printing png file with file system watcher vb.net

I'm trying to print a newly created png file. I'm using File system watcher to react when file is being created and getting path of it.

    Private Sub FileSystemWatcher1_Created(sender As Object, e As FileSystemEventArgs) Handles FileSystemWatcher1.Created
    Dim MyFile As String = e.FullPath.ToString
    Try
        AddHandler PrintDocument1.PrintPage, AddressOf Me.PrintImage
        PrintDocument1.Print()
    Catch ex As Exception
        MsgBox(ex, MsgBoxStyle.Critical, "Error during Print")
    End Try
    End Sub

but when I want to print it I don't know how direct that path to the code from MSDN as with this code Me.PrintImage and Me.PrintImage(MyFile) returns an error

WithEvents PrintDocument1 As New PrintDocument
Private Sub PrintImage(ByVal sender As Object, ByVal ppea As PrintPageEventArgs, MyFile As String)
    ppea.Graphics.DrawImage(Image.FromFile(MyFile), ppea.Graphics.VisibleClipBounds)
    ppea.HasMorePages = False
End Sub

How can i just direct my file to this printing service? code i found was based on static path to the file and was not in the file system watcher and i can't seem to find a way to tie them together. Please help!

Solution

Please consider the following:

You can't change the signature of a delegate/event like:

Private Sub PrintImage(ByVal sender As Object, ByVal ppea As PrintPageEventArgs, MyFile As String)

You always can declare a class members to access them anywhere in the class. You can declare the MyFile like so:

Public Class Form1
    Private MyFile As String
End Class

Now you can assign its value in the FileSystemWatcher1_Created event and read that value in the PrintImage event. To read more: How to: Control the Scope of a Variable (Visual Basic)

You should subscribe to an event just once:

Public Class Form1

    Private MyFile As String
    Private PrintDocument1 As PrintDocument

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        PrintDocument1 = New PrintDocument
        AddHandler PrintDocument1.PrintPage, AddressOf PrintImage
    End Sub

    Private Sub PrintImage(sender As Object, e As PrintPageEventArgs)
        '...
    End Sub
End Class

Or just use the WithEvents and Handles clause the same way you have in the FileSystemWatcher1_Created event.

Public Class Form1

    Private MyFile As String
    Private WithEvents PrintDocument1 As PrintDocument

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        PrintDocument1 = New PrintDocument
    End Sub

   Private Sub PrintImage(sender As Object, e As PrintPageEventArgs) Handles PrintDocument1.PrintPage
         '...
    End Sub
End Class

Or use the designer to add an instance of the PrintDocument component and subscribe to its events. just like the FileSystemWatcher component.

Put it all together and you should get something like:

Public Class Form1

    Private MyFile As String
    Private WithEvents PrintDocument1 As PrintDocument

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        PrintDocument1 = New PrintDocument
    End Sub

    Private Sub FileSystemWatcher1_Created(sender As Object, e As FileSystemEventArgs) Handles FileSystemWatcher1.Created
        MyFile = e.FullPath
        PrintDocument1.Print()
    End Sub

    Private Sub PrintImage(sender As Object, e As PrintPageEventArgs) Handles PrintDocument1.PrintPage
        If Not File.Exists(MyFile) Then
            Return
        End If

        Try
            Using bmp = New Bitmap(New MemoryStream(File.ReadAllBytes(MyFile)))
                e.Graphics.DrawImage(bmp, e.Graphics.VisibleClipBounds)
            End Using
        Catch ex As ArgumentException
            Console.WriteLine("Not Image!")
        Catch ex As Exception
            Console.WriteLine(ex.Message)
        End Try
    End Sub

    Protected Overrides Sub OnFormClosed(e As FormClosedEventArgs)
        MyBase.OnFormClosed(e)

        PrintDocument1.Dispose()
    End Sub
End Class

A better approach IMHO is to collect the created files in a list and send them to the printer as one print-job. Useful when - for example - you paste multiple files into the FileSystemWatcher.Path. The FileSystemWatcher.Created event is raised for each file and the PrintDocument.Print method in the preceding code is called for each one as well. We can reduce the print calls to just one to do the same task.

The code below is a quick Lambda-Expression-Way example.

Imports System.IO
Imports System.Windows.Forms
Imports System.Drawing.Printing
Imports System.Collections.Generic

Public Class Form1

    Private ReadOnly watcher As FileSystemWatcher
    Private ReadOnly timer As Timer 'System.Windows.Forms.Timer
    Private ReadOnly printDoc As PrintDocument
    Private MyFiles As Queue(Of String)

    Sub New()
        InitializeComponent()

        MyFiles = New Queue(Of String)

        watcher = New FileSystemWatcher With {
            .Path = "PathToWatch",
            .EnableRaisingEvents = True,
            .SynchronizingObject = Me
        }
        AddHandler watcher.Created,
            Sub(s, e)
                If Not MyFiles.Contains(e.FullPath) Then
                    MyFiles.Enqueue(e.FullPath)
                    timer.Start()
                End If
            End Sub

        timer = New Timer With {.Interval = 200}
        AddHandler timer.Tick,
            Sub(s, e)
                timer.Stop()
                printDoc.Print()
            End Sub

        printDoc = New PrintDocument
        AddHandler printDoc.PrintPage,
            Sub(s, e)
                Dim imgFile = MyFiles.Dequeue
                If Not File.Exists(imgFile) Then
                    Return
                End If

                Try
                    Using bmp = New Bitmap(New MemoryStream(File.ReadAllBytes(imgFile)))
                        e.Graphics.DrawImage(bmp, e.Graphics.VisibleClipBounds)
                    End Using
                Catch ex As ArgumentException
                    Console.WriteLine("Not Image!")
                Catch ex As Exception
                    Console.WriteLine(ex.Message)
                End Try

                e.HasMorePages = MyFiles.Count > 0
            End Sub
    End Sub

    Protected Overrides Sub OnFormClosed(e As FormClosedEventArgs)
        MyBase.OnFormClosed(e)

        watcher.Dispose()
        timer.Dispose()
        printDoc.Dispose()
    End Sub
End Class