blame2ppm.rb

#! /your/favourite/path/to/ruby
# -*- coding: utf-8 -*-
# Copyright (c) 2013 Urabe, Shyouhei
#
# Permission is hereby granted, free of  charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without  restriction, including without limitation the rights
# to  use, copy, modify,  merge, publish,  distribute, sublicense,  and/or sell
# copies  of the  Software,  and to  permit  persons to  whom  the Software  is
# furnished to do so, subject to the following conditions:
#
#    The above copyright notice and this permission notice shall be included
#    in all copies or substantial portions of the Software.
#
# THE SOFTWARE  IS PROVIDED "AS IS",  WITHOUT WARRANTY OF ANY  KIND, EXPRESS OR
# IMPLIED,  INCLUDING BUT  NOT LIMITED  TO THE  WARRANTIES  OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE  AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
# AUTHORS  OR COPYRIGHT  HOLDERS  BE LIABLE  FOR  ANY CLAIM,  DAMAGES OR  OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# Hilbert curve generator.  Yields (x, y),  where (x, y) are a series of points
# starts from  (0, 0) towards (2**n-1,  2**n-1), in sequence  of Hilbert curve.
# Algorithm translated from http://en.wikipedia.org/wiki/Hilbert_curve
def hilbert n
	(0..Float::INFINITY).lazy.map do |d|
		x = y = 0
		t = d
		s = 1
		while s < n do
			rx = 1 & (t / 2)
			ry = 1 & (t ^ rx)
			if ry == 0 then
				if rx == 1 then
					x = s - 1 - x
					y = s - 1 - y
				end
				x, y = y, x
			end
			x += s * rx
			y += s * ry
			t /= 4
			s *= 2
		end
		next x, y
	end
end

# Nearest  value to  x,  where it  is  grater than  or equal  to  x, and  2**n.
# Alrothinm translated from the "Hacker's Delight".
def clp2 x
	n = x.to_i - 1
	n |= n >> 1
	n |= n >> 2
	n |= n >> 4
	n |= n >> 8
	n |= n >> 16
	n |= n >> 32
	n + 1
end

# Outputs PPM, assumes vector of 24bit pixmap.
def ppmout bmp, file
	open file, 'w' do |fp|
		x = bmp.size
		y = bmp.max_by(&:size).size
		fp.printf "P3\n%d %d\n255\n", y, x
		x.times do |i|
			y.times do |j|
				k = bmp[i] ? (bmp[i][j] || 0) : 0 # can be nil
				r, g, b = (k / 256 / 256) % 256, (k / 256) % 256, k % 256
				fp.printf "%d %d %d ", r, g, b
			end
			fp.puts
		end
	end
end

def failed
	abort "cd WORKING_DIRECTORY && ruby #$0 OUTFILE COMMIT"
end

# ARGV handling
filename = ARGV.shift or failed
treeish = case ARGV.shift
			 when /\A[0-9a-fA-F]+\Z/ then ARGV.first
			 when NilClass           then 'HEAD'
			 else failed
			 end

# Check git
failed unless system "git", "show", treeish, out: IO::NULL, err: IO::NULL

# Get tree
who   = {}
total = 0.0
order = []
IO.popen %W"git ls-tree -r --name-only #{treeish}", 'rb' do |fp|
	fp.each_slice 5 do |a| #! <- FIXME: magic number
		a.map do |i|
			order << i
			Thread.start(i) do |j|
				IO.popen %W"git blame --line-porcelain --root -M -C #{treeish} -- #{j.chomp}", 'r:binary' do |fq|
					a = who[j] = fq.each_line.grep(/^author /).map do |k|
						/^author (.+)$/.match(k).captures.last
					end
					total += a.size
				end
				STDERR.write j
			end
		end.map(&:join)
	end
end

# Generate bitmap, w/ regularization
require 'zlib'

dim = clp2 Math.sqrt(total)
col = {}
bmp = []
gen = hilbert(dim)
order.each do |i|
	who[i].each do |w|
		col[w] ||= Zlib.crc32(w)
		x, y = gen.next
		bmp[x] ||= []
		bmp[x][y] = col[w]
	end
end

ppmout bmp, filename

# 
# Local Variables:
# mode: ruby
# coding: utf-8-unix
# indent-tabs-mode: t
# tab-width: 3
# ruby-indent-level: 3
# fill-column: 79
# default-justification: full
# End:

sample.png