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