[mapguide-internals] RFC 14(CartographicStylizationEngine)comments

[Carsten Hess]

Jason,

DPI may not be available just yet in the browsers but it will be at some
point :)

http://webkit.org/blog/?p=55 is a good write up about how the browsers
start caring about the same thing.


Cheers,
  Carsten

-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Jason
Birch
Sent: Thursday, February 15, 2007 3:54 PM
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] RFC
14(CartographicStylizationEngine)comments

Oh, I get it now.  Sometimes I'm a bit slow... ;)

I'm fine with that personally; I can do the whole screen measurement
thing.  

But...  how does MapGuide know how big a pixel is on the user's screen
when it serves the image?  I don't think that the browser has access to
the DPI; the OS may not even know the true DPI if the LCD is doing
automatic resizing/interpolation?  I can't think of any way of taking
what I measure as 1cm across on my screen, and ensuring that it is
served to all users with the same size.  In the end, you're serving
pixels (in the AJAX viewer anyway)...  Specifying the symbol in real
world distance may set up some unreasonable expectations.

Jason

-----Original Message-----
From: Carsten Hess
Subject: RE: [mapguide-internals] RFC
14(CartographicStylizationEngine)comments

I am saying you should specify it in real units. Ideally you can take
your ruler to the screen and measure it to be one inch wide if you say
it is one inch wide. If you say it is one pixel wide then this is pretty
meaningless as one pixel is differently sized on all different devices -
a pixel is not a unit. I want to use real units to size symbols, line
width, etc even if we define them in device space. 
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