Tatoo the Background of your Virtual Machines
You may know the popular Bginfo from Sysinternals and that even Azure uses this utility to tatoo the background of virtual machines.
I wondered if PowerShell (alone) would make it and avoid the dependency on an external binary.
I started to use Google and finally decided to fork the following code available on github: https://github.com/fabriceleal/Imagify/blob/master/imagify.ps1
I also needed to find the way to set a wallpaper under Windows 7 and later… I decided to extend this PowerTip: http://powershell.com/cs/blogs/tips/archive/2014/01/10/change-desktop-wallpaper.aspx because the rundll32 tricks doesn’t work.
I created two functions, one to create a new background image either from scratch and based on a colored theme (blue, grey and black) or from the existing wallpaper and the second one to set this image as a wallpaper.
Function New-BGinfo { Param( [Parameter(Mandatory)] [string] $Text,
\[Parameter()\]
\[string\] $OutFile= "$($env:temp)\\BGInfo.bmp",
\[Parameter()\]
\[ValidateSet("Left","Center")\]
\[string\]$Align="Center",
\[Parameter()\]
\[ValidateSet("Blue","Grey","Black")\]
\[string\]$Theme="Blue",
\[Parameter()\]
\[string\]$FontName="Arial",
\[Parameter()\]
\[ValidateRange(9,45)\]
\[int32\]$FontSize = 12,
\[Parameter()\]
\[switch\]$UseCurrentWallpaperAsSource
) Begin {
Switch ($Theme) {
Blue {
$BG = @(58,110,165)
$FC1 = @(254,253,254)
$FC2 = @(185,190,188)
$FS1 = $FontSize+1
$FS2 = $FontSize-2
break
}
Grey {
$BG = @(77,77,77)
$FC1 = $FC2 = @(255,255,255)
$FS1=$FS2=$FontSize
break
}
Black {
$BG = @(0,0,0)
$FC1 = $FC2 = @(255,255,255)
$FS1=$FS2=$FontSize
}
}
Try {
\[system.reflection.assembly\]::loadWithPartialName('system.drawing.imaging') | out-null
\[system.reflection.assembly\]::loadWithPartialName('system.windows.forms') | out-null
# Draw string > alignement
$sFormat = new-object system.drawing.stringformat
Switch ($Align) {
Center {
$sFormat.Alignment = \[system.drawing.StringAlignment\]::Center
$sFormat.LineAlignment = \[system.drawing.StringAlignment\]::Center
break
}
Left {
$sFormat.Alignment = \[system.drawing.StringAlignment\]::Center
$sFormat.LineAlignment = \[system.drawing.StringAlignment\]::Near
}
}
if ($UseCurrentWallpaperAsSource) {
$wpath = (Get-ItemProperty 'HKCU:\\Control Panel\\Desktop' -Name WallPaper -ErrorAction Stop).WallPaper
if (Test-Path -Path $wpath -PathType Leaf) {
$bmp = new-object system.drawing.bitmap -ArgumentList $wpath
$image = \[System.Drawing.Graphics\]::FromImage($bmp)
$SR = $bmp | Select Width,Height
} else {
Write-Warning -Message "Failed cannot find the current wallpaper $($wpath)"
break
}
} else {
$SR = \[System.Windows.Forms.Screen\]::AllScreens | Where Primary |
Select -ExpandProperty Bounds | Select Width,Height
Write-Verbose -Message "Screen resolution is set to $($SR.Width)x$($SR.Height)" -Verbose
# Create Bitmap
$bmp = new-object system.drawing.bitmap($SR.Width,$SR.Height)
$image = \[System.Drawing.Graphics\]::FromImage($bmp)
$image.FillRectangle(
(New-Object Drawing.SolidBrush (
\[System.Drawing.Color\]::FromArgb($BG\[0\],$BG\[1\],$BG\[2\])
)),
(new-object system.drawing.rectanglef(0,0,($SR.Width),($SR.Height)))
)
}
} Catch {
Write-Warning -Message "Failed to $($\_.Exception.Message)"
break
} } Process {
# Split our string as it can be multiline
$artext = ($text -split "\\r\\n")
$i = 1
Try {
for ($i ; $i -le $artext.Count ; $i++) {
if ($i -eq 1) {
$font1 = New-Object System.Drawing.Font($FontName,$FS1,\[System.Drawing.FontStyle\]::Bold)
$Brush1 = New-Object Drawing.SolidBrush (
\[System.Drawing.Color\]::FromArgb($FC1\[0\],$FC1\[1\],$FC1\[2\])
)
$sz1 = \[system.windows.forms.textrenderer\]::MeasureText($artext\[$i-1\], $font1)
$rect1 = New-Object System.Drawing.RectangleF (0,($sz1.Height),$SR.Width,$SR.Height)
$image.DrawString($artext\[$i-1\], $font1, $brush1, $rect1, $sFormat)
} else {
