Re: DrawContext -- reports on self?

On Sun, Aug 28, 2011 at 10:59:23PM -0500, Bob Friesenhahn wrote:
> On Mon, 29 Aug 2011, [email protected] wrote:
>
>> How can I tell whether a DrawContext dc; type is allocated or not? The
>> structure is described as opaque, and I see no reporting APIs that I
>> can pass this to.
>
> This type is allocated by DrawAllocateContext().  It is a pointer-based 
> handle declared like:
>
>   typedef struct _DrawContext *DrawContext;
>
> so
>
>   if (dc != (DrawContext) NULL)
>
> or
>
>   if (dc != 0)
>
> should work fine for determining if it was allocated already.

Hrmm... so I should:

DrawContext *dc;
dc=DrawAllocateContext(); /* like this? */


I was having a tough time w/ leaks and core dumps w/ my various attempts... am currently:

DrawContext dc;
dc=DrawAllocateContext(); /* this is leak-free, crash-free */

but my tests: if(!dc) { // no draw context... } were not working like I expected.

Comments?

-bch

> If DrawAllocateContext() fails to allocate the context structure  
> (indicating a serious problem) then the program will simply exit with a 
> fatal error.  If one of the allocated members of the structure fails to 
> be allocated, then (DrawContext) NULL is returned, and an error message 
> is saved to image->exception.
>
> Bob
> -- 
> Bob Friesenhahn
> [email protected], http://www.simplesystems.org/users/bfriesen/
> GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

-- 
Brad Harder
Method Logic Digital Consulting
http://methodlogic.net/
http://twitter.com/bcharder


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