Read binary file

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From	Herbert Kleebauer <klee@unibwm.de>
Newsgroups	comp.lang.javascript
Subject	Read binary file
Date	Wed, 16 Mar 2016 23:20:35 +0100
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There is a picture (1.jpg) on web server A and I want to make
a modified version available using a web server B. Because
of copyright I can't just copy the picture, modify it and
store it on server B. Instead a html file (test.htm) and
a data file which describes how the picture has to be
modified (diff.dat) is stored on server B. When a user
loads the html file into his browsers, the javascript code
loads the original picture from server A and the modification
file from server B, changes the picture and displays it.

I'm not familiar with javascript, but with help of Google
I hacked together a few lines of code. But it only works if
all three files are on the same server:

http://ikomi.de/test/test.htm
http://ikomi.de/test/1.jpg
http://ikomi.de/test/diff.dat


If the picture is on a different server, there seems to be
an access violation. How can I avoid this violation or in
which other way can I read a binary file from a different
web server into a javascript array.



<html><head><title>jpg</title>
<script type="text/javascript">

function load_binary_resource(url) {
  var req = new XMLHttpRequest();
  req.open('GET', url, false);
  req.overrideMimeType('text\/plain; charset=x-user-defined');
  req.send(null);
  if (req.status != 200) return '';
  return req.responseText;}

var original = load_binary_resource("http://ikomi.de/test/1.jpg");
var diff = load_binary_resource("http://ikomi.de/test/diff.dat");

data='';
for (i = 0; i < diff.length; i++) {
  m=i%original.length;
  data += String.fromCharCode((original.charCodeAt(m)^diff.charCodeAt(i))&0xff);}

document.write('<img src="data:image/jpg;base64,');
document.write(btoa(data));
document.write('">');

</script></head><body></body></html>

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Thread

Read binary file Herbert Kleebauer <klee@unibwm.de> - 2016-03-16 23:20 +0100
  Re: Read binary file Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-03-17 01:04 +0100
    Re: Read binary file Stefan Weiss <krewecherl@gmail.com> - 2016-03-17 02:34 +0100
      Re: Read binary file Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-03-17 07:56 +0100
    Re: Read binary file Herbert Kleebauer <klee@unibwm.de> - 2016-03-17 08:31 +0100
      Re: Read binary file Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-03-17 19:10 +0100
        Re: Read binary file Stefan Weiss <krewecherl@gmail.com> - 2016-03-17 19:59 +0100
          Re: Read binary file Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-03-17 21:43 +0100
            Re: Read binary file Herbert Kleebauer <klee@unibwm.de> - 2016-03-17 22:36 +0100
              Re: Read binary file Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-03-17 23:15 +0100
              Re: Read binary file Stefan Weiss <krewecherl@gmail.com> - 2016-03-18 00:43 +0100
                Re: Read binary file Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-03-18 17:22 +0100
                Re: Read binary file Herbert Kleebauer <klee@unibwm.de> - 2016-03-18 21:14 +0100
                Re: Read binary file Matthias Wiehl <mw@kwarg.de> - 2016-03-19 00:02 +0100
                Re: Read binary file Herbert Kleebauer <klee@unibwm.de> - 2016-03-19 08:48 +0100
                There is no javascript (was: Read binary file) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-03-19 13:02 +0100
                Re: There is no javascript (was: Read binary file) Mark - <nonemail@spamspamapam.net> - 2016-03-19 14:33 +0000
                Re: There is no javascript (was: Read binary file) Andrew Poulos <ap_prog@hotmail.com> - 2016-03-20 14:30 +1100
                Re: There is no javascript (was: Read binary file) Mark - <nonemail@spamspamapam.net> - 2016-03-20 13:07 +0000
                Re: There is no javascript (was: Read binary file) John Harris <niam@jghnorth.org.uk.invalid> - 2016-03-20 10:39 +0000
                Re: There is no javascript (was: Read binary file) John Harris <niam@jghnorth.org.uk.invalid> - 2016-03-20 11:19 +0000
                Re: There is no javascript (was: Read binary file) Philip Herlihy <thiswillbounceback@you.com> - 2016-03-21 17:06 +0000
                Re: Read binary file Scott Sauyet <scott.sauyet@gmail.com> - 2016-03-22 17:18 -0700
                Re: Read binary file "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2016-03-23 10:12 +0100
                Re: Read binary file John Harris <niam@jghnorth.org.uk.invalid> - 2016-03-23 16:27 +0000
                Re: Read binary file Herbert Kleebauer <klee@unibwm.de> - 2016-03-24 10:41 +0100
                Re: Read binary file "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2016-03-24 11:14 +0100
                Re: Read binary file John Harris <niam@jghnorth.org.uk.invalid> - 2016-03-24 11:41 +0000
                Re: Read binary file "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2016-03-24 13:36 +0100
                Re: Read binary file John Harris <niam@jghnorth.org.uk.invalid> - 2016-03-25 10:07 +0000
                Re: Read binary file "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2016-03-25 11:28 +0100
                Re: Read binary file "Christoph M. Becker" <cmbecker69@arcor.de> - 2016-03-24 11:31 +0100
                Re: Read binary file Herbert Kleebauer <klee@unibwm.de> - 2016-03-24 12:34 +0100
                Re: Read binary file "Christoph M. Becker" <cmbecker69@arcor.de> - 2016-03-24 17:15 +0100
                Re: Read binary file Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-03-24 11:33 +0000
                Re: Read binary file "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2016-03-24 11:05 +0100
                Re: Read binary file Scott Sauyet <scott.sauyet@gmail.com> - 2016-03-23 20:16 -0700
                Re: Read binary file "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2016-03-24 10:36 +0100
                Re: Read binary file "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2016-03-24 11:18 +0100
                Re: Read binary file Scott Sauyet <scott.sauyet@gmail.com> - 2016-03-27 10:22 -0700
                Re: Read binary file "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2016-03-28 00:18 +0200
                Re: Read binary file Scott Sauyet <scott.sauyet@gmail.com> - 2016-03-28 05:35 -0700
                Re: Read binary file "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2016-03-29 00:53 +0200
  Re: Read binary file Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-03-17 02:23 +0100
  Re: Read binary file Herbert Kleebauer <klee@unibwm.de> - 2016-03-17 08:42 +0100
  Re: Read binary file Dr J R Stockton <reply1600@merlyn.demon.co.uk.invalid> - 2016-03-20 22:03 +0000

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