png2uri-README.txt - third_party/libpng - Git at Google

 /*
  png2uri

  NO COPYRIGHT RIGHTS ARE CLAIMED TO THIS SOFTWARE.

  To the extent possible under law, the author has waived all copyright and
  related or neighboring rights to this work. This work is published from
  the United States of America in 2012.

  The png2uri software may be used freely in any way.

  The source is the original work of the person named below.  No other person
  or organization has made contributions to this work.

  ORIGINAL AUTHORS
      The following people have contributed to the code or comments in this
      file.  None of the people below claim any rights with regard to the
      contents of this file.

      Glenn Randers-Pehrson <glennrp@users.sourceforge.net>

  png2uri is a command-line application that creates an HTML "img" tag on
  standard output containing a data URI, from a PNG file or from standard
  input. Other formats besides the default, PNG, are supported, via the "-f"
  or "--format" option or, if that option was not supplied, by inspection of
  the filename extension.

  Usage: png2uri [-f format|--format format] [-u|--uri_only] [file]

         options: -f|--format TYPE:
                  write "image/TYPE" instead of "image/png" in the
                  data uri.  TYPE can be png, jpg, jpeg, bmp, or gif,
                  or any of those in upper case.  To write any other
                  type, include the complete MIME type as in
                  "--format image/x-jng" or "-f audio/mpeg".

                  -u|--uri_only|--url_only
                  omit the surrounding "img" tag and only write the
                  data URI.

  Requires /bin/sh and a base64(1) that encodes its input in base64
  according to RFC-3548 and writes the result on standard output, and
  a working "sed".  Versions 1.0.0 through 1.0.3 used uuencode(1) instead
  of base64(), but a surprising number of machines that I've tried
  (5 out of 11) don't have uuencode installed, while all 11 had base64(1)
  which is a "core utility" rather than a "shar utility".  Using base64()
  has an additional advantage that the lines are always folded to the same
  width, 76 characters wide, while uuencode sometimes writes shorter lines.

  REFERENCES:
     http://en.wikipedia.org/wiki/Data_URI_scheme

     Masinter, L. "RFC 2397 - The "data" URL scheme",
       Internet Engineering Task Force, August 1998

     http://en.wikipedia.org/wiki/Base64

     IETF, "RFC 3548 - The Base16, Base32, and Base64 Data Encodings",
       July 2003.

  OTHER IMPLEMENTATIONS

  If you prefer a web-based converter or a java application, this isn't
  it. Use your search engine and look for "png data uri" to find one.
  Here are some:

    A PHP script:
       http://css-tricks.com/snippets/php/create-data-uris/

    Hixie's web-based converter
       http://software.hixie.ch/utilities/cgi/data/data/

    Websemantics' web-based converter
       http://websemantics.co.uk/online_tools/image_to_data_uri_convertor

    Mike Scalora's web-based converter
       http://www.scalora.org/projects/uriencoder/

    Data URL Maker (a web-based drag-and-drop converter), CSS Optimizer,
    and Data URL Toolkit (a PERL implementation)
       http://dataurl.net/#about

  CHANGE LOG

    Version 1.0.0, July 3, 2012:

       Initial release.

    Version 1.0.1, July 4, 2012:

       The string "base64" could conceivably appear within the encoded data
       and any line containing "base64" is removed; revised script to
       use "====" instead to remove the first line of uuencode output.

       Implemented "-u" and "--url_only" option.

    Version 1.0.2, July 4, 2012:

       Implemented "-f TYPE" and "--format TYPE" option.

    Version 1.0.3, July 5, 2012:

       Changed environment variable "format" to PNG2URI_FMT reduce possibility`
       of name conflict, and changed "uri_only" to PNG2URI_URI.  Fixed some
       indentation.

    Version 1.0.4, July 6, 2012:

       Use "base64" instead of "uuencode" when "uname" returns "Linux" to
       generate the output, because "base64" seems to be more prevalently
       available. On Gnu/Linux platforms, uuencode must be installed as part
       of "sharutils", which often doesnn't happen.  SunOS and FreeBSD don't
       supply "base64" so we use "uuencode" instead.

