B4J Question SOLVED - Any way to know if a particular key is currently pressed?

Mikelgiles · Jan 29, 2020

I need to know if the ALT ( or other) key is depressed while working on a B4XTable grid. I just need to know if the key is being depressed at any given time, or if it was being depressed when a mouse click happens, or at the same time as a B4XTable_CellClicked(or longclicked). I see a eventdata altdown but have not figured out how to use it(not available in B4J?).

There is certainly a lot more power in this language than I accustomed to and the longer I work with it the more I am understanding that I don't know. I am wondering if I should spend some time learning java and how much help that would be.

XbNnX_507 · Jan 29, 2020

Hi, this could help.

sorex · Jan 29, 2020

when you add the GameView library you have the ability to read out keyboard presses.

If it is suitable for what you want to do that's up to you to test it.

In theory if you set a global var during keypress and erase it when the keys are release you should get what you want.

MicroDrie · Feb 7, 2020

You can find a small B4J sample program with only the jFX library here: https://www.b4x.com/android/forum/threads/can-a-keyboard-event-be-detected. It detect the left and the right control, Shift, Alt, Alt gr keys.

stevel05 · Feb 7, 2020

This project has a little bit of inline java that works with the JNA jar's which are downloadable from here https://github.com/java-native-access/jna. It currently checks for the Ctrl key. Alt key is 0x12.

Click the buttons then the download link top right of the page that opens, not the text link. And save them in your additional Libraries folder.

The code was taken from this github project https://github.com/Col-E/Simplified-JNA/blob/master/src/me/coley/simplejna/Keyboard.java

You need to know the Virtual key code for the keys you want which are available here : https://docs.microsoft.com/en-us/op.../ms-tvtt/261ddfb0-ce10-4380-9b7a-4b50f482b8ec

The library jars are quite large, but the method works and is queryable, rather than event driven if you don't find another way.

MicroDrie · Feb 7, 2020

You can find a small B4J sample program without a library here: Can a Keyboard event be detected.

Mikelgiles · Feb 21, 2020

sorex said:
when you add the GameView library you have the ability to read out keyboard presses.

If it is suitable for what you want to do that's up to you to test it.

In theory if you set a global var during keypress and erase it when the keys are release you should get what you want.

Thanks to sorex this problem is solved and works perfect. Thank you sorex!!!

I added the library GameViewHelper, added code in 3 places to get the function setup amd in one place where I needed to know if the Shift key was depressed. The same thing could be done for other keys such as "Alt" or "Ctrl" with very little code added.

Add library GameViewHelper

B4J code:

'Process_Globals
    Public GameViewHelper As GameViewHelper
    Public KeyAlt, KeyShift,KeyCtrl As Boolean

'AppStart
    GameViewHelper.AddKeyListener("GVH",MainForm)   ', Main.MainForm)

'Main Module

Sub GVH_KeyPressed (KeyCode As String) As Boolean
    If KeyCode =  "Shift" Then KeyShift = True '"Alt" & "Ctrl" also work
End Sub
Sub GVH_KeyReleased(Keycode As String) As Boolean
    If Keycode =  "Shift" Then KeyShift = False
End Sub

Sub B4XTable_CellClicked
        If KeyShift = True Then Return

B4J Question SOLVED - Any way to know if a particular key is currently pressed?

Mikelgiles

Active Member

XbNnX_507

Active Member

sorex

Expert

MicroDrie

Well-Known Member

stevel05

Expert

Attachments

MicroDrie

Well-Known Member

Mikelgiles

Active Member

Similar Threads

B4J Question SOLVED - Any way to know if a particular key is currently pressed?

Mikelgiles

Active Member

XbNnX_507

Active Member

sorex

Expert

MicroDrie

Well-Known Member

stevel05

Expert

Attachments

MicroDrie

Well-Known Member

Mikelgiles

Active Member

Similar Threads

Privacy & Transparency

Privacy & Transparency