[RESOLVED] Loading random image

Hi,
I have made a function which opens a random image, but sometimes I get the 'Index out of bounds of array' error.

Code:

VB Code:

Private Sub OpenRandomImage() Handles mnuOpenRandom.Click
        If FolderBrowserDialog.ShowDialog <> vbOK Then Exit Sub
        Dim Path As String = FolderBrowserDialog.SelectedPath
        Dim BmpFiles, GifFiles, JpegFiles, JpgFiles, PngFiles As Array
        BmpFiles = IO.Directory.GetFiles(Path & "\", "*.bmp")
        GifFiles = IO.Directory.GetFiles(Path & "\", "*.gif")
        JpegFiles = IO.Directory.GetFiles(Path & "\", "*.jpeg")
        JpgFiles = IO.Directory.GetFiles(Path & "\", "*.jpg")
        PngFiles = IO.Directory.GetFiles(Path & "\", "*.png")
        Dim Bmp, Gif, Jpeg, Jpg, Png As Integer
        For Each File In BmpFiles
            Bmp = Bmp + 1
        Next
        For Each File In GifFiles
            Gif = Gif + 1
        Next
        For Each File In JpegFiles
            Jpeg = Jpeg + 1
        Next
        For Each File In JpgFiles
            Jpg = Jpg + 1
        Next
        For Each File In PngFiles
            Png = Png + 1
        Next
        If Bmp = 0 And Gif = 0 And Jpeg = 0 And Jpg = 0 And Png = 0 Then
            MsgBox("There are no supported images in the selected directory." & vbCrLf & _
                   "Supported images are of type .BMP, .GIF, .JPEG, .JPG and .PNG.", vbOKOnly + vbExclamation, "Warning")
            OpenRandomImage()
        End If
SelectRandomFile:
        Dim RandomNumber As Integer = Int((4 - 0 + 1) * Rnd() + 0)
        ' Check if the files exist
        If RandomNumber = 0 And Bmp = 0 Then GoTo SelectRandomFile
        If RandomNumber = 1 And Gif = 0 Then GoTo SelectRandomFile
        If RandomNumber = 2 And Jpeg = 0 Then GoTo SelectRandomFile
        If RandomNumber = 3 And Jpg = 0 Then GoTo SelectRandomFile
        If RandomNumber = 4 And Png = 0 Then GoTo SelectRandomFile
        Dim a As Integer
        Randomize()
        ' Prepare BMP files
        If RandomNumber = 0 Then
            Dim Files(Bmp - 1)
            For Each File In BmpFiles
                Files(a) = File
                a = a + 1
            Next
            Randomize()
            Dim SelectedFile As String = Files(Int(((Bmp - 1) - 0 + 1) * Rnd() + 0))
            If SelectedFile = picPicture.ImageLocation Then GoTo SelectRandomFile
            ResetImage()
            picPicture.ImageLocation = SelectedFile
            On Error GoTo SelectRandomFile
        End If
        ' Prepare GIF files
        If RandomNumber = 1 Then
            Dim Files(Gif - 1)
            For Each File In GifFiles
                Files(a) = File
                a = a + 1
            Next
            Randomize()
            Dim SelectedFile As String = Files(Int(((Gif - 1) - 0 + 1) * Rnd() + 0))
            If SelectedFile = picPicture.ImageLocation Then GoTo SelectRandomFile
            ResetImage()
            picPicture.ImageLocation = SelectedFile
        End If
        ' Prepare JPEG files
        If RandomNumber = 2 Then
            Dim Files(Jpeg - 1)
            For Each File In JpegFiles
                Files(a) = File
                a = a + 1
            Next
            Randomize()
            Dim SelectedFile As String = Files(Int(((Jpeg - 1) - 0 + 1) * Rnd() + 0))
            If SelectedFile = picPicture.ImageLocation Then GoTo SelectRandomFile
            ResetImage()
            picPicture.ImageLocation = SelectedFile
            On Error GoTo SelectRandomFile
        End If
        ' Prepare JPG files
        If RandomNumber = 3 Then
            Dim Files(Jpg - 1)
            For Each File In JpgFiles
                Files(a) = File
                a = a + 1
            Next
            Randomize()
            Dim SelectedFile As String = Files(Int(((Jpg - 1) - 0 + 1) * Rnd() + 0))
            If SelectedFile = picPicture.ImageLocation Then GoTo SelectRandomFile
            ResetImage()
            picPicture.ImageLocation = SelectedFile
        End If
        ' Prepare PNG files
        If RandomNumber = 4 Then
            Dim Files(Png - 1)
            For Each File In PngFiles
                Files(a) = File
                a = a + 1
            Next
            Randomize()
            Dim SelectedFile As String = Files(Int(((Png - 1) - 0 + 1) * Rnd() + 0))
            If SelectedFile = picPicture.ImageLocation Then GoTo SelectRandomFile
            ResetImage()
            picPicture.ImageLocation = SelectedFile
        End If
        lblStatus.Text = "Ready"
    End Sub

Can anyone help??

