Linux Development

Month Three : Week One

        This month is all about Linux and Mac development. The first week I decided to start with Linux because I am most familiar with it and was fairly confident I could deliver on time. The major issue I encountered was just the fact that X11 is rarely used by itself by an end-user, and because of this there is not a lot of useful documentation or example projects that display correct usage of many common window functions that I need to implement. Most posts tell me to not use raw X11 and to just use a toolkit, which does not help me at all because I am essentially trying to be the toolkit.

        The manner in which this issue manifested itself most often was when messing with the fullscreen functionality of the X11 window.  X11 has no easy to use fullscreen toggle or even a good way to check if the window is currently fullscreen. The most frustrating and time consuming way this would inhibit me is when I would manage to get the window fullscreen, nothing short of a user pressing the maximize button could get it out of fullscreen mode. Resizing, unmapping, taking the border off, nothing worked. Which essential meant if the window ever became fullscreen it would be impossible to restore it to its normal size through code. It took lots of trial and error to eventually discover that it is much easier to create a custom ClientMessage and fill that message with the information to set the window to fullscreen or out of fullscreen instead of trying to manually resize it. There is a massive list of properties that denote every attribute of an X11 window, and it is possible to peek and edit these properties by grabbing their ID's using Atoms and then putting them into a set or delete message and sending that off to the window with XSendEvent. Eventually I discovered that fullscreen mode on an X11 window is denoted by two properties being set on the window,  _NET_WM_STATE_MAXIMIZED_HORZ and _NET_WM_STATE_MAXIMIZED_VERT.

By grabbing these two properties and sending a property delete message to the window, I was able to get the window to exit fullscreen mode set itself to its proper internal size. Once I was able to get the window out of fullscreen it was trivial to do move and resize it.