Tutorials

First, you have to connect to the remote host by enabling X11 forwarding. This can be done using -X or -Y
(trusted X11 forwarding) parameter at the ssh command line:

ssh -Y 
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If you wish to omit these parameters, you can enable the ForwardX11Trusted directive in ~/.ssh/ssh_config
configuration file. You can also check this directive in the remote host configuration (eg /etc/ssh/sshd_config).

In Qt, plugins are used to create custom database drivers, image formats, text codecs, styles and widgets as stand-alone components.

There are two ways to use plugins:

1. compiling the plugin into a dynamic library (ie. dll on Windows) that is detected and loaded at runtime
2. linking the plugin statically against your application (the only option for statically compiled Qt)

In this tutorial, I'll show you how to use MySQL and PostgreSQL database drivers using the first method.

When developing an application that implies user authentification or sensitive data, you'll need to encrypt or hash data. There are few C/C++ APIs that provide encryption, digital signature and hashing algorithms. One of them, QCA, is developed using Qt datatypes and conventions. I chosen to use it because it is cross-platform, since my application had to run on both Windows and Linux. I encountered few issues at installing it, so I thought that it might be a good idea to write a tutorial about it.

In this tutorial, I'll show you how to compile QCA and QCA-ossl plugin with mingw. QCA has built-in support for the SHA1 and MD5 hash algorithms, and a weak random number source, so we must compile QCA-ossl plugin, that adds support for some well-known encryption, hashing and digital signature algorithms. Then I'll show you how to include QCA into your project, then encrypt and decrypt some data.

In my last Qt project, which was an spreadsheet application (like Microsoft Excel or OpenOffice Calc), I wanted to implement an PDF export feature. At first I decided to use an report generator, but then I found out that Qt has some classes that can be used for saving PDF files.

In this tutorial, I'll show you how to generate a PDF file for a spreadsheet, using a function that opens a file save dialog (supposing that you created a Gui Application) and another function that generates the PDF file. Of course, you could modify the functions described below so it can use any "model" (ie. data source).