Graphic display software for Raspberry Pi 3B+

Introduction In order to evaluate the single card computer Raspberry Pi (Rpi) as a presentation device we are going to make a simple graphical application for testing purposes. The final application will be a radio direction finder where the deviation from ”boresight” is presented as the direction of an arrow and the power of the received signal is to be presented as arrow length. The objective is an executable running on a Raspberry Pi 3B+ which takes directional data (angle) as input and displays the deviation from ”zero angle” as an arrow in a window on the Rpi desktop. Furthermore the length of the arrow should also be adjustable by the other input parameter (length). The intention is to use this code as a static library to be called by other C++ code, which will supply the input parameters. Scope of work This work package contains the following deliveries: 1. Source code in C++ 11 (no copyright restrictions on delivered code). (GCC compiler.) 2. Makefile to compile and link source file on the Rpi 3. Description of prerequisites to make compilation of code on the Rpi (e.g. neccessary libraries). (Chosen included libraries should be freely available, like GNU libraries for example.) 4. The documentation of comments in source code and an explanation of what libraries to install and how to generate the executable will be sufficient as documentation. The graphical output should be a resizeable window with an arrow base centred in the middle of the window. The maximum length of the arrow should be half the side length of the shortest side of the window. The rotating arrow will thus always be within the window, even if expressing maximum power in the ”smallest” direction. Angle ”zero” mean the arrow is pointing forward . Whereas a negative angle in the function call makes the arrow point leftwards, and a positive angle similarly makes the arrow incline to the right. Only angles -180 < 0 < +180 degrees are allowed. The colour of the arrow as well as its background should be easily adjustable by changes in the source code. The window and the arrow direction and size should remain unchanged between function calls, and when called only change arrow size and direction depending on calling parameters. (Somewhat like an analogue speedometer.)