Perf: ColorEdit4 layout-only fast path for fully clipped rows, cached drag/slider value text, @native on color/group widgets; t_widget_cost + t_colors_hash

tools/test/roblox_mock.luau

@@ -160,7 +160,7 @@ ROBLOX = setmetatable({
     Color3 = { new = function(r, g, b) return { R = r or 0, G = g or 0, B = b or 0 } end },
     Content = { fromObject = function(o) return { Object = o } end },
     warn = function(...) print("WARN", ...) end,
-    os = { clock = function() return FAKE_TIME end, time = os.time },
+    os = { clock = function() return FAKE_TIME end, time = os.time, realclock = os.clock },
 }, { __index = realG })
 
 local mod = newInst("ModuleScript", "ImGui", ReplicatedStorage); rawset(mod, "_src", "ImGui.luau")

tools/test/scripts/t_colors_hash.luau

@@ -0,0 +1,32 @@
+-- Checksum of draw data + layout of Style Editor > Colors while scrolling its list (fast-path equivalence check)
+local G = require(game:GetService("ReplicatedStorage"):WaitForChild("ImGui"))
+local ImGui, ImVec2 = G.ImGui, G.ImVec2
+ImGui.CreateContext()
+G.ImGui_ImplRoblox.Init()
+local io = ImGui.GetIO()
+local realBTI = ImGui.BeginTabItem
+ImGui.BeginTabItem = function(label, p_open, flags)
+    if label == "Colors" then flags = bit32.bor(flags or 0, G.ImGuiTabItemFlags.SetSelected) end
+    return realBTI(label, p_open, flags)
+end
+local frame, h = 0, 0
+local function mix(v) h = (h * 31 + math.floor(v * 64 + 0.5)) % 2147483647 end
+game:GetService("RunService").Stepped:Connect(function()
+    frame += 1
+    G.ImGui_ImplRoblox.NewFrame()
+    io.DeltaTime = 1 / 60
+    io:AddMousePosEvent(200, 400 + (frame % 5) * 13)
+    if frame > 5 then io:AddMouseWheelEvent(0, (frame % 60 < 35) and -1 or 1) end
+    ImGui.NewFrame()
+    ImGui.SetNextWindowPos(ImVec2(20, 20)); ImGui.SetNextWindowSize(ImVec2(550, 700))
+    ImGui.Begin("Style Editor"); ImGui.ShowStyleEditor(); ImGui.End()
+    ImGui.Render()
+    for _, dl in ImGui.GetDrawData().CmdLists:iter() do
+        local vb, id = dl.VtxBuffer.Buf, dl.IdxBuffer.Data
+        for i = 1, dl.VtxBuffer.Size do local o = (i - 1) * 36; mix(buffer.readf64(vb, o)); mix(buffer.readf64(vb, o + 8)); mix(buffer.readu32(vb, o + 32) / 64) end
+        for i = 1, dl.IdxBuffer.Size do mix(id[i]) end
+    end
+    for _, w in ipairs(ImGui.GetCurrentContext().Windows.Data) do mix(w.ContentSize.x); mix(w.ContentSize.y); mix(w.Scroll.y); mix(w.ScrollMax.y) end
+    G.ImGui_ImplRoblox.RenderDrawData(ImGui.GetDrawData())
+    if frame == ARG_FRAMES - 1 then print("COLORSHASH", h) end
+end)

tools/test/scripts/t_widget_cost.luau

@@ -0,0 +1,71 @@
+-- Per-widget cost: wraps every ImGui.* function with self-time timing, shows the Style Editor on its Colors tab
+-- (or the demo with --open-only ...), prints a table sorted by total self time and by cost per call.
+local G = require(game:GetService("ReplicatedStorage"):WaitForChild("ImGui"))
+local ImGui, ImVec2 = G.ImGui, G.ImVec2
+ImGui.CreateContext()
+G.ImGui_ImplRoblox.Init()
+local io = ImGui.GetIO()
+local STYLE = type(ARG_OPEN) ~= "table"
+
+local realBTI = ImGui.BeginTabItem
+ImGui.BeginTabItem = function(label, p_open, flags)
+    if label == "Colors" and STYLE then flags = bit32.bor(flags or 0, G.ImGuiTabItemFlags.SetSelected) end
+    return realBTI(label, p_open, flags)
+end
+
+local self_t, calls = {}, {}
+local stack_child = {} -- time spent in nested wrapped calls, per depth
+local depth, enabled = 0, false
+local clock = os.realclock or os.clock -- harness fakes os.clock; realclock is the real one
+for name, fn in pairs(ImGui) do
+    if type(fn) == "function" and name ~= "NewFrame" and name ~= "Render" and name ~= "EndFrame" then
+        ImGui[name] = function(...)
+            if not enabled then return fn(...) end
+            depth += 1; stack_child[depth] = 0
+            local t0 = clock()
+            local r = table.pack(fn(...))
+            local dt = clock() - t0
+            local own = dt - stack_child[depth]
+            depth -= 1
+            if depth > 0 then stack_child[depth] += dt end
+            self_t[name] = (self_t[name] or 0) + own; calls[name] = (calls[name] or 0) + 1
+            return table.unpack(r, 1, r.n)
+        end
+    end
+end
+
+local frame = 0
+game:GetService("RunService").Stepped:Connect(function()
+    frame += 1
+    G.ImGui_ImplRoblox.NewFrame()
+    io:AddMousePosEvent(5, 5)
+    ImGui.NewFrame()
+    enabled = frame > 10
+    if STYLE then
+        ImGui.SetNextWindowPos(ImVec2(20, 20)); ImGui.SetNextWindowSize(ImVec2(550, 900))
+        ImGui.Begin("Style Editor"); ImGui.ShowStyleEditor(); ImGui.End()
+    else
+        ImGui.ShowDemoWindow(true)
+    end
+    enabled = false
+    ImGui.Render()
+    G.ImGui_ImplRoblox.RenderDrawData(ImGui.GetDrawData())
+    if frame == ARG_FRAMES - 1 then
+        local nf = frame - 10
+        local names = {}
+        local total = 0
+        for k, v in pairs(self_t) do table.insert(names, k); total += v end
+        table.sort(names, function(a, b) return self_t[a] > self_t[b] end)
+        print(string.format("TOTAL %.3f ms/frame (wrapped calls, incl. wrapper overhead)", total / nf * 1000))
+        print("== by self time per frame")
+        for i = 1, math.min(20, #names) do local k = names[i]
+            print(string.format("%7.3f ms %6.1f%%  %5d calls  %6.1f us/call  %s", self_t[k] / nf * 1000, 100 * self_t[k] / total, calls[k] / nf, self_t[k] / calls[k] * 1e6, k)) end
+        table.sort(names, function(a, b) return self_t[a] / calls[a] > self_t[b] / calls[b] end)
+        print("== by cost per call (>= 1 call/frame)")
+        local shown = 0
+        for _, k in ipairs(names) do
+            if calls[k] >= nf and shown < 15 then shown += 1
+                print(string.format("%6.1f us/call  %5d calls  %s", self_t[k] / calls[k] * 1e6, calls[k] / nf, k)) end
+        end
+    end
+end)