From afd0a36003bdeb327e0cbc4b5cdaf7ce71a638d3 Mon Sep 17 00:00:00 2001
From: Chris Titus <contact@christitus.com>
Date: Wed, 1 Jul 2026 22:55:35 -0500
Subject: [PATCH] Replace install render timer with dispatcher callbacks

---
 .../Start-WinUtilInstallAppRendering.ps1      | 54 ++++++++++---------
 pester/install-rendering.Tests.ps1            | 13 ++---
 2 files changed, 35 insertions(+), 32 deletions(-)

diff --git a/functions/private/Start-WinUtilInstallAppRendering.ps1 b/functions/private/Start-WinUtilInstallAppRendering.ps1
index b15ef7aa..afface44 100644
--- a/functions/private/Start-WinUtilInstallAppRendering.ps1
+++ b/functions/private/Start-WinUtilInstallAppRendering.ps1
@@ -13,6 +13,28 @@ function Invoke-WinUtilInstallAppRenderBatch {
     }
 }
 
+function Complete-WinUtilInstallAppRendering {
+    $sync.InstallAppEntriesRendered = $true
+    Write-WinUtilPerformanceCheckpoint -Name "Install app entries rendered"
+}
+
+function Invoke-WinUtilInstallAppRenderNextBatch {
+    if ($sync.InstallAppRenderQueue.Count -gt 0) {
+        $categoryBatch = $sync.InstallAppRenderQueue.Dequeue()
+        Invoke-WinUtilInstallAppRenderBatch -CategoryBatch $categoryBatch
+    }
+
+    if ($sync.InstallAppRenderQueue.Count -gt 0) {
+        $sync.Form.Dispatcher.BeginInvoke(
+            [System.Windows.Threading.DispatcherPriority]::Background,
+            [action]{ Invoke-WinUtilInstallAppRenderNextBatch }
+        ) | Out-Null
+        return
+    }
+
+    Complete-WinUtilInstallAppRendering
+}
+
 function Start-WinUtilInstallAppRendering {
     if ($null -eq $sync.InstallAppRenderQueue) {
         return
@@ -20,30 +42,11 @@ function Start-WinUtilInstallAppRendering {
 
     $sync.InstallAppEntriesRendered = $false
 
-    if ($sync.Form -and $sync.Form.Dispatcher -and ("System.Windows.Threading.DispatcherTimer" -as [type])) {
-        $timer = New-Object System.Windows.Threading.DispatcherTimer
-        $timer.Interval = [TimeSpan]::FromMilliseconds(1)
-        $timer.Add_Tick({
-            param($sender)
-
-            $dispatcherTimer = [System.Windows.Threading.DispatcherTimer]$sender
-            $dispatcherTimer.Stop()
-
-            if ($sync.InstallAppRenderQueue.Count -gt 0) {
-                $categoryBatch = $sync.InstallAppRenderQueue.Dequeue()
-                Invoke-WinUtilInstallAppRenderBatch -CategoryBatch $categoryBatch
-            }
-
-            if ($sync.InstallAppRenderQueue.Count -gt 0) {
-                $dispatcherTimer.Start()
-                return
-            }
-
-            $sync.InstallAppEntriesRendered = $true
-            Write-WinUtilPerformanceCheckpoint -Name "Install app entries rendered"
-        })
-        $sync.InstallAppRenderTimer = $timer
-        $timer.Start()
+    if ($sync.Form -and $sync.Form.Dispatcher) {
+        $sync.Form.Dispatcher.BeginInvoke(
+            [System.Windows.Threading.DispatcherPriority]::Background,
+            [action]{ Invoke-WinUtilInstallAppRenderNextBatch }
+        ) | Out-Null
         return
     }
 
@@ -52,6 +55,5 @@ function Start-WinUtilInstallAppRendering {
         Invoke-WinUtilInstallAppRenderBatch -CategoryBatch $categoryBatch
     }
 
-    $sync.InstallAppEntriesRendered = $true
-    Write-WinUtilPerformanceCheckpoint -Name "Install app entries rendered"
+    Complete-WinUtilInstallAppRendering
 }
diff --git a/pester/install-rendering.Tests.ps1 b/pester/install-rendering.Tests.ps1
index a264e732..d680c1c2 100644
--- a/pester/install-rendering.Tests.ps1
+++ b/pester/install-rendering.Tests.ps1
@@ -15,21 +15,22 @@ Describe "Install app rendering startup contract" {
         $categoryScript | Should -Match 'Pre-group apps by category before creating WPF controls'
     }
 
-    It "renders queued apps through a dispatcher timer when a form dispatcher exists" {
+    It "renders queued apps through dispatcher callbacks when a form dispatcher exists" {
         $renderScript = Get-Content -Path (Join-Path $script:repoRoot "functions\private\Start-WinUtilInstallAppRendering.ps1") -Raw
 
-        $renderScript | Should -Match 'System\.Windows\.Threading\.DispatcherTimer'
+        $renderScript | Should -Match 'Dispatcher\.BeginInvoke'
+        $renderScript | Should -Match 'Invoke-WinUtilInstallAppRenderNextBatch'
         $renderScript | Should -Match 'Initialize-InstallAppEntry'
         $renderScript | Should -Match 'Install app entries rendered'
     }
 
-    It "does not rely on local timer variables after the dispatcher tick fires" {
+    It "does not use dispatcher timers for deferred install rendering" {
         $renderScript = Get-Content -Path (Join-Path $script:repoRoot "functions\private\Start-WinUtilInstallAppRendering.ps1") -Raw
 
-        $renderScript | Should -Match 'param\(\$sender\)'
-        $renderScript | Should -Match '\$dispatcherTimer = \[System\.Windows\.Threading\.DispatcherTimer\]\$sender'
+        $renderScript | Should -Not -Match 'DispatcherTimer'
+        $renderScript | Should -Not -Match '\$timer'
+        $renderScript | Should -Not -Match '\$dispatcherTimer'
         $renderScript | Should -Not -Match '\$timer\.Stop\(\)'
-        $renderScript | Should -Match '\$dispatcherTimer\.Start\(\)'
         $renderScript | Should -Not -Match '& \$renderCategory'
     }