Make MPO tweak a three-state control (#4897)

* refactor: make MPO tweak a three-state control * docs: explain MPO tweak states * docs: address code review comments * refactor: make Multiplane Overlay config-driven
2026-08-10 18:11:16 +10:00 · 2026-08-09 14:02:42 -05:00
parent 7f18b4fd60
commit bc607b6c91
12 changed files with 457 additions and 17 deletions
@@ -0,0 +1,78 @@
+function Set-WinUtilRegistryComboState {
+    <#
+    .SYNOPSIS
+        Applies and verifies a config-defined registry combo-box state.
+
+    .PARAMETER Registry
+        Registry settings containing a value mapping for each supported state.
+
+    .PARAMETER State
+        The state name to apply.
+    #>
+    param(
+        [Parameter(Mandatory)]
+        $Registry,
+
+        [Parameter(Mandatory)]
+        [string]$State
+    )
+
+    if ($Registry[0].Values.PSObject.Properties.Name -notcontains $State) {
+        throw "Unknown registry state '$State'."
+    }
+
+    # Preserve exact prior values so a partial update can be rolled back.
+    $previousValues = foreach ($setting in @($Registry)) {
+        $currentValue = Get-WinUtilRegistryComboValue -Setting $setting
+        [pscustomobject]@{ Setting = $setting; Exists = $currentValue.Exists; Value = $currentValue.Value }
+    }
+
+    try {
+        foreach ($setting in @($Registry)) {
+            $configuredValue = $setting.Values.PSObject.Properties[$State].Value
+            $previousValue = $previousValues | Where-Object Setting -EQ $setting
+            if ($configuredValue -ne "<RemoveEntry>" -or $previousValue.Exists) {
+                Set-WinUtilRegistry -Name $setting.Name -Path $setting.Path -Type $setting.Type -Value $configuredValue
+            }
+        }
+
+        # Set-WinUtilRegistry reports write errors without throwing, so verify each result explicitly.
+        foreach ($setting in @($Registry)) {
+            $configuredValue = $setting.Values.PSObject.Properties[$State].Value
+            $currentValue = Get-WinUtilRegistryComboValue -Setting $setting
+            $writeMatches = if ($configuredValue -eq "<RemoveEntry>") {
+                -not $currentValue.Exists
+            } else {
+                $currentValue.Exists -and [string]$currentValue.Value -eq [string]$configuredValue
+            }
+            if (-not $writeMatches) {
+                throw "The registry values did not match the requested state."
+            }
+        }
+    } catch {
+        $applyError = $_.Exception.Message
+        if ([string]::IsNullOrWhiteSpace($applyError)) {
+            $applyError = "The registry values did not match the requested state."
+        }
+        $rollbackFailed = $false
+        foreach ($previousValue in $previousValues) {
+            try {
+                $currentValue = Get-WinUtilRegistryComboValue -Setting $previousValue.Setting
+                if ($previousValue.Exists -or $currentValue.Exists) {
+                    $rollbackValue = if ($previousValue.Exists) { $previousValue.Value } else { "<RemoveEntry>" }
+                    Set-WinUtilRegistry -Name $previousValue.Setting.Name -Path $previousValue.Setting.Path -Type $previousValue.Setting.Type -Value $rollbackValue
+                }
+                $restoredValue = Get-WinUtilRegistryComboValue -Setting $previousValue.Setting
+                if ($restoredValue.Exists -ne $previousValue.Exists -or ($restoredValue.Exists -and [string]$restoredValue.Value -ne [string]$previousValue.Value)) {
+                    $rollbackFailed = $true
+                }
+            } catch {
+                $rollbackFailed = $true
+            }
+        }
+        if ($rollbackFailed) {
+            throw "Unable to apply registry state '$State': $applyError. The previous registry state could not be restored."
+        }
+        throw "Unable to apply registry state '$State': $applyError"
+    }
+}