On Oct 29, 2005, at 10:30 PM, John Horner wrote:
I installed the ImageMagick package found here:
http://www.entropy.ch/software/macosx/welcome.html#imagemagick
and it says it installed OK, although I can't do "mogrify -args
file" I have to do "/usr/local/bin/mogrify -args file"
That's your first clue - the package you installed has (correctly,
IMNSHO) been configured to use the default prefix of /usr/local. That
means that its command-line tools are in /usr/local/bin, libraries
in /usr/local/lib, header files in /usr/local/include, etc.
That's a *good* thing, because those locations are safe from future
updates to the Apple-managed directories /usr/bin, /usr/lib, and /usr/
include.
The reason you need to spell out the full path to /usr/local/bin/
mogrify is simply that /usr/local/bin is not in your $PATH. This is
very basic Unix 101 - just edit ~/.bashrc and add a line like this:
PATH=$PATH:/usr/local/bin
Then I go to install the perl Image::Magick module from CPAN, which
fails with hundreds of lines of errors which look like they relate
to the Magick.xs and Magick.c files:
Magick.xs:177: warning: no semicolon at end of struct or union
Magick.xs:181: warning: data definition has no type or storage class
Magick.xs:182: error: parse error before '}' token
Errors can have a "cascade" effect, where an earlier error can
trigger later ones. So, when troubleshooting, always look at the
*first* error, not the last one. At the beginning of these hundreds
of lines, you'll find the root cause, an error that looks like this:
Magick.xs:63:32: error: magick/ImageMagick.h: No such file or
directory
So, why can't it find ImageMagick.h, and how do you tell it where to
find that file? When all else fails, read the instructions. ;-)
In the CPAN shell, use "look Image::Magick" to download and unpack
the module, and open up a subshell in the build directory. Use "less
README.txt" to read the instructions. Immediately after the line that
reads "cd PerlMagick", we find:
Next, edit Makefile.PL and change LIBS and INC to include the
appropriate path information
and I notice that I'm installing not actually Image::Magick but
something called PerlMagick, although I have installed a module
called Image::Magick but it doesn't actually work when called, i.e.
when I run this:
$image->Read('pic.jpg');
it returns the error "can't open file `'".
PerlMagick is the name of the package. Image::Magick is one of
several modules included in the PerlMagick package.
BTW, if you've already installed it, why are you installing it again???
One further mystery is that the Image::Magick module doesn't seem
to work like a regular Perl module at all. I'm told, on this page:
http://www.imagemagick.org/script/perl-magick.php
to use it like this:
$x = $image->Crop(geometry=>'100x100"+100"+100');
warn "$x" if "$x";
Looks like perfectly legal Perl to me.
rather than what I expect:
$image->Crop(geometry=>'100x100"+100"+100') or die "$!";
I'm confused. Why would you expect a module to work in a manner
that's contrary to what its documentation clearly states?
so, what's the point of a Perl module which doesn't work like Perl?
Every heard the expression "There's More Than One Way to Do It"?
A couple of possible reasons come to mind for writing the Crop()
method that way. My immediate suspicion is that the Perl module
simply provides a thin "wrapper" around the C functions, and the C
functions were written that way. Or it may have been the module
author's preference.
Whatever the reason, it's just a trivial stylistic issue - hardly
something worth getting all bent out of shape over.
And what is PerlMagick? Is it a binary containing the same code as
ImageMagick or just an interface to it?
ImageMagick is a library. PerlMagick provides Perl-language access to
the C functions in that library.
sherm--
Cocoa programming in Perl: http://camelbones.sourceforge.net
Hire me! My resume: http://www.dot-app.org
