I am trying to code a custom shell implementation in C++ for linux. In that, I have to implement a functionality which will run when Ctrl+R is pressed, and another when the Tab key is pressed. How do I detect when these two keys are pressed in C++? For Ctrl+C and Ctrl+Z, I used signal() function, but I am at a loss about what to do for these two.
Related
I need to make a custom hotkey for the alt-tab function. I'm doing this with SendInput by sending the corresponding keys, and it works fine.
However, if a hotkey already includes the alt key, the program only needs to press and release tab; but doing so causes the alt-tab menu to get stuck on screen even, and the only way to make it go away is to close my program. How could that possibly happen, and what does closing my program have to do with the menu disappearing?
On the other hand, sending (alt down)(tab down)(tab up)(alt up) keys regardless of whether alt is already down works in all cases, but I can't rely on this behavior for other reasons.
I'm using WinXP if that helps, I haven't tried it on the Win7 computer yet.
Had a similar problem caused by doing PostMessage WM_KEYDOWN, VK_TAB, in an event triggered by operator clicking ALT-N to cancel an action. The ALT key was thus still down when the tab was sent. Since our code never sends a WM_KEYUP, it must have confused Win XP. Left the alt-tab menu on the screen until the application exited.
I don't know if this related, but Alt+Ctrl+Tab causes the menu to stuck, just like if Alt would stick when press Alt+Tab. So may be you are sending Ctrl signal somehow.
I am writing a win32 application that needs to take hotkeys while not on focus(it runs in the background without drawing a window). I use RegisterHotKey to assing a few keys but that blocks the for every other process. For example I assign the 'c' key and when I press it in notepad nothing happens.
RegisterHotKey() registers global hotkeys. Hotkeys are processed before regular keyboard input processing, meaning that if you register a hotkey successfully, pressing that key will result in you getting your hotkey message rather than the app with focus getting the normal WM_KEYDOWN/WM_CHAR messages. You have effectively blocked other apps from seeing that key press.
This is by design.
Obviously the solution to avoid clashes like you describe is to not register a hotkey that other applications may use. If you register C without any qualifiers as a hotkey, then no other program will see the C key being pressed. Instead you should use qualifiers like Ctrl/Shift/Alt to prevent your hotkey from interfering with the normal use of the keyboard.
There is no way to register a hotkey that's global unless some other program is active. If you want to achieve the situation where, say, your hotkey works while the desktop is active but nothing else is, you could use a message hook to inject code into the desktop's process (via SetWindowsHookEx()) and intercept key presses that way. But you can't do it with RegisterHotKey().
I just tried UnregisterHotKey(), simulated the key with keybd_event(), then RegisterHotKey() again. I don't recommend it as a production code, it's probably better to use hooks for that, but as a quick hack I just wanted to say that it works.
GetAsyncKeyState()
can be used to determine if certain keys are pressed, even when the program is running in the background.
I'm trying to use V-USB on an AVR microcontroller to mimic a HID keyboard, and I found how to send keys and how to release ALL of them, by calling usbSetInterrupt() with 0 for the key value, but is there a way to release one key and not another?
I'm using this for a game controller so, for example, I'm holding down the button that corresponds to Left-Arrow and press and release the A button. I want it to register as:
Left Arrow Press
A Press
A Release
Left Arrow Release
But all I can do now is basically momentary press on each. Each time I press a button down it registers as press AND release on the computer. Is there a way to call usbSetInterrupt() or something else telling it that only one of the previously pressed keys has now been released?
I'm trying to create a simple bot in Qt and need therefor a way of simulating keyboard presses OUTSIDE the Qt application itself.
I've successfully made this possible by using the "old" keybd_event
keybd_event(Qt::Key_A,0,0, 0); // Pressing the 'A-button"
and that works out fine. But i can't make it when i'm trying to execute a 'select all' command which needs two buttons to be pressed at once.
As i researched the problem on Google i was refereed to the 'SendInput' function with the message 'This function (keybd_event) has been superseded. Use SendInput instead.'
The problem now is that I've little knowledge of windows API and especially in the contex of "Qt" and would like guidance on how to get started.
keybd_event is actually not Qt function, but part of Windows Api.
Both keybd_event and SendInput allow you to send press event and release event. If you want to send combination ctrl+A you should send events as follows:
press Ctrl -> press A -> release A -> release Ctrl
If you want to use keybd_event, you need to call it 4 times subsequently, if you want to use SendInput, you can make an array of 4 events.
You should use keyboard codes from Windows API to simulate keyboard events, while Qt's codes may coincide with Microsoft's.
Also you should understand that this solution has nothing to do with Qt, it Windows specified.
You just found all links to docs you would need, I think you should start studing it and ask more concrete questions, if you would have any problems.
The down arrow key of my laptop is very loose and it does not seems to last very long.
Is it possible to write any programm(in any language but especially C++) hat simulates the down arrow key.say I made a programm such that when I press A,B,C on the key board it simulates down arrow key.
If not then,
Is there any software available to do this?
Use the On-screen keyboard
If you want to simulate input, use the SendInput API. This injects input at a fairly low level, windows automatically routes it to the appropriate thread based on who has focus. Call it twice, once to send the key down, and again to send the key up.
Perhaps the easiest thing to do is to write a simple app that calls RegisterHotkey for some combination like ctrl-alt-Z, and then calls SendInput for a keypress then keyrelease of the down arrow key.
You might need to wait a short time after receiving WM_HOTKEY to give you time to release the set of hotkeys so that the down arrow gets processed alone without those modifiers from your hotkey interfering with it. (...otherwise the focused app might think you typed in shift+alt+downarrow instead of plain downarrow!)
if you're using linux, xmodmap: http://www.xfree86.org/4.2.0/xmodmap.1.html
I think that you are actually looking for Sharpkeys www.randyrants.com/sharpkeys/
This works with the windows registry and can be used to change mappings of keys.
You can easily write a program that sends WM_KEYDOWN and WM_KEYUP messages to the window which has the current focus. Once you have this program, bind it to a function key in the properties for the .exe file.