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From Jeremias Maerki <...@jeremias-maerki.ch>
Subject Re: Table row background images
Date Fri, 29 Feb 2008 06:14:19 GMT
The problem with PCL (or at least PCL5 which I've worked with) is that
it doesn't support clipping [1]. Clipping makes these things a lot
easier. In the absence of clipping capabilities, you'd basically have to
emulate the clipping in the painter code rather than in the print
processor which complicates things. One relatively simple possibility
would be to paint the background image to an in-memory buffer, clip
there and then paint the resulting bitmap using PCL means but that costs
a lot of performance and memory. A little more advanced would be to keep
track which tile actually gets clipped and process the tiles
individually. Obviously this hasn't been done, yet. Help is definitely

[1] HP/GL2 actually supports clipping but often doesn't help to
efficiently overcome the limitations of PCL.

Note also that many Windows PCL printer drivers just paint a single big
bitmap for the whole page instead of using the various PCL capabilities.
For complex pages this produces perfect quality but it comes with a
cost: In-memory build up of the page may be slower and and the resulting
print files are often bigger. However, with FOP's Java2D capabilities it
would actually be relatively easy to write a second PCL renderer which
just generates a bitmap image of each page and converts that to PCL. The
user would then have the choice between accuracy and speed.

On 28.02.2008 17:08:43 David Gerdt wrote:
> I'm finding a difference in how background images for table rows are rendered in PDF
versus PCL. When producing a pdf, the image will fill only the row and be clipped where it
runs outside the bounds of the row. This is what I want. However, when producing PCL which
is really my ultimate goal, the whole image is displayed and overflows the bounds of the row.
> This behavior occurs in both 0.94 and Trunk. I have tried applying the background-image
attribute to the table-row, table-cell, and the block each individually, with the same results.
> I am not sure exactly what the intended behavior should be (clip the image or let it
go) but I'm more confused by the difference between the PDF and the PCL which are rendered
from the same fo file.
> What I'm really trying to do is create a white background for a table row when rendered
in PCL. The background-color attribute produces this effect in a PDF but not in a PCL file.
I'm trying to work around this by setting the background-image to a plain white gif, but am
running into the problems above.
> Any insight on these issues? I can provide a fo file if you like, but I figured these
issues were broad enough to not require the specific fo.
> Thanks!

Jeremias Maerki

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