On 12 May 2009, at 07:14, Chunk 1978 wrote:
Is it possible to have a view, say a simple square that is 5cm x 5cm, always maintain it size regardless of the mac's resolution?
Yes.
it seems the only way possible to produce a square of 5cm x 5cm programatically is to include the screens resolution into the equation. but besides having different resolution settings on different macs and setting up a resolution event listener, some screens have different PPI than other screens (or so i assume?).
Well there are two perspectives on this, I suppose. The first is that the default co-ordinate transforms in Cocoa are supposed to result in a 1x1 rectangle being 1pt x 1pt in size. *However* this is predicated on the assumption that the screen is 72dpi, so that 1pt x 1pt = 1px x 1px.
Plainly the 72dpi assumption is not really true for modern displays (which are usually 100dpi or so), but it will mean that your app will match others on the system.
If, however, you really want the display to physically show a 5cm x 5cm block, you can obtain the screen's actual dimensions in millimeters from CGDisplayScreenSize() and then use those numbers in conjunction with the pixel dimensions to calculate a suitable transform.
Please remember if you do something like this that some machines have more than one display. You may not need to handle the case where your window overlaps two displays at once (perhaps it's enough to just pick one), but you do nevertheless need to be aware of the problem.
Kind regards, Alastair. -- http://alastairs-place.net _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
