Welcome to TechScreen

Welcome to the TechScreen site. This side shall support the exchange of knowledge in the domain of Web Engineering and related aspects. As a side effect, this side is used for research on knowledge management technologies. User can pose challenges in the problem domain and can participate in quizzes. Further a bibliography about arcticles in different related domains is continously extended. Finally, questionnaires on different issues are provided. To be able to participate you need an account and a password from TU Wien's TISS system.

CSS Tooltip

I once had to deal with the tooltip of a dropdown menu. The button which opened the menu right below it (on mouseover) had a tooltip which always appeared below the button as well, covering part of the first menu item, which made it annoying for the user to deal with.

Create Colorblind Friendly Homepage

A kollegue of mine was born with colorblindness. He struggles to differenciate between red and green. Quite often he tendet to criticise my homepages and app-layouts that he couldn't see the difference between an green status point and red error status point. After studying this matter, how to make layouts more user friendly I discovered several pages, where colors can be compared whether they are distiguishable or not: (e.g.

Editable SVG text

HTML5 has introduced contenteditable attribute. This attribute specifies whether the content of an element is editable or not. How to make svg text editable? To put html elements in an svg element, we need to use <foreignObject>. Within that object we can add any html element, for example div that has attribute contenteditable. The problem is that we want svg text to be editable, and not div. Solution is to add svg elements inside contenteditable div. When the contenteditable attribute is not set on an element, the element will inherit it from its parent.

SVG text align browser support

I had a task to build an online editor for creating graphic content, like visit cards. I chose to work with svg. All svg elements (e.g. line, rectangle, circle etc.) are positioned in a parent component with x and y attributes (like in a coordinate system). I wanted to have a text element with a rectangle around it which indicates that the text is in edit mode. In order to position the text inside the rectangle, I had to calculate x and y values.

Installing TrueCrypt on mac

Working on an assignment for a Digital Forensics course, I had to open some TrueCrypt container. In order to do so, I downloaded TrueCrypt zip and extracted it. The version I downloaded was 7.2. I then proceeded to install it, but I got an error saying: “TrueCrypt requires MAC OS X 10.4 or later”. Just to be sure, I checked my MAC OS version - it was 10.14.0. Apparently, the logic condition that tests the OS version was not correct and I found myself unable to install TrueCrypt.

Copy text without formatting from PDF or other Rich Text source

I want to copy a text from a Rich Text source (like PDF, Word document, Notes taking app, etc), but without the formatting, so I can copy-paste like normal text.
 Most of the time when I copy text from PDF, it is copied with a lot if new lines, but I want to just make a list of technologies or quotes to use in my articles/documents. What is nice and quick way to copy formatted and paste as unformatted text, when there is no such option in the context menu?

Java Async testing

A Java Spring Boot powered REST Api has operations, which require minutes to finish, because of multiple HTTP connections and database queries with lots of data. These tasks are executed Asynchronously. 
The functionality needs to be tested in the integration tests (using less data, so the operation runs in seconds). Now we use Thread.sleep(…) and the tests take 10minutes to finish every time, while we see the operations finished sometimes for 2-3 seconds and the overall required time would be 5minutes.

Integration testing with RabbitMQ and Postgres in Spring Boot when using CI (and not only)

The application to test uses Postgres and RabbitMQ. It also uses “spring-boot-starter-amqp” and its “RabbitTemplate”. The app runs migrations with Flyway and uses Postgres syntax. Because of inconvenience and since there is CI (Continuous Integration) in a remote server, running RabbitMQ and Postgres instances can’t be provided. How can we set up our test environment to provide those RabbitMQ and Postgres DB instances, so it is clean on each test suite run?

Circumvent a license key

A friend developed an application, that was protected by a license key. Since I was curious how he implemented the key-checking and the application overall I decided to hack the app and write a key generator to use the app. The application was written in java, I looked out for a java decompiler and finally used the „java decompiler“ application. As a result I had a lot of java files. The only problem is, that the naming wasn’t useful at all. For example „class a“ doesn’t say anything about the class. So it took me a while to understand the main parts of the code.

Display pdf document in an more pleasant way

I had an pdf with about 1000 Sites consisting only of tables. To navigate and find something in this Document wasn’t that easy. This leads me to develop a web application that should represent the data in a more pleasant way. First I had to analyze the PDF Document, there are several different pdf versions and standards, the second thing that have to be checks is the structure of the document. For example the document could consists of only pictures, which would make the task harder, since there is no text. In my case the pdf structure was straight forward and consists of text boxes.

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