add a decent video capture example

Author: monkstone

samples/processing_app/library/video/ascii_capture.rb

@@ -0,0 +1,106 @@
+#
+# ASCII Video
+# by Ben Fry, translated to ruby-processing by Martin Prout.
+#
+#
+# Text characters have been used to represent images since the earliest computers.
+# This sketch is a simple homage that re-interprets live video as ASCII text.
+# See the key_pressed function for more options, like changing the font size.
+#
+load_library :video
+include_package 'processing.video'
+
+attr_reader :bright, :char, :cheat_screen, :font, :font_size, :letters, :video
+
+# All ASCII characters, sorted according to their visual density
+LETTER_STRING = %q{ .`-_':,;^=+/\"|)\\<>)iv%xclrs{*}I?!][1taeo7zjLunT#JCwfy325Fp6mqSghVd4EgXPGZbYkOA&8U$@KHDBWNMR0Q}
+LETTER_ORDER = LETTER_STRING.scan(/./)
+def setup
+  size(640, 480)
+  # This the default video input, see the GettingStartedCapture
+  # example if it creates an error
+  @video = Capture.new(self, 160, 120)
+  # @cheat_screen = true
+  # Start capturing the images from the camera
+  video.start
+  @font_size = 1.5
+  @font = load_font(data_path('UniversLTStd-Light-48.vlw'))
+  # for the 256 levels of brightness, distribute the letters across
+  # the an array of 256 elements to use for the lookup
+  @letters = (0...256).map do |i|
+    LETTER_ORDER[map1d(i, (0...256), (0...LETTER_ORDER.length))]
+  end
+  # current brightness for each point
+  @bright = Array.new(video.width * video.height, 128)
+end
+
+def capture_event(c)
+  c.read
+  background 0
+end
+
+def draw
+  return unless (video.available == true)
+  capture_event(video)
+  push_matrix
+  hgap = width / video.width
+  vgap = height / video.height
+  scale([hgap, vgap].max * font_size)
+  text_font(font, font_size)
+  index = 0
+  video.load_pixels
+  (0...video.height).each do
+    # Move down for next line
+    translate(0,  1.0 / font_size)
+    push_matrix
+    (0...video.width).each do
+      pixel_color = video.pixels[index]
+      # Faster method of calculating r, g, b than red(), green(), blue()
+      r = pixel_color >> 16 & 0xff
+      g = pixel_color >> 8 & 0xff
+      b = pixel_color & 0xff
+      # Another option would be to properly calculate brightness as luminance:
+      # luminance = 0.3*red + 0.59*green + 0.11*blue
+      # Or you could instead red + green + blue, and make the the values[] array
+      # 256*3 elements long instead of just 256.
+      pixel_bright = [r, g, b].max
+      # The 0.1 value is used to damp the changes so that letters flicker less
+      diff = pixel_bright - bright[index]
+      bright[index] += diff * 0.1
+      fill(pixel_color)
+      text(letters[bright[index]], 0, 0)
+      # Move to the next pixel
+      index += 1
+      # Move over for next character
+      translate(1.0 / font_size, 0)
+    end
+    pop_matrix
+  end
+  pop_matrix
+  if cheat_screen
+    # image(video, 0, height - video.height)
+    # set() is faster than image() when drawing untransformed images
+    set(0, height, video)
+  end
+end
+
+#
+# Handle key presses:
+# 'c' toggles the cheat screen that shows the original image in the corner
+# 'g' grabs an image and saves the frame to a tiff image
+# 'f' and 'F' increase and decrease the font size
+#
+def key_pressed
+  case key
+  when 'g'
+    save_frame
+  when 'c'
+    @cheat_screen = !cheat_screen
+  when 'f'
+    @font_size *= 1.1
+  when 'F'
+    @font_size *= 0.9
+  else
+    p 'Controls are g to save_frame, f & F to set font size'
+  end
+end

samples/processing_app/library/video/data/UniversLTStd-Light-48.vlw

@@ -11,7 +11,7 @@ def setup
   p 'Matching cameras available:'
   size_pattern = Regexp.new(format('%dx%d', width, height))
   select = cameras.grep size_pattern # filter available cameras
-  select.map { |cam| p cam }
+  select.uniq.map { |cam| p cam.strip }
   fail 'There are no matching cameras.' if (select.length == 0)
   start_capture(select[0])
 end