Cropping pages with QuickPDF Library

I’m quite sure I’ve carefully perused QuickPDF’s documentation, examples, references (both developer’s and functions’), yet I could find neither a simple explanation nor an example of a simple and straightforward operation: cropping pages. I’ve read the definition of methods like SetCropBox and SetRenderCropType, still I couldn’t understand how actually cropping is performed, where “actually cropping” trivially means, e.g. : “QuickPDF, take page three in the document loaded into the library and crop it with these top, left, height, width parameters I’m giving you”.

I assume this must be a very simple operation, hence I think / hope helping me will be easy and requiring a very short reply.

Thank you very much.

First, thank you for your reply.

Richard,

here's a very simple sample:

pdf := TDebenuPDFLibrary.Create;   try     pdf.LoadFromFile('d:\downloads\testseite.pdf', '');     pdf.SetOrigin(0);     dLeft := pdf.GetPageBox(2,0);     dTop := pdf.GetPageBox(2, 1);     dWidth := pdf.GetPageBox(2,2);     dHeight:= pdf.GetPageBox(2,3);     // CropBox :=  (dLeft, dTop, dLeft + dWidth, dTop - dHeight)        // reduze size by 50 PDF units     pdf.SetPageBox(2, dLeft + 50, dTop - 50, dWidth - 2 * 50, dHeight - 2 * 50);     pdf.SaveToFile('d:\downloads\testseite_red.pdf')   finally     pdf.Free;   end;

But please be aware that visually you will see only a change, when crop box is inside or equal media box (simplified said).
More general: what you see on screen is the intersection of Crop and Media box.

HTH,
Uli

I should add that your code works for me.  I tried it on an A4 PDF and got a PDF 174.6mm by 261.8mm, with the edge strips of the original document missing.

I know this is a bit late, but I needed to do some "cropping" work and based it on ukobsa's example.  I have discovered a few less-than-obvious things. 

First is that the example code only changes the first page.  It is necessary to use a page selection loop to change all of the pages -- that seems to work fine.

Second - this does not actually "crop" anything out of the file -- all of the existing data on each page is still there and the file remains about the same size.  I am guessing that the "SetCropBox" call just adds a small thing to each page telling it where the "useful" data is.

Adobe Acrobat does recognize the "CropBox" and does more or less what you would expect.  I'm not sure of exactly how it treats the cropbox on printing, but it is at least reasonable.

Thanks - Howard


Edited by HNRSoftware - 07 Apr 18 at 2:59PM