Custom SimpleCursor adapter BindView calls

Question

I wanted to know if there is a way to make the BindView work only once per item?

Are items that we scroll away from the screen getting destroyed? and when they come back we must run bindview again?

The reason is I got my adapter to Download an image and set it on the item.

when i scroll the image is getting downloaded again, even if i didnt quit the application.

the bindview is called each time an item "returns" into display so even tho i already downloaded it, it will preform the asyntask again ( the asyntask is called in the adapter)

I even tried saving BLOB on my database after each download, to know when to call the asyntast and when just to make a bitmap out of the array

if(photoBArray != null){    
            Bitmap bitmap = BitmapFactory.decodeByteArray(photoBArray, 0, photoBArray.length);
                holder.icon.setImageBitmap(bitmap);
            }else{
            holder.icon.setImageResource(R.drawable.loader);
            String urlString = "https://maps.googleapis.com/maps/api/place/photo?maxwidth=100&photoreference="
                    + c.getString(c.getColumnIndex(PlacesDBHelper.PHOTO_REFERENCE_COL))+"&key=API_KEY";
            Log.e("Photo REFERENCE", c.getString(c.getColumnIndex(PlacesDBHelper.PHOTO_REFERENCE_COL)));
            try {
                URL url = new URL(urlString); // create new URL object from url string
                new ImageDownloader(holder.icon, this).execute(url);
            }catch (Exception e){
                Log.e("Error in url", e.getMessage());
            }
            }

I am using chrisbanes pulltorefresh listview as well, im not sure if thats the casue for the problem

Bottom line question: how to make an item look steady and ready when he gets back into the screen and not beeign created again? ( cause even if i dont dowloand an image and only setting a bitmap, the action of setimagebitmap might be visible on a slow phone)

Thanks in advance!

Answer 1

The entire point of ListView is to recycle row views. They aren't destroyed, they are passed back to the adapter to be bound with new data for another row. It is expected that getView (or bindView in the case of cursor adapters) will be called again if you scroll an item off screen far enough and then scroll it back on screen.

What you need is an image caching layer between the download task and the adapter. When bindView happens, first check the cache to see if the image is there. If it is, use it. If it's not, download it and add it to the cache, then use it.