Chain Positioning of buttons

[pas06]

Hi,

I did some tests today with my Addon https://mods.curse.com/addons/wow/27...egroundenemies
I wanted to test how it would look like with 30 or 40 players in a row. I noticed that it gets really laggy when entering the testmode. I found out that the problem is caused by my function BattleGroundEnemies:ButtonPositioning()
The function looks like this (i added the print for debug reasons)

function BattleGroundEnemies:ButtonPositioning()
 
    local previousButton = self
    for number, name in ipairs(self.EnemySortingTable) do
        local enemyButton = self.Enemies[name]
        enemyButton.Position = number
        
        enemyButton:ClearAllPoints()
        if self.db.profile.Growdirection == "downwards" then
            local startTime = debugprofilestop()
            enemyButton:SetPoint("TOPLEFT", previousButton, "BOTTOMLEFT", 0, -self.db.profile.SpaceBetweenRows)
            enemyButton:SetPoint("TOPRIGHT", previousButton, "BOTTOMRIGHT", 0, -self.db.profile.SpaceBetweenRows)
            print(debugprofilestop() - startTime)
        else
            enemyButton:SetPoint("BOTTOMLEFT", previousButton, "TOPLEFT", 0, self.db.profile.SpaceBetweenRows)
            enemyButton:SetPoint("BOTTOMRIGHT", previousButton, "TOPRIGHT", 0, self.db.profile.SpaceBetweenRows)
        end
        previousButton = enemyButton
    end
end

I found out that the duration for each iterations grows Exponential
The outputs of this prints

[07:32:21] 0.0022993683815002
[07:32:21] 0.0028104186058044
[07:32:21] 0.003065824508667
[07:32:21] 0.0028104186058044
[07:32:21] 0.0033213496208191
[07:32:21] 0.0048542618751526
[07:32:21] 0.0079201459884644
[07:32:21] 0.013796448707581
[07:32:21] 0.025548875331879
[07:32:21] 0.050075829029083
[07:32:21] 0.096063911914825
[07:32:21] 0.19136130809784
[07:32:21] 0.37837928533554
[07:32:21] 0.76135736703873
[07:32:21] 1.6034492850304
[07:32:21] 3.1299964189529
[07:32:21] 6.1787472963333
[07:32:21] 12.497247099876
[07:32:21] 25.104099035263
[07:32:21] 50.724030435085
[07:32:21] 100.23934215307
[07:32:21] 200.18180602789
[07:32:22] 405.05413562059
[07:32:22] 822.46883159876
[07:32:24] 1608.76526737

As you can see those 2 SetPoint() calls took 1.6 seconds
is this a bug or am i just doing something wrong?

[Fizzlemizz]

It wouldn't hurt to save self.db.profile.SpaceBetweenRows and self.db.profile.Growdirection to local variables at the start of the function rather than doing a table lookup once or twice each iteration.

[pas06]

yeah, i know, but this is not whats causing this huge durations
Edit: Just a side note, i commented all SetScripts out to make shure that this problem is not caused by any attached scripts.

[MunkDev]

Just speculating here, but since you're anchoring both top corners to the bottom corners of the previous button (or vice versa), is it possible that the slowdown happens because it needs to go back up the chain with each iteration to find out where to draw the next button? When you anchor two opposite corners, it'll ultimately use the distance between them to determine the span instead of whatever value you feed to it.

A conversation between them might look like a little bit like this:
- "I was supposed to anchor to you and match your width. Where should I draw myself?"
- "I don't really know, I'll ask the guy I'm anchored to because he's in control of my position."
* repeat until the first button is reached *

function BattleGroundEnemies:ButtonPositioning()
 
    local previousButton, buttons = self, self.Enemies
    local spaceBetweenRows = self.db.profile.SpaceBetweenRows
    local growDownwards = (self.db.profile.Growdirection == "downwards")
    local mainWidth = self:GetWidth()
 
    for number, name in ipairs(self.EnemySortingTable) do
        local enemyButton = buttons[name]
        enemyButton.Position = number
        
        enemyButton:SetWidth(mainWidth)
        enemyButton:ClearAllPoints()
        if growDownwards then
            enemyButton:SetPoint("TOPLEFT", previousButton, "BOTTOMLEFT", 0, -spaceBetweenRows)
        else
            enemyButton:SetPoint("BOTTOMLEFT", previousButton, "TOPLEFT", 0, spaceBetweenRows)
        end
        previousButton = enemyButton
    end
end

Try this to confirm or debunk this theory. (And please report your findings even if it solves your problem.)

[pas06]

Thanks, this really helped a lot, it now works without any lag. So i will change my code to only anchor one Point and set the width for each individual button. And i thought this way of positioning is smart since i only need to adjust the parents width to change the width of all attached buttons with 30 buttons it crashed my client

[MunkDev]

That might seem like the most intuitive approach, but if you think about how the UI engine needs to work in order to draw your frames in the right place, creating a chain of relative positioning entails a lot of unnecessary calculation because of their interdependent relationships, as opposed to just knowing a single point where it should anchor and a plain number to determine the width.

[pas06]

I haven't thought about that its that complicated to get the actual position of a frame. I thougth that there is some sort of database of each frame and its position (so that the points don't need to be calculated through the whole chain) Anyways, thanks for you help