[mapguide-internals] RFC 14(CartographicStylizationEngine)comments

[Carsten Hess]

Ha! Now you touch one of the things I think are part of the deadly sins
of software: Mixing UI and data model design ...

Those two need to be separate! The data model has to support all UI
configurations we dream up but that does not mean it should be easy to
write this UI against the data model...

Anyways, mostly though I agree with everything you guys discussed in
terms of UI having to be able to handle that but for one thing: The
pixel sizing. Sizing things in pixel unfortunately is meaningless as
pixels are not a real unit. Or, they are only meaningful on the computer
you defined it on. 

We should define things in real units (e.g. inches, mm or points for
fonts). All devices out there define their resolution in dpi (= dots per
inches) which is how we convert from units to pixel.
 
For the MapGuide screen display we currently assume (read: hardcode) 96
dpi at all times if I recall that right. So in a way you could put pixel
into the UI and it would kinda work right now because we assume 96dpi.
However at some point we may want to support things like high definition
tablet PC screens or other devices that have a higher than 96 dpi
resolution...

So I suggest we focus on specifying maps in real units instead of in
pixel. This will make sure your maps will be legible on all devices
going forward and not just the current configuration you use to set it
up on. 

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 1:55 PM
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] RFC
14(CartographicStylizationEngine)comments

My goal:  making things harder for the programmer :)

(yes, I think we agree)

Jason 

-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Traian
Stanev
Sent: Thursday, February 15, 2007 10:34
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] RFC
14(CartographicStylizationEngine)comments


> About being able to set size, etc, based on expressions...  These
would
> have to be defined at the layer level, wouldn't they?

Yes. That's why symbol expressions can be parametrized in the
SymbolInstance (which is in the layer definition). See the
ParameterOverrides element. In any case, this doesn't matter for the
ScaleX and ScaleY since those are defined in the SymbolInstance which is
already part of the layer definition.

> I don't really care about how this is stored in the schema, but if the

> UI makes it more difficult for me to perform these tasks, it will
reduce
> my productivity and increase my frustration level... :)

So we agree? :). I believe that with the schema as is, the UI can
determine enough about the symbol to make things easy for the user (not
necessarily for the programmer).

Traian
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