[RESOLVED] Implementing my own arrow key navigation on a textbox

Due to some weird circumstance, I am now having to manipulate the arrow key navigation on an active textbox. I figured I can use the API to get information on the lines... Here is my unfinished code snippet

Code:

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Dim startSel As Long, endSel As Long
    Dim delta As Long, lineCnt As Long, currentLine As Long
   
    'Get the initial values
    SendMessageLong activeTextBox.hwnd, EM_GETSEL, startSel, endSel
    delta = endSel
    'lines are 0-based
    lineCnt = SendMessageLong(activeTextBox.hwnd, EM_GETLINECOUNT, 0, 0)
    currentLine = SendMessageLong(activeTextBox.hwnd, EM_LINEFROMCHAR, delta, 0)
    'calculate delta
    Select Case KeyCode
        Case vbKeyUp
            'calculate up
            If currentLine > 0 Then
               
            End If
        Case vbKeyDown
            'calculate down
            If currentLine < lineCnt - 1 Then
               
            End If
        Case vbKeyLeft
            'calculate left
            If delta > 0 Then
                delta = delta - 1
            End If
        Case vbKeyRight
            'calculate right
            delta = delta + 1
    End Select

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Now for the KeyUp and Keydown, I need to place the current cursor into the correct line. Currently, what I have in mind is to calculate the character index for each line and get the delta character change and use that to send an api call for EM_SETSEL.

Basically what I'd do is, call sendmessage on EM_GETLINE, get all character count, determine the line where delta should fall, determine the new char index from that line and then add the character counts of all preceding lines, and that will be my delta.

Is there another straightforward API call for this? or some other clever way perhaps? :wave:

Well, I figured out that I have to keep track of the achor for SHIFT+Arrow keys to behave at least in an acceptable manner.

If nobody has other ideas, then I suppose i'd have to go with my idea then. :(

Found the solution! and I didn't have to loop which is awesome. :)

All SendMessageSetLong is a SendMessage Api call alias.

vb Code:

Private Function GetDeltaCharPosition(ByVal textHwnd As Long, ByVal currentCharDelta As Long, ByVal currentLine As Long, ByVal arrowDirection As Direction) As Long
    Dim newLine As Long
    Dim newCharLineStart As Long, currentCharLineStart As Long
    Dim newWidth As Long
    Dim currentWidth As Long
    
    If arrowDirection = Direction.Up Then
        newLine = currentLine - 1
    Else
        newLine = currentLine + 1
    End If
    
    newCharLineStart = SendMessageSetLong(textHwnd, EM_LINEINDEX, newLine, 0)
    currentCharLineStart = SendMessageSetLong(textHwnd, EM_LINEINDEX, currentLine, 0)
    
    newWidth = SendMessageSetLong(textHwnd, EM_LINELENGTH, newCharLineStart, 0)
    currentWidth = currentCharDelta - currentCharLineStart
    
    If currentWidth <= newWidth Then
        GetDeltaCharPosition = newCharLineStart + currentWidth
    Else
        GetDeltaCharPosition = newCharLineStart + newWidth
    End If
    
End Function