I'm writing an LCD controller, and one feature I want to add is the ability to catch keyboard strokes so that you can do stuff like instant messaging over the LCD. I found xsnoop.c but it's outdated. I'm using xorg-x11-server 1.6.4-0.1.fc11 on Fedora 11. I'm also using Qt. I didn't find anything in the docs that might help, but figured I'd mention it.
Any hints?
I've just tried compiling xsnoop.c and there was a line
#include <vroot.h>
which needs to be just removed, but apart from that it works.
Related
I'm trying to implement a service that would monitor language/layout changes. I switch between English and Russian languages. So far I've found this question and tried to implement and install both sinks suggested there.
However, there are problems. ITfActiveLanguageProfileNotifySink::OnActivated is not triggered at all; ITfLanguageProfileNotifySink::OnLanguageChange is not triggered, too; ITfLanguageProfileNotifySink::OnLanguageChanged is triggered only when the main window of my program is in foreground, but it doesn't contain any information on the language. Is there any way to monitor input language change event globally?
I found another way to detect such changes: to use SetWindowsHookEx with WH_SHELL. One of the available event is HSHELL_LANGUAGE which is exactly what I need and the test project seems to work just fine.
There's an article by Alexander Shestakov that describes a program very similar to what I'm trying to achieve and it also has a link to github project that I use as an example.
I want to create command line game in Linux but I don't know to get the key state. I heard of getch() but that stops the program.
I spent a little while reading around. Apparently, this is a hard thing to do without the help of a library. Many people recommended the library ncurses. If you want to try to do it by yourself, you need to learn about switching terminal modes and crazy stuff like that. This thread was very informative: Non-blocking keyboard read - C/C++
In this article, the author implements a cKeyboard class, which directly listens for events from /dev/event0. The class is then used as follows:
#include "keyboard.h"
cKeyboard kb;
...
if (kb.getKeyState(KEY_UP)) {
// do something
}
It works perfectly for me, but I had to change event0 to event4.
I need to block alt+shift keys event using C++, or some way to block changing language.
Thanks in advance.
I would go about it a bit differently. I would catch current langauge settings at startup than change it for desired one.
At the even of alt+shift i would just set it back to the desired type again.
It should be fairy easy to do with net framework.
Here is a short article about manipulating languages: How to change input language programmatically
And main class on msdna: InputLanguage documentation
To actually prevent alt+shift from moving into windows system you would have to play with hooks.
Here is an article about blocking keystrokes before windows process them.
Just an idea. You can catch WM_KEYDOWN message and call ActivateKeyboardLayout to switch language.
Using C++ you can install a keyboard hook procedure like the one suggested here and filter (swallow/don't propagate) the key(s) you want to forbid.
My understanding of MSDN is that you can pretend to process WM_INPUTLANGCHANGEREQUEST and then do nothing, so that Windows will not do anything further and the language will not actually change. But some users say that doesn't work any more.
http://msdn.microsoft.com/en-us/library/ms632630(VS.85).aspx
Maybe you can implement ITfInputProcessorProfileActivationSink::OnActivated, and when you get called you can change back to the previous language by calling ITfInputProcessorProfiles::ActivateLanguageProfile. At the beginning of your app you would call ITfInputProcessorProfiles::GetActiveLanguageProfile.
Maybe you can implement ITfLanguageProfileNotifySink::OnLanguageChange, set *pfAccept
to FALSE and return S_OK.
http://msdn.microsoft.com/en-us/library/windows/desktop/ms628770(v=vs.85).aspx
All of the above have a problem. If the user intentionally changes languages on the client, for example by clicking on the client's task bar instead of pressing Alt+Shift, the above methods will prevent their change anyway.
I wonder if RegisterHotKey would let you register Alt+Shift for your own window even though the system already had it defined.
The thing you are trying to implement is keyboard hook. The detailed explanation with source code in C/C++ can be found here:
http://www.codeproject.com/Articles/67091/Mouse-and-KeyBoard-Hooking-utility-with-VC
Also other helpful examples can be found here:
http://www.codeproject.com/Articles/1264/KeyBoard-Hooks
http://www.codeproject.com/Articles/9513/Disable-keyboard-and-show-images-for-the-children
Hope this helps.
Kind regards,
Bo
I'm writing a program in C++ to implement the keyboard backlight feature from OS X on MacBook Pro's running a Linux distro. So far, it turns the backlight on, on boot and if no keyboard and mouse events are registered for 20 seconds, it will turn it back off, and of course turn it on yet again when an event is registered. Next thing I need the program to do, is to capture keypresses on the keyboard-backlight-up/down keys, but I'm not sure how to approach this.
I am currently using XScreenSaverQueryInfo to get the idle time of keyboard and mouse events, so a method using X11 API would be okay. I have done a lot of googling but havent found a way that I felt sure about going with. The problem I'm seeing with lots of the methods I found, is that they use keycode to identify the key, but I dont think that would be a viable solution since the program should work for any keyboard-layout available.
Any idea of a method and API I should go with? What would work the best?
Regards,
The normal way to do this is with XGrabKey(). It uses keycodes, but you wouldn't hardcode the keycode, you'd get it with XKeysymToKeycode(). To be more correct you'd also want to redo the grab when you get a MappingNotify (XMappingEvent). (Note, MappingNotify, not MapNotify.) If there isn't a keysym for these keys - there probably isn't on old X versions, but hopefully newer X.org versions have one - then you just have to hardwire the keycode. Which won't be very robust or portable but probably works for everyone on Linux with the same hardware model.
Be prepared that key grabs are global, so if you try to XGrabKey() and something else has already grabbed that key, you'll get an X error - by default that exits the program. Another quirk of XGrabKey() is that it grabs the key with a precise modifier set. For example, to handle both with and without NumLock, you need to grab twice. See Global Hotkey with X11/Xlib
In a normal Linux setup (if you wanted to get a feature like this into upstream projects), the desktop environments don't want lots of separate apps fighting over the key grabs and getting errors. So there will be some central coordination points, such as the window manager or a special daemon might do all the keybindings and forward commands to other processes as needed. So you would probably want to look at patching the same upstream code that handles other special keys like this, if you were trying to get your feature integrated into distributions by default.
Another thing to be aware of is the Xkb API, which is a lot more complicated. There is some brain-bending way to grab keys with Xkb but I don't know of any advantage to going that route.
If you haven't done that yet, familiarize yourself with xev. Start it, give it the focus, and press the keys, to see what's happening.
I'm looking to add an element to my wxWidgets GUI that behaves like a terminal emulator. Not in terms of a shell which executes commands, but just the input-output setup of an application running in a terminal.
Basically, the requirements are:
Streaming input/output: When you enter a character, it is added to an input stream, and when something is piped to the terminal, it prints out immediately.
No editing: Once you type in a character, it's permanently there, since it's probably been consumed by the application running in the terminal.
Some sort of scrolling (even if it just shows a few lines or something).
It would be nice if there is something that already does this, but suggestions on how to implement this with already existing controls such as wxTextCtrl would also be welcome.
I know this is a couple weeks late, but hopefully it's still useful. I've got a project called Chameleon that uses a wxWidgets-based VT100 terminal widget, which was itself based off of a project called taTelnet. The Chameleon source is available from my website (download page here). Not sure if it's exactly what you're looking for, but it might give you some ideas. Feel free to let me know if you have any questions about it.
wxWidgets supports redirecting STDOUT to a wxTextCtrl via wxStreamToTextRedirector. As for input, you could override the OnChar event in a wxTextCtrl-derived class to handle this.