UIScrollingSliderClass

--- wafflecow321
local uis = game:GetService("UserInputService")
local slider = {}
slider.__index = slider
--[[
All slide have their dragging frame named handle
]]--
local DEFAULTXALIGN = 0.5
---- private functions
local function getAbsoluteCanvasSize(sFrame)
    local size = sFrame.Parent.AbsoluteSize and Vector2.new(sFrame.CanvasSize.X.Scale, sFrame.CanvasSize.Y.Scale) * sFrame.Parent.AbsoluteSize or Vector2.new(0, 0)
    return size + Vector2.new(sFrame.CanvasSize.X.Offset, sFrame.CanvasSize.Y.Offset)
end
local function v2FromV3(v3)
    return Vector2.new(v3.X, v3.Y)
end
---- public/object functions
function slider:startDrag(input, gp)
    if gp then return end
    if not self.dragging and input.UserInputType == Enum.UserInputType.MouseButton1 then
        self.dragging = true
    end
end
function slider:endDrag(input, gp)
    if input.UserInputType == Enum.UserInputType.MouseButton1 then
        self.dragging = false
    end
end
function slider:updateDrag(input, gp)
    local bar, handle, scrollingFrame = self.frame, self.frame.Handle, self.scrollingFrame
    if self.dragging then
        -- get y scale position
        local inputPosition = v2FromV3(input.Position)
        local objectSpace = inputPosition - handle.Parent.AbsolutePosition
        local yScale = math.clamp(objectSpace.Y/bar.AbsoluteSize.Y,0,1)
        --- apply position
        handle.Position = UDim2.new(self.xAlign, 0, yScale, 0)
        --- update scrolling frame
        if scrollingFrame then
            local absCanvasSize = getAbsoluteCanvasSize(scrollingFrame)
            scrollingFrame.CanvasPosition = Vector2.new(0, yScale * (absCanvasSize.Y - scrollingFrame.AbsoluteWindowSize.Y))
        end
    end
end
function slider:scrollingFrameUpdate()
    if not self.dragging and self.scrollingFrame then
        local absCanvasSize = getAbsoluteCanvasSize(self.scrollingFrame)
        local canvPosition = self.scrollingFrame.CanvasPosition
        self.frame.Visible = absCanvasSize.Y > self.scrollingFrame.AbsoluteWindowSize.Y
        self.frame.Handle.Position = UDim2.new(self.xAlign, 0, canvPosition.Y/(absCanvasSize.Y - self.scrollingFrame.AbsoluteWindowSize.Y), 0)
    end
end
--- constructor
function slider.new(sliderFrame, scrollingFrame, xAlign)
    local s = setmetatable({}, slider)
    s.frame = sliderFrame
    s.scrollingFrame = scrollingFrame
    s.xAlign = xAlign or DEFAULTXALIGN
    --- handle sliding behavior
    if s.frame:FindFirstChild("Handle") then
        s.frame.Handle.InputBegan:Connect(function(...)
            s:startDrag(...)
        end)
        s.frame.Handle.InputEnded:Connect(function(...)
            s:endDrag(...)
        end)
        uis.InputChanged:Connect(function(...)
            s:updateDrag(...)
        end)
    else
        warn("No Handle Frame in sliding frame, can't create slider")
    end
    --- handle scrollingframe changes
    if s.scrollingFrame then
        local function a(...)
            return s:scrollingFrameUpdate(...)
        end
        a()
        scrollingFrame:GetPropertyChangedSignal("CanvasPosition"):Connect(a)
        scrollingFrame:GetPropertyChangedSignal("CanvasSize"):Connect(a)
    end
    return s
end

return slider