_KEYHIT Riddle me this???

[Pete]

Here is a modified version of the _KEYHIT Wiki example...

Code: (Select All)

DefLng A-Z

Screen _NewImage(800, 600, 8)

Cls , 1

font = _LoadFont("cyberbit.ttf", 24)

unifont = _LoadFont("cyberbit.ttf", 24, "UNICODE")

_Font font



Do

    x = _KeyHit

    If x And x <> oldx Then

        Select Case x

            Case Is > 0

                Color 10

                Print "Pressed "; 'positive value means key pressed

                oldx = x

            Case Else 'negative value means key released

                Color 2

                Print "Released ";

                x = -x

                oldx = 0

        End Select

        Select Case x

            Case Is < 256

                If x < 256 Then 'ASCII code values

                    Print "ASCII "; x;

                    If x >= 32 And x <= 255 Then Print "[" + Chr$(x) + "]" Else Print

                End If

            Case 256 To 65536 '2 byte key codes

                Print "2-BYTE-COMBO "; x And 255; x \ 256;

                x2 = x \ 256

                If x2 >= 32 And x2 <= 255 Then Print "[" + Chr$(x2) + "]" Else Print

            Case 100000 To 199999 'QB64 Virtual Key codes

                Print "SDL VK"; x - 100000

            Case Else

                If x >= 200000 And x < &H40000000 Then

                    Print "QB64 VK"; x - 200000

                    _Continue

                End If

                If x >= &H40000000 Then 'Unicode values (IME Input mode)

                    Print "UNICODE "; x - &H40000000; "0x" + Hex$(x - &H40000000) + " ...";

                    cx = Pos(1): cy = CsrLin

                    _Font unifont

                    Locate cy, cx

                    Color 15

                    z$ = MKL$(x - &H40000000) + MKL$(0)

                    Print z$ + z$ + z$;

                    _Font font

                    Locate cy, 1: Print

                End If

        End Select

    End If

Loop

Do this...

PRESS ALT.
RELEASE ALT.

So why does it record just the SDK value when alt is pressed, but records both the SDK and ASCII values when released? I'd feel better about the operation if it did not cycle back to deliver the -18 ASCII value after previously delivering the -308 SDK value when the Alt key was released.

Pete

[SMcNeill]

The problem here is GLUT itself.   Try a few more various keys -- such as CTRL + any number key...  Those won't report at all for you.

Glut is BROKEN when it comes to keyboard handling.  We honestly and truly need to yank that BLEEPER out and replace it with *anything* else.  The problem with that is... it controls so FLIPPING much of the crap we do.  We'd basically end up with the same crappy issues that popped up when Galleon began to swap from SDL to GLUT -- half the commands didn't work and they all needed to be patched up and tweaked to start operating properly once again.

Slowly, I think we're moving away from GLUT dependency with all the new libraries and such to handle things.  Hopefully, in the next 5 years (if the world doesn't end by then), we'll be able to fully gank GLUT out and replace it with something proper and all these type of issues will disappear for us.

Until then, all you can do is what I do -- Cuss GLUT!!

(And use my keyhit library as a replacement on Windows.)

[krovit]

PRESS ALT.
RELEASE ALT.

So why does it record just the SDK value when alt is pressed, but records both the SDK and ASCII values when released? I'd feel better about the operation if it did not cycle back to deliver the -18 ASCII value after previously delivering the -308 SDK value when the Alt key was released.

Pete

Well! If you're asking yourself... what can I say?

Anyway, just to contribute something if it helps:

if I press or release the left ALT, I get a line that says 'Pressed/Released SDL VK 308'.
Instead, if I press the right ALT, I get TWO lines that say 'Pressed/Released SDL VK 306 / 307'.

I don't know if what I'm saying means anything to you...

---

[...] Hopefully, in the next 5 years (if the world doesn't end by then) [...]

  I knew there were 'thinking' people in here...

[DSMan195276]

I think this is fixed in the latest version, the `-19` is no longer reported. We upgrade FreeGLUT in 3.12.0 and I suspect that fixed it.

That said, the underlying issues with `_KeyHit` are both a GLUT and QB64 problem. _KeyHit is IMO a bad API because it's acts like it supports both text input and individual key state, but those things don't mix. If you look at the kinds of events Windows sends to programs you'll see it clearly separates keyboard physical key press/release events (`WM_KEYUP`, `WM_KEYDOWN`, etc.) from text input events (`WM_CHAR`). `WM_CHAR` does not have a concept of press/release because the value does not directly map to a physical key, think of it like `INKEY$`. `WM_KEYUP` and `WM_KEYDOWN` do report press/release, but they do not report ASCII/text values, so there's no difference between hitting 'a' and 'A' as it's the same physical key.

_KeyHit is basically both of those combined - It's designed to give you the text input capabilities like `INKEY$` but also the press/release events associated with physical keys. It gets messy because the inputted text does not really have press/release events in that fashion.

Unfortunately GLUT made the same mistake as QB64, it's fundamentally broken because its `glutKeyboardUpFunc` callback conflates inputted ASCII values with key release events. These do not map directly to physical keys and thus the release events do not always make sense (try the sequence of "Press shift, press a, release shift, release a").

[TerryRitchie]

The example program works correctly in version 3.13.1

[Pete]

Thanks @TerryRitchie

I just installed QB64 Phoenix Pi. It worked correctly on that version, too.

Also responded to your On ERROR question in the other thread.

+2 to DSMan for the full explanation. Steve also mentioned the problems with GLUT and _KEYHIT. 

I'm weary of switching from the devil I know (INKEY$) to the devil I don't know (_KEYHIT), but as long as the newer versions have resolved the double release reporting issue, I'm a bit more confident the switch may be possible.


Thanks again guys,

Pete