Update struct in .tag property.

[Abrium]

Hey guys can someone take a peek at this code and tell me where I am going wrong. I am creating labels at runtime. Inside the .tag property I have a structure. Everytime I attempt to update the structure the .tag property doesn't update.

Here is the structure:

    Public Structure structChip
        Dim kingStatus As Boolean
        Dim currentTileLoc As Integer
        Dim currX As Integer
        Dim currY As Integer
        Dim previousTileLoc As Integer
        Dim prevX As Integer
        Dim prevY As Integer
        Dim jumped As Boolean
        Dim selected As Boolean
        Dim name As String
        Dim checkerColor As String
        Dim boardSquareColor As String
    End Structure

Here is how I am attempting to update it. As I step through it the structure itself is updated but the instance of the structure inside the tag doesn't seem to update. Any ideas?

                Dim checkers As New Windows.Forms.Label
                With checkers
                    .Name = checkArray.Name
                    .Image = Image.FromFile("..\checkerGreentileRed1.gif")
                    .AutoSize = False
                    .Size = New Size(40, 40)
                    .Parent = frmBoard.picBoard
                    .Visible = True
                    .BringToFront()
                    .Location = New Point(x, y)
                    .Tag = Nothing
                    'update the structure
                    checkStruct.previousTileLoc = checkStruct.currentTileLoc
                    checkStruct.prevX = checkStruct.currX
                    checkStruct.prevY = checkStruct.currY
                    checkStruct.currentTileLoc = tile
                    checkStruct.currX = x
                    checkStruct.currY = y
                    checkStruct.checkerColor = greenWithRed
                    checkStruct.selected = False
                    .Tag = checkStruct
                End With

[jmcilhinney]

That second code snippet looks like how you're creating it in the first place, not how you're updating it later.

The issue is almost certainly the fact that you're using a structure, which means that getting the value creates a copy. To update the object in the Tag of the Label you would first need to get it, which creates a copy, then modify that copy and, finally, overwrite the original with the copy by assigning it back to the Tag of the Label. If it was a class you could just do this:

DirectCast(myLabel.Tag, SomeClass).SomeProperty = someValue

because classes are reference types. With value types, i.e. structures, you must do this:

Dim tag As SomeStructure = DirectCast(myLabel.Tag, SomeStructure)
 
tag.SomeProperty = someValue
myLabel.Tag = tag

[Abrium]

Worthy of mentioning that the controls are in an array?

[Abrium]

Alright J, lemme give that a shot. Not that I doubt the your Kung-Fu.... I doubt my ability!! hahah! I don't know why I do this to myself.

[Abrium]

Alright tried casting it and it through an exception. I altered the code to the following. From what I can see the structure itself does update. As I step through it I can see the values correctly stored. However, I am not saving them correctly to the tag. I have altered the code to such:

Dim checkers As New Windows.Forms.Label
                With checkers
                    'STRUCT
                    Dim checkStruct As frmBoard.structChip
                    checkStruct = frmBoard.checkersArray(count)
 
                    .Name = checkArray.Name
                    .Image = Image.FromFile("..\checkerGreentileRed1.gif")
                    .AutoSize = False
                    .Size = New Size(40, 40)
                    .Parent = frmBoard.picBoard
                    .Visible = True
                    .BringToFront()
                    .Location = New Point(x, y)
                    .Tag = Nothing
                    'update the structure
                    checkStruct.previousTileLoc = checkStruct.currentTileLoc
                    checkStruct.prevX = checkStruct.currX
                    checkStruct.prevY = checkStruct.currY
                    checkStruct.currentTileLoc = tile
                    checkStruct.currX = x
                    checkStruct.currY = y
                    checkStruct.checkerColor = greenWithRed
                    checkStruct.selected = False
                    .Tag = checkStruct
                End With

[Abrium]

I always always updated structures the same way, through loops and setting structure vars equal to different values. I just don't understand why it updates but doesn't save in the .tag information of the label.

[jmcilhinney]

So, if you put a breakpoint on the End With line, what is the value of checkers.Tag?

[Abrium]

its the correct data. It just seems that when I go through the event added to the label its pulling from the wrong spot (thats what it looks like) so what I think is happening is that I AM updating that structure there BUT I'm not appending it to the structure stored in the .tag. Hold on a sec though I think Im going about this all wrong.

I already have my array of 24 game pieces I don't see a reason why I need to recreate them. I am going to try this by just updated the .location property and moving them. However, that still don't solve my struct update issue. Give me a few minutes to hammer away at this. Maybe I'll find the issue.

[jmcilhinney]

its the correct data. It just seems that when I go through the event added to the label its pulling from the wrong spot (thats what it looks like) so what I think is happening is that I AM updating that structure there BUT I'm not appending it to the structure stored in the .tag.

I'm afarid that that doesn't make much sense. From your code, my guess is that the problem is that you're getting a copy of your structure from an array, then updating it and assigning it to the Label's Tag, but you aren't pushing your changes back to the array, so the array and the Tag are different.

[Abrium]

Damn,

You're right, I'm updating... pushing to the piece but I'm not updating the eff'ing array! FAK. lol... Only at midnight do these problems come about. Let me look at that. As soon as I started reading statement I didn't even have to finish it. I need another redbull.

[jmcilhinney]

Structures have their place but you ALWAYS need to be aware of the fact that whenever you get a structure instance from a field, property or method result, you're actually getting a copy. As such, any changes you made MUST be pushed back to the original if you want them to be in sync. That generally means assigning the updated copy back to the original variable.

[Abrium]

what time is it over there Jm?

[jmcilhinney]

what time is it over there Jm?

You posted at 4:38 PM, my time.

[Abrium]

Alright, I got this to work. It may not be pro but it works. Let me know if you can see any way to improve this that is within my realm of expertise.

So when I create the checkers at runtime I do so with the following code:

'Begin load with White/green with red tiles.
        If color = "white" And tile = "red" Then
            For counter = 1 To 12
                Dim x As Integer
                Dim y As Integer
                Dim gameTile As Integer
                gameTile = LoadRedBottom(counter - 1)
                detTileCords(gameTile, x, y)
                Dim checkers As New Windows.Forms.Label
                With checkers
                    Dim checkerChip As New frmBoard.structChip
                    .Name = "checkers" & counter
                    .Image = Image.FromFile("..\checkerWhitetileRed1.gif")
                    .AutoSize = False
                    .Size = New Size(40, 40)
                    .Parent = frmBoard.picBoard
                    .Visible = True
                    .BringToFront()
                    .Location = New Point(x, y)
                    checkerChip.kingStatus = False
                    checkerChip.currentTileLoc = gameTile
                    checkerChip.currX = x
                    checkerChip.currY = y
                    checkerChip.previousTileLoc = 0
                    checkerChip.prevX = 0
                    checkerChip.prevY = 