Re: Core Animation geometry, layer hosting, and resolution independence

FROM : Nathan Vander Wilt
DATE : Wed Mar 12 23:06:52 2008

> > CALayers don't have this bounds/frame distinction
>
> They do, actually. The bounds is the internal view
> of the coordinate 
> system, and the frame is the external view.


At first this sounded incorrect, because it's
emphasized that frame is just a function of other
properties....but I was overlooking "transform" as one
of those. Interesting...not sure if this helps clear
the situation or not.

> > it almost seems
> > that 1 unit always corresponds to 1 pixel. How
> does
> > Core Animation's geometry relate to NSView's
> > resolution independent geometry?
>
> I think you're right about the pixels. That's news
> to me; I'm stumped. 
> Hopefully some CA expert can enlighten us.


Despite the apparent help -[NSView
convertPointToBase:] gives, I'd still appreciate a
summary of the way all the many many CALayer
(/sublayer), NSView and Quartz context transformations
work together in light of resolution independence:

When one draws a rectangle in a CALayer delegate, and
the -drawLayer:: concatenates (and/or sets?) its own
transform before drawing, when the layer has a
transform, and the root parent layer has both a
transform and a sublayer transform, and the host
NSView has different bounds than frame, and there is
resolution independence / interface scaling.....*deep
breath*..... where/what order are all these transforms
applied to our brave rectangle victim. And between
what levels of all that does a (mouse, drawing, layer
origin) point need to be transformed for use, and how?

[As if that weren't confusing me enough, I'm actually
also applying a cartographic projection or three to
half of my source data...so being clear on the
Cocoa/Core Animation/Quartz interaction would help me
focus on just the map issues.]

thanks,
-natevw

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