Scriptaculous Slider in Rails3 form

So there is an excellent slider. http://madrobby.github.com/scriptaculous/slider/ It is perfect to set up a select form element where values are predefined numbers or integers. First you have to download http://script.aculo.us/downloads the slider.js file and move it to the /public/javascripts directory. Then insert this row in your layout, /app/views/layouts/application.html.erb after the defaults.

<%= javascript_include_tag "slider.js" %>

Then we define CSS style for the slider as the same as at the script.aculo.us homepage. (/app/public/stylesheets/style.css)

div.slider {
 width:256px;
 margin:10px 0;
 background-color:#ccc;
 height:10px;
 position: relative;
}

div.slider div.handle {
 width:10px;
 height:15px;
 background-color:#f00;
 cursor:move;
 position: absolute;
}

Then we create a helper for it. (/app/helpers/application_helper.rb)

def slider(attributes={})
  unless attributes.nil? then
  values=attributes[:values]
  default_value=attributes[:default_value].to_s
  object=attributes[:object].to_s
  instance=attributes[:instance].to_s
  unit=attributes[:unit] || ""
  text_div_id=object + "_" + instance + "_slider_text_div"
  slider_id=object + "_" + instance + "_slider"
        
  concat(raw(
    "<div id=\"#{slider_id}\" class=\"slider\">
       <div class=\"handle\"></div>
     </div>"
  ))

  concat(raw(hidden_field(object, instance, :value => default_value.to_i)))
  concat(raw("<div id=\"#{text_div_id}\">" + default_value + " " + unit + "</div>"))
        
  js_text = <<JS3
  (function() {
    var zoom_slider = $('#{slider_id}');
    var text_div = $('#{text_div_id}');
    var hidden_item = $('#{object + "_" + instance}');
    var values=#{values.inspect};
    
    var values_length = values.length;
    var min=40;
    var max=200;

    var unit = Math.ceil((max - min) / values_length);
    var range = $R(min, max - unit);

    var pix_values = new Array();
    for(i=1;i<=values_length;i++){
      pix_values[i-1]=min + (unit * (i - 1));
    }
        
    var default_value=pix_values[#{values.index(default_value.to_i)}];

    new Control.Slider(zoom_slider.down('.handle'), zoom_slider, {
      range: range,
      sliderValue: default_value,
            increment: unit,
            values: pix_values,
      onSlide: function(value) {
                text_div.innerHTML=values[pix_values.indexOf(value)] + " #{unit}";
                hidden_item.value=values[pix_values.indexOf(value)];
      },
      onChange: function(value) { 
                text_div.innerHTML=values[pix_values.indexOf(value)] + " #{unit}";
                hidden_item.value=values[pix_values.indexOf(value)];
      }
    });
  })();
        
JS3
      concat(raw(javascript_tag(js_text)))
  end
end

Then just define your form element in your view / form:

<table><tbody><tr><td>
<% slider :object        => "config",
          :instance      => "mem_size",
          :unit          => "MB",
          :values        => [512, 1024, 1536, 2048, 2560, 3072, 4096].sort,
          :default_value => 1024 %>
</td></tr></tbody></table>

That"s all! Questions?