android转换图像中的Pdf渲染器是透明背景

Question

I'm a newbie for android developing. I'm working on converting Pdf to Image and storing it in a location. I have used the PdfRenderer (API level 21) to convert the PDF to bitmap Image. The converted image is Transparent background. Please guide me to convert the image with white background. So that I can convert it to binary digits.

PdfRenderer renderer = new PdfRenderer(ParcelFileDescriptor.open(pdfFile, ParcelFileDescriptor.MODE_READ_ONLY));

        Bitmap bitmap;
        final int pageCount = renderer.getPageCount();
        System.out.println("pageCount"+pageCount);
        for (int i = 0; i < pageCount; i++) {
            PdfRenderer.Page page = renderer.openPage(i);

            int width = getResources().getDisplayMetrics().densityDpi / 72 * page.getWidth();
            int height = getResources().getDisplayMetrics().densityDpi / 72 * page.getHeight();
            bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
page.render(bitmap, null, null, PdfRenderer.Page.RENDER_MODE_FOR_PRINT);
            storeImage(bitmap,"test.bmp");//I have wrote a function here to save the image

This is the Transparent Image I get after converting

Thanks in advance.

Answer 1

I have used canvas and it worked

Canvas canvas = new Canvas(bitmap);
canvas.drawColor(Color.WHITE);
canvas.drawBitmap(bitmap, 0, 0, null);

Thank you.

Answer 2

Using Abdul's answer, this is the complete implementation that worked for me to avoid having a transparent background in a bitmap that came from a Pdf.

int pageCount = renderer.getPageCount();
for (int pageIndex = 0; pageIndex < pageCount; pageIndex++) {
    PdfRenderer.Page page = renderer.openPage(pageIndex);
    Bitmap bitmap = Bitmap.createBitmap(page.getWidth(), page.getHeight(), Bitmap.Config.ARGB_8888);
    // Paint bitmap before rendering
    Canvas canvas = new Canvas(bitmap);
    canvas.drawColor(Color.WHITE);
    canvas.drawBitmap(bitmap, 0, 0, null);
    // Render Pdf page into bitmap
    page.render(bitmap, null, null, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);
    page.close();
    bitmaps.add(bitmap);
}