Differences between coordinate systems

Hi,

I'd like to know the differences between coordinate systems. Actually how they map to each other. What's the logic underneath?

Ok device coordinates are physical coordinates but what do logical coordinates stand for then? Why do I need them?


King regards..

its all in the docs:
http://qt-project.org/doc/qt-4.8/coordsys.html

That's where I actually got the mess about the coordinate systems. I mean I couldn't follow after the window-viewport conversion section.

Quote:

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I mean I couldn't follow after the window-viewport conversion section.

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But that is not a question any one can answer - its not a question at all.
Ask exactly and specifically things you don't understand.
Just explaining in general will be repeating what is in the docs, and you say you can't follow on it.