How to convert Pdf pages into bitmaps using PdfRender in every android api version's?

Question

I have looked through several codes and imported many libraries, i tried using PdfRender which is quite easy to use but it doesn't work below api version 21 and android-pdfviewer library code it makes the apk size lot bigger when i imported and used it in my project. Can anyone suggest some library or code to convert pdf every pages into bitmaps and saving it in arraylist which should not make apk size bigger and should support every versions of android.

Below i have attched my code PdfRender

ParcelFileDescriptor  pdfFile = ParcelFileDescriptor.open(pdf,
                            ParcelFileDescriptor.MODE_READ_ONLY);
              PdfRenderer pdfRenderer = new PdfRenderer(pdfFile);
                    if (pdfRenderer != null) {
                        for (int i = 0; i < pdfRenderer .getPageCount(); i++) {
                            // Open page with specified index
                            try {
                                if (pdfPage != null) {
                                    pdfPage .close();
                                }
                            } catch (Exception e) {
                                e.printStackTrace();
                            }
                            pdfPage = pdfRenderer.openPage(i);
                            Bitmap bitmap = Bitmap.createBitmap(olamPage.getWidth(),
                                    pdfPage .getHeight(), Bitmap.Config.ARGB_8888);

                            //Pdf page is rendered on Bitmap
                            pdfPage .render(bitmap, null, null,
                                    PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);
                            // ArrayList Adding Bitmaps
                            pdfBitmaps.add(bitmap);
                        }