Private/Invoke-OnFluenceUi.ps1
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<# Copyright (c) 2026, Dan Cunningham. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. #> function Invoke-OnFluenceUi { <# .SYNOPSIS Runs a script on a UI (STA) thread that owns the single WPF Application. .DESCRIPTION Get-FluenceUiHostMode chooses Inline for the application's own STA thread or Runspace for the module-owned STA thread. A foreign application on another thread is rejected before dispatch because a PowerShell callback cannot safely run without its execution context. Returns the script's result as a bare value in every case. Only the runspace path wraps the output in a single-element PSDataCollection (PowerShell.Invoke); that is unwrapped here so callers never re-implement the unwrap. .PARAMETER Script The script to run on the UI thread. On the runspace path it is transported by text, so it cannot capture the caller's variables, functions or closures. .PARAMETER ArgumentList Positional arguments bound to the script's param block. .NOTES Does not itself require a host application; it establishes one. State flag $script:OwnsApplication keeps routing stable once we have created our own application. #> [CmdletBinding()] [OutputType([object])] param ( [Parameter(Mandatory = $true)] [scriptblock]$Script, [Parameter()] [object[]]$ArgumentList = @() ) $mode = Get-FluenceUiHostMode if ($mode -eq 'Inline') { $script:OwnsApplication = $true return (& $Script @ArgumentList) } $script:OwnsApplication = $true $output = Invoke-InFluenceStaRunspace -Script $Script -ArgumentList $ArgumentList # Normalize the return shape so every case yields the bare value. PowerShell.Invoke wraps output # in a PSDataCollection; the script's real payload is a single object (the dialog/window result # hashtable), so unwrap a non-empty collection to its last element and an empty collection to # $null. This keeps callers free of a duplicated IList-unwrap and lets them null-check the result. if ($output -is [System.Collections.IList]) { if ($output.Count -ge 1) { return $output[$output.Count - 1] } return $null } return $output } |