Module: TkImageMap::Utils

Defined in:
lib/drx/tk/imagemap.rb

Overview

class ImageMap

Class Method Summary collapse

Class Method Details

.parse_imap(filepath) ⇒ Object

Parses an HTML image map.



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# File 'lib/drx/tk/imagemap.rb', line 215

def self.parse_imap(filepath)
  hotspots = []
  require 'rexml/document'
  doc = REXML::Document.new(File.open(filepath))
  doc.root.elements.each do |elt|
    if elt.is_a? REXML::Element and elt.name == 'area'
      attrs  = elt.attributes
      url    = attrs['href']
      coords = attrs['coords'].split(/,|\s+/).map{|c|c.to_i}  # @todo: A circle's radius can be a percent.
      case attrs['shape']
      when 'poly';
        if args = to_oval(coords)
          hotspots << {
            :args => args,
            :class => TkcOval,
            :url => url,
          }
        else
          hotspots << {
            :args => coords,
            :class => TkcPolygon,
            :url => url,
          }
        end
      when 'rect';
        hotspots << {
          :args => coords,
          :class => TkcRectangle,
          :url => url,
        }
      when 'circle';
        cx, cy, radius = coords
        hotspots << {
          :args => [cx - radius, cy - radius, cx + radius, cy + radius],
          :class => TkcOval,
          :url => url,
        }
      else raise "I don't support shape '#{attrs['shape']}'"
      end
    end
  end
  return hotspots
end

.to_oval(coords) ⇒ Object

DOT outputs oval elements as polygons with many many sides. Since Tk doesn’t draw them well, we convert such polygons to ovals.



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# File 'lib/drx/tk/imagemap.rb', line 193

def self.to_oval(coords)
  require 'enumerator'
  #points = coords.each_slice(2).to_a # Doesn't work for older 1.8's.
  points = coords.enum_for(:each_slice, 2).to_a
  if points.size < 10
    # If there are few sides, we assume it's a real polygon.
    return nil
  end
  # Alas, Ruby 1.8.6 doesn't have #minmax
  xs = points.map {|p| p[0]}
  ys = points.map {|p| p[1]}
  x_min, x_max = xs.min, xs.max
  y_min, y_max = ys.min, ys.max
  # @todo: try to figure out if the points trace a circle?
  #center_x = x_min + (x_max - x_min) / 2.0
  #center_y = y_min + (y_max - y_min) / 2.0
  #points.each do |x,y|
  #end
  return [x_min, y_min, x_max, y_max]
end