Re: Use of C gm function inside C++ code (AutoOrientImage example)

On Wed, 22 Nov 2017, Przemysław Sobala wrote:

> Hello
>
> What's the best way I can use a C libGraphicsMagick function in C++ code?
>
> Let's use AutoOrientImage (from magick/shear.h) as an example.
> I tried:
>
>
> Magick::Image image;
> image.read(.....)
>
> // auto orient
> MagickLib::ExceptionInfo tmpException;
> MagickLib::Image *tmpImage = AutoOrientImage(image.image(),
> 	image.orientation(), &tmpException);
> image.replaceImage(tmpImage);

The best thing to do is to implement the missing method in the 
Magick++ library itself and send us a patch so it can be added. :-)

A typical method implementation (in the library) is:

   ExceptionInfo exceptionInfo;
   GetExceptionInfo( &exceptionInfo );
   MagickLib::Image* newImage =
     AddNoiseImageChannel ( image(),
                            channel_,
                            noiseType_,
                            &exceptionInfo );
   replaceImage( newImage );
   throwImageException( exceptionInfo );

which is very close to what you have except your code is missing the

   GetExceptionInfo( &exceptionInfo );

line.  Initializing this structure is important since it contains 
pointer members and some decisions are made based on its current 
state.

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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