TextSize Approximation with TextScaled Enabled

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1

Hello everyone!

Allow me to get straight to the point.

  • With TextLabels, there is currently no property or API to get the actual “TextSize” of a TextLabel when the property TextScaled is enabled.

Why is this an issue?

  • The TextWrapped property is force enabled with TextScaled, so now instead of just having 1 row of text (A simple TextLabel.TextBounds.Y), you could have multiple rows!!

Okay but does it look good?

  • The popping out is the viewport updating the TextBounds before I manually update TextSize

This code block provided below is a quick way to get an “approximated” TextSize. From my testing it is nearly perfect, only occasionally being a pixel off.

local Params = Instance.new("GetTextBoundsParams")

function getTextBoundParams(TextLabel, TextSize)
    Params.Size = TextSize
    Params.Font = TextLabel.FontFace
    Params.Width = math.huge
    Params.Text = TextLabel.Text
    Params.RichText = TextLabel.RichText
    return Params
end

function GetTextSize(TextLabel)
    if TextLabel.TextScaled then
        local smallSample, bigSample = 1, 100

        local lower = TextService:GetTextBoundsAsync(getTextBoundParams(smallSample))
        local upper = TextService:GetTextBoundsAsync(getTextBoundParams(bigSample))
        local verticalBound = math.floor(TextLabel.TextBounds.Y)

        local volume = math.floor(TextLabel.TextBounds.X) * verticalBound
        local lowerVolume = (lower.X * lower.Y) / volume -- Scalar to compare TextSize 1 TextBounds vs the actual TextBounds of the TextLabel
        local upperVolume = (upper.X * upper.Y) / volume -- Same as lowerVolme but TextSize 100

        local s1 = math.sqrt(lowerVolume)
        local s2 = math.sqrt(upperVolume)

        -- Linearly interpolate the volumes by the slope to find the "perfect" volume along the slope.
        local textSizeApproximation = smallSample + (1 - s1) * (bigSample - smallSample) / (s2 - s1)
        local rows = math.round(verticalBound / textSizeApproximation)

        return math.floor(verticalBound / rows)
    end
    return TextLabel.TextSize
end

Let me know if this has helped you at all and feel free to pitch in!

7 Likes
2

Hi, MasterDevelopments here, so I wanted to make an honest answer., I feel like this is very useful in MY opinion. The code is great, nothing there I don’t like or think needs major changing, but some suggestions.

  1. Make it a Module. A script is fine, but a module is reusable
  2. I find this useful, but please, and by please, I mean please recycle your params. its unoptimized
  3. Don’t use self unless it’s an OOP or metatable, either then that, please do noit’sits annoying.
1 Like
3

Thanks for the reply!

My response regarding your suggestion:

  1. I made this so anyone could easily read it & refactor it into their own systems
  2. (Same as #1, not entirely sure what you mean though since the same Instance is used?)
  3. That was an oversight, I had refactored this code from my own system that used OOP, it is now fixed.
4

Oh, my bad on number 2, In the video you kept creating params when you were changing your viewport size, but silly me, anyways, I refactored your code, here you are:

local TextService = game:GetService("TextService")

local TextSizeEstimator = {}
TextSizeEstimator.__index = TextSizeEstimator

function TextSizeEstimator.new(label)
    assert(label:IsA("TextLabel"), "TextSizeEstimator expects a TextLabel")
    local self = setmetatable({}, TextSizeEstimator)
    self.Label = label
    self.Params = Instance.new("GetTextBoundsParams")
    self.Params.Font = label.FontFace
    self.Params.Width = math.huge
    self.Params.Text = label.Text
    self.Params.RichText = label.RichText
    return self
end

function TextSizeEstimator:GetBounds(size)
    self.Params.Size = size
    return TextService:GetTextBoundsAsync(self.Params)
end

function TextSizeEstimator:Estimate()
    if not self.Label.TextScaled then
        return self.Label.TextSize
    end

    if not self.Label.Text or self.Label.Text == "" then
        return 0
    end

    local smallSize, largeSize = 1, 100
    local boundsSmall = self:GetBounds(smallSize)
    local boundsLarge = self:GetBounds(largeSize)

    local actualBounds = self.Label.TextBounds
    local volume = actualBounds.X * actualBounds.Y

    local volumeSmall = boundsSmall.X * boundsSmall.Y
    local volumeLarge = boundsLarge.X * boundsLarge.Y

    local scaleSmall = math.sqrt(volumeSmall / volume)
    local scaleLarge = math.sqrt(volumeLarge / volume)

    local estimatedSize = smallSize + (1 - scaleSmall) * (largeSize - smallSize) / (scaleLarge - scaleSmall)
    local rows = math.max(1, math.round(actualBounds.Y / estimatedSize))

    return math.floor(actualBounds.Y / rows)
end

return TextSizeEstimator

also, I made a little helper for input Tired of Rewriting Keybind Logic? InputManager Handles It All—Context, Debounce, Gamepad, Touch - Resources / Community Resources - Developer Forum | Roblox