLeftIn);
        viewFlipper.setOutAnimation(slideLeftOut);

        if (currImg < max)
            currImg++;
        if (currImg == max)
            currImg = 0;

        if (currentView == 0) {
            currentView = 1;
            ImageView iv = (ImageView) findViewById(R.id.ImageView02);
            iv.setImageResource(images[currImg]);
        } else if (currentView == 1) {
            currentView = 2;
            ImageView iv = (ImageView) findViewById(R.id.ImageView03);
            iv.setImageResource(images[currImg]);
        } else {
            currentView = 0;
            ImageView iv = (ImageView) findViewById(R.id.ImageView01);
            iv.setImageResource(images[currImg]);
        }
        viewFlipper.showNext();
    }
    else if (direction == PREV) {
        viewFlipper.setInAnimation(slideRightIn);
        viewFlipper.setOutAnimation(slideRightOut);

        if (currImg > 0)
            currImg--;
        else if (currImg <= 0)
            currImg = (max-1);

        if (currentView == 0) {
            currentView = 2;
            ImageView iv = (ImageView) findViewById(R.id.ImageView03);
            iv.setImageResource(images[currImg]);
        } else if (currentView == 2) {
            currentView = 1;
            ImageView iv = (ImageView) findViewById(R.id.ImageView02);
            iv.setImageResource(images[currImg]);
        } else {
            currentView = 0;
            ImageView iv = (ImageView) findViewById(R.id.ImageView01);
            iv.setImageResource(images[currImg]);
        }
        viewFlipper.showPrevious();

And inside XML file:

        <ViewFlipper android:id="@+id/imageflipper"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" >

        <ImageView android:id="@+id/ImageView01"
            android:layout_width="wrap_content" 
            android:layout_height="wrap_content"        
            android:scaleType="centerInside"        
            android:layout_gravity="center" />

        <ImageView android:id="@+id/ImageView02"
            android:layout_width="wrap_content" 
            android:layout_height="wrap_content"        
            android:scaleType="centerInside"        
            android:layout_gravity="center" />

        <ImageView android:id="@+id/ImageView03"
            android:layout_width="wrap_content" 
            android:layout_height="wrap_content"        
            android:scaleType="centerInside"        
            android:layout_gravity="center" />

        </ViewFlipper>