Android: Custom Horizontal Progress Bar Animation

Question

I'm trying to create a progress bar where the bar itself animates in a vertical spin as it progresses horizontally. I'm successfully using my progress drawable as the drawable via:

<ProgressBar
        android:id="@+id/progressBar"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        style="@android:style/Widget.ProgressBar.Horizontal"
        android:progressDrawable="@drawable/custom_progress"
        android:layout_marginRight="5dp" />

Here is my drawable:

But I want it to have a subtle roll effect as its progressing. So it would look like the vertical lines are moving backwards sorta. You follow? Any help is much appreciated. Thanks.

EDIT: I tried created an animation-list as my progress drawable but I'm still not able to see the animation. Can an animation-list be inside of a clip for the progress item?

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@android:id/background" android:drawable="@drawable/gutter"></item>

<item android:id="@android:id/progress">

<clip>
    <animation-list android:oneshot="false">
        <item android:drawable="@drawable/progress_bar_animate" android:duration="100" />
        <item android:drawable="@drawable/progress_bar_animate2" android:duration="100" />
        <item android:drawable="@drawable/progress_bar_animate3" android:duration="100" />
        <item android:drawable="@drawable/progress_bar_animate4" android:duration="100" />
        <item android:drawable="@drawable/progress_bar_animate5" android:duration="100" />
        <item android:drawable="@drawable/progress_bar_animate6" android:duration="100" />
        <item android:drawable="@drawable/progress_bar_animate7" android:duration="100" />
    </animation-list>
</clip>

</item>
</layer-list>

Answer 1

Yahoo! Finally ! Works ! (BUT !!!! can cause memory leak with big images. It's fixed in the post below)

This code takes the tile picture (tile1), repeats it(TileMode.REPEAT), makes shifted animation (10 fragments), adds this in Animation set.

private void initAnimation() {
//      R.drawable.tile1 is PNG
        Bitmap b = BitmapFactory.decodeResource(getResources(),R.drawable.tile1);
        AnimationDrawable shiftedAnimation = getAnimation(b);

//      R.id.img_3 is ImageView in my application
        View v = findViewById(R.id.img_3);
        v.setBackground(shiftedAnimation);
        shiftedAnimation.start();
}

private Bitmap getShiftedBitmap(Bitmap bitmap, int shiftX) {
    Bitmap newBitmap = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());
    Canvas newBitmapCanvas = new Canvas(newBitmap);

    Rect srcRect1 = new Rect(shiftX, 0, bitmap.getWidth(), bitmap.getHeight());
    Rect destRect1 = new Rect(srcRect1);
    destRect1.offset(-shiftX, 0);
    newBitmapCanvas.drawBitmap(bitmap, srcRect1, destRect1, null);

    Rect srcRect2 = new Rect(0, 0, shiftX, bitmap.getHeight());
    Rect destRect2 = new Rect(srcRect2);
    destRect2.offset(bitmap.getWidth() - shiftX, 0);
    newBitmapCanvas.drawBitmap(bitmap, srcRect2, destRect2, null);

    return newBitmap;
}

private List<Bitmap> getShiftedBitmaps(Bitmap bitmap) {
    List<Bitmap> shiftedBitmaps = new ArrayList<Bitmap>();
    int fragments = 10;
    int shiftLength = bitmap.getWidth() / fragments;

    for(int i = 0 ; i < fragments; ++i){
        shiftedBitmaps.add( getShiftedBitmap(bitmap,shiftLength * i));
    }

    return shiftedBitmaps;
}

private AnimationDrawable getAnimation(Bitmap bitmap) {
    AnimationDrawable animation = new AnimationDrawable();
    animation.setOneShot(false);

    List<Bitmap> shiftedBitmaps = getShiftedBitmaps(bitmap);
    int duration = 50;

    for(Bitmap image: shiftedBitmaps){
        BitmapDrawable navigationBackground = new BitmapDrawable(getResources(), image);
        navigationBackground.setTileModeX(TileMode.REPEAT);

        animation.addFrame(navigationBackground, duration);
    }
    return animation;
}

Answer 2

I don't think this can be done the way I thought it could. The reason being that I can't reference the animated-list, which at that point is a ClipDrawable, and cast it to an AnimateDrawable which is necessary so I can programmatically start the animation. It's also necessary to contain it in the clip element as that's the ProgressBar's way of masking an image so it only displays part of the image as its progressing.

Aside from faking my own progress bar using ImageViews and animating those I don't see another way around it for this specific ProgressBar.