When you want to implement interactive tools or very specific graphical user interfaces, it is time to look into plugin development. In the previous exercises, we introduced the QGIS Python API. Therefore, we can now focus on the necessary steps to get our first QGIS plugin started. The great thing about creating plugins for QGIS is that there is a plugin for this! It's called Plugin Builder. And while you are at it, also install Plugin Reloader, which is very useful for plugin developers. Because it lets you quickly reload your plugin without having to restart QGIS every time you make changes to the code. When you have installed both plugins, your Plugins toolbar will look like this:
Before we can get started, we also need to install Qt Designer, which is the application we will use to design the user interface. If you are using Windows, I recommend WinPython (http://winpython.github.io/) version 2.7.10.3 (the latest version with Python 2.7 at the time of...