$font2 = New-Object System.Drawing.Font($FontName,$FS2,\[System.Drawing.FontStyle\]::Bold)
$Brush2 = New-Object Drawing.SolidBrush (
\[System.Drawing.Color\]::FromArgb($FC2\[0\],$FC2\[1\],$FC2\[2\])
)
$sz2 = \[system.windows.forms.textrenderer\]::MeasureText($artext\[$i-1\], $font2)
$rect2 = New-Object System.Drawing.RectangleF (0,($i\*$FontSize\*2 + $sz2.Height),$SR.Width,$SR.Height)
$image.DrawString($artext\[$i-1\], $font2, $brush2, $rect2, $sFormat)
}
}
} Catch {
Write-Warning -Message "Failed to $($\_.Exception.Message)"
break
} } End {
Try {
# Close Graphics
$image.Dispose();
# Save and close Bitmap
$bmp.Save($OutFile, \[system.drawing.imaging.imageformat\]::Bmp);
$bmp.Dispose();
# Output our file
Get-Item -Path $OutFile
} Catch {
Write-Warning -Message "Failed to $($\_.Exception.Message)"
break
} }
} # endof function
Function Set-Wallpaper { Param( [Parameter(Mandatory=$true)] $Path,
\[ValidateSet('Center','Stretch','Fill','Tile','Fit')\]
$Style = 'Stretch'
)
Try {
if (-not (\[System.Management.Automation.PSTypeName\]'Wallpaper.Setter').Type) {
Add-Type -TypeDefinition @"
using System;
using System.Runtime.InteropServices;
using Microsoft.Win32;
namespace Wallpaper {
public enum Style : int {
Center, Stretch, Fill, Fit, Tile
}
public class Setter {
public const int SetDesktopWallpaper = 20;
public const int UpdateIniFile = 0x01;
public const int SendWinIniChange = 0x02;
\[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)\]
private static extern int SystemParametersInfo (int uAction, int uParam, string lpvParam, int fuWinIni);
public static void SetWallpaper ( string path, Wallpaper.Style style ) {
SystemParametersInfo( SetDesktopWallpaper, 0, path, UpdateIniFile | SendWinIniChange );
RegistryKey key = Registry.CurrentUser.OpenSubKey("Control Panel\\\\Desktop", true);
switch( style ) {
case Style.Tile :
key.SetValue(@"WallpaperStyle", "0") ;
key.SetValue(@"TileWallpaper", "1") ;
break;
case Style.Center :
key.SetValue(@"WallpaperStyle", "0") ;
key.SetValue(@"TileWallpaper", "0") ;
break;
case Style.Stretch :
key.SetValue(@"WallpaperStyle", "2") ;
key.SetValue(@"TileWallpaper", "0") ;
break;
case Style.Fill :
key.SetValue(@"WallpaperStyle", "10") ;
key.SetValue(@"TileWallpaper", "0") ;
break;
case Style.Fit :
key.SetValue(@"WallpaperStyle", "6") ;
key.SetValue(@"TileWallpaper", "0") ;
break; }
key.Close();
}
}
} "@ -ErrorAction Stop
} else {
Write-Verbose -Message "Type already loaded" -Verbose
}
# } Catch TYPE\_ALREADY\_EXISTS
} Catch {
Write-Warning -Message "Failed because $($\_.Exception.Message)"
}
\[Wallpaper.Setter\]::SetWallpaper( $Path, $Style ) }
Let’s see these two functions in action.
First define some multiline text to be written in the image.
$os = Get-CimInstance Win32_OperatingSystem ($o = [pscustomobject]@{ HostName = $env:COMPUTERNAME UserName = ‘{0}\{1}’ -f $env:USERDOMAIN,$env:USERNAME ‘Operating System’ = ‘{0} Service Pack {1} (build {2})’ -f $os.Caption, $os.ServicePackMajorVersion,$os.BuildNumber }) | ft -AutoSize $BootTime = (New-TimeSpan -Start $os.LastBootUpTime -End (Get-Date)).ToString()
$t is the multiline text defined as here-string
$t = @” $($o.HostName) Logged on user: $($o.UserName) $($o.’Operating System’) Uptime: $BootTime “@
- Exemple 1: ala Backinfo
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$WallPaper = New-BGinfo -text $t
Set-Wallpaper -Path $WallPaper.FullName -Style Center
- Exemple 2: ala Bginfo using the current wallpaper
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$BGHT = @{
Text = $t ;
Theme = "Black" ;
FontName = "Verdana" ;
UseCurrentWallpaperAsSource = $true ;
}
$WallPaper = New-BGinfo @BGHT
Set-Wallpaper -Path $WallPaper.FullName -Style Fill
# Restore the default VM wallpaper
Set-Wallpaper -Path "C:\Windows\Web\Wallpaper\Windows\img0.jpg" -Style Fill
This proof of concept based on just a few hundred lines of PowerShell proves that the dependency on Bginfo could be avoided…