PNG::Color

     # File lib/png.rb, line 215
215:     def self.from str, name = nil
216:       str = "%08x" % str if Integer === str
217:       colors = str.scan(/[\da-f][\da-f]/).map { |n| n.hex }
218:       colors << name
219:       self.new(*colors)
220:     end

     # File lib/png.rb, line 339
339:     def self.from_hsv h, s, v
340:       r = g = b = v # gray
341:       unless s == 0.0 then
342:         h += 255 if h < 0
343:         h  = h / 255.0 * 6.0
344:         s  = s / 255.0
345:         v  = v / 255.0
346:         i  = h.floor
347:         f  = h - i
348:         p = v * (1 - (s))
349:         q = v * (1 - (s * (f)))
350:         w = v * (1 - (s * (1-f)))
351:         r, g, b = case i
352:                   when 0,6 then
353:                     [ v, w, p ]
354:                   when 1 then
355:                     [ q, v, p ]
356:                   when 2 then
357:                     [ p, v, w ]
358:                   when 3 then
359:                     [ p, q, v ]
360:                   when 4 then
361:                     [ w, p, v ]
362:                   when 5 then
363:                     [ v, p, q ]
364:                   else
365:                     raise [h, s, v, i, f, p, q, w].inspect
366:                   end
367:       end
368:       self.new((r * 255).round, (g * 255).round, (b * 255).round)
369:     end

     # File lib/png.rb, line 225
225:     def initialize red, green, blue, alpha = MAX, name = nil
226:       @values = "%c%c%c%c" % [red, green, blue, alpha]
227:       @name = name
228:     end

     # File lib/png.rb, line 291
291:     def a; @values.getbyte 3; end

     # File lib/png.rb, line 286
286:     def b; @values.getbyte 2; end

     # File lib/png.rb, line 296
296:     def blend color
297:       return Color.new(((r + color.r) / 2), ((g + color.g) / 2),
298:                        ((b + color.b) / 2), ((a + color.a) / 2))
299:     end

     # File lib/png.rb, line 281
281:     def g; @values.getbyte 1; end

     # File lib/png.rb, line 304
304:     def intensity i
305:       return Color.new(r,g,b,(a*i) >> 8)
306:     end

     # File lib/png.rb, line 276
276:     def r; @values.getbyte 0; end

     # File lib/png.rb, line 269
269:     def rgb # TODO: rgba?
270:       return r, g, b
271:     end

     # File lib/png.rb, line 320
320:     def to_ascii
321:       return '  ' if a == 0x00
322: 
323:       brightness = (((r + g + b) / 3) * a) / 0xFF
324: 
325:       %(.. ,, ++ 00)[brightness / 64]
326:     end

     # File lib/png.rb, line 374
374:     def to_hsv # errors = 54230 out of 255^3 are off by about 1 on r, g, or b
375:       rgb = self.rgb
376:       r, g, b = rgb
377:       h, s, v = 0, 0, rgb.max
378: 
379:       return h, s, v if v == 0
380: 
381:       range = v - rgb.min
382:       s = 255 * range / v
383: 
384:       return h, s, v if s == 0
385: 
386:       h = case v
387:           when r then
388:             0x00 + 43 * (g - b) / range # 43 = 1/4 of 360 scaled to 255
389:           when g then
390:             0x55 + 43 * (b - r) / range
391:           else
392:             0xAA + 43 * (r - g) / range
393:           end
394: 
395:       return h.round, s.round, v.round
396:     end

     # File lib/png.rb, line 258
258:     def | o
259:       self == Background ? o : self
260:     end