  TO DO

  1. Test on various other platforms. I assume we'll soon find one that has
     neither "uuencode" nor "base64".  The following have been tried

     Ubuntu 10.04 (uuencode output was folded to 60 characters)
        Linux glenn.rp 2.6.32-41-generic #91-Ubuntu SMP Wed Jun 13 11:43:55
           UTC 2012 x86_64 GNU/Linux
        Linux nancy.rp 2.6.32-41-generic #91-Ubuntu SMP Wed Jun 13 11:43:55
           UTC 2012 x86_64 GNU/Linux (uuencode not found.  Fixed that with
           "sudo aptitude install sharutils", then finally fixed by using
           base64() instead of uuencode())

     Ubuntu 12.04 (uuencode not found but manpage for POSIX uuencode exists;
        base64 works)
        Linux scooby 3.0.0-22-generic #36-Ubuntu SMP Tue Jun 12 17:37:42 UTC 2012
           x86_64 x86_64 x86_64 GNU/Linux

     SunOS 5.10 (uuencode data is folded to 68 characters)
        Does not work with "base64"!  Reconfigured png2uri to use "uuencode".
        on non-Linux platforms.
        SunOS freddy 5.10 Generic_147441-13 i86pc i386 i86pc
        SunOS blade 5.10 Generic_144488-12 sun4u sparc SUNW,Sun-Blade-2500

     Sunos 5.11 (uuencode data is folded to 68 characters)
        SunOS weerd 5.11 oi_151a4 i86pc i386 i86pc

     FreeBSD 8.0 (uuencode data is folded to 76 characters)
        "base64 not found"; use uuencode.
        FreeBSD shaggy.simplesystems.org 8.0-RELEASE-p1 FreeBSD 8.0-RELEASE-p1
            #1: Mon Dec 21 11:26:14 CST 2009
            zsh@shaggy.simplesystems.org:/usr/src/sys/i386/compile/GENERIC
            i386

     Red Hat? (uuencode not found but manpage for POSIX uuencode
     exists; worked when base64 was used instead of uuencode)
        Linux studio.imagemagick.org 2.6.18-308.4.1.el5xen #1 SMP Tue Apr 17
            17:49:15 EDT 2012 x86_64 x86_64 x86_64 GNU/Linux
        Linux magick.imagemagick.org 3.4.4-3.fc17.x86_64 #1 SMP Tue Jun 26
            20:54:56 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
        Two other Redhat Enterprise platforms also worked with base64, but
            uuencode was not installed.

  2. Find out if the script works on Windows and Mac or can be modified to
  do so.

  3. Make it work as a drag-and-drop application.

  4. But keep it simple!

 */
	/*
	png2uri

	NO COPYRIGHT RIGHTS ARE CLAIMED TO THIS SOFTWARE.

	To the extent possible under law, the author has waived all copyright and
	related or neighboring rights to this work. This work is published from
	the United States of America in 2012.

	The png2uri software may be used freely in any way.

	The source is the original work of the person named below. No other person
	or organization has made contributions to this work.

	ORIGINAL AUTHORS
	The following people have contributed to the code or comments in this
	file. None of the people below claim any rights with regard to the
	contents of this file.

	Glenn Randers-Pehrson <glennrp@users.sourceforge.net>

	png2uri is a command-line application that creates an HTML "img" tag on
	standard output containing a data URI, from a PNG file or from standard
	input. Other formats besides the default, PNG, are supported, via the "-f"
	or "--format" option or, if that option was not supplied, by inspection of
	the filename extension.

	Usage: png2uri [-f format\|--format format] [-u\|--uri_only] [file]

	options: -f\|--format TYPE:
	write "image/TYPE" instead of "image/png" in the
	data uri. TYPE can be png, jpg, jpeg, bmp, or gif,
	or any of those in upper case. To write any other
	type, include the complete MIME type as in
	"--format image/x-jng" or "-f audio/mpeg".

	-u\|--uri_only\|--url_only
	omit the surrounding "img" tag and only write the
	data URI.

	Requires /bin/sh and a base64(1) that encodes its input in base64
	according to RFC-3548 and writes the result on standard output, and
	a working "sed". Versions 1.0.0 through 1.0.3 used uuencode(1) instead
	of base64(), but a surprising number of machines that I've tried
	(5 out of 11) don't have uuencode installed, while all 11 had base64(1)
	which is a "core utility" rather than a "shar utility". Using base64()
	has an additional advantage that the lines are always folded to the same
	width, 76 characters wide, while uuencode sometimes writes shorter lines.

	REFERENCES:
	http://en.wikipedia.org/wiki/Data_URI_scheme

	Masinter, L. "RFC 2397 - The "data" URL scheme",
	Internet Engineering Task Force, August 1998

	http://en.wikipedia.org/wiki/Base64

	IETF, "RFC 3548 - The Base16, Base32, and Base64 Data Encodings",
	July 2003.

