I need a program to respond while not active/not selected by user or minimized to KeyCodes.
Anyone got ideas? In VB.NET.
This won't work out of the box as key messages are only sent to the active window. A minimized window is never active.
What you could try is register system-wide hotkeys. You could also try to install a keyboard hook, however, this would affect the entire system and your application would receive all the keystrokes performed. This would require efficient filtering.
Related
I'm building an application using vb.net that should record some specific user actions, one of these actions is the screen shutdown, is there a way to do that? Maybe a system event or something that i can check periodically to know if the screen is active or not.
I've already found some code to check if the screensaver is running but i want to know if there's a way to detect if the screen is phisically turned off.
How can I prevent other windows within my application from receiving focus? I want to bring a loading window to the front and let it do its thing, but I don't want the user to be able to interact with the other windows in the app.
I could simply hide the other windows in the app, but that feels kind of jarring for users to have their windows just suddenly disappear. At the same time, I can't let the user continue interacting with the other windows during a load since the load will be updating data on every window (synchronization problems would occur). I can add additional locking mechanisms, but I'd rather not if it is as simple as forcing a single window to stay on top and remain in focus.
Thanks!
Look into modal windows.
https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/WinPanel/Concepts/UsingModalWindows.html
You can make a whole window or panel run in application-modal fashion,
using the application’s normal event loop machinery but restricting
input to the modal window or panel. Modal operation is useful for
windows and panels that require the user’s attention before an action
can proceed. Examples include error messages and warnings, as well as
operations that require input, such as open dialogs, or dialogs that
apply to multiple windows.
I am designing an application to connect remotely to another computer. I want to display an NSAlertPanel on connecting however it is 'blocking' the remote side from continuing with the session until OK is pressed with the usual NSAlertPanel setup.
Is there a way to have an NSAlertPanel which is non-blocking? Thanks.
When you run your alert panel modally, you block the run loop of the associated thread, which is the main thread in this case.
To display a window on connection, you can use custom sheets. It's easy to use and explained in the documentation page below:
https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Sheets/Tasks/UsingCustomSheets.html
However, if you need to run your alert modally, an alert that is blocking interactions with the whole application, you may need to move your connection part to another thread, which is a good practice in both cases.
I have an issue with WindowsHookEx in vb.net. If my pc is overloaded especially from 3D rendering, windows automatically disconnects my keyboard hook and my hotkeys stop working. I searched around and it seems that there is no way to detect whether a hook is active or disconnected. So I tried this method presented by "moodforaday"
Is it possible to detect when a low-level keyboard hook has been automatically disconnected by Windows?
hook-has-been-automatically-d
He states that using GetLastInputInfo periodically and store GetLastInputInfo to another variable when a key is used and compare the results. If the tick is much newer than your older variable then its likely that its disconnected. Its a great method but the ticks can go up from other things like the mouse. In my Hook class there is no Mouse hook therefore I cannot store a variable of the tick count when the mouse is moved. So now I ended up having it create a new instance of the hook class and hook again. It checks every second if the stored tick is older than new tick by 10000 ticks.
Is it alright to keep creating new instances of Hooks? It will keep Hooking/Unhooking constantly and I'm wondering if that is going to be a problem for Windows.
Also if anyone has another method to detect if a hook is disconnected please let me know would fix this whole hassle.
Do your 3D rendering in a background thread. Use Control.Invoke only for code where you directly access UI controls.
Alternately, you could split the rendering into very small pieces and post them to yourself as messages, to be handled on the main thread. This way you will be able to handle both internal and external messages.
In both cases, your application will be responding in a timely fashion, Windows will have no reason to consider it non-responding, and your keyboard shortcuts will stay in place.
During development i have observed that certain PDAs with Windows CE and possibly Windows Mobile too are sending the Enter key twice in the key pressed event thus i execute twice the code that lies under the control's key press event for the return button.
I suspect that this is a hardware bug and i would like to ask how you resolved it without changing your application logic.
Without changing the logic? You really can't (unless there is a hardware or firmware fix). I'd guess the simplest mechanism (that requires a logic change) is to treat two Enter keys or keypresses in a short period (say < 100ms) then ignore the second.
I don’t know if this will help but if you read the keyboard port Enter is seen as two bytes rather than one.
This happened to me too and it turned out it was because the "enable character repeat" option was enabled in control panel->keyboard. The default repeat delay was way too fast for the keypad that we used, so I just slowed it down and the problem went away.