StarCube is continuation of MIC Akcelerator 2.0.

I will participate as member of mentors team. My primary focus will be: Software development in startup company. I’m looking forward to discuss new challenging topics.

It’s fairly easy to use. Just pass a text to function and QR code is ready:

jquery('#qrcode').qrcode("this plugin is great");

Here is small application that generates QR codes on the fly as you type.

You can also download QR code as image (use: Chrome, FF, Opera or Safari for download).

Link to standalone QR code HTML5 application.

The roadshow will start in Prague – 26.1. 2012.

Next stops on roadshow in Europe: Magdeburg, Essen, Nuremberg, Frankfurt am Main, Paris, London, Manchester.

Check out cool micro-site: SafeQ4.com.

SafeQ is solution for managing, monitoring and securing prints. You can find more details about SafeQ at YSoft website.

Tomcat was complaining that certificates are not correct (PKIX): the trustAnchors parameter must be non-empty.

Solution for Debian was quite easy after I found correct path to cacerts. Java cacerts for OpenJDK are stored in file: /etc/ssl/certs/java/cacerts.

To import certificate it is sufficient to use keytool:

keytool -import -keystore /etc/ssl/certs/java/cacerts -file cert.pem \
-alias ci.sinusgear.com

Then I restarted Tomcat and problem with trustAnchors disappeared.

Meeting Agenda – November 2011

Flex Components Lifecycle / Tomas Lehuta

The Future of 2D in Flash / Peter “Shtif” Štefček

Making Things / Martin Cagalinec & Ivan Klim

You can find out more about Adobe Slovakia User Group at groups.adobe.com.

Recording are available thanks to Franto and Lharp.

[SK] Odkaz na aplikáciu.
[EN] Link to application.

Note: Map is based on one geocache puzzle.

By now you know, that when you need simple server to serve static pages just for you to play, you use Python’s SimpleHTTPServer.

But this time I wanted more: I wanted to to able to use serve images caught by my webcam. CGI server would be quick answer. While there is class in python doing that, I did not wanted to play with it. I needed something quick to do and maybe I was just little lazy to do so this day.

First thought: one window while cycle with cam-grabber, in the other window SimpleHTTPServer. Well, the solution lacked elegance, as it was not one-liner-styled enough. And then it occurred to me: why not use Netcat?

Building Blocks

At first, I needed to get data from camera. I had figured how to do that some time ago.

vgrabbj -i vga -d /dev/video0 -a -z 10 -q 100

Let’s just elaborate on that a little bit. vgrabbj takes `640×480` image from video4linux device `/dev/video0`, with enabled brightness adjustment, taking 10 images just to adjust, and using 100% quality of JPEG, and sending it to stdout.

Another building block is “server” to serve something that returned command. NetCat is our fiend. Little-bit of HTTP-fu is needed, but not much.

{ echo -ne 'HTTP/1.0 200 OK\r\nConnection: Close\r\n\r\n'; cat file; } | nc -l 1234

We will be serving JPEG, so we add appropriate HTTP header (unless you can see things in binary garbage).

Content-Type: image/jpeg

It may happen that file-size of image will cripple user’s comfort over slower network. What about speeding it up by sending response gzipped? We will need header

Content-Encoding: gzip

and we will have to use… you guessed it: gzip.

gzip -f

However, gzip will not reduce the size of JPEG much, as it already has entropy quite high. We can decrease quality of image i.g. by switch -q of vgrabbj, but in this case I would prefer ImageMagick for reasons that will become clear in a moment. Another possibility how to deal with this issue is scaling image down, which can be done here as well.

convert - -quality 75 -

It will also be nice to have a non-crippled copy of served file. Can do that: tee.

Serving repeatedly can be done by i.e. by while loop. Small functional enhancement: it will be nice to have so called “auto-refresh”. Adding one HTTP header will do that for us. Say every 5 seconds.

Refresh: 5

Some cooling enhancements? Server header:

Server: CoolServer!

Assembling

And now just put it all together.

while :; do { echo -ne 'HTTP/1.0 200 OK\r\nServer: Kwak!\r\nConnection: Close'\
'\r\nRefresh: 5\r\nContent-Type: image/jpeg\r\nContent-Encoding: gzip\r\n\r\n'\
; vgrabbj -i vga -d /dev/video0 -a -z 10 -q 100 | tee omg-`date +'%Y-%m-%d-%H'\
'%M%S'`.jpg | convert - -quality 75 - | gzip -f; } | nc -l 1234; done

Feel free to unwrap it .
And a non-one-liner (little bit more readable) version:

#!/bin/bash
PORT=1234
QUALITY=75
REFRESH=5
HEADER='HTTP/1.0 200 OK\r\n'
HEADER=$HEADER'Server: CoolServer!\r\n'
HEADER=$HEADER"Refresh: $REFRESH\r\n"
HEADER=$HEADER'Connection: Close\r\n'
HEADER=$HEADER'Content-Type: image/jpeg\r\n'
HEADER=$HEADER'Content-Encoding: gzip\r\n'
HEADER=$HEADER'\r\n'
while :; do
    {
        echo -ne "$HEADER"
        vgrabbj -i vga -d /dev/video0 -a -z 10 -q 100 \
        | tee omg-`date +'%Y-%m-%d-%H%M%S'`.jpg \
        | convert - -quality "$QUALITY" - \
        | gzip -f
    } \
    | nc -l "$PORT"
done

Notes

• Some versions of nc may need to be called more like `nc -l -p 1234`.
• First photo will be served from time you started script, every other from time the last shoot was taken. (Exercise for patient reader: why it is so? ). This might not be issue, as it speeds up reading of photo on request.
• Previous can be solved by creating script, that can be called by nc on connection. That way you can create even interactive “CGI” script, that will read (and parse) input from std in and write response to stdout. Not all versions of nc are able to do that.
• Another exercise: Will you be able to secure your communication using stunnel.

Enjoy

Console window is displayed when you run application.

When you set focus to some other window like Search results and application prints something on output then Eclipse will automatically switch to Console window. Your search results are gone.

There is simple way how to get rid of such a behavior.

Go to Window -> Preferences -> Run/Debug -> Console. Uncheck options:

• Show when program writes to standard out
• Show when program writes to standard error

Check out WordPress.TV.

Do you want to join some WordPress events around the world? Then check out WordCamp.org Central.

msbuild MyProject.vcproj /p:Configuration="Release"

Let say that we want to use #define in the source code. It is necessary to define it in Configuration Properties > C++ > Command Line:

/DSIMPLE_DEFINE

This just pass SIMPLE_DEFINE as flag.

How to deal with string define which should behave like string? E.g.:

#define URL "http://georgik.sinusgear.com"

The trick is in escaping quotes. We can add following define to Command Line:

/DURL=\"http://georgik.sinusgear.com\"

It will transform into .vcproj file:

AdditionalOptions="/DURL=\"http://georgik.sinusgear.com\""

Let’s make one more step.

How to acquire such a define from environment variable? E.g. with following build.bat file:

set URL="http://georgik.sinusgear.com"
msbuild MyProject.vcproj /p:Configuration="Release"

It requires only small modification of .vcproj file:

AdditionalOptions="/DURL=\"$(URL)\""

Small recap of flow: set env variable – pass it to XML – pass it compiler – pass it to code