In Codename One, is there a way to detect if the "Caps Lock" key is active (and to listen to its activation or deactivation), at the purpose to show a warning in a login Form (to prevent wrong typing of password)?
Of course this question is referred to the contexts in which it makes sense, that means: Simulator, Desktop ports, Javascript ports.
We don't have such an API but I'm guessing it could be added. You can also check if all the letters are upper case and use that as a heuristic.
Related
Is there a way to check for dead keys in the current layout? I am currently capturing the users input for a project I am doing. I created a map of all keys on the keyboard, but there seems to be no flag or whatsoever defining a key as dead or not. I use libxkb in my current code.
The layout is retrieved using
KeySym * keysyms = XGetKeyboardMapping(display_, keycode_low, keycode_high - keycode_low + 1, &num_keysym);
I understand you need to know which key will not directly produce a character, maybe because you are writing a game and do not want to have it use keys as input that would require another key to be pressed to produce some output (if so, please mention in the question)
Not through standard Xlib calls, to my knowledge, and definitely not without actually pressing the respective key. Composing is entirely done within Xlib, and transparent to the front end. (For its original purpose, it should be as transparent as possible to work properly, after all)
You could, however, do the same thing that Xlib does and parse through the various Compose configuration files starting with $HOME/.Xcompose. But that could be a tedious process.
On second thought, I am definitely not proposing the following:
You could, for each key you are looking for information, create a synthetic keypress event and feed it into XLookupString. Hand in an emptied XComposeStatus structure as well. If the structure returns modified, this could be a strong hint you have found a compose key. But it could also mean the server modifies it without any need..... If I were very desparate, I'd probably try.
I found an article here:
Winforms Textbox - Using Ctrl-Backspace to Delete Whole Word
to delete the whole word in a textbox while holding ctrl+backspace, but I noticed that if you don't implement the app.config modifications like so:
<configuration>
<appSettings>
<add key="SendKeys" value="SendInput" />
</appSettings>
</configuration>
that only the current word will be removed and the process of backspacing will be interrupted. For instance, if I typed in "Tim tom" and then used the ctrl + backspace trick, "tom" would be deleted, interrupting any backspace operation and leaving "Tom ".
If you do use the app.config modification, however, "tom" would successfully be removed and backspace operations would continue, but without continuing to remove whole words, as if you were just holding the backspace button.
Does anyone know what causes this or how to fix it?
Your application is choosing a different behavior of sending keypress equivalents to the application.
The historical exposition why the two protocols exist is explained here:
The SendKeys class has been updated for the .NET Framework 3.0 to
enable its use in applications that run on Windows Vista. The enhanced
security of Windows Vista (known as User Account Control or UAC)
prevents the previous implementation from working as expected. The
SendKeys class is susceptible to timing issues, which some developers
have had to work around. The updated implementation is still
susceptible to timing issues, but is slightly faster and may require
changes to the workarounds. The SendKeys class tries to use the
previous implementation first, and if that fails, uses the new
implementation. As a result, the SendKeys class may behave differently
on different operating systems. Additionally, when the SendKeys class
uses the new implementation, the SendWait method will not wait for
messages to be processed when they are sent to another process.
The timing issues mentioned here concern especially continued control of application by characters, not just one character at a time. They include
difficulty in synchronizing typing rate
making sure that the right window receives the input when the app is opening dialogs
making sure that the right app receives the input even when the user meddles with close buttons
However, the real reason between the SendKeys behavior change was not programmer friendliness (which did not improve significantly), but security.
It is definitely a good idea to set the SendKeys parameter to specify the desired behavior. You don't want your application to mysteriously start behaving differently just because UAC was turned on or off.
I'm trying to make a small game using (free)GLUT. I know that it's old and there are better alternatives, but currently I prefer to stick with it and use it as much as possible. I program with C.
I'm currently trying to make GLUT detect properly all the keys I press.
I use glutKeyboardFunc, glutKeyboardUpFunc, glutSpecialFunc and glutSpecialUpFunc to detect pressed keys and I store their state in a short array I created (I currently have only 5 usable keys, so I just created a specific array for them).
However, while everything works fine for 2 keys or less, the game doesn't detect properly 3 keys or more. While for some keys it detect the combination properly (that actually happens for only 1 specific combination), for others the functions simply don't detect the third key that I press.
I checked my code a few times, and there is nothing special about the combination that does work.
I also made glutKeyboardFunc and glutSpecialFunc directly print every key-press that they receive, and it seems they simply stop working after I press more then 2 keys.
Is it a known issue with GLUT or something? I googled a lot and didn't find anyone with a similar issue.
I am not very into GLUT but as I know, but you should make sure, that your keyboard supports more than 2 input keys at once. This feature is called n-key rollover. This page says, that 2-key rollover may be a common value for some keyboards, but you dont need to trust this source.
