Is there any difference between a CGRect and an NSRect? In particular, I'm wondering about the position of the origin. Are there any important differences I need to know about?
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A:
They're the same. This link has more information. Copied here for quick reference:
CGRectis the CoreGraphics equivalent ofNSRect.They are deliberately made to have the same layout in memory. As such, it is allowed to convert an
NSRectto aCGRectby doing this:CGRect cgrect = *(CGRect *)&nsrect;CoreGraphics also provides a
CGRectMake()function which works the same asNSMakeRect()(note the reversal of verb and object in the names) except it returns aCGRect.
Carl Norum
2010-01-27 23:16:45
Well, that's allowed except that it breaks strict aliasing rules in the compiler. I'll fix that wiki page. Use NSRectFromCGRect and NSRectToCGRect to convert.
Ken
2010-01-28 00:04:46
In 64-bit, or when you compile with `NS_BUILD_32_LIKE_64`, `NSRect` is defined as `CGRect`, so you don't even need to jump through the pointer hoop.
Peter Hosey
2010-01-28 01:52:53
A:
In particular, I'm wondering about the position of the origin.
That depends on where you got the rect and where you're using it. In general, Core Graphics and UIKit use flipped co-ordinates (origin upper-left, positive y going down), whereas AppKit uses unflipped co-ordinates (origin lower-left, positive y going up). But it is possible to flip or unflip co-ordinates from each API, and some classes, such as NSImage and NSView, make it very easy to do so.
Peter Hosey
2010-01-28 01:55:33