Auto crop the blank space on margin

[hilmanski]

Hi

I'd like to ask are there any way to "auto crop" the white space of the PDF. So we left with the area that only has content in it.

For example this PDF

will give us this result

*I know we can set it manually with setSize or crop.
What I'm asking here, is there any way to "AUTO" crop it? or detect the content at least.
I've try getCropBox, getArtBox, bleedbox, mediabox.. it gave me the same width and height as the original PDF

Thanks!