You can find more info in the README file on github.

# rmagick
image = Magick::ImageList.new(filename).first
puts image['EXIF:Model'] # The camera model used to take the picture

# mini_magick
image = MiniMagick::Image.from_file(filename)
puts image["EXIF:Model"]

The problem is that I can’t do the same thing with image_science, because it has no methods that return exif data, so I want to add a method to the ImageScience class to do that.
Looking the FreeImage documentation I found some helpful functions, FreeImage_GetMetadata and FreeImage_TagToString. With these 2 functions I’m able to get an exif tag and convert it to a readable string. Each one of the available tags belongs to one of the following meta models:

FI_ENUM(FREE_IMAGE_MDMODEL) {
  FIMD_NODATA         = -1,
  FIMD_COMMENTS       = 0,	// single comment or keywords
  FIMD_EXIF_MAIN      = 1,	// Exif-TIFF metadata
  FIMD_EXIF_EXIF      = 2,	// Exif-specific metadata
  FIMD_EXIF_GPS       = 3,	// Exif GPS metadata
  FIMD_EXIF_MAKERNOTE = 4,	// Exif maker note metadata
  FIMD_EXIF_INTEROP   = 5,	// Exif interoperability metadata
  FIMD_IPTC           = 6,	// IPTC/NAA metadata
  FIMD_XMP            = 7,	// Abobe XMP metadata
  FIMD_GEOTIFF        = 8,	// GeoTIFF metadata
  FIMD_ANIMATION      = 9,	// Animation metadata
  FIMD_CUSTOM         = 10	// Used to attach other metadata types to a dib
};

Ok, now I can extract the model of the camera:

FreeImage_GetMetadata(FIMD_EXIF_MAIN, bitmap, "Model", &tag);
printf(FreeImage_TagToString(FIMD_EXIF_MAIN, tag, NULL));

As you can see, I need to pass the model of the “Model” tag. But if I don’t know which model to use, I can loop through all of them until the returned value of the FreeImage_GetMetadata function is not NULL:

for(model = 0; model < 11; model++) {
  if(FreeImage_GetMetadata(model, bitmap, tagName, &tag))
    return rb_str_new2(FreeImage_TagToString(model, tag, NULL));
}

Finally I can write a ruby module that extends ImageScience and adds the ability to get an exif tag:

module ImageScienceExifData

  def [](key)
    if key =~ /^EXIF:(\w+)?/
      get_exif($1)
    end
  end

  inline do |builder|
    if test ?d, "/opt/local" then
      builder.add_compile_flags "-I/opt/local/include"
      builder.add_link_flags "-L/opt/local/lib"
    end
    builder.add_link_flags "-lfreeimage"
    builder.add_link_flags "-lstdc++" # only needed on PPC for some reason. lame
    builder.include '"FreeImage.h"'

    builder.prefix <<-"END"
      #define GET_BITMAP(name) FIBITMAP *(name); Data_Get_Struct(self, FIBITMAP, (name)); if (!(name)) rb_raise(rb_eTypeError, "Bitmap has already been freed")
    END

    builder.c <<-"END"
      VALUE get_exif(char *tagName) {
        GET_BITMAP(bitmap);
        FITAG *tag = NULL;
        const char *value;
        int model;

        for(model = 0; model < 11; model++) {
          if(FreeImage_GetMetadata(model, bitmap, tagName, &tag))
            return rb_str_new2(FreeImage_TagToString(model, tag, NULL));
        }

        return Qnil;
      }
    END

  end
end
ImageScience.send(:include, ImageScienceExifData)

ImageScience.with_image(filename) do |img|
  puts img["EXIF:Model"]
end

The output with the picture I used is the following :

NIKON
COOLPIX S3
2006:12:10 12:09:17

It doesn’t work with all the exif names but for now it’s ok for my needs. The next step is to add the code above in my rails application and use it with attachment_fu. I’ll write another post about that soon.

