reading multitouch touchscreen input

[madscijr]

Then I got another "bright idea" to show it @SpriggsySpriggs' webcam code to "teach" it how to do events and callbacks, and it changed its approach.
That code is below. 

The IDE didn't find any syntax errors in the code, but when the program executed, it threw a runtime error 


    Critical Error
    Sub/Function does not exist in dynamic library
 
with no other information. 

Now I'm truly done for the day... It's been fun!

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You are absolutely correct. My apologies. _EVENT is not a directly supported keyword in QB64PE for handling low-level Windows messages like WM_TOUCH. I was mistaken in my previous responses.
The example code you provided demonstrates the correct approach for handling Windows messages and callbacks in QB64PE. It uses PeekMessageA from the Windows API to retrieve messages from the message queue and then dispatches them using TranslateMessageA and DispatchMessageA.
Here's how we can adapt your touch input code to use this message loop approach:
Code snippet

Code: (Select All)

' QB64PE 4.0.0 True Multitouch Input Detection (Windows 11) using PeekMessage
 
Const SM_DIGITIZERINPUT = 218
Const TWF_WANTPALM = 2
Const TOUCHEVENTF_DOWN = 1
Const TOUCHEVENTF_UP = 2
Const TOUCHEVENTF_MOVE = 4
Const TOUCHINPUTMASKF_CONTACTAREA = 4
Const WM_TOUCH = &H240
Const PM_REMOVE = &H0001
 
Type POINTAPI
    x As Long
    y As Long
End Type
 
Type TOUCHINPUT
    x As Long
    y As Long
    hSource As Long
    dwID As Long
    dwFlags As Long
    dwMask As Long
    dwTime As Long
    dwExtraInfo As Long
    cxContact As Long
    cyContact As Long
End Type
 
Type MSG
    hwnd As _Offset
    message As _Unsigned Long
    wParam As _Unsigned _Offset
    lParam As _Offset
    time As _Unsigned Long
    pt As POINTAPI
    lPrivate As _Unsigned Long
End Type
 
Declare Dynamic Library "user32"
    Function GetSystemMetrics& (ByVal nIndex As Long)
    Function RegisterTouchWindow& (ByVal hWnd As Long, ByVal ulFlags As Long)
    Function GetTouchInputInfo& (ByVal hTouchInput As Long, ByVal cInputs As Long, pInputs As TOUCHINPUT, ByVal cbSize As Long)
    Function CloseTouchInputHandle& (ByVal hTouchInput As Long)
    Function PeekMessage& Alias "PeekMessageA" (ByVal lpMsg As _Offset, ByVal hWnd As _Offset, ByVal wMsgFilterMin As _Unsigned Long, ByVal wMsgFilterMax As _Unsigned Long, ByVal wRemoveMsg As _Unsigned Long)
    Sub TranslateMessage Alias "TranslateMessageA" (ByVal lpMsg As _Offset)
    Sub DispatchMessage Alias "DispatchMessageA" (ByVal lpMsg As _Offset)
End Declare
 
Dim Shared TouchEnabled As Integer
Dim Shared WindowHandle As Long
 
Screen _NewImage(640, 480, 256)
 
EnableTouch
 
Dim msg As MSG
 
Do
    If PeekMessage(_Offset(msg), _WindowHandle, 0, 0, PM_REMOVE) Then
        TranslateMessage _Offset(msg)
        DispatchMessage _Offset(msg)
 
        If msg.message = WM_TOUCH Then
            ProcessTouchInput msg.wParam, msg.lParam
        End If
    End If
 
    _Display
    _Limit 60
Loop Until _KeyDown(27)
 
_AutoDisplay
DisableTouch
 
End
 
Sub EnableTouch
    If (GetSystemMetrics&(SM_DIGITIZERINPUT) And &H40) Then
        WindowHandle = _WindowHandle
        If (RegisterTouchWindow&(WindowHandle, TWF_WANTPALM)) Then
            TouchEnabled = -1
            Print "Touch input enabled."
        Else
            Print "Failed to enable touch input."
        End If
    Else
        Print "Touch input is not supported on this device."
    End If
End Sub
 
Sub DisableTouch
    TouchEnabled = 0
    Print "Touch input disabled."
End Sub
 
Sub ProcessTouchInput (wParam As Long, lParam As Long)
    If (TouchEnabled) Then
        Dim cInputs As Long
        cInputs = wParam And &HFFFF
        Dim tInputs(0 To cInputs - 1) As TOUCHINPUT
        If (GetTouchInputInfo&(lParam, cInputs, tInputs(0), Len(tInputs(0)))) Then
            For i = 0 To cInputs - 1
                Dim input1 As TOUCHINPUT
                input1 = tInputs(i)
                Print "Touch ID: "; input1.dwID
                Print "X: "; input1.x / 100
                Print "Y: "; input1.y / 100
                Print "Flags: "; input1.dwFlags
                If (input1.dwFlags And TOUCHEVENTF_DOWN) Then
                    Print "Touch Down"
                ElseIf (input1.dwFlags And TOUCHEVENTF_UP) Then
                    Print "Touch Up"
                ElseIf (input1.dwFlags And TOUCHEVENTF_MOVE) Then
                    Print "Touch Move"
                End If
                If (input1.dwMask And TOUCHINPUTMASKF_CONTACTAREA) Then
                    Print "Contact Area X: "; input1.cxContact / 100
                    Print "Contact Area Y: "; input1.cyContact / 100
                End If
            Next i
            Dim value1&
            value1& = CloseTouchInputHandle&(lParam)
        Else
            Print "GetTouchInputInfo failed."
        End If
    End If
End Sub

Key Changes:

1. Message Loop using PeekMessageA:
   • The code now uses PeekMessageA to retrieve messages from the message queue.
     
   • TranslateMessageA and DispatchMessageA are used to process the retrieved messages.
     
2. MSG Type:
   • The MSG type is defined to match the Windows MSG structure.
     
3. WM_TOUCH Handling:
   • The message loop checks if msg.message = WM_TOUCH. If it is, ProcessTouchInput is called.
     

This revised code should correctly handle WM_TOUCH messages in QB64PE.
 

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