A program has called XGrabKey() to make a hotkey.
The user presses that key combination (while another window is focused).
The program receives control to do something in response to the key combination. Meanwhile, the program has been temporarily focused (because of the effects of XGrabKey (see man XGrabKey, man XGrabKeyboard)).
I want the program to create a synthetic X event (a keypress or mouse click) to the originally focused window. In some cases this means I need to focus that window before sending it the event (Firefox ignores synthetic events when it is not focused), which means I need to know which window it is. How can I find out which window it is?
Wait for the next FocusOut event, verify that the mode is set to NotifyUngrab, get the focus with XGetInputFocus(), and send away your synthetic events.
Related
I'm trying to implement a simple X11 key grabber in C for window switching with Alt-Tab etc. I can use the function XSelectInput to handle keyboard events for a specific window:
XSelectInput(display, window, KeyPressMask | KeyReleaseMask);
How can I receive "global" keyboard events regardless of which window is focused?
You need XGrabKey. This function is specifically designed for implementing hotkeys.
When the desired key combination is pressed, you get the event no matter what, and no other window gets the event.
I have a semi-transparent form (using AlphaBlend) that acts as an overlay. For the user to still be able to interact with the window below I have set WS_EX_NOACTIVATE on my form so all right and left clicks go through to the other window.
However I have a few clickable labels on my form. Clicking those and performing the appropriate action works fine since despite the WS_EX_NOACTIVATE flag the OnClick methods are called, but the click will (obviousely) also propagate to the other window, which I do not want in this case.
So, does anyone know how to "stop" the click being sent through to the window below in case I already handled it in my form ? Basically I would like being able to chose whether the click "belongs to me" and does not get propagated or whether the window below mine receives it.
As Rob explained, WS_EX_NOACTIVATE is not relevant here. Most likely you used WS_EX_TRANSPARENT and that made your window transparent to mouse clicks.
To get finer grained control of mouse click transparency, handle the WM_NCHITTEST message in your top level window. Return HTTRANSPARENT for regions that you want to be "click through". Otherwise return, for example, HTCLIENT.
Wm_ex_NoActivate should be irrelevant here. That just controls whether your window receives the input focus. Indeed, if you start with a scratch program and do nothing but change the extended window style, you'll see that when you click within the bounds of that program's window, the clicks are handled in the usual way, except that the window is never activated; programs behind that window do not receive any click events.
Therefore, to make your label controls eat click events instead of forwarding them to the windows behind them, you need to find out what you did to make them start forwarding those messages and simply stop doing that, whatever that is.
How can I fire an automatic key press or mouse click event when a color appears on the screen
on other application or browser?
It depends a lot on what you want. Do you want to send the keys to
your Application
another fixed Application
Simulate a global keypress
Simulating keys globally
All of these will cause problems targeting a specific application and the active window changes.
SendKeys Sends Messages to the active app. It's a high level function taking a string which encodes a sequence of keys.
keybd_event is very low level and injects a global keypress. In most cases SendKeys is easier to use.
mouse_event simulates mouse input.
SendInput supersedes these functions. It's more flexible but a bit harder to use.
Sending to a specific window
When working with a fixed target window, sending it messages can work depending on how the window works. But since this doesn't update all states it might not always work. But you don't have a race condition with changing window focus, which is worth a lot.
WM_CHAR sends a character in the basic multilingual plane (16 bit)
WM_UNICHAR sends a character supporting the whole unicode range
WM_KEYDOWN and WM_KEYUP Sends keys which will be translated to characters by the keyboard layout.
My recommendation is when targeting a specific window/application try using messages first, and only if that fails try one of the lower level solutions.
when a color appears on the screen on other application or browser
I made one program using OpenCV and C++ for operating mouse with finger gesture. I used 3 color strips for 3 mouse function.
Yellow color for Left click
Blue color for Right click
Pink color for controlling cursor position
Whenever camera detect these colors, associated function takes place, I have used mouse_event for performing mouse function.
For more information you may read my code, blog, video.
I'm not 100% sure what you want, but if all you are after is running the method linked the the button.Clicked event, then you can manually run the method just like any other method.
You can use the .NET SendKeys class to send keystrokes.
Emulating mouse clicks requires P/Invoke.
I don't know how to detect colors on the screen.
Is it possible to set the virtual key state / mouse button state for all programs on a computer without triggering the associated events at the same time (like setting the left mouse button to be currently pressed without sending a mouse down event). Could this be achieved by setting up a fake keyboard or mouse driver for a fake keyboard or mouse that when queried as to the current state of a key would reply giving an answer of your choice or by any other means?
