Copies to lockscreen, copies to desktop, applies watermark, detects and applies closest resolution

SetBackground.ps1

#expected to be executed from a folder with wallpapers in the format of BackGroundWIDTHxHEIGHT.jpg (e.g. Background1920x1200.jpg)

$consoleDebug = $true
$remoteDebug = $false

$LogFile = "$($env:temp)\Wallpaper_$([int]((get-date -UFormat "%s") / 86400)).log"
Function LogMessage($message)
{
    if ($consoleDebug)
    {
        write-host $message
    }
    if ($remoteDebug)
    {
        Add-Content $LogFile -value "$($(date).ToString("ddMMMyyy HH:mm:ss.fff")):`t`t$message" -ea 0
    }
}

#code to force wallpaper to change
Add-Type @"
using System;
using System.Runtime.InteropServices;
using Microsoft.Win32;
namespace Wallpaper
{
    public class Setter {
        [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        private static extern int SystemParametersInfo(int uAction, int uParam, string lpvParam, int fuWinIni);
        public static void SetWallpaper(string path) {
            SystemParametersInfo(20, 0, path, 0x01 | 0x02);
        }
    }
}
"@

#set directory for manual run nonsense
[system.io.directory]::SetCurrentDirectory($pwd.ProviderPath)

#default resolution
$width = 1600
$height = 1200

try
{
    $monitor = Get-WmiObject win32_desktopmonitor
    $width = $monitor.ScreenWidth
    $height = $monitor.ScreenHeight
}
catch {
    #it's ok, just continue with defaults
    LogMessage "Failed to get native resolution: $($_.exception.message)"
}

#aspect needed to determine closest matches
$aspect = $width/$height

LogMessage "width: $width"
LogMessage "height: $height"
LogMessage "aspect: $aspect"

LogMessage "Copying backgrounds to lockscreen"
cp *.jpg $env:SystemRoot\SysNative\oobe\info\backgrounds -Force
LogMessage "Backgrounds copied"

#default to use if no exact or closest same aspect is matched
$default = "Background1600x1200.jpg"
#default for portrait backgrounds e.g. 960/1280
if ($aspect -lt 1)
{
    $default = "Background1024x1280.jpg"
}

#distance for closest resolution
$distance = [int]::maxvalue

#iterate through all backgrounds to find exact or closest match
ls *.jpg |% {
    #extract resolution from file name
    $res = $_.Name -Replace "Background", "" -replace ".jpg", ""
    $resolution = $res -split "x"
    $w = $resolution[0]
    $h = $resolution[1]
    $a = $w/$h
    if ($width -eq $w -and $height -eq $h) #exact match
    {
        $default = $_.Name
        $distance = 0
    }
    elseif ($aspect -eq $a) { #matches aspect, find distance
        $d = [math]::abs($width - $w) + [math]::($height - $h)
        if ($d -lt $distance) #distance is closer than before
        {
            $distance = $d
            $default = $_.Name
        }
    }
}

LogMessage "Closest resolution detected is $default at distance of $distance"

LogMessage "Watermarking background with computer info"
try
{
    $image = new-object System.Drawing.Bitmap $pwd\$default
    $g = [System.Drawing.Graphics]::FromImage($image)
    $g.InterpolationMode = [System.Drawing.Drawing2D.InterpolationMode]::HighQualityBicubic
    $g.DrawString($(hostname), $(New-Object System.Drawing.Font "verdana", 32), `
        [System.Drawing.SystemBrushes]::HighlightText, $image.Width - 500, $image.Height - 160)
    $mac = (Get-WmiObject win32_networkadapterconfiguration -Namespace "root\CIMV2" |? {$_.IPEnabled -eq "True"}).MacAddress
    if ($mac.Count -gt 0)
    {
        $g.DrawString($mac[0], $(New-Object System.Drawing.Font "verdana", 32), `
            [System.Drawing.SystemBrushes]::HighlightText, $image.Width - 500, $image.Height - 100)
    }
    $image.Save("$pwd\Background_Temp.jpg", ([System.Drawing.Imaging.ImageFormat]::Jpeg))
    $default = "BackGround_Temp.jpg"
    LogMessage "Watermark applied"
}
Catch {
    LogMessage "Failed to apply watermark: $($_.message.exception)"
}

LogMessage "Copying to desktop background"
cp $default $env:SystemRoot\SysNative\oobe\info\backgrounds -force
cp $default $env:SystemRoot\Web\Wallpaper\theWallpaper.jpg -force

try
{
    $user = (get-wmiobject win32_computerscreen -ea 0).username
    $user = $(user -split "\\")[1]
    if (test-path $env:SystemDrive\Users\$user\AppData\Roaming\Microsoft\Windows\Themes)
    {
        cp $default $env:SystemDrive\Users\$user\AppData\Roaming\Microsoft\Windows\Themes\TranscodedWallpaper.jpg -force
        [Wallpaper.Setter]::SetWallpaper("$env:SystemRoot\Web\Wallpaper\theWallpaper.jpg")
        LogMessage "Set wallpaper for logged in user $user"
    }
}
catch {}

LogMessage "Complete"