I have two programs that needed raw input from a hid whether the program was in the foreground or not. The first needed to see a wireless presenter trigger only and the other needed to see specific keys. The three key examples are just some of the ways that I needed to deal with the input.
Code:
'specific buttons on a (kensington) presenter hid
%Hid_Left = 33 '%VK_PGUP
%Hid_Right = 34 '%VK_PGDN
%Hid_Bottom = 66 '%VK_B
Global capturehid As Long 'flag used to capture hid handle
'--------------------------------------------------------------------------------
Function FRMMAIN_WM_CREATE (hWndForm As Dword, ByVal UserData As Long) As Long
Local rdi As RID_DEVICE_INFO
Dim ridl(1) As RAWINPUTDEVICELIST
GetRawInputDeviceList(ByVal %Null, nDevices&, SizeOf(ridl(0))) 'get hid count
ReDim ridl(nDevices&) 'hid array
GetRawInputDeviceList(ridl(0), nDevices&, SizeOf(ridl(0))) 'get hids
Dim rid(nDevices&) As RAWINPUTDEVICE 'hid register array
i& = 0 'keyboard counter
For d& = 0 To nDevices& - 1 'hid loop
GetRawInputDeviceInfo(ridl(d&).hDevice, %RIDI_DEVICEINFO, rdi, SizeOf(rdi)) 'get hid info
Select Case rdi.dwtype 'poll hid type
Case %RIM_TYPEMOUSE 'mouse
Case %RIM_TYPEKEYBOARD 'keyboard (the presenter shows up as a keyboard too)
rid(i&).usUsagePage = 1
rid(i&).usUsage = 6
rid(i&).dwFlags = %RIDEV_EXINPUTSINK 'capture input always
rid(i&).hwndTarget = hWndForm
Incr i&
Case %RIM_TYPEHID 'other hid
End Select
RegisterRawInputDevices(rid(0), i&, SizeOf(rid(0))) 'register hids
Next
End Function
'--------------------------------------------------------------------------------
Function FRMMAIN_CUSTOM (hWndForm As Dword, wMsg As Long, wParam As Dword, lParam As Long) As Long
Static hidDevice As Dword
Static hidF9 As Long
Select Case wMsg
Case %WM_INPUT
GetRawInputData(lParam, %RID_INPUT, ByVal %Null, dwSize&, SizeOf(RAWINPUTHEADER)) 'get size of hid input
lpb$ = Space$(dwSize&) 'set string for hid input
GetRawInputData(lParam, %RID_INPUT, ByVal StrPtr(lpb$), dwSize&, SizeOf(RAWINPUTHEADER)) 'get hid input
Dim raw As RAWINPUT
LSet raw = lpb$ 'convert input string to rawinput
'if you only want to see a specific hid then set the capture flag and push a key on the hid to capture the hid handle
If capturehid = %True Then
If (raw.keyboard.message And %WM_KEYUP) = %WM_KEYUP Then 'only looking for keyup to avoid multiple triggers while capturing
hidDevice = raw.Header.hDevice 'set hid handle
capturehid = %False 'reset capture flag
End If
Exit Function 'don't process key while capturing
End If
If hidDevice And raw.Header.hDevice <> hidDevice Then Exit Function 'only process specific hid if captured
ztrace Str$(raw.keyboard.vkey) 'show all key numbers.
Select Case raw.keyboard.vkey 'get key pressed
'example key #1
Case %VK_TAB
If GetForegroundWindow <> HWND_FRMMAIN Then Exit Function 'tab key is only used if program is on top
If (raw.keyboard.message And %WM_KEYDOWN) = %WM_KEYDOWN Then 'only act on keydown (multiple times if held down)
ztrace "Tab key (down)"
End If
'example key #2
Case %VK_F9
If (raw.keyboard.message And %WM_KEYUP) = %WM_KEYUP Then 'F9 keyup only resets hidF9 flag
hidF9 = %False
Exit Function
ElseIf (raw.keyboard.message And %WM_KEYDOWN) = %WM_KEYDOWN Then 'F9 keydown is only recognized once until the hidF9 flag is reset
If hidF9 = %False Then
hidF9 = %True
ztrace "F9 key (down)"
End If
End If
'example key #3
Case %Hid_Left 'Page Up 'presenter hid left key
If (raw.keyboard.message And %WM_KEYUP) <> %WM_KEYUP Then Exit Function 'only act on keyup
ztrace "hid left button (up)"
End Select
End Select
End Function
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