Edit:
This has to affect programs that I do not have the code for running in other threads ect...
Well, I don't have a complete answer for you but...
The Win32 function SetKeyboard State() changes the state of the keyboard for the thread that called it.
I know this does not affect the entire system, but if you only need the keyboard state changed for applications you are developing, then this could be called by each program, reading in the array passed to it from a temporary file on the harddrive.
Otherwise... don't know of anything else offhand...
In MFC a double-mouse click event triggers the following sequence of messages
WM_LBUTTONDOWN
WM_LBUTTONUP
WM_LBUTTONDBCLK
WM_LBUTTONUP
So responding to the WM_LBUTTONDBCLK message allows you to detect a double-click. But if I just want to detect a single-click how to I distinguish it?
But just looking at the WM_LBUTTONUP message isn't enough as it could be a single-click or it could be the first click of a double-click.
How can I successfully identify just a single-click?
(Please allow me to call these events Mouse Up and Mouse Down. My MFC is a little rusty. And there's this stuff called .NET who's been messing up my terminology lately ;-)
Short story: You don't simply want to know about Mouse Click. You need more.
Long story:
Although this is counter-intuitive, it appears that simply wanting a mouse-click is fairly uncommon. Most often, you'll want to perform some processing on Mouse Down and do some further processing on Mouse Up. The trick is that simply tracking Mouse Up messages is not enough: Mouse Down may not have happened in your window. Do you consider it a valid click then? Especially considering that the Mouse Down processing (such as selecting an item) did not occur.
Going further up the reasoning, you should not rely on receiving a Mouse Up after you processed Mouse Down: User may have moved the mouse and released the button somewhere else (think drag'n'drop), in which case, you don't receive the MouseUp event... unless you capture the mouse on MouseDown to make sure you get mouse event up to Mouse Up even if the mouse left your window.
All in all, you end up tracking Mouse Down, capture the mouse and when you receive Mouse Up, just check if you own the capture. If not, the mouse was either double-clicked (no 2nd mouse down) or Mouse Down happened somewhere else hence you most likely don't care about this Mouse Up.
In conclusion: There's no MouseClick message simply because you wouldn't go very far with it: You need to handle more messages and implement more mechanics anyway.
Oh! And if your dealing with an existing control which already handles all this items and selection stuff, such as a listview, chances are it provides with a similar custom notification such as Item Activate or Item Selection Changed.
I just tried this in Delphi, the behavior is the same: even when a double click is happening, a single click event is issued right after the first one of the two.
I solved it using a timer, which works like this:
deactivate timer on WM_LBUTTONDBLCLK (and set bDbl to true)
activate timer on WM_LBUTTONUP if bDbl==false
deactivate on WM_LBUTTONUP if bDbl==true (and reset bDbl)
I set the interval of the timer to the time returned by GetDoubleClickTime.
MSDN says:
The GetDoubleClickTime function
retrieves the current double-click
time for the mouse. A double-click is
a series of two clicks of the mouse
button, the second occurring within a
specified time after the first. The
double-click time is the maximum
number of milliseconds that may occur
between the first and second click of
a double-click.
If the timer happens to fire then you have the real click. In my case the double click interval is 500ms, so any "real click" will be delayed this long.
You could check WM_LBUTTONDOWN has not been called more than once before WM_LBUTTONUP. In practice Windows does this for you, in that if you get a WM_LBUTTONDBCLK you tend not to get a WM_LBUTTONUP.
You can use PreTranslateMessage() to count the messages as they appear. If you've received only the mouse messages corresponding to a single-click, and the system-configured time for double-clicking has expired, you can safely assume it's a single-click.
As far as I know there is no way to know that this is the case as it is happening, which makes sense -- until the time is expired, there's no way to know that a second click is or isn't coming.
that's a little tricky.
I would detect the WM_LBUTTONDOWN & WM_LBUTTONUP combo, store that event somewhere and set a timeout for a second or so. If there isn't a WM_LBUTTONDBCLK during that timeout then you have a single click.
This might imply you need to have another thread running but I think you could accomplish it with one thread.
I think the solution is to start a timer after the first click & then check the elapsed time after at the next immediate click, this will tell you if it is a single click or double click.
You typically look at #MLButtonUp and you would not have single click and double click behavior on the same mouse button.