How to add up and down arrow functionality to a MultiLine TextBox

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1

Hey, so I get that this is obviously a bug and should be fixed, but at the moment it isn’t so I just want to hack a solution in for now.

Anyway, I want to be able to navigate my TextBox, which has MultiLine set to true, using the up and down arrows.

Here’s the code I have so far, it allows me to get both the current line that I’m on as well as the column I’m in, this will be important later.

local UIS = game:GetService("UserInputService")
local InputArea = script.Parent

function Split(Str, Del)
    local Result = {}
    for Match in (Str..Del):gmatch("(.-)"..Del) do
	    table.insert(Result, Match)
    end
    return Result
end

function GetLineNumber()
    local Selection = InputArea.Text:sub(0, InputArea.CursorPosition-1)
    local _, Count = Selection:gsub("\n", "")
    return Count + 1
end

function GetSelection(Line)
    local Selection = InputArea.CursorPosition
    local Lines = Split(InputArea.Text, "\n")
    for i = 1, Line-1 do
	    Selection -= Lines[i]:len()
    end
    return Selection
end

function GetColumnNumber()
    local Line = GetLineNumber()
    local Selection = GetSelection(Line) - (Line - 1)
    return Selection
end

UIS.InputBegan:Connect(function(Input, IsTyping)
    if not IsTyping then return end
    if not script.Parent:IsFocused() then return end
    if Input.KeyCode == Enum.KeyCode.Up then
	    -- Need to subtract `InputArea.CursorPosition` by an amount to make it exactly one line above.
    elseif Input.KeyCode == Enum.KeyCode.Down then
	    -- Need to add an amount to `InputArea.CursorPosition` to make it exactly one line below.
    end
end)

So, obviously, I’ll need to put code in to increment or decrement the TextBox.CursorPosition attribute. The amount it will need to be changed by depened on the column it’s in, and also the length of the line that it’s moving to.

The issue obviously being, how in the world do I figure out exactly how much it needs to be incremented or decremented by?

Sorry if this is pretty complex, but I’m completely stuck.

2

Update, I totally got it!

I added this function, and since I already know the desired line and column, this is basically just converting that into the real position number.

function MoveCursor(Line, Column)
    local Lines = Split(InputArea.Text, "\n")
    local Line = math.clamp(Line, 1, #Lines)
    local Column = math.clamp(Column, 1, Lines[Line]:len()+1)
    local Position = Column
    for i = 1, Line-1 do
    	Position += Lines[i]:len()
    end
    InputArea.CursorPosition = Position + (Line - 1)
end