I am trying to understand the exact behaviour of RB with regards to
printing images, scaling portions of an image to another image and
how come a single print can generate such massive use of VM.
I have uploaded a sample (RB5.5.5) if anyone wants to look and feel
free to copy these techniques:
http://www.oofile.com.au/files/REALbasic/ImagePrinter.rb.sit
On Windows, certain printers get their actual resolution reported.
On OS/X they seem to be always reported as 300 dpi but the advice
from Apple has been to ignore this.
The problem comes when you are doing an application which does image
composition and thus scaling your pictures according to the reported
resolution of the printer.
There is a complicating factor of the limiting size of Quickdraw
pictures. You can't just take a 400 pixel image and create a 1200 dpi
graphics context for it.
So I came up with an idea, after weeks of stewing - what would happen
if I ignored the printer resolution, creating "high resolution"
intermediate pictures, drawing a portion of the picture into each
(effectively scaling up) and then draw those on the printer graphics
port, scaling down as necessary to make them fit. This is to check
out the assumption that a really high resolution image would print
better if little high-res tiles were actually to be passed to the
printer.
I'm not entirely convinced this is actually resulting in anything
useful.
What I suspect is also happening is that a copy of the image is being
retained each time I draw a portion of it. So, if your tiling sizes
result in say 40 tiles of the image, you have 40 copies being
retained and sent to the printer to draw offset and suitably clipped.
I would *love* some confirmation from RS that anything like this is
the case but will settle for informed opinion :-)
thanks
Andy
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