geometry.rb
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# This Geometry class was yanked from RMagick. However, it lets ImageMagick handle the actual change_geometry.
# Use #new_dimensions_for to get new dimensions
# Used so I can use spiffy RMagick geometry strings with ImageScience
class Geometry
# @ is removed until support for them is added
FLAGS = ['', '%', '<', '>', '!']#, '@']
RFLAGS = { '%' => :percent,
'!' => :aspect,
'<' => :>,
'>' => :<,
'@' => :area }
attr_accessor :width, :height, :x, :y, :flag
def initialize(width=nil, height=nil, x=nil, y=nil, flag=nil)
# Support floating-point width and height arguments so Geometry
# objects can be used to specify Image#density= arguments.
raise ArgumentError, "width must be >= 0: #{width}" if width < 0
raise ArgumentError, "height must be >= 0: #{height}" if height < 0
@width = width.to_f
@height = height.to_f
@x = x.to_i
@y = y.to_i
@flag = flag
end
# Construct an object from a geometry string
RE = /\A(\d*)(?:x(\d+)?)?([-+]\d+)?([-+]\d+)?([%!<>@]?)\Z/
def self.from_s(str)
raise(ArgumentError, "no geometry string specified") unless str
if m = RE.match(str)
new(m[1].to_i, m[2].to_i, m[3].to_i, m[4].to_i, RFLAGS[m[5]])
else
raise ArgumentError, "invalid geometry format"
end
end
# Convert object to a geometry string
def to_s
str = ''
str << "%g" % @width if @width > 0
str << 'x' if (@width > 0 || @height > 0)
str << "%g" % @height if @height > 0
str << "%+d%+d" % [@x, @y] if (@x != 0 || @y != 0)
str << FLAGS[@flag.to_i]
end
# attempts to get new dimensions for the current geometry string given these old dimensions.
# This doesn't implement the aspect flag (!) or the area flag (@). PDI
def new_dimensions_for(orig_width, orig_height)
new_width = orig_width
new_height = orig_height
case @flag
when :percent
scale_x = @width.zero? ? 100 : @width
scale_y = @height.zero? ? @width : @height
new_width = scale_x.to_f * (orig_width.to_f / 100.0)
new_height = scale_y.to_f * (orig_height.to_f / 100.0)
when :aspect
new_width = @width unless @width.nil?
new_height = @height unless @height.nil?
when :<, :>, nil
scale_factor =
if new_width.zero? || new_height.zero?
1.0
else
if @width.nonzero? && @height.nonzero?
[@width.to_f / new_width.to_f, @height.to_f / new_height.to_f].min
else
@width.nonzero? ? (@width.to_f / new_width.to_f) : (@height.to_f / new_height.to_f)
end
end
new_width = scale_factor * new_width.to_f
new_height = scale_factor * new_height.to_f
new_width = orig_width if @flag && orig_width.send(@flag, new_width)
new_height = orig_height if @flag && orig_height.send(@flag, new_height)
end
[new_width, new_height].collect! { |v| [v.round, 1].max }
end
end
class Array
# allows you to get new dimensions for the current array of dimensions with a given geometry string
#
# [50, 64] / '40>' # => [40, 51]
def /(geometry)
raise ArgumentError, "Only works with a [width, height] pair" if size != 2
raise ArgumentError, "Must pass a valid geometry string or object" unless geometry.is_a?(String) || geometry.is_a?(Geometry)
geometry = Geometry.from_s(geometry) if geometry.is_a?(String)
geometry.new_dimensions_for first, last
end
end