I've lost some time trying to get joystick support for my an application using SDL, mostly because the initialization steps where these:
SDL_Init(SDL_INIT_JOYSTICK|SDL_INIT_VIDEO);
SDL_JoystickEventState(SDL_ENABLE);
It didn't work if I just initialized the joystick, it needed to be done together with the video. I want this to be very minimalistic, so it would be nice to know if there's a way to initialize just the joystick. If not, can someone tell me if there's any disadvantage of initializing the video and never using it?
I'm on Ubuntu here, but I expect this to run in various platforms. Does this behavior vary in different environments?
Thanks :)
I had similiar issues when developing a small CLI app that took joypad input. Basically, it didn't work without SDL_INIT_VIDEO because SDLs event system stems from the video driver, at least on Linux (X11).
It is perfectly fine to init video without ever creating a window (it works at least). I've tested this approach on both Win32 and Linux, so it does seem to work fine multiplatform as well.
I have a similar issue, I solved it by not using the event loop. Instead I manually update the joysticks and then use the SDL functions to check the joysticks.
SDL_Init(SDL_INIT_JOYSTICK);
SDL_JoystickEventState(SDL_DISABLE);
joystick = SDL_JoystickOpen(0);
SDL_Joystick* joystick;
while(true)
{
SDL_JoystickUpdate();
SDL_JoystickGetAxis(joystick, 0);
}
Related
I would like to make a Graphical interface for a home-made program using SFML on Raspberry Pi2. I am using Raspbian. I recompiled the graphical lib
It works fine unsing startx first, then using my application, which wors perfectly fine.
But I can't figure if it is possible or how to launch my application directly after boot without launching startx (just to optimise the cpu of the Raspberry).
Starting my program direcly after boot, I get the following error:
Failed to open X11 display: make sure the DISPLAY environnement variable is set correctly.
Aborted.
I already tested the classic export DISPLAY=:0.0 but without sucess.
I interested myself in x and xinit, but I am not sure that would even do it.
Where should I start looking? I don't need a complete solution, even a hint or an idea would be nice!
I checked to see if it was possible to open a graphical app without the X desktop environment and as that answer states, with Firefox at least, you need the X server which SFML also probably needs in order to create a window.
The answer states:
Basically something like:
$ X
Then you just start Firefox in this X server:
$ DISPLAY=:0 firefox
You can switch from the X server and the framebuffer by using
CTRL+ALT+F1 and CTRL+ALT+F7.
You could try that and see if it helps.
Also, still searching, I found a forum post on the sfml website about what you're trying to accomplish stating somewhere:
SFML requires OpenGL, so as far as I know you need at least X running,
but you probably don't need gnome, KDE or a similar Desktop
Environment on top.
The forum guy asking for help seems to have managed to get X11 and a SFML basic render window to work on Ubuntu server after someone posted a link to xinitrc. I guess, that's the route to go from here.
I asked this question in the Raspberry PI section, so please forgive me for posting this here again. Its just there doesn't seem to be as active as this section of the forum. So, onto my question...
I have an idea and I'm working on it right now. I just wanted to see what the community's thought was on using a screensaver as digital signage. Every tutorial I've read shows someone using chromium in kiosk mode, and while that's fine and works well for some uses, it doesn't work for what I need. I have successfully completed a chromium kiosk, and it was cool. But the signage that I need to create now, has to work without internet. I've thought about installing LAMP locally on the PI, and still using chromium. I still may have to if this idea doesn't pan out. All I need from the signage is a Title Message in the top center, and a message body underneath it, with roughly 300-400 character limit. My idea is to write a screensaver module, in C, that will work with a screensaver such as xscreensaver. The module would need to be able to load messages from a directory on the pi. Then for my clients to update their signage text, I would write a simple client that sent commands as well as the text via SSH to the pi. I want to know what other people think about this. Is it a good idea? Bad idea? Should I "waste" my time doing something like this?
Thanks in advance.
I am already using a rPi as digital signage, just over a year. I am using two different setups:
version 1 uses Raspian loading xdesktop and qiv image viewer to cycle images stored on the Pi itself, synchronized with a remote server. The problem I found was power and SD stability, when the power fails, which it will do no matter what, just when... The Sd card can become corrupt due to all the writing that Raspian does all the time. Certainly does not really need to write to SD.
version 2 uses a RO-filesystem and a command line image tool. Uses the same process to show images from local, and sync with server. But power fail causes no ill effects.