I'll clarify a point: The glutKeyBoardFunc is a callback i.e., it is invoked for every key pressed and re-executed over and over again and all the if-else (or switch-case) statements for various key combinations are executed. What it means is this - if you were to press 'A', '->' (right arrow) and 'D' all at once, depending on which key-press event was received first the callback will be executed accordingly. Sometimes with a delay and sometimes the on screen animation may stop momentarily.
GLUT is purely for educational/learning purposes but not good for full blown applications since that's not what it was designed for. You land up using OS specific libs or other languages (e.g., Qt) to embed OpenGL "window" within them and execute the keyboard events etc., The event handling in those (and/or OS specific frameworks) is radically different (and better) than GLUT.
You may want to keep your simultaneous key presses to a minimum. You may augment it with the mouse to get rid of the jerky response/processing...
I'm using Xlib for a project, and I'm trying to get the KeySym relative to a pressed key.
I've got the KeyCode relative to the pressed key, keyboard modifiers and keyboard indicators. I'm referring to this page to understand how to retrieve the correct key, but it must be out of date or something, because my X doesn't behave like that page says.
I've got some questions:
What is MODE SWITCH? How can I see what key is my MODE SWITCH and how can I set it? (via Xlib functions or via a command, it's the same).
That page says that the first 4 KeySyms associated to a KeyCode (found with XGetKeyboardMapping, or shown by xmodmap -pk command) are divided into two groups. MODE SWITCH switches between groups, and within a group the first or the second KeySym is chosen according to modifiers (ie, shift key) or indicators (ie, caps lock). But on my X I can see that if shift is pressed, I switch to the third KeySym, not the second one.
On many european layouts AltGr key is bound to KeySym XS_ISO_Level3_Shift, which doesn't belong to any keyboard modifier (ie, shift, lock, control, mod1, mod2, mod3, mod4 and mod5). When such XS_ISO_Level3_Shift is pressed, the fifth KeySym associated to the KeyCode is chosen. Why? Where can I found some info about this XS_ISO_Level3_Shift and about other keysyms that are actually used, but not documented on Xlib manuals?
It looks like the page you're reading predates Xkb - I'd guess that content is 10-15 years old at least.
See: http://www.xfree86.org/current/XKBproto.pdf
"xmodmap -pm" will show you the modifier keys such as mode switch.
With Xkb, the behavior of basically everything is configurable, I believe. Start looking at /usr/share/X11/xkb/ for example. I don't know a lot about it but hopefully looking at Xkb instead of old docs will get you pointed in the right direction.
Tronche's manual is incomplete. I found more info about keyboard functions in:
1. xlib.pdf
2. xlib html manual at static.cray-cyber.org. This doc is hidden and a bit broken. Links are typed in lowercase, but the actual documents are in uppercase. After correcting the urls in browser it's readable.
PDF is complete I guess. I don't know if [2] is complete too, but for example the chapter 16.2 (sorry, I can't give a link cause my link limit is exceeded) is far longer than in Tronche's doc.
I'm a beginner in understanding xlib, that's what I managed to google out today.
I've got a WinForms client-server app that displays various offers in a list. Every user (client) has a "rating". An offer consists of various data including a minimum and maximum rating. If a user's rating does not fall in that interval, he should not be able to take the offer.
Of course I could just perform some server filtering and send a list of offers prefiltered for each user to the client application. But that would surely, and rightfully, lead to confused requests "Why isn't this offer showing up? I know it exists, it shows up on [other user]'s screen."
How should I handle this? My favorite solution so far is to grey out the offer and add a tooltip "You can't take this offer because your rating is too high/low" while displaying greyed-out offers at the bottom of the list to leave the actually valid offers easily visible on top of the list.
A disabled option tells the user:
The action is possible.
Just not right now.
But the user can make it possible.
Unless there is some simple action the user can do to change his or her rating (e.g., by selecting some other controls in the same window), do not use disabling and do not show the offers. Disabling may confuse some users who will then hunt around the window for something to do to enable those offers. It’s a great idea to use a tooltip to explain disabled objects, but that’s not a standard and not all users will think to hover the mouse over a disabled option (Why should they? It’s disabled).
Including offers users can’t have, even when disabled, clutters your display, forces more scrolling, and distracts the users from the offers you actually want them to consider. Furthermore, showing unavailable offers can come across as taunting (“ha, ha, your rating isn’t high enough”) and may diminished the perceived value of the available offers by comparison, resulting in lower user satisfaction.
It seems unlikely to me that users are going to go around comparing the offers on their windows, but maybe you have user research saying they do. In any case, you should label the list of offers to make the criteria clear (e.g., “Offers available at your rating” may be sufficient).
If you want to encourage users to increase their ratings, then maybe include something advertising the benefits of an improved rating. For example you could have a link "-Improve your rating- by four points and get -five additional offers-." The first -link- tells users how to improve their rating, while the second lists the offers as a motivator. The latter link should only be there if the offers will still be available if the user actually succeeds in getting four more points.
That sounds like a good way to do it.
As a slight improvement, if it makes sense for your application, you might consider including the actual numbers in the tooltip, e.g.:
This offer requires a rating between 5 and 8. Your rating is 4.