	OTHER IMPLEMENTATIONS

	If you prefer a web-based converter or a java application, this isn't
	it. Use your search engine and look for "png data uri" to find one.
	Here are some:

	A PHP script:
	http://css-tricks.com/snippets/php/create-data-uris/

	Hixie's web-based converter
	http://software.hixie.ch/utilities/cgi/data/data/

	Websemantics' web-based converter
	http://websemantics.co.uk/online_tools/image_to_data_uri_convertor

	Mike Scalora's web-based converter
	http://www.scalora.org/projects/uriencoder/

	Data URL Maker (a web-based drag-and-drop converter), CSS Optimizer,
	and Data URL Toolkit (a PERL implementation)
	http://dataurl.net/#about

	CHANGE LOG

	Version 1.0.0, July 3, 2012:

	Initial release.

	Version 1.0.1, July 4, 2012:

	The string "base64" could conceivably appear within the encoded data
	and any line containing "base64" is removed; revised script to
	use "====" instead to remove the first line of uuencode output.

	Implemented "-u" and "--url_only" option.

	Version 1.0.2, July 4, 2012:

	Implemented "-f TYPE" and "--format TYPE" option.

	Version 1.0.3, July 5, 2012:

	Changed environment variable "format" to PNG2URI_FMT reduce possibility`
	of name conflict, and changed "uri_only" to PNG2URI_URI. Fixed some
	indentation.

	Version 1.0.4, July 6, 2012:

	Use "base64" instead of "uuencode" when "uname" returns "Linux" to
	generate the output, because "base64" seems to be more prevalently
	available. On Gnu/Linux platforms, uuencode must be installed as part
	of "sharutils", which often doesnn't happen. SunOS and FreeBSD don't
	supply "base64" so we use "uuencode" instead.

	TO DO

	1. Test on various other platforms. I assume we'll soon find one that has
	neither "uuencode" nor "base64". The following have been tried

	Ubuntu 10.04 (uuencode output was folded to 60 characters)
	Linux glenn.rp 2.6.32-41-generic #91-Ubuntu SMP Wed Jun 13 11:43:55
	UTC 2012 x86_64 GNU/Linux
	Linux nancy.rp 2.6.32-41-generic #91-Ubuntu SMP Wed Jun 13 11:43:55
	UTC 2012 x86_64 GNU/Linux (uuencode not found. Fixed that with
	"sudo aptitude install sharutils", then finally fixed by using
	base64() instead of uuencode())

	Ubuntu 12.04 (uuencode not found but manpage for POSIX uuencode exists;
	base64 works)
	Linux scooby 3.0.0-22-generic #36-Ubuntu SMP Tue Jun 12 17:37:42 UTC 2012
	x86_64 x86_64 x86_64 GNU/Linux

	SunOS 5.10 (uuencode data is folded to 68 characters)
	Does not work with "base64"! Reconfigured png2uri to use "uuencode".
	on non-Linux platforms.
	SunOS freddy 5.10 Generic_147441-13 i86pc i386 i86pc
	SunOS blade 5.10 Generic_144488-12 sun4u sparc SUNW,Sun-Blade-2500

	Sunos 5.11 (uuencode data is folded to 68 characters)
	SunOS weerd 5.11 oi_151a4 i86pc i386 i86pc

	FreeBSD 8.0 (uuencode data is folded to 76 characters)
	"base64 not found"; use uuencode.
	FreeBSD shaggy.simplesystems.org 8.0-RELEASE-p1 FreeBSD 8.0-RELEASE-p1
	#1: Mon Dec 21 11:26:14 CST 2009
	zsh@shaggy.simplesystems.org:/usr/src/sys/i386/compile/GENERIC
	i386

	Red Hat? (uuencode not found but manpage for POSIX uuencode
	exists; worked when base64 was used instead of uuencode)
	Linux studio.imagemagick.org 2.6.18-308.4.1.el5xen #1 SMP Tue Apr 17
	17:49:15 EDT 2012 x86_64 x86_64 x86_64 GNU/Linux
	Linux magick.imagemagick.org 3.4.4-3.fc17.x86_64 #1 SMP Tue Jun 26
	20:54:56 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
	Two other Redhat Enterprise platforms also worked with base64, but
	uuencode was not installed.

	2. Find out if the script works on Windows and Mac or can be modified to
	do so.

	3. Make it work as a drag-and-drop application.

	4. But keep it simple!

	*/