<function name="PerformLayout" parent="PANEL" type="hook"> <description> Called whenever the panels' layout needs to be performed again. This means all child panels must be re-positioned to fit the possibly new size of this panel. This can be triggered in numerous ways: * <page>Panel:InvalidateLayout</page> was called this or previous frame (depending on the argument) * <page>Panel:SetPos</page> called more than once on the same panel ([Issue](https://github.com/Facepunch/garrysmod-issues/issues/5519)) * A child element was added to this panel (TODO: Verify me) * The size of this panel has changed <warning>Do **NOT** call this function directly. Use <page>Panel:InvalidateLayout</page> instead!</warning>⤶ ⤶ You should not call this function directly. Use <page>Panel:InvalidateLayout</page> instead.⤶ You can use `vgui_visualizelayout 1` to visualize panel layouts as they happen for debugging purposes. Panels should not be doing this every frame. </description> <realm>Client</realm> <args> <arg name="width" type="number">The panels current width.</arg> <arg name="height" type="number">The panels current height.</arg> </args> </function> <example> <description>Creating a resizeable DFrame with a 'sidebar' that rescales along with the DFrame</description> <code> local frame = vgui.Create("DFrame") frame:SetSize(500, 400) frame:Center() frame:SetSizable(true) -- oPerformLayout stores the original PerformLayout function -- We store it because we are going to overwrite it with our own to scale the Sidebar -- We then call the original function to maintain proper functionality of the frame -- You can find the original PerformLayout here https://github.com/Facepunch/garrysmod/blob/master/garrysmod/lua/vgui/dframe.lua#L234-L258 local oPerformLayout = frame.PerformLayout frame.PerformLayout = function(pnl, w, h) oPerformLayout(pnl, w, h) pnl.Sidebar:SetWide(w * 0.5) end frame.Sidebar = frame:Add("DPanel") frame.Sidebar:Dock(LEFT) frame.Sidebar.Paint = function(pnl, w, h) surface.SetDrawColor(255, 0, 0) surface.DrawRect(0, 0, w, h) end frame.Sidebar.PerformLayout = function(pnl, w, h) local buttonWidth = w * 0.5 local buttonHeight = h * 0.5 pnl.Button:SetSize(buttonWidth, buttonHeight) -- now we center our button pnl.Button:SetPos(w / 2 - buttonWidth / 2, h / 2 - buttonHeight / 2) end frame.Sidebar.Button = frame.Sidebar:Add("DButton") frame.Sidebar.Button:SetText("Hello!") </code> </example>