android - サムネイルのロード時の AsyncTask での ViewHolder タグの問題

Question

CursorAdapterテキストとその横に画像を表示する独自のカスタムを作成しようとしています。ビューホルダーパターンとAsyncTask画像の読み込みに使用しています。私が書いたコードは正常に動作し、リストを下にスクロールし始めるまで、サムネイルに読み込まれる画像が、上にスクロールされた上の行に表示された画像の複製であるよりも、すべてをうまく読み込みます。ここで私が間違っていることを見つけてください。助けていただければ幸いです。

public class MyCustomCurserAdapter extends CursorAdapter {

    private static class ViewHolder {
        public TextView nameText;
        public ImageView imageThumbnail;
        public int position;
    }

    public MyCustomCurserAdapter(Context context, Cursor c, int flags) {
        super(context, c, flags);
    }

    @Override
    public void bindView(View view, Context arg1, Cursor cursor) {
        ViewHolder holder = (ViewHolder)view.getTag();

        int pathCol = cursor.getColumnIndex(NewPicSQLiteHelper.COLUMN_PATH);
        String imageInSD = cursor.getString(pathCol);  
        File imgFile = new  File(imageInSD);

        if(imgFile.exists()){

            int nameCol = cursor.getColumnIndex(NewPicSQLiteHelper.COLUMN_PIC_NAME);
            String name = cursor.getString(nameCol);

            if (name != null) 
                holder.nameText.setText(name);

            ImageTask task = new ImageTask(holder,cursor.getPosition());
            task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, imgFile.getAbsolutePath());
        }
    }

    @Override
    public View newView(Context arg0, Cursor cur, ViewGroup parent) {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        View view = inflater.inflate(R.layout.new_pic_item, parent, false);

        ViewHolder holder;

        holder = new ViewHolder();
        holder.nameText = (TextView) view.findViewById(R.id.pic_name_entry);
        holder.imageThumbnail = (ImageView) view.findViewById(R.id.pic_thumbnail);
        holder.imageThumbnail.setTag(Integer.valueOf(cur.getString(NewPicSQLiteHelper.INDEX_COLUMN_ID)));
        holder.position = cur.getPosition();
        // The tag can be any Object, this just happens to be the ViewHolder
        view.setTag(holder);
        return view;

    }



    private class ImageTask extends AsyncTask<String, Void, Bitmap>{
        private final WeakReference <ImageView> imageViewReference;

        int viewID;
        ViewHolder taskHolder;

        public ImageTask(ViewHolder holder,int position) {
            taskHolder = holder;
            ImageView imageView = taskHolder.imageThumbnail;
            imageViewReference = new WeakReference <ImageView> (imageView);
            viewID = position;
        }

        @Override
        protected Bitmap doInBackground(String... params) {
            String path = params[0];
            return decodeSampledBitmapFromResource(path,75,75);
        }


        @Override
        protected void onPostExecute(Bitmap result) {
            if (imageViewReference != null) {
                ImageView imageView = imageViewReference.get();
                if (imageView != null) {
                    Log.d("AsyncTask", "ImageView null");
                    if (result != null) {
                        if(viewID == taskHolder.position){
                            imageView.setImageBitmap(result);
                            imageView.setVisibility(ImageView.VISIBLE);
                            Log.d("AsyncTask", "Image position right");
                        }
                    } else {

                        Log.d("AsyncTask", "Image positions wrong");
                        imageView.setVisibility(ImageView.INVISIBLE);
                    }
                }
            }
        }


        private Bitmap decodeSampledBitmapFromResource(String orgImagePath, int reqWidth, int reqHeight) {

            ////.........
        }



        private int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
            ////.........

}