SPINNERS

-- Usage:
-- spinner = CreateSpinner(parent)
-- spinner:SetTexture('texturePath')
-- spinner:SetBlendMode('blendMode')
-- spinner:SetVertexColor(r, g, b)
-- spinner:SetClockwise(boolean) -- true to fill clockwise, false to fill counterclockwise
-- spinner:SetReverse(boolean) -- true to empty the bar instead of filling it
-- spinner:SetValue(percent) -- value between 0 and 1 to fill the bar to

-- Some math stuff
local cos, sin, pi2, halfpi = math.cos, math.sin, math.rad(360), math.rad(90)
local function Transform(tx, x, y, angle, aspect) -- Translates texture to x, y and rotates about its center
    local c, s = cos(angle), sin(angle)
    local y, oy = y / aspect, 0.5 / aspect
    local ULx, ULy = 0.5 + (x - 0.5) * c - (y - oy) * s, (oy + (y - oy) * c + (x - 0.5) * s) * aspect
    local LLx, LLy = 0.5 + (x - 0.5) * c - (y + oy) * s, (oy + (y + oy) * c + (x - 0.5) * s) * aspect
    local URx, URy = 0.5 + (x + 0.5) * c - (y - oy) * s, (oy + (y - oy) * c + (x + 0.5) * s) * aspect
    local LRx, LRy = 0.5 + (x + 0.5) * c - (y + oy) * s, (oy + (y + oy) * c + (x + 0.5) * s) * aspect
    tx:SetTexCoord(ULx, ULy, LLx, LLy, URx, URy, LRx, LRy)
end

-- Permanently pause our rotation animation after it starts playing
local function OnPlayUpdate(self)
    self:SetScript('OnUpdate', nil)
    self:Pause()
end

local function OnPlay(self)
    self:SetScript('OnUpdate', OnPlayUpdate)
end

local function SetValue(self, value)
    -- Correct invalid ranges, preferably just don't feed it invalid numbers
    if value > 1 then value = 1
    elseif value < 0 then value = 0 end

    -- Reverse our normal behavior
    if self._reverse then
        value = 1 - value
    end

    -- Determine which quadrant we're in
    local q, quadrant = self._clockwise and (1 - value) or value -- 4 - floor(value / 0.25)
    if q >= 0.75 then
        quadrant = 1
    elseif q >= 0.5 then
        quadrant = 2
    elseif q >= 0.25 then
        quadrant = 3
    else
        quadrant = 4
    end

    -- Show/hide necessary textures if we need to
    if self._quadrant ~= quadrant then
        self._quadrant = quadrant
        if self._clockwise then
            for i = 1, 4 do
                self._textures[i]:SetShown(i < quadrant)
            end
        else
            for i = 1, 4 do
                self._textures[i]:SetShown(i > quadrant)
            end
        end
    end

    -- Move scrollframe/wedge to the proper quadrant
    self._scrollframe:SetAllPoints(self._textures[quadrant])

    -- Rotate the things
    local rads = value * pi2
    if not self._clockwise then rads = -rads + halfpi end
    Transform(self._wedge, -0.5, -0.5, rads, self._aspect)
    self._rotation:SetRadians(-rads)
end

local function SetClockwise(self, clockwise)
    self._clockwise = clockwise
end

local function SetReverse(self, reverse)
    self._reverse = reverse
end

local function OnSizeChanged(self, width, height)
    self._wedge:SetSize(width, height) -- it's important to keep this texture sized correctly
    self._aspect = width / height -- required to calculate the texture coordinates
end

-- Creates a function that calls a method on all textures at once
local function CreateTextureFunction(func, self, ...)
    return function(self, ...)
        for i = 1, 4 do
            local tx = self._textures[i]
            tx[func](tx, ...)
        end
        self._wedge[func](self._wedge, ...)
    end
end

-- Pass calls to these functions on our frame to its textures
local TextureFunctions = {
    SetTexture = CreateTextureFunction('SetTexture'),
    SetBlendMode = CreateTextureFunction('SetBlendMode'),
    SetVertexColor = CreateTextureFunction('SetVertexColor'),
}

local function CreateSpinner(parent)
    local spinner = CreateFrame('Frame', nil, parent)

    -- ScrollFrame clips the actively animating portion of the spinner
    local scrollframe = CreateFrame('ScrollFrame', nil, spinner)
    scrollframe:SetPoint('BOTTOMLEFT', spinner, 'CENTER')
    scrollframe:SetPoint('TOPRIGHT')
    spinner._scrollframe = scrollframe

    local scrollchild = CreateFrame('frame', nil, scrollframe)
    scrollframe:SetScrollChild(scrollchild)
    scrollchild:SetAllPoints(scrollframe)

