When receiving character input, is there a way to know whether the character code in wParam was generated as a result of the keyboard state we get back from GetKeyboardState()? For example, if you hit Ctrl+A then the character 'a' would not be a result of the control key but if you're using a Swedish keyboard and type Ctrl+Alt+7 the result would be {. In that case, is there any way of knowing that the keyboard state (Ctrl and Alt) were necessary to generate that character code?
(To be honest, as an English speaker who has really only ever used a US keyboard layout, I have no definite idea that this will work, but...) I believe that the VkKeyScan function (or VkKeyScanEx) might do what you want.
As input, it takes a character, not a scan code or a virtual key, so this is the wParam value that you get from WM_CHAR.
Its return is a value that provides both the virtual-key code (which I guess you can ignore) in the low-byte, and the (mis-named) "shift state" in the high-byte, which is actually a set of flags representing the qualifier keys needed to produce that character.
So if you get a WM_CHAR message and wanted to tell if the control key was needed in order to generate it, in theory you could do:
case WM_CHAR:
if (HIBYTE(VkKeyScan((TCHAR)wParam)) & 2) {
// control pressed!
}
break;
If you are only looking at the data provided by the WM_CHAR message, then no. You would likely have to look at the WM_KEY... messages to keep track of what the surrounding keystrokes where doing at the time, if Get(Async)KeyboardState() does not provide what you need.
Related
I am trying to inject key combinations (like ALT+.) into a tty using the TIOCSTI in Python.
For some key combinations I have found the corresponding hex code for Bash shells using the following table which works good.
From this table I can see that for example CTRL+A is '\x01' etc.
import sys,os,Queue
import termios,fcntl
# replace xx with a tty num
tty_name = "/dev/pts/xx";
parent_fd = os.open(tty_name, os.O_RDWR)
special_char = "Ctrl_a"
if special_char == "Ctrl_a":
send_char = '\x01'
if special_char == "Ctrl_e":
send_char = '\x05'
if special_char == "Ctrl_c":
send_char = '\x03'
fcntl.ioctl(self.parent_fd, termios.TIOCSTI, send_char)
But how can I get the hex codes for other combinations such as
ALT+f etc. I need a full list or a way how to get this information for any possible combo as I want to implement most bash shortcuts for moving, manipulating the history etc. to inject.
Or is there any other way to inject key-combinations using TIOCSTI ?
As I can only send single chars to a tty I wonder if there is anything else possible.
Thank you very much for your help!
The usual working of "control codes" is that the "control" modifier substracts 64 from the character code.
"A" is ASCII character 65, so "Ctrl-A" is "65-64=1".
Is it enough for you to extend this scheme to your situation?
So, if you need the control code for, for example, "Device Control 4" (ASCII code 20), you'd add 64, to obtain "84", which is "T".
Therefore, the control-code for DC4 would be "Control+T".
In the reverse direction, the value for "Control+R" (history search in BASH) is R-64, so 82-64=18 (Device Control 2)
ASCIItable.com can help with a complete listing of all character codes in ASCII
Update: Since you were asking specifically for "alt+.":
The 'Control mean minus 64" doesn't apply to Alt, unfortunately; that seems to be handled completely differently, by the keyboard driver, by generating "key codes" (also called "scancodes", variably written with or without spaces) that don't necessarily map to ASCII. (Keycodes just happen to map to ASCII for 0-9 and A-Z, which leads to much confusion)
This page lists some more keycodes, including "155" for "alt+."
I'm having trouble aborting IME composition on Windows.
I'm handling WM_IME_STARTCOMPOSITION and positioning my candidate window, and WM_IME_COMPOSITION as I press a key to start composing as you'd expect. I'm then handling WM_IME_ENDCOMPOSITION at the end and normal use cases are fine.
However, my problem is when I change focus inside of the application. I don't receive WM_IME_ENDCOMPOSITION so I have to deal with this situation manually. What I am doing is this:
ImmNotifyIME( himc, NI_COMPOSITIONSTR, CPS_CANCEL, 0 );
ImmNotifyIME( himc, NI_CLOSECANDIDATE, 0, 0 );
The candidate list correctly disappears, but the composition string isn't cleared. If I then call ImmGetCompositionString with GCS_COMPSTR, it's still there. Therefore if I give focus back, receive WM_IME_STARTCOMPOSITION and the first WM_IME_COMPOSITION - I end up inheriting the previous composition string, which I don't want. I want to start afresh.
