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# GraphicsMagick Wand C API

The GraphicsMagick Wand C library provides a mid-level abstract C language programming interface for GraphicsMagick. It is originally based on the Wand API provided in ImageMagick as of August 2003. After August 2003, ImageMagick changed its license to one unusable by GraphicsMagick so this version of the Wand library is not completely in sync with the current ImageMagick version.

The API is divided into a number of categories. While reading this documentation, please reference the types documentation as required:

> - Drawing: Wand vector drawing interfaces.
> - Magick: Wand image processing interfaces
> - Pixel: Wand pixel access/update interfaces

The following is a simple example program which (assuming the program name is rotate) is executed similar to rotate infile outfile. It reads from file infile, rotates the image 30 degrees using a black background, and writes the result to file outfile:

    #include <stdlib.h>
    #include <stdio.h>
    #include <string.h>
    #include <wand/magick_wand.h>

    int main(int argc,char **argv)
    {
      MagickWand *magick_wand;
      MagickPassFail status = MagickPass;
      const char *infile, *outfile;

      if (argc != 3)
        {
          fprintf(stderr,"Usage: %s: infile outfile\n",argv[0]);
          return 1;
        }

      infile=argv[1];
      outfile=argv[2];

      // Initialize GraphicsMagick API
      InitializeMagick(*argv);

      // Allocate Wand handle
      magick_wand=NewMagickWand();

      // Read input image file
      if (status == MagickPass)
        {
          status = MagickReadImage(magick_wand,infile);
        }

      // Rotate image clockwise 30 degrees with black background
      if (status == MagickPass)
        {
          PixelWand *background;
          background=NewPixelWand();
          PixelSetColor(background,"#000000");
          status = MagickRotateImage(magick_wand,background,30);
          DestroyPixelWand(background);
        }

      // Write output file
      if (status == MagickPass)
        {
          status = MagickWriteImage(magick_wand,outfile);
        }

      // Diagnose any error
      if (status != MagickPass)
        {
          char *description;
          ExceptionType severity;

          description=MagickGetException(magick_wand,&severity);
          (void) fprintf(stderr,"%.1024s (severity %d)\n",
                         description,severity);
        }

      // Release Wand handle
      DestroyMagickWand(magick_wand);

      // Destroy GraphicsMagick API
      DestroyMagick();

      return (status == MagickPass ? 0 : 1);
    }

To compile on Unix, the command looks something like this:

    gcc -o demo demo.c -O `GraphicsMagickWand-config --cppflags --ldflags --libs`

The GraphicsMagickWand-config script reproduces the options which were used to compile the GraphicsMagick wand library. Using compatible options ensures that your program will compile and run.

Copyright © GraphicsMagick Group 2009 - 2012