Hi,

is there some convenience method somewhere to turn an NSRect into a CGRect (CoreGraphics)?

Thanks for any pointers.

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From Mac OS X 10.5 (Leopard) onwards, Apple provide an inline function to do this:

CGRect NSRectToCGRect(NSRect nsrect);

as well as the matching function:

NSRect NSRectFromCGRect(CGRect cgrect);

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Apple’s documentation talks about this (http://developer.apple.com/releasenotes/Cocoa/AppKitOlderNotes.html)

NSRect vs CGRect

We intend to fold these two types into one. However, this has not happened for Public Beta. For situations where you need to pass these back and forth, we recommend you use a macro or inline function which basically does something like: *(CGRect *)&nsRect *(NSRect *)&cgRect

–zootbobbalu

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1. Potentially dangerous typecast (Method, that is used in Apple CG examples):

*(CGRect *)&nsRect;

Aside from being dangerous if the definition of NSRect or CGRect changes, this method is dangerous because it can cause bugs due to “type punning” (see http://en.wikipedia.org/wiki/Type_punning). A safer approach would use a “union” (see below).

1. Inline function:

static inline CGRect NSRectToCGRect(NSRect nsRect) { CGRect cgRect;

cgRect.origin.x = nsRect.origin.x; cgRect.origin.y = nsRect.origin.y; cgRect.size.width = nsRect.size.width; cgRect.size.height = nsRect.size.height;

return cgRect; }

1. Macro:

#define NSRectToCGRect(r) CGRectMake(r.origin.x, r.origin.y, r.size.width, r.size.height)

1. An alternate, union-based macro.

#define NSRectToCGRect(r) (((union {NSRect a; CGRect b;})r).b)

This union uses a GCC approved safe type pun through a union. See here: http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Optimize-Options.html#index-fstrict_002daliasing-542

– JP

– Point 4 and Point 1 comments by MG

Why not an inline function like�:

static inline CGRect NSRectToCGRect(NSRect nsRect) { return (CGRect)&nsRect; }

– DB

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Wow, that’s fantastic, thanks!

I suppose the only way to turn an NSBezierPath to a CG path is to go the inline function route and contruct a new cg path to return point by point from the points in the BezierPath?

But thanks for this, it’s great.

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Note: Core Graphics already has an inline CGRectMake. That being said, NSRect, HIRect and CGRect all carry the same definition (HIRect is just a typedef of CGRect).

To answer your question, NSBezierPath is NOT bridged to a CG, So yes you would need to create and build a new CGMutablePathRef, or just use CGPathRef’s to begin with.

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There is a more usable, though perhaps less portable, way. Assuming Apple will eventually merge these types, this just plans for the future. In a precompiled header, or in any case before importing any foundation headers, include these three #define lines:

#include

#define _NSPoint CGPoint NSPoint; inline void _IgnoreNSPoint( void ) #define _NSSize CGSize NSSize; inline void _IgnoreNSSize( void ) #define _NSRect CGRect NSRect; inline void _IgnoreNSRect( void )

#import

The dummy functions are inline so they can be in a CodeWarrior precompiled header, but that may not work with strict C. I also wrapped the whole precompiled header in some #pragmas so I can keep unused variable warnings:

#pragma warn_unusedvar off

…

#pragma warn_unusedvar reset

I avoid Xcode like the plague, but if you must use it there may be similar #pragmas and #defines to accomplish the same thing.

Once these #defines are in place an NSRect is a typedef of CGRect so you can use them interchangeably. Just remember to convert for coordinate systems and the like. The benefit of this ugly code is that you do not have to edit NSGeometry.h directly.

Enjoy

Eric Cole