Centre-align images in generated iText PDF document

Question

I am using a library "com.itextpdf:itextg" for generating PDF files. My requirement is to add images to PDF file in A4 format, One Image per page.

ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
Image image = Image.getInstance(stream.toByteArray());
image.scaleToFit(PageSize.A4);
document.add(image);

By default, images are added as top-aligned and some space is left vacant at bottom of the PDF document page.

I want to centre-align Images, so that equal space is left from all sides and the image is placed at the centre.

I know we have a method setAbsolutePosition, but it requires absoluteX and absoluteY. I needed something relative like CENTRE_HORIZONTAL and CENTRE_VERTICAL. Can someone help in generating PDF with images centre-aligned (vertically and horizontally)?

Answer 1

If you really need A4 pages, then you need to calculate the X, Y position for the scaled image so that it is centered both horizontally and vertically.

image.scaleToFit(PageSize.A4.getWidth(), PageSize.A4.getHeight());
float x = (PageSize.A4.getWidth() - image.getScaledWidth()) / 2;
float y = (PageSize.A4.getHeight() - image.getScaledHeight()) / 2;
image.setAbsolutePosition(x, y);
document.add(image);

This will center the image on an A4 page.

However, if I were you, I wouldn't try to center images on an A4 page. Instead, I'd adapt the page size to the size of the image instead.

Answer 2

horizontal center alignment of image can achieve by following code

        Image signature = Image.getInstance(stream.toByteArray());
        signature.scaleAbsolute(70f, 70f);
        signature.setAlignment(Element.ALIGN_CENTER);