Creating Dynamic array of PictureBoxes

Hey all,

This may be something incredibly simple, but I am not so good at VB.Net's features. Anyways this is the idea, and then what I have so far.
I want a GroupBox to contain 5 Pictureboxes that should be initialized to nothingness when the program starts off. Then on a click event they will be drawn dynamically( I hope) to contain randomly generated images.

What I have follows and it just keeps spitting out System.NullReferrenceException error messages. I know I am missing something silly, but can;t seem to find it.


Public diceRoll As PictureBox()
Const picHeight = 64
Const picWidth = 72

Sub InitializeRoll()
Dim count As Integer = 0
Dim upper As Integer = 5
Dim xPos As Integer = 240
Dim yPos As Integer = 40
ReDim diceRoll(upper)

For count = 0 To 5
Me.Controls.Add(diceRoll(count))
diceRoll(count) = picDie(count)

diceRoll(count).Height.Equals(picHeight)
diceRoll(count).Width.Equals(picWidth)
diceRoll(count).Location.X.Equals(xPos)
diceRoll(count).Location.Y.Equals(yPos)
'diceRoll(count).Visible = False
diceRoll(count).Image = Nothing

yPos += 70

Next

End Sub


There is some other surrounding code as well...and this isn't very clean but I just want to see if this idea will work before I go too much further. Thanks in advance for any help.

Laeys

When you redim an array of controls like that, you probably want to initialize each member of the control array to a new picturebox instance.
So, before you add the picturebox to the form, why don't you try setting it to a new instance. :)

Thanks IcePlug. I will do that, but I think I found another way to do what i want...more or less.

I do have another problem though. I am not sure why this line doesn't seem to work

' *************************************************
' this is really klodgy any ideas?
' what I am trying to do is to assign a value to a structure member
' based on the number of pips on the image that is randomly
' generated.
' *************************************************

Sub DieValue1(ByVal picKeeper1 As PictureBox)

If picKeeper1.Image Is Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die1" & SUF) Then
newDice.d1 = 1
ElseIf picKeeper1.Image Is Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die2" & SUF) Then
newDice.d1 = 2
ElseIf picKeeper1.Image Is Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die3" & SUF) Then
newDice.d1 = 3

ElseIf picKeeper1.Image Is Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die4" & SUF) Then
newDice.d1 = 4
ElseIf picKeeper1.Image Is Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die5" & SUF) Then
newDice.d1 = 5
ElseIf picKeeper1.Image Is Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die6" & SUF) Then
newDice.d1 = 6
End If
End Sub



thanks again

That actually looks like 12-15 lines. :p

Anyway, pictures are not comparable like that.
Even if you make thousands of Image.FromFiles, they'll all be 'different', but their pixel data will remain the same.

Instead, you could load all of your pictures into an ImageList, and then assign them to controls there... then do your comparisons with the images in the image list. :)

not quite getting that. Like I said I am relatively new to VB.Net. Thanks for your help though. I have got an ImageList object, but there is nothing in it I can change except for the images I put in there. Also if I do use it like:

diceRoll(i) = DiceList.Images(i)


The image quality is so much less than if I just load the image into a PictureBox. That being said I am not sure how to compare this to an image file.

OK, nevermind, don't use the ImageList control... that is for Toolbars and listviews and other controls.

Instead, use a bitmap array.
Dim Bmps(19) As Bitmap

When you start the program, you will load all of your unique images into the bitmap array.
Bmps(0) = Image.FromFile(Pth & "rock.gif")

Then, to assign an image to a picturebox:
PB.Image = Bmps(4)

To check if the pictures are equal:
If PB.Image Is Bmps(4) Then
:)

I feel like a moron here...but I have been beating my head against this NullException error

An unhandled exception of type 'System.NullReferenceException' occurred in dynamicimages.exe

Additional information: Object reference not set to an instance of an object.


So here is what I have without the windows generated code



Imports System.IO



Public Class Form1
Inherits System.Windows.Forms.Form


Public diceRoll(5) As PictureBox


' For the random number generator
Dim objRandom As Random = New Random
Dim intRandom As Integer

Const PRE As String = "/Images/"
Const SUF As String = ".png"

' image placeholder
Public bmpDice(5) As Bitmap




Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click


initRoll()
Call DisplayDie(diceRoll)

'This was a test to see if the array worked
'diceRoll(1).Image = bmpDice(0) End Sub



Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

' filling up the array
bmpDice(0) = Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die1" & SUF)
bmpDice(1) = Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die2" & SUF)
bmpDice(2) = Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die3" & SUF)
bmpDice(3) = Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die4" & SUF)
bmpDice(4) = Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die5" & SUF)
bmpDice(5) = Image.FromFile(Directory.GetCurrentDirectory _
& PRE & "die6" & SUF)

End Sub


Function Roll() As Integer
intRandom = objRandom.Next(1, 7)
Return (intRandom)

End Function


Function DisplayDie(ByVal diceRoll() As PictureBox)

Dim i As Integer
initRoll()

For i = 0 To 5
Call Roll()
Select Case intRandom
Case 1
diceRoll(i).Image = bmpDice(i)
Case 2
diceRoll(i).Image = bmpDice(i)
Case 3
diceRoll(i).Image = bmpDice(i)
Case 4
diceRoll(i).Image = bmpDice(i)
Case 5
diceRoll(i).Image = bmpDice(i)
Case Else
diceRoll(i).Image = bmpDice(i)
End Select
Next i
End Function



Private Sub initRoll()

diceRoll(1) = picDie1
diceRoll(2) = picDie2
diceRoll(3) = picDie3
diceRoll(4) = picDie4
diceRoll(5) = picDie5

End Sub


End Class


Works fine in my original project. Was using this as a test and was going to integrate the ability to dynamically draw the 'dice'. I can;t seem to figure out the error though. Thanks again.

Are you getting the error for the diceRoll pictureboxes?
Because I don't see where you are instantiating them to new instances.

diceroll(0) = New PictureBox
:)