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Re: [RFC] Reading images

From: Pete French
Subject: Re: [RFC] Reading images
Date: Sun, 21 Sep 2003 16:17:10 +0100

> No, and that's the important point. When you draw a 100x100 image into a
> 100x100 rectangle, those coordinates are in user space (in points,
> unless you changed it). If the device is not exactly 72 dpi, the
> coordinates in device space will be different. Eg. on a 144 dpi device
> (like a high resolution screen), the image will be 200x200 in device
> space, and since GSReadRect: reads raw pixels from the device, you'd get
> a 200x200 image back.


now I am getting confused! If I make a view with a content rect that is
100x100, and then focus on it and init a bitmap from it, then is that
bitmap going to be 100x100 ? Thats what I expect it to be.

> Well, you'd have to make sure that the window is 1024x1024 device
> pixels, which may not correspond to 1024x1024 in the default user space.

...under what circumstances will this not be true ?

I'm thinking thatn theres a gap in my understanding of the default
settings somewhere. I though that if I wrote some code to make a
window 100 by 100 and ran it on any system (OSX, OpenStep, GNustep) then
I would get 100 pixels square on the screen. This is (admittedly) derived
from experience rather than ever actaully reading it documented as such
anywhere though.


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