add readme for cfdg

Author: monkstone

processing_app/library/file_chooser/README.md

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+### Obtaining and Using contextfreeart ###
+
+For debian users it should be as simple as `sudo apt-get install cfdg` installs commandline version.
+
+For others check [contextfreeart website][download], if you get the command line version you could easily automate running cfdg program.
+
+### Black and White Demo
+
+```ruby
+load_library :chooser
+attr_reader :img, :data, :skip, :invert
+
+def settings
+  size 500, 500
+end
+
+def setup
+  sketch_title 'Pixellator'
+  color_mode(HSB, 360, 1.0, 1.0)
+  resizable
+  fill 0, 0, 200
+  text('Click Window to Load Image', 10, 100)
+  @skip = 5 # controls apparent resolution
+  @data = []
+  @invert = true
+end
+
+def draw
+  unless img.nil?
+    img.filter(INVERT) if invert
+    @invert = false
+    image(img, 0, 0) 
+  end  
+end
+
+def write_data(name, data)
+  df = "  %s [x %d y %d s %0.2f hue 0 sat 0.7 brightness 0]\n"
+  open(data_path('data.cfdg'), 'w') do |pw|
+    pw.puts format("shape %s{\n", name)
+    data.each do |row|
+      pw.puts format(df, *row)
+    end
+    pw.puts "}\n"
+  end
+end
+
+def write_start(start, data)
+  open(data_path(format('%s.cfdg', start)), 'w') do |pw|
+    pw.puts 'CF::Background = [b 1]'
+    pw.puts format("startshape %s\n", start)
+    pw.puts "shape dot{CIRCLE[]}\n"
+    pw.puts "import data.cfdg\n"
+  end
+  write_data start, data
+end
+
+def file_selected(selection)
+  if selection.nil?
+    puts 'Nothing Chosen'
+  else
+    @img = load_image(selection.get_absolute_path)
+    surface.set_size(img.width, img.height)
+  end
+end
+
+def mouse_clicked
+  @img = nil
+  # java_signature 'void selectInput(String, String)'
+  select_input('Select Image File', 'file_selected')
+end
+
+def key_pressed
+  case key
+  when 'p', 'P'
+    export = Thread.new do
+      pixellate
+    end
+    export.join
+    puts 'done'
+  when 's', 'S'
+    save_frame(data_path('original.png'))
+  else
+    puts format('key %s was pressed', key)
+  end
+end
+
+def pixellate
+  load_pixels
+  shp = 'dot'
+  (skip...img.width).step(skip) do |x|
+    (skip...img.height).step(skip) do |y|
+      pix = pixels[x + y * width]
+      sz = brightness(pix) * skip
+      data << [
+        shp, -width / 2 + x, height / 2 - y, sz.round(2)
+      ] if sz > 0.4
+    end
+  end
+  write_start 'haddock', data
+end
+```
+
+If for example the chosen sketch was 590 * 600 pixels you might use the following to generate the pixellated image using the `cli` assuming `haddock.cfdg` is in the local folder. Windows users might need to use different escapes for path, but then they've got a GUI to use if they want. 
+
+```bash
+cfdg haddock.cfdg -w 1180 -h 1200 -o phil.png
+```
+
+But there is much more you can do (look up che che for a much more sophisticated cfdg file).
+
+
+NB: You could add grayscale filter if you are strating with a coloured image.
+
+
+[download]:http://www.contextfreeart.org/mediawiki/index.php/Download_page

processing_app/library/file_chooser/gray.rb

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+load_library :chooser
+attr_reader :img, :data, :skip, :invert
+
+def settings
+  size 500, 500
+end
+
+def setup
+  sketch_title 'Pixellator'
+  color_mode(HSB, 360, 1.0, 1.0)
+  resizable
+  fill 0, 0, 200
+  text('Click Window to Load Image', 10, 100)
+  @skip = 5 # controls apparent resolution
+  @data = []
+  @invert = true
+end
+
+def draw
+  unless img.nil?
+    img.filter(INVERT) if invert
+    @invert = false
+    image(img, 0, 0) 
+  end  
+end
+
+def write_data(name, data)
+  df = "  %s [x %d y %d s %0.2f hue 0 sat 0.7 brightness 0]\n"
+  open(data_path('data.cfdg'), 'w') do |pw|
+    pw.puts format("shape %s{\n", name)
+    data.each do |row|
+      pw.puts format(df, *row)
+    end
+    pw.puts "}\n"
+  end
+end
+
+def write_start(start, data)
+  open(data_path(format('%s.cfdg', start)), 'w') do |pw|
+    pw.puts 'CF::Background = [b 1]'
+    pw.puts format("startshape %s\n", start)
+    pw.puts "shape dot{CIRCLE[]}\n"
+    pw.puts "import data.cfdg\n"
+  end
+  write_data start, data
+end
+
+def file_selected(selection)
+  if selection.nil?
+    puts 'Nothing Chosen'
+  else
+    @img = load_image(selection.get_absolute_path)
+    surface.set_size(img.width, img.height)
+  end
+end
+
+def mouse_clicked
+  @img = nil
+  # java_signature 'void selectInput(String, String)'
+  select_input('Select Image File', 'file_selected')
+end
+
+def key_pressed
+  case key
+  when 'p', 'P'
+    export = Thread.new do
+      pixellate
+    end
+    export.join
+    puts 'done'
+  when 's', 'S'
+    save_frame(data_path('original.png'))
+  else
+    puts format('key %s was pressed', key)
+  end
+end
+
+def pixellate
+  load_pixels
+  shp = 'dot'
+  (skip...img.width).step(skip) do |x|
+    (skip...img.height).step(skip) do |y|
+      pix = pixels[x + y * width]
+      sz = brightness(pix) * skip
+      data << [
+        shp, -width / 2 + x, height / 2 - y, sz.round(2)
+      ] if sz > 0.4
+    end
+  end
+  write_start 'haddock', data
+end