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# Rubygame -- Ruby code and bindings to SDL to facilitate game creation
# Copyright (C) 2004-2007 John Croisant
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# Lesser General Public License for more details.
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
module Rubygame
# *NOTE*: SFont is DEPRECATED and will be removed in Rubygame 3.0!
# Use ImageFont instead.
# *NOTE*: you must require 'rubygame/sfont' manually to gain access to
# Rubygame::SFont. It is not imported with Rubygame by default!
# SFont is a type of bitmapped font, which is loaded from an image file
# with a meaningful top row of pixels, and the font itself below that. The
# top row provides information about what parts of of the lower area
# contains font data, and which parts are empty.
# The image file should contain all of the glyphs on one row, with the
# colorkey color at the bottom-left pixel and the "skip" color at the
# top-left pixel.
# The colorkey color is applied to the image file when it is loaded, so
# that all pixels of that color appear transparent. Alternatively, if the
# alpha value of pixel [0,0] is 0 (that is, if it is fully transparent),
# the image file is assumed to have a proper alpha channel, and no colorkey
# is applied. The skip color is used in the top row of pixels to indicate
# that all the pixels below it contain empty space, and that the next
# pixel that is not the skip color marks the beginning of the next glyph.
# The official SFont homepage, with information on SFont and sample font
# files, can be found at More
# information on SFont, and a useful utility for automatically generating
# the top row for a font, can be found at:
class SFont
@@default_glyphs = [\
# Returns an array of strings, each string a single ASCII character
# from ! (33) to ~ (126). This is the default set of characters in a
# SFont. The full set is as follows:
# ! " # $ % & ' ( ) * + , - . / 0 1 2 3 4 5 6 7 8 9 : ; < = > ? @
# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [ \ ] ^ _ `
# a b c d e f g h i j k l m n o p q r s t u v w x y z { | } ~
def SFont.default_glyphs
# Create a now SFont instance.
# This function takes these arguments:
# filename:: the name of the image file from which the font should be
# loaded. Or, a Surface with a font image on it. The
# Surface will be copied onto separate Surfaces for each
# glyph, so the original Surface can be recycled.
# glyphs:: array of strings, one for each glyph, in the order they
# are found in the image file. If glyphs is not provided,
# or is nil, it is assumed to be the normal SFont order;
# that is, ASCII characters ! (33) to ~ (126). See
# SFont.default_glyphs for a full list.
# spacew:: represents the width of a space character ( ). You can
# either specify the width in pixels, or specify a
# character whose width, as found in the image, should be
# used. Alternatively, you could add a space character to
# the list of glyphs, and to the image file. If +spacew+
# is not given or is nil, and the space character is not
# in the list of glyphs, it will have the same width as
# the double-quote character (").
def initialize(filename,glyphs=nil,spacew=nil)
Rubygame.deprecated("Rubygame::SFont", "3.0",
"Use Rubygame::ImageFont instead.")
# load the surface containing all the glyphs
surface = nil
if filename.is_a? String
surface = Surface.load(filename)
elsif filename.is_a? Surface
surface = filename
@height = surface.height
colorkey = surface.get_at(0,@height-1)
# set colorkey if "transparent" color is not actually transparent
if colorkey[3] != 0
surface.colorkey = colorkey[0..2]
@glyphs = {}
@skip = surface.get_at(0,0)[0..2]
# split the glyphs into separate surfaces
glyphs = (glyphs or @@default_glyphs)
start_x = 2
glyphs.each{ |glyph| start_x = load_glyph(surface,glyph,start_x) }
if not glyphs.include?(" ")
if spacew == nil
spacew = @glyphs['"'].width
elsif spacew.kind_of? Numeric
spacew = spacew.to_i
elsif spacew.kind_of? String
if glyphs.include? spacew
spacew = @glyphs[spacew].width
spacew = @glyphs['"'].width
raise(ArgumentError,"spacew must be Numeric, String, \
or nil (got %s)"%[spacew.class])
@glyphs[" "] =[spacew,@height])
# Return the height of the font, in pixels. This is the same as the
# height of the image file (all glyphs are the same height).
attr_reader :height
# This is a private function which is used to parse the font image.
# Create a Surface for a single glyph, and store it as a value in the
# +@glyphs+ hash, indexed by the glyph (string) it represents.
# Starting at a pixel in the "skip" region to the left of the glyph.
# Scans to the right along the top row until it finds a non-skip pixel
# (this is where the glyph starts) and then scans until it finds a skip
# pixel (this is where the glyph ends.
# Returns the x value it stops at, plus 1. This should be fed back in
# for the +start_x+ of the next glyph.
# This _private_ method takes these arguments:
# surface:: the Surface containing all glyph image data.
# glyph:: a string containing the current glyph
# start_x:: the x position to start scanning at.
def load_glyph(surface,glyph,start_x) # :doc:
# find where this glyph starts
while(surface.get_at(start_x,0)[0..2] == @skip)
start_x += 1
rescue IndexError
return -1
end_x = start_x
# find how wide this glyph is
while(surface.get_at(end_x,0)[0..2] != @skip)
end_x += 1
rescue IndexError
return -1
# make a new surface for the glyph and blit the image onto it
rect =, 0, end_x-start_x, surface.h)
@glyphs[glyph] =
return end_x+1
private :load_glyph
# This is a private function which is used to render a string.
# Blit a single glyph to a Surface at the given position.
# This _private_ method takes these arguments:
# glyph:: a string containing the glyph to blit.
# surface:: the target surface to blit onto.
# pos:: an Array of the x and y values to blit the glyph to.
def blit_glyph(glyph,surface,pos) # :doc:
private :blit_glyph
# Pretends to render the given string, and returns the width in pixels
# of the surface that would be created if it were rendered using
# SFont#render. If you want the height too, you can get it with
# SFont#height (the height is contant).
# This method takes this argument:
# string:: the string to pretend to render.
def string_width(string)
w = 0
string.each_byte { |glyph| w += @glyphs["%c"%[glyph]].width }
return w
# Renders the given string to a Surface, and returns that surface.
# This method takes this argument:
# string:: the text string to render.
def render(string)
size = [self.string_width(string),self.height]
render =
x = 0
string.each_byte { |glyph|
x += @glyphs["%c"%[glyph]].width
return render
end # class SFont
end # module Rubygame
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