Adapter to work with MuPDF

PDFPageAdapter

public final class PDFPageAdapter extends BaseAdapter {
  //region Fields
  private final SparseArray<PointF> mPageSizes;
  private final Context mContext;
  private final MuPDFCore mCore;
  private final int mPages;
  //endregion

  //region Constructors
  public PDFPageAdapter(Context context, MuPDFCore core) {
    mPageSizes = new SparseArray<PointF>();
    mContext = context;
    mPages = core.countPages();
    mCore = core;
  }

  //endregion

  //region Base Adapter
  @Override public int getCount() {
    return mPages;
  }

  @Override public Object getItem(int position) {
    return null;
  }

  @Override public long getItemId(int position) {
    return position;
  }

  @Override public View getView(final int position, View convertView, ViewGroup parent) {
    final MuPDFPageView pageView;
    if (convertView == null) {
      Bitmap b = Bitmap.createBitmap(parent.getMeasuredWidth(), parent.getMeasuredHeight(), ARGB_8888);
      pageView = new MuPDFPageView(mContext, null, mCore, new Point(parent.getMeasuredWidth(), parent.getMeasuredHeight()), b);
    } else {
      pageView = (MuPDFPageView) convertView;
    }

    PointF pageSize = mPageSizes.get(position);
    if (pageSize != null) {
      pageView.setPage(position, pageSize);
    } else {
      pageView.blank(position);
      AsyncTask<Void,Void,PointF> sizingTask = new AsyncTask<Void,Void,PointF>() {
        @Override
        protected PointF doInBackground(Void... arg0) {
          return mCore.getPageSize(position);
        }

        @Override
        protected void onPostExecute(PointF result) {
          super.onPostExecute(result);
          mPageSizes.put(position, result);
          if (pageView.getPage() == position)
            pageView.setPage(position, result);
        }
      };

      sizingTask.execute((Void) null);
    }
    return pageView;
  }
  //endregion
}