[reportlab-users] Best practices for adding bleed with crop marks?

[Stevens, Ian]

In order to send PDFs to a printer, I had to add a bleed margin of 1/8".
I went in the following direction and am wondering if there was a better
way:
 
- Overload BaseDocTemplate with an optional bleed parameter in its
constructor, which stores it in the object
- Overload BaseDocTemplate.build() to:
    - Increase the pagesize by twice the bleed amount
    - Create copies of any pageTemplates and offset any frames therein
by the bleed amount.  
    - Any frames right on the edge of the page are assumed to contain
colour content which may bleed, so those frames are widened by the bleed
amount, not offset
    - Call BaseDocTemplate.build()
    - Restore the BaseDocTemplate pageTemplates, pagesize and frames to
their original state
- Overload BaseDocTemplate.handlePageEnd() to draw crop marks
 
Any templates overloading the above new class are responsible for:
 
- Offsetting any objects drawn directly on the canvas by the bleed
amount
- Adjusting the width/height of any objects drawn directly on the canvas
which extend to the edge.
- Widening/padding any flowables which are added to frames on the edge
of the page.  (eg. increasing the width of a table with a colour
background lying on the page edge by the bleed amount.)
 
It's not a perfect solution and I'm wondering if it could have been
better implemented, possibly with less work from those overloading the
new BaseDocTemplate.  Any input would be appreciated.
 
thanks,
Ian.
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