    -- Wedge thing
    local wedge = scrollchild:CreateTexture()
    wedge:SetPoint('BOTTOMRIGHT', spinner, 'CENTER')
    spinner._wedge = wedge

    -- Top Right
    local trTexture = spinner:CreateTexture()
    trTexture:SetPoint('BOTTOMLEFT', spinner, 'CENTER')
    trTexture:SetPoint('TOPRIGHT')
    trTexture:SetTexCoord(0.5, 1, 0, 0.5)

    -- Bottom Right
    local brTexture = spinner:CreateTexture()
    brTexture:SetPoint('TOPLEFT', spinner, 'CENTER')
    brTexture:SetPoint('BOTTOMRIGHT')
    brTexture:SetTexCoord(0.5, 1, 0.5, 1)

    -- Bottom Left
    local blTexture = spinner:CreateTexture()
    blTexture:SetPoint('TOPRIGHT', spinner, 'CENTER')
    blTexture:SetPoint('BOTTOMLEFT')
    blTexture:SetTexCoord(0, 0.5, 0.5, 1)

    -- Top Left
    local tlTexture = spinner:CreateTexture()
    tlTexture:SetPoint('BOTTOMRIGHT', spinner, 'CENTER')
    tlTexture:SetPoint('TOPLEFT')
    tlTexture:SetTexCoord(0, 0.5, 0, 0.5)

    -- /4|1\ -- Clockwise texture arrangement
    -- \3|2/ --

    spinner._textures = {trTexture, brTexture, blTexture, tlTexture}
    spinner._quadrant = nil -- Current active quadrant
    spinner._clockwise = true -- fill clockwise
    spinner._reverse = false -- Treat the provided value as its inverse, eg. 75% will display as 25%
    spinner._aspect = 1 -- aspect ratio, width / height of spinner frame
    spinner:HookScript('OnSizeChanged', OnSizeChanged)

    for method, func in pairs(TextureFunctions) do
        spinner[method] = func
    end

    spinner.SetClockwise = SetClockwise
    spinner.SetReverse = SetReverse
    spinner.SetValue = SetValue

    local group = wedge:CreateAnimationGroup()
    local rotation = group:CreateAnimation('Rotation')
    spinner._rotation = rotation
    rotation:SetDuration(0)
    rotation:SetEndDelay(1)
    rotation:SetOrigin('BOTTOMRIGHT', 0, 0)
    group:SetScript('OnPlay', OnPlay)
    group:Play()

    return spinner
end

----------
-- Demo
----------

local spinner1 = CreateSpinner(UIParent)
spinner1:SetPoint('BOTTOMRIGHT', UIParent, 'CENTER', -2, 2)
spinner1:SetSize(64, 64)
spinner1:SetTexture('interface/icons/inv_mushroom_11')

spinner1:SetClockwise(false)
spinner1:SetReverse(false)

local spinner2 = CreateSpinner(UIParent)
spinner2:SetPoint('BOTTOMLEFT', UIParent, 'CENTER', 2, 2)
spinner2:SetSize(64, 64)
spinner2:SetTexture('interface/icons/inv_mushroom_11')

spinner2:SetClockwise(true)
spinner2:SetReverse(false)

local spinner3 = CreateSpinner(UIParent)
spinner3:SetPoint('TOPRIGHT', UIParent, 'CENTER', -2, -2)
spinner3:SetSize(64, 64)
spinner3:SetTexture('interface/icons/inv_mushroom_11')

spinner3:SetClockwise(true)
spinner3:SetReverse(true)

local spinner4 = CreateSpinner(UIParent)
spinner4:SetPoint('TOPLEFT', UIParent, 'CENTER', 2, -2)
spinner4:SetSize(64, 64)
spinner4:SetTexture('interface/icons/inv_mushroom_11')

spinner4:SetClockwise(false)
spinner4:SetReverse(true)

local f = CreateFrame('frame')
local timespent = 0
f:SetScript('OnUpdate', function(self, elapsed)
    timespent = timespent + elapsed
    if timespent >= 3 then
        timespent = 0
    end

    local value = timespent / 3
    spinner1:SetValue(value)
    spinner2:SetValue(value)
    spinner3:SetValue(value)
    spinner4:SetValue(value)
end)