Android Java：高效的位图动画分配

Question

I have 17 bitmaps of the same size that are frames of a character walking animation, and I want them to loop in my code. I want to be able to use inBitmap since I am reusing the same bitmaps. I have a few questions about doing this:

1. can I / should I cache the bitmaps, and if so how?

2. is there any more memory efficient way of doing this?

My code looks like this: (i am using a custom draw view)

onCreate:

        bitmapOptions.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(getResources(), R.drawable.walk0, bitmapOptions);
        aBitmap = Bitmap.createBitmap(bitmapOptions.outWidth,
                bitmapOptions.outHeight, Bitmap.Config.ARGB_8888);
        bitmapOptions.inJustDecodeBounds = false;
        bitmapOptions.inBitmap = aBitmap;
        bitmapOptions.inSampleSize = 1;
        BitmapFactory.decodeResource(getResources(), R.drawable.walk0, bitmapOptions);
        ship = Bitmap.createBitmap(aBitmap, 0, 0, aBitmap.getWidth(), aBitmap.getHeight(), shipMatrix, true);

onDraw:

@Override
protected void onDraw(Canvas canvas) 
{
shipRectf.right = ship.getWidth();
shipRectf.left = 0;
shipRectf.top = 0;
shipRectf.bottom = ship.getHeight();
canvas.drawBitmap(ship, null, shipRectf, null);
}

Animating:

Runnable walkData = new Runnable()
    {
        public void run(){
            try{    

                BitmapFactory.Options shipOptions = null;
                shipOptions = bitmapOptions;

                if(shipOptions != null){
                shipOptions.inBitmap = aBitmap;
                }
            if(walkAnim==true)
                {
                    walkNum = (walkNum + 1) % imageIDs.length;
                   //walknum = index, imageids = int[] {R.drawables}
                    aBitmap = BitmapFactory.decodeResource(getResources(), imageIDs[walkNum], shipOptions);
                    ship = Bitmap.createBitmap(aBitmap, 0, 0, aBitmap.getWidth(), aBitmap.getHeight(), shipMatrix, true);
                                           invalidate();

                }
                if(walkAnim==false)
                {
                    walkNum = 0;
                    ship = BitmapFactory.decodeResource(getResources(), imageIDs[walkNum], shipOptions);
                }


            handler3.postDelayed(this, 50);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    };

Answer 1

Loading your bitmaps at runtime like that is going to end up being very slow.

What I do is load all my bitmaps when the game is created, and store them in an array. Then when you are drawing you just reference the bitmap array and get the correct image for the current frame. It uses more memory but that's always the trade-off for faster runtime.