Adding support for calculating JPG dimensions

This commit is contained in:
Deepak Jois 2010-02-18 09:58:16 -08:00
parent f9d75b3bce
commit a075a10f59

View File

@ -1,34 +1,99 @@
module Compass::SassExtensions::Functions::ImageSize module Compass::SassExtensions::Functions::ImageSize
def image_width(image_file) def image_width(image_file)
width = compute_size(image_file).first image_path = real_path(image_file)
width = ImageProperties.new(image_path).size.first
Sass::Script::Number.new(width,["px"]) Sass::Script::Number.new(width,["px"])
end end
def image_height(image_file) def image_height(image_file)
height = compute_size(image_file).last image_path = real_path(image_file)
height = ImageProperties.new(image_path).size.last
Sass::Script::Number.new(height, ["px"]) Sass::Script::Number.new(height, ["px"])
end end
private private
# Returns an array [width,height] containing image dimensions def real_path(image_file)
def compute_size(image_path) path = image_file.value
path = image_path.value
# Compute the real path to the image on the file stystem if the images_dir is set. # Compute the real path to the image on the file stystem if the images_dir is set.
real_path = if Compass.configuration.images_dir if Compass.configuration.images_dir
File.join(Compass.configuration.project_path, Compass.configuration.images_dir, path) File.join(Compass.configuration.project_path, Compass.configuration.images_dir, path)
else
File.join(Compass.configuration.project_path, path)
end
case real_path
when /\.png$/i
IO.read(real_path)[0x10..0x18].unpack('NN')
when /\.gif$/i
IO.read(real_path)[6..10].unpack('SS')
when /\.jpe?g$/i
# FIXME jpgs are not straightforward
raise Compass::Error, "JPEG files are not supported yet."
else else
raise Compass::Error, "File is either not an image, or is not supported." File.join(Compass.configuration.project_path, path)
end end
end end
class ImageProperties
def initialize(file)
@file = file
@file_type = File.extname(@file)[1..-1]
end
def size
@dimensions ||= send("get_size_for_#{@file_type}")
end
private
def get_size_for_png
IO.read(@file)[0x10..0x18].unpack('NN')
end
def get_size_for_gif
size = IO.read(@file)[6..10].unpack('SS')
size.inspect
end
def get_size_for_bmp
d = IO.read(@file)[14..28]
d[0] == 40 ? d[4..-1].unpack('LL') : d[4..8].unpack('SS')
end
def get_size_for_jpg
get_size_for_jpeg
end
def get_size_for_jpeg
jpeg = JPEG.new(@file)
[jpeg.width, jpeg.height]
end
end
class JPEG
attr_reader :width, :height, :bits
def initialize(file)
if file.kind_of? IO
examine(file)
else
File.open(file, 'rb') { |io| examine(io) }
end
end
private
def examine(io)
raise 'malformed JPEG' unless io.getc == 0xFF && io.getc == 0xD8 # SOI
class << io
def readint; (readchar << 8) + readchar; end
def readframe; read(readint - 2); end
def readsof; [readint, readchar, readint, readint, readchar]; end
def next
c = readchar while c != 0xFF
c = readchar while c == 0xFF
c
end
end
while marker = io.next
case marker
when 0xC0..0xC3, 0xC5..0xC7, 0xC9..0xCB, 0xCD..0xCF # SOF markers
length, @bits, @height, @width, components = io.readsof
raise 'malformed JPEG' unless length == 8 + components * 3
when 0xD9, 0xDA: break # EOI, SOS
when 0xFE: @comment = io.readframe # COM
when 0xE1: io.readframe # APP1, contains EXIF tag
else io.readframe # ignore frame
end
end
end
end
end end