var Pagination = {  

  initLinks: function() {
    $('container').select('div.pagination a').invoke('observe', 'click', Pagination.linkHandler);
  },

  linkHandler: function(event) {
    event.stop();
    new Ajax.Updater('container', event.element().getAttribute('href'),{
      method: 'get',
      onComplete: Pagination.initLinks
    });
  }

}

document.observe('dom:loaded', Pagination.initLinks);

Obviously the code it’s not optimized, it’s just an example, but it works. You only need create a list of records inside a div caled ‘container’, and that div will be update with the content loaded by the ajax request.

[UPDATE] I like the prototype OO way to write js. So I wote the same thing with a class:

var Pagination = Class.create({ 

  initialize: function() {
    this.options = Object.extend({
      container: 'container'
    }, arguments[0] || {});
    this.initLinks();
  },  

  initLinks: function() {
    $(this.options.container).select('div.pagination a').invoke('observe', 'click', this.linkHandler.bind(this));
  },  

  linkHandler: function(event) {
    event.stop();
    new Ajax.Updater('container', event.element().getAttribute('href'),{
      method: 'get',
      onComplete: this.initLinks.bind(this)
    });
  }

});

document.observe('dom:loaded', function() {
  new Pagination();
});

The latest version is more customizable because the constructor could receive a list of options. For now it’s only one, you can specify the container that will be updated, but you could add more options like the name of the spinner to show during requests and so on.

function sort(list, element, id, old_position, new_position) {
  new Ajax.Request('/admin/gallery_item/sort/', {
    evalScripts:true,
    parameters: {
      id: id,
      old_position: old_position,
      new_position: new_position
    }
  });
}

document.observe('dom:loaded', function() {
  new LiteSortable('list', {
    onUpdate: sort
  });
});

And the server code become like the following:

def sort
  old_position, new_position = params[:old_position].to_i, params[:new_position].to_i
  @item = GalleryItem.find(:first, :conditions => ["id = ? AND position = ?", params[:id], old_position])
  if @item
    x, y, z = old_position < new_position ? ["-", "<", ">"] : ["+", ">", "<"]
    GalleryItem.update_all("position = (position #{x} 1)", ["parent_id IS NULL AND gallery_id = ? AND position #{y}= ? AND position #{z}= ?", @item.gallery_id, new_position, old_position])
    @item.update_attribute('position', new_position)
  else
    @error = true
  end
end

If @error is true, it means that the dragged image it’s been deleted or moved by somone else.
If you want to use LiteSortable you can check out the entire project with:

svn co http://dev.gravityblast.com/svn/projects/js/LiteSortable/

…or save download the lite_sortable.js file from here.

http://dev.gravityblast.com/svn/projects/radiant/extensions/gallery/

You can check it out with

svn co http://dev.gravityblast.com/svn/projects/radiant/extensions/gallery/

The new version uses attachment_fu, and the filesystem organization is changed. In order to use the new version with galleries created by old versions of the Gallery extension you must run this rake task:

rake RAILS_ENV="production" radiant:extensions:gallery:version_0_7_0:upgrade_filesystem_structure

I suggest making a backup of all your pictures before running the above rake task. Let me know if everything works correctly!

svn co http://dev.gravityblast.com/svn/projects/radiant/extensions/copy_move/

Thanks to Benny Degezelle now it works with the shards extension. This is the best way to hack the Radiant admin UI! Benny also helped me updating the rake tasks and rewriting the CopyMove html structure so it is similar to the other admin screens…Thanks Benny :)I also moved all the code in a separated controller, wrote a complete test suite, and added the ability to choose the status for the copied pages.

I’ve just moved my repositories from darcs.bigchieflabs.com to darcs.gravityblast.com. Here you can find my projects, primarily extensions for radiant like Gallery, CopyMove, DefaultPageParts, Dynamic, Subscriber, Newsletter…