#requires -version 2.0

#this command conflict with any utilities such as Snagit that use the PrintScreen key
#PowerShell must also be run in STA mode.

Function New-ScreenShot {
<#
.Synopsis
Create a screen capture.
.Description
This function is a "quick and dirty" approach to creating a screen capture from
PowerShell. It uses a SendKeys method to use the PrintScreen button. The default
behavior is to capture the current window. But you can use -Full to capture the
entire desktop. 

You need to specify a filename and path. Use a valid graphics extension such as:
png,bmp,gif,jpg,tif,wmf,emf, or exif.

NOTE: Because this command uses key combinations, it might conflict with screen
capture programs such as Snagit.

.Parameter Path
The file name and path for the screen shot.
.Parameter Full
Capture the full screen.
.Parameter Passthru
Write the file object to the pipeline.
.Example
PS C:\> New-Screenshot c:\work\data.png
.Example
PS C:\> New-Screenshot c:\work\mydesk.jpg -full -passthru | invoke-item
.Example
PS C:\> get-wmiobject win32_logicaldisk -filter "drivetype=3" | out-consolegraph -property Freespace -GraphColor Yellow -ClearScreen ; new-screenshot c:\work\freespace.png

You can find Out-ConsoleGraph at http://jdhitsolutions.com/blog/2013/01/graphing-with-the-powershell-console/
.Inputs
None
.Outputs
None
.Notes
Version:  0.9
Author :  Jeffery Hicks (http://jdhitsolutions.com/blog)
#>

[cmdletbinding(SupportsShouldProcess=$True)]

Param(
[Parameter(Position=0,Mandatory=$True,HelpMessage="Enter the path and filename")]
[ValidateNotNullorEmpty()]
[ValidateScript({
#verify the folder exists
$folder = Split-Path -Path $_

#Validation differs depending on whether v2 or v3
if ($PSVersionTable.psversion -eq "2.0") {
   Test-Path -Path $folder
}
else { 
    if (! (Test-Path -Path $folder)) {
        #write a custom error message for v3
        Throw "Can't verify that $folder exists."
    }
    else {
        $True
    }
 } 
})]
[string]$Path,
[switch]$Full,
[switch]$Passthru
)

If ($host.Runspace.ApartmentState -ne "STA") {
    Write-Warning "You must run this in a PowerShell session with an apartment state of STA"
    Return
}

#load the necessary assemblies
Add-Type -AssemblyName "System.Drawing","System.Windows.Forms"

if ($Full) {
    #capture the full desktop
    [Windows.Forms.Sendkeys]::SendWait("{PrtSc}")  
}
else {
    #capture the current window
    [Windows.Forms.Sendkeys]::SendWait("%{PrtSc}")  
}

#pause enough to give time for the capture to take place
start-sleep -Milliseconds 250

#create bitmap object from the screenshot
$bitmap = [Windows.Forms.Clipboard]::GetImage()  

#split off the file extension and use it as the type
[string]$filename=Split-Path -Path $Path -Leaf
[string]$FileExtension= $Filename.Split(".")[1].Trim()

#get the right format value based on the file extension
Switch ($FileExtension) {
    "png"  {$FileType=[System.Drawing.Imaging.ImageFormat]::Png}
    "bmp"  {$FileType=[System.Drawing.Imaging.ImageFormat]::Bmp}
    "gif"  {$FileType=[System.Drawing.Imaging.ImageFormat]::Gif}
    "emf"  {$FileType=[System.Drawing.Imaging.ImageFormat]::Emf}
    "jpg"  {$FileType=[System.Drawing.Imaging.ImageFormat]::Jpeg}
    "tiff" {$FileType=[System.Drawing.Imaging.ImageFormat]::Tiff}
    "wmf"  {$FileType=[System.Drawing.Imaging.ImageFormat]::Wmf}
    "exif" {$FileType=[System.Drawing.Imaging.ImageFormat]::Exif}

    Default {
      Write-Warning "Failed to find a valid graphic file type"
      $FileType=$False
      }
} #switch

#Save the file if a valid file type was determined
if ($FileType) {

 If ($PSCmdlet.ShouldProcess($path)) {
    Try {
        $bitmap.Save($Path.Trim(),$FileType)
        if ($Passthru) {
            #write the file object to the pipeline
            Get-Item -Path $Path.Trim()
        } #if $passthru
    } #try
    Catch {
        Write-Warning "Failed to save screen capture. $($_.Exception.Message)"
    } #catch
 } #if shouldprocess
} #if $filetype

#clear the clipboard
[Windows.Forms.Clipboard]::Clear()

} #end function