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require 'zlib'
module Compass
# A simple class to represent and create a PNG-File
# No drawing features given
# Just subclass and write [R,G,B]-Byte-Values into the <tt>@data</tt> matrix
# Build for compactness, so not much error checking!
#
# Code based on seattlerb's png, see http://seattlerb.rubyforge.org/png/
class PNG
CRC_TABLE = (0..255).map do |n|
(0...8).inject(n){|x,i| x = ((x & 1) == 1) ? 0xedb88320 ^ (x >> 1) : x >> 1}
end
class << self
def crc(chunkdata='')
chunkdata.unpack('C*').inject(0xffffffff){|crc, byte| CRC_TABLE[(crc ^ byte) & 0xff] ^ (crc >> 8) } ^ 0xffffffff
end
def chunk(type, data="")
[data.size, type, data, crc(type + data)].pack("Na*a*N")
end
end
# Initiates a new PNG-Object
# * <tt>width</tt>: Width of the image in pixels
# * <tt>height</tt>: Height of the image in pixels
# * <tt>background</tt>: Background-color represented as [R,G,B]-Byte-Array
def initialize(width, height, background = [255,255,255])
@height = height
@width = width
@data = Array.new(@height) { |x| Array.new(@width, background) }
end
BITS = 8
RGB = 2 # Color Types ( RGBA = 6)
NONE = 0 # Filter
# binary representation of the PNG, write to file with binary mode
def to_blob
blob = []
blob << [137, 80, 78, 71, 13, 10, 26, 10].pack("C*")
blob << PNG.chunk('IHDR', [@width, @height, BITS, RGB, NONE, NONE, NONE].pack("N2C5"))
blob << PNG.chunk('IDAT', Zlib::Deflate.deflate(self.png_join))
blob << PNG.chunk('IEND', '')
blob.join
end
def png_join
@data.map { |row| "\0" + row.map { |p| "%c%c%c" % p}.join }.join
end
end
class GridBuilder < PNG
include Actions
attr_reader :column_width, :gutter_width, :filename, :able_to_generate, :options
# ==== Options
# * <tt>options</tt>
# * <tt>:column_width</tt> -- Width (in pixels) of current grid column
# * <tt>:gutter_width</tt> -- Width (in pixels) of current grid gutter
# * <tt>:height</tt> -- Height (in pixels) of a row
# * <tt>:filename</tt> -- Output path of grid.png file
def initialize(options={})
@column_width = options[:column_width] || 0
gutter_width = options[:gutter_width] || 0
height = options[:height] || 20
width = @column_width + gutter_width
width = 10 if width == 0
@filename = options[:filename]
@options = options
super(width, height, [0xe9,0xe9,0xe9])
end
def working_path
options[:working_path]
end
# generates (overwriting if necessary) grid.png image to be tiled in background
def generate!
(0...@height-1).each do |line|
@data[line] = Array.new(@width){|x| x < @column_width ? [0xe8, 0xef, 0xfb] : [0xff,0xff,0xff] }
end
if File.exists?(filename)
if options[:force]
overwrite = true
else
msg = "#{filename} already exists. Overwrite with --force."
raise Compass::FilesystemConflict.new(msg)
end
end
directory File.dirname(filename)
write_file(filename, self.to_blob, options, true)
end
end
end
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