ImmSetCompositionString() looks also like it would work but I can't figure out how to get it to clear the string.
Does anyone have any suggestions? MSDN seems to suggest that the calls to ImmNotifyIME() would do the job, but I must be missing something.
You may clear composition with this:
ImmSetCompositionStringW(himc, SCS_SETSTR, L"", sizeof(wchar_t), L"", sizeof(wchar_t));
In addition, in my application, when input loses focus I release input context:
ImmReleaseContext(hwnd, himc);
And get it again when focus gained:
ImmGetContext(hwnd);
The SetWindowText function's documentation does not set a limit on the length of the string that may be used as a window title.
In the documentation for WM_SETTEXT (the message sent by calling SetWindowText), it is noted that the return value of this message's processing may be:
FALSE (for an edit control), LB_ERRSPACE (for a list box), or CB_ERRSPACE (for a combo box) if insufficient space is available to set the text in the edit control.
However, it says nothing about the case when a window's title is being set. Is a strict limit set, or is it up to the programmer to use common sense to provide their own title length limit?
I have posted this because I am developing a graphics engine which allows the user to supply their own title for the main window. The idea is that I would define a constant such as
const static int MAX_APP_TITLE_LENGTH = /* ??? */;
within my application class, and check the length of the user-provided title string against this.
If the title string is too long, I can throw a warning message and truncate it, rather than passing it straight into SetWindowText with unintended consequences.
EDIT: After some discussion in the comments, it seems that Windows will not complain even if a string of length 100,000 is used as a window title, so this issue is not worth worrying about (beyond the basic sanitization of input, of course)!
There is technically no limit to the title size, but the lpClassName field has a strict limit of 256 chars (i didnt want you to think you could have an infinite class name and your code crash.)
SOURCE: https://learn.microsoft.com/en-us/windows/win32/api/winuser/ns-winuser-wndclassexw
(First off, I have already posted this on the Telerik forums (link), but this site gets more traffic, so I'm hoping to get some help sooner.)
I am trying to achieve some custom value formatting with the CurrencyTextBox, but the way that the control handles values is making things decidedly hard.
What I want to do is this: if the user enters a value that does not contain a "." character, it will format that value as cents instead of dollars. So if a user enters "16", I want the control to display (and contain a value of) $0.16. If the user enters a value with a ".", I would like the control to function as normal. If the user enters "16.", "16.0" or "16.00", I want the control to display (and contain a value of) "$16.00". This application will be used by people in the retail business and this is how they expect inputs for price values to function.
However, whether I subscribe to the OnChange event or even the "blur" event on the textbox itself, it is stripping the "." character if there is either nothing after it or only 0's after it. Example: If I enter in a value of "16.", "16.0" or "16.00", the value pulled from the textbox in javascript will be "16". And since I have to check for the presence of the "." character, this breaks my logic to properly format the value.
So I'm looking for some help or suggestions. Here is the javascript that I have right now to properly format the value as required. As you can see, if the value does not contain a "." character, the value is divided by 100, which is exactly what I want. Stripping this character is killing my logic. :)
$('custom-price').find('input').live('blur', function (e) {
var sender = $(this).data('tTextBox');
var priceVal = $(this).val(); // $(this).attr('value') also returns the value with the character stripped, FYI
if (priceVal.indexOf(".") == -1) {
priceVal = priceVal / 100;
}
sender.value(priceVal);
});
Try the same using ascii code for "." operator (46). OnKeyPress if you find ascii code 46 change the format for control..
Regards,
Dhaval Shukla
I tried to use the virtual key code provided by wParam, however that didn't work very well:
multiple keys mapped to the same key code
some keys were not recognized at all
virtual keys seemed to be adapted to the keyboard layout (which i don't want/need)
Then i saw that the lParam will give me a scancode along with an "extended" flag, which seem to produce a different value for every single key on the keyboard when calculated like this:
value = (lParam & 0x01FF0000) >> 16;
Will this value always be identical for the same key on the keyboard, even across various keyboards/systems?
Scancodes can be different for different keyboards. Best to use virtual key codes. From http://msdn.microsoft.com/en-us/library/ms646267(v=vs.85).aspx:
Assigned to each key on a keyboard is a unique value called a scan
code, a device-dependent identifier for the key on the keyboard. A
keyboard generates two scan codes when the user types a key—one when
the user presses the key and another when the user releases the key.
The keyboard device driver interprets a scan code and translates
(maps) it to a virtual-key code, a device-independent value defined by
the system that identifies the purpose of a key.