I am not using screensaver to display images, that seemed redundant to me, and unnecessary to wait for the SS to start just to display the images.
Some of the images are created using imagemagik, which is nicely dynamic where needed.
I am a beginner to DBus and wrote one sample application using dbus but i am facing a weird problem. My app is running fine on guest os as Ubuntu (On virtual box with windows host ) but the same app is not working on standalone Ubuntu system (also tried on meego, no luck thr as well).
Then, i verified the obvious doubts on dbus, glib libraries versions. Its same on both the environments, and the issue is consistent. I mean the app always runs without any prob on virtual box and always crashes on the standalone ubuntu.
Here is the brief desc about the issue.
App is supposed to send 150 signals on dbus and another app is
receiving these signals. (No issues here in send & receive).
I have an array of DbusMessage[150] (also tried with the list of 150 DBusMessage)...appending the arguments on to the dbus msg and sending on to bus..one at a time...no looping...
The sequence of dbus APIs are all correct and verified by referencing multiple sample source code.
All of above works fine, but on the standalone ubuntu system, i can always see segmentation fault, on dbus_connection_send() call.
I reverified everypossible places where in "seg faults" can happen and it all looks fine to me. This is how i am appending my arg to dbus message.
dbus_message_append_args(pDbusMsg, DBUS_TYPE_ARRAY, DBUS_TYPE_BYTE, &pData, sizeof(pData),
DBUS_TYPE_INVALID) != TRUE)
then connection send..and then calling dbus_connection_flush(). Also as my app has to send the same message again (but not immediately), i am re registering the same signal by calling dbus_message_new_signal()..i have verified all the pointers / memory / dbusmessage..everything looks fine and works fine on virtualized ubuntu os.
Just to add, i tried sending with dbus_connection_send_preallocated() and it works fine for few messages(10-15~), but not consistent enough.
Have you ever had this kind of issue, please let me know any clue to solve this prob....Any help would be appreciated or any examples/tutorials as well taking into consideration I'm just starting out with dbus :P
Thanks
I dont know if you have heard about dbus related debugging tools. For beginning you can try calling the exposed functions using some dbus-debugging-tool. If it doesnt throw segmentation fault when you call using the tool, then probably you should look for issues in your code. Otherwise you should check things related to environment.
One such tool is - DFeet
Another such debugger(commandline based) is provided by Qt people as well.
The app is using my library which works using threads to do some operation; also it uses SIP VOIP library (obviously it is using threads). GUI is bound to interfaces of both libraries.
I noticed a weird behavior of my app. Usually it works just fine but sometimes after some time (3-5 minutes) it suddenly closes.
It is too irregular to debug it or diagnose.
Anyone had that kind of problem? Any idea what could be the reason for that?
I would recommend you add an application level error handler so that you can log any errors that are occuring that you might be missing. It is as simple as
Application.Current.DispatcherUnhandledException += HandleApplicationException;
Here is an MSDN article that describes it:
http://msdn.microsoft.com/en-us/library/system.windows.application.dispatcherunhandledexception.aspx
I'm writing a program in C and want it to have an option that will keep a mac laptop awake even if the lid is closed so processes can continue. There seems to be very little information available on this topic so I really don't know where to begin. If anyone knows how to accomplish this or where I can find more information I would really appreciate (i.e. will I need to work with the BIOS for this or are there built in functions?). Also, if it's easier to do it in another language that is fine as I'm not stubbornly set on using C.
You need to write a kernel extension for this. The OS doesn't support it by default because the laptops aren't designed to properly cool themselves with the lid closed and internal display enabled. SleepLess is a $10 utility that'll do what you want, too. If you warp the display or something, it's your own fault. :-).
If you want to write something yourself, LidSleep.kext looks like a good start (it does the opposite, i.e. sleeping on lid close) and comes with source code.
(It is possible and supported to wake up some Mac laptops with the screen closed by using an external input device.)
You can do this using the I/O Kit framework, see QA1340 listing 2 for sample code using IOPMAssertionCreateWithName to temporarily prevent sleep.
The link to LidSleep.kext listed above is not working, so I can inform that the author of NoSleep has made the source code available here, so you can see for yourself how it can be done:
https://code.google.com/p/macosx-nosleep-extension/
If your laptop is a reasonably recent model, you don't need to add anything. If you are running Lion, it simply works. If you're running an older OS you have to wake up the laptop by sending it a keystroke or mouse click from an external keyboard or mouse. See http://support.apple.com/kb/ht3131