Capturing keyboard input without focus on the programwindow - c++

I am doing a VoIP client and I want to start/stop on WM_KEYDOWN and WM_KEYUP messages for a certain input, say K. When the main window has focus, this is np, but how do I enable it outside of the window? For example, if the window is not in focus and I'm just looking at the desktop or am in a videogame. How does one perform something like this? I am not sure where to begin.
Also -- I guess you somehow has to poll every input even outside the program, is that expensive?
win32 c++ btw

You need to install keyboard hooks: http://msdn.microsoft.com/en-us/library/ms644990(v=VS.85).aspx
This can be very troubling though for every running application if something steals its keyboard messages.

I don't think you want this - if I'm typing a document into Word and I hit K, I'm going to be very angry when your application pops up instead of a "k" appearing in my document.
Windows allows you to assign shortcut keys to an icon on the desktop, but it limits them to the function keys or to combinations containing both Alt and Ctrl. Right-click on a desktop icon and go to Properties, and look for the field marked "Shortcut key".

Related

Trying to write a c++ console program to change a setting controlled by a windows checkbox

Is it possible to create a keyboard shortcut to switch between the monitor and portion selection of this wacom preferences window, via a c++ console program?
Sorry if this is poorly worded, I've had trouble trying to find the right words to search for ways to do it.
I think it should be possible, although a bit tedious. You should be able to use the Windows API, and try to EnumWindows/EnumDesktopWindows to identify the respective application Window, and its respective controls (which are also Windows).
You should identify the window title, and class ids, for the app window, and the checkbox button controls, then when you enumerate through all the desktop windows, you can identify the ones you are interested in.
Then you can use the SendMessage() API to send messages to the controls (Windows) of interest to manipulate them.
It's a bit tedious, but sounds possible.
An example of use here to get an idea:
http://www.cplusplus.com/forum/windows/25280/

How can I prevent RegisterHotKey from blocking the key for other applications?

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.

Keyboard messages from child controls

I am currently developing a user interface DLL that uses the WIN32 API. The DLL must work for numerous platforms, XP, WIN CE, etc. I have managed to incorporate docking, anchoring and so on but appear to have a problem regarding owner-drawn buttons. I can draw the button's correct state, focus, clicked, default. However, I cannot receive key notifications. I specifically want to perform a click operation on a button that currently has focus, should the user press enter.
Note that I am using a windows message loop rather than a dialog message loop. I use windows hooks to hook into the window creation and set the user data to 'point' to my control instance. If I test for WM_KEYDOWN in the main message loop I can get a handle to my button control instance and could forward the message to the relevant control. Unfortunately, I am dealing with a lot of legacy code and this may not be an ideal solution.
So, my question is what is the best way forward. Is subclassing the button control's window procedure a viable option or is there an easier way?
Many thanks in advance.
The comments above are correct. The button with focus should be getting the key messages. But buttons don't (by themselves) respond to Enter--they respond to Space. It sounds like what you're missing is the typical dialog keyboard navigation, like Tab key moving the focus and Enter activating the "default" button.
If you've got a typical Windows message pump, and you want the keyboard behavior normally associated with dialogs, then you need to use the IsDialogMessage API in your message loop. This means your window is essentially a "modeless dialog".
Looks like standard window proc subclassing should do the trick. See http://msdn.microsoft.com/en-us/library/windows/desktop/ms633591(v=vs.85).aspx for details.

Qt - c++ simulate keypress

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.

Down arrow key of my laptop?

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.