When importing / linking to PDF files as ”rasters” I'm lacking an important feature for preserving the bleed that the PDF files might have.
In the current implementation, PDF files that are imported/linked to APP as “raster images”, will lose their bleed area when going through APP. This due to the fact that APP always uses the imported file’s Trimbox. This means that if the PDF has “correctly defined” PDF boxes (MediaBox larger than Trimbox) the bleed will always be left outside and that makes the PDF import unusable for these files. Today you will not be able to use APP for imposition of business cards PDF with bleed defined in Media Boxes. You will simply never be able to output the bleed through APP. This is, of course a problem because if bleed is there, it needs to be outputted in order to be able to print the document correctly.
Expose the PDFlib option “boxexpand” which will let you choose which box to apply when importing the “PDF-image”. Information about the boxes needs to be available in APP in order to decide which box should be applied.
Here's the documentation of the PDFlib "boxexpand"
(Float or list with four floats) Expand the page box selected via the pdiusebox option on all four sides by the same amount (if one value is provided) or on the left/right/bottom/top sides individually (if four values are provided). Negative values are allowed to reduce the page size. This option may be used to place
content which is located outside of all page boxes of the imported page, or to add margins. Default:
Let’s imagine a project placing/importing PDF-ads in a magazine with APP:
1. A PDF ad has “correctly defined” trimbox 210x297, mediabox 220x307
This PDF has a bleed so you want to import it with the mediabox so you can output the bleed but when placing it (for instance on an A4) you will want to use the trimbox, which defines where the PDF is intended to be cut off. You need information about the boxes to calculate while creating a frame container for the ad (in this case a 220x307mm).
2. PDF has “correctly defined” trimbox and mediabox both set to 210x297 mm
Since the trimbox and mediabox is the same you can reasonably say that this PDF has NO bleed. Even here you need information about the boxes to calculate the container frame size (in this case an A4).
3. Old fashion PDF without boxes PDF at all. Document size is 210x297 mm
Since there are no boxes you can NOT know whether this PDF was intended to bleed or not. APP cannot “see” the cutting guides. In this case it is important that the imported PDF lacks information about the boxes and not just set all the boxes to document size. Otherwise this PDF would seem the same as case 2 above - and it’s not. The APP developer will have to decide then how to handle that – to assume that there is bleed or not.