On which line of your code does the error occur?

At this lines:

VB Code:

Files(a) = File

But this error doesn't occur very often.

I can't quite get a handle this code (its friday!) But what is saying is that 'a' is higher than the amount of objects that are in 'Files'. Given that you are using a random number as a starting point for this, i would think that when the random number is in a certain range it is causing this error. Try using a fixed value as a starting point instead of a random number.

A couple of side points:

I would say this is a lot of code just to select a random file. I would say that something similar could be done in a handful of lines. i.e:

Load all available image file paths from your directory
Create an array containing these file paths
Generate a random number between 0 and the size of the array.
Select the file path from the array.

Using gotos, is generally considered very bad practice. If you need to re-use code, contain it in a new Sub of function, and call that when required.

Ok, I'll try to get rid of the Goto's and see if that works better.

It still gives me that error... :(

Just getting rid of the Goto lines isn't going to help.

I would say ditch most of that code and go with:

vb Code:

Dim Folderpath as string = FolderBrowserDialog.SelectedPath
Dim Files() As String = Directory.GetFiles(Folderpath)
Dim Rnd As New Random
Dim RandNo As Integer = Rnd.Next(0, UBound(Files))
 
Dim YourSelectedRandomfile As String = Files(RandNo)

You will need to add some code to check their are some images in the selected folder, that should be just a case of looping through Files() for any with extension of your selected types.

if u want this code to work i would suggest setting a = 0 after every for...next loop after a is declared as integer.

the error is because it a keeps adding up in every for...next loop and is not reset.

Thanks guys, I'll try that right now.

Well, I suddenly realise that my very long code wasn't neccesary at all.
This worked even better:

vb Code:

If FolderBrowserDialog.ShowDialog <> vbOK Then Exit Sub
        Dim Files As Array = IO.Directory.GetFiles(FolderBrowserDialog.SelectedPath)
        Dim NumFiles As Integer
        For Each File In Files
            NumFiles = Numfiles + 1
        Next
        If NumFiles = 0 Then
            MsgBox("There are no supported images in the selected directory." & vbCrLf & _
                   "The .BMP, .GIF, .JPEG, .JPG and .PNG formats are supported only.", vbOKOnly + vbExclamation, "No supported images")
            OpenRandomImage()
        End If
SelectRandomFile:
        Dim RandomNumber As Integer = Int(((NumFiles - 1) - 0 + 1) * Rnd())
        Dim RandomFile As String = UCase(Files(RandomNumber))
        If RandomFile.EndsWith(".BMP") = False And RandomFile.EndsWith(".GIF") = False And RandomFile.EndsWith(".JPEG") = False And RandomFile.EndsWith(".JPG") = False And RandomFile.EndsWith(".PNG") = False Then GoTo SelectRandomFile
        picPicture.ImageLocation = RandomFile
        UpdateImageLocation()

I'll get rid of the Goto later, this was only temporarily.

Thanks for your help guys, especially enrico1982.

You already have the count so why are you using an integer and looping the items?

Code:

---

If Files.Count = 0 Then

---

Thinking about it your example is accepting all extension's and using a GoTo statement to loop. This is pretty poor so let's create a class to only allow extension's we permit. For this we will be using the directory info class. I also thought it might be a neat idea to make the extension random also.

An idea would be to add already used images to a List(of

vb Code:

Option Strict On
 
Imports System.IO
 
Public Class RandomImage
 
Private ReadOnly _acceptedExtensions() As String = {".jpg", ".jpeg", ".tif", ".bmp", ".gif", ".png"}
Private ReadOnly _rng As New Random()
 
Public Function RandomImage(ByVal path As String) As String
    Dim dir As New DirectoryInfo(path)
    Dim image As String = String.Empty
 
     While image = String.Empty
          Dim images = dir.GetFiles(String.Format("*{0}", RandomExtension), SearchOption.AllDirectories)
          If Not images.Count = 0 Then
             image = images(_rng.Next(0, images.Length - 1)).FullName
          End If
      End While
 
        Return image
    End Function
 
Private Function RandomExtension() As String
   Return _acceptedExtensions(_rng.Next(0, 5))
End Function
 
End Class