# code: 
# * George Moschovitis  <gm@navel.gr>
# * Elias Athanasopoulos  <elathan@navel.gr>
#
# (c) 2004 Navel, all rights reserved.
# $Id: gfx.rb 101 2004-10-22 12:35:39Z gmosx $

module N

# = GfxUtils
# 
# General graphics utilities collection.
#
# === Design:
#
# A simple wrapper around ImageMagick.
#
# Implement as a module to avoid class polution. You can
# still Ruby's advanced features to include the module in your
# class. Passing the object to act upon allows to check for nil,
# which isn't possible if you use self.
#
#
module GfxUtils

	# === Input:
	# width, height = dimensions for the scaled image.
	#
	def self.create_thumbnail(src, dest, width, height)
		# gmosx: [0] selects the 1st frame in case of animated gifs.
		# gmosx: SOS!!! the +profile "*" is need to strip metadata that
		#      fuckup the internet explorer!
		if (dest =~ /jpg$/i) or (File.stat(src).size > 60000)
			# keep only the first frame
			system %|convert +profile "*" +compress -scale '#{width}x#{height}>' -antialias #{src}[0] #{dest}|
		else
			system %|convert +profile "*" +compress -scale '#{width}x#{height}>' -antialias #{src} #{dest}|
		end
	end

	# Use ImageMagick to grab the EXIF data
	# contained in a jpeg file and store it to a 
	# hash: EXIF field => EXIF value.
	#
	# A sample EXIF table:
	#
	# Make=Canon
	# Model=Canon PowerShot S110
	# Orientation=1
	# X Resolution=180/1
	# YResolution=180/1
	# ResolutionUnit=2
	# DateTime=2002:05:16 21:02:36
	# YCbCrPositioning=1
	# ExifOffset=196
	# ExposureTime=1/80
	# FNumber=28/10
	# ExifVersion=0210
	# DateTimeOriginal=2002:05:16 21:02:36
	# DateTimeDigitized=2002:05:16 21:02:36
	# ComponentsConfiguration=...
	# CompressedBitsPerPixel=3/1
	# ShutterSpeedValue=202/32
	# ApertureValue=95/32
	# ExposureBiasValue=0/3
	# MaxApertureValue=194698/65536
	# SubjectDistance=772/1000
	# MeteringMode=5
	# Flash=1
	# FocalLength=173/32
	# MakerNote=.
	# UserComment=
	# FlashPixVersion=0100
	# ColorSpace=1
	# ExifImageWidth=1600
	# ExifImageLength=1200
	# InteroperabilityOffset=1328
	# unknown=R98
	# unknown=0100
	# unknown=1600
	# unknown=1200
	# FocalPlaneXResolution=1600000/206
	# FocalPlaneYResolution=1200000/155
	# FocalPlaneResolutionUnit=2
	# SensingMethod=2
	# FileSource=.
	#
	def self.grab_exif(path)
		info = %x|identify -format "%[EXIF:*]" #{path}|.split("\n")
	
		exif = {}
		info.each { |l|
			tag, value = l.split("=")
			exif[tag] = value
		} 
		
		unless exif.empty?
			return exif
		else
			return nil
		end
	end
	
end

end # module