Gd Thumbnail

#!/usr/bin/env lua

-- gd thumbnail

-- Create a jpg thumbnail from gif/jpg/png image

-- (C) 2007 by Alex Kloss [http://www.it-rfc.de]

-- licensed under the terms of the LGPL2: http://www.fsf.org/licensing/licenses/lgpl.html



-- uses lua-gd: http://lua-gd.luaforge.net

require('gd')



-- thumbnail(imagein,imageout,maxsize) imageout and maxsize are optional

-- returns the output image name on success, nil on failure

function thumbnail(imagein,imageout,maxsize)

	-- sanitizing input options

	local maxsize = maxsize or 40

	local imageout = imageout or "t"..imagein

	-- loading input image

	local im = (imagein:match('%.jpe?g$') and gd.createFromJpeg(imagein) or

		imagein:match('%.png$') and gd.createFromPng(imagein) or

		imagein:match('%.gif$') and gd.createFromGif(imagein))

	-- getting the size right

	local x,y = im:sizeXY()

	local tx = y > x and x/y*maxsize or maxsize

	local ty = x > y and y/x*maxsize or maxsize

	-- creating the thumbnail

	local tn = gd.createTrueColor(tx,ty)

	gd.copyResampled(tn,im,0,0,0,0,tx,ty,x,y)

	if tn:jpeg(imageout,75) then return imageout

	else return nil end

end



-- command line if not called as library

if (arg ~= nil) then

	for n,i in ipairs(arg) do

		print(thumbnail(i) or "thumbnail creation failed")

	end

end