graphics: Generate the HELP screen programatically.

The original Doom HELP screen showed the default key bindings for the
game's controls. This is not so useful nowadays: at worst it's
outright misleading because the player might not be using the
defaults, but it's also redundant because most modern source ports
allow the key bindings to be changed via the menus, which doubles as a
convenient list of the current key bindings.

Z0k suggested an alternative HELP screen that shows the items and
powerups available in the game. More discussion can be seen in this
thread: http://www.doomworld.com/vb/freedoom/69458-help/

graphics/text/smtextgen

@@ -0,0 +1,203 @@
+#!/usr/bin/env python
+#
+# Copyright (c) 2014
+# Contributors to the Freedoom project.  All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#  * Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+#  * Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#  * Neither the name of the freedoom project nor the names of its
+#    contributors may be used to endorse or promote products derived from
+#    this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+# OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# ----------------------------------------------------------------------
+#
+# Script to generate text graphics using the "small" (HUD) font.
+#
+
+from glob import glob
+import sys
+import subprocess
+import re
+
+# ImageMagick commands used by this script:
+CONVERT_COMMAND = 'convert'
+IDENTIFY_COMMAND = 'identify'
+
+# Background color for output files.
+BACKGROUND_COLOR = '#00ffff'
+
+# Width of a space character in pixels.
+SPACE_WIDTH = 4
+
+# Height of the font.
+FONT_HEIGHT = 7
+
+# Regexp to match dimensions/x,y coordinate pair.
+DIMENSION_MATCH_RE = re.compile(r'(\d+)[x,](\d+)')
+
+# Output from 'identify' looks like this:
+#  fontchars/font033.gif GIF 9x16 9x16+0+0 8-bit sRGB 32c 194B 0.000u 0:00.000
+IDENTIFY_OUTPUT_RE = re.compile(r'(\S+)\s(\S+)\s(\d+)x(\d+)\s')
+
+def get_image_dimensions(filename):
+	proc = subprocess.Popen([IDENTIFY_COMMAND, filename],
+	                        stdout=subprocess.PIPE)
+	proc.wait()
+
+	line = proc.stdout.readline().decode('utf-8')
+	match = IDENTIFY_OUTPUT_RE.match(line)
+	assert match is not None
+	return (int(match.group(3)), int(match.group(4)))
+
+def invoke_command(command):
+	"""Invoke a command, printing the command to stdout.
+
+	Args:
+	  command: Command and arguments as a list.
+	"""
+	for arg in command:
+		if arg.startswith('-'):
+			sys.stdout.write("\\\n    ")
+
+		if ' ' in arg or '#' in arg:
+			sys.stdout.write(repr(arg))
+		else:
+			sys.stdout.write(arg)
+
+		sys.stdout.write(' ')
+
+	sys.stdout.write('\n')
+	return subprocess.call(command)
+
+class Font(object):
+	def __init__(self):
+		self.get_font_widths()
+
+	def compile_kerning_table(self, kerning_table):
+		"""Given a dictionary of kerning patterns, compile Regexps."""
+
+		result = {}
+		for pattern, adjust in kerning_table.items():
+			result[re.compile(pattern)] = adjust
+		return result
+
+	def get_font_widths(self):
+		charfiles = glob('../stcfn*.gif')
+		self.char_widths = {}
+		for c in range(128):
+			filename = self.char_filename(chr(c))
+			if filename not in charfiles:
+				continue
+			w, _ = get_image_dimensions(filename)
+			self.char_widths[chr(c)] = w
+
+	def __contains__(self, c):
+		return c in self.char_widths
+
+	def char_width(self, c):
+		return self.char_widths[c]
+
+	def char_filename(self, c):
+		return '../stcfn%03d.gif' % (ord(c))
+
+	def draw_commands_for_text(self, text, x, y):
+		text = text.upper()
+		result = []
+
+		x1, y1 = x, y
+
+		for c in text:
+			if c == '\n':
+				y1 += FONT_HEIGHT
+				x1 = x
+			elif c == ' ':
+				x1 += SPACE_WIDTH
+
+			if c not in self:
+				continue
+
+			filename = self.char_filename(c)
+			result.extend([
+				'-draw',
+				'image over %i,%i 0,0 "%s"' %
+				    (x1, y1, filename)
+			])
+			x1 += self.char_width(c)
+
+		return result
+
+
+def parse_command_line(args):
+	if len(args) < 4 or (len(args) % 2) != 0:
+		return None
+
+	result = {
+		'filename': args[0],
+		'strings': [],
+	}
+
+	m = DIMENSION_MATCH_RE.match(args[1])
+	if not m:
+		return None
+	result['dimensions'] = (int(m.group(1)), int(m.group(2)))
+
+	i = 2
+	while i < len(args):
+		m = DIMENSION_MATCH_RE.match(args[i])
+		if not m:
+			return None
+
+		xy = (int(m.group(1)), int(m.group(2)))
+
+		result['strings'].append((xy, args[i + 1]))
+		i += 2
+
+	return result
+
+
+args = parse_command_line(sys.argv[1:])
+
+if not args:
+	print "Usage: smtextgen <filename> <size> [...text commands...]"
+	print "Where each text command looks like:"
+	print "  [x,y] [text]"
+	sys.exit(0)
+
+smallfont = Font()
+
+command_line = [
+	CONVERT_COMMAND,
+	'-size', '%ix%i' % args['dimensions'],
+	'xc:none',
+]
+
+for xy, string in args['strings']:
+	command_line.extend(smallfont.draw_commands_for_text(
+	    string, xy[0], xy[1]))
+
+command_line.extend((
+	'-background', BACKGROUND_COLOR,
+	'-flatten', args['filename'],
+))
+
+invoke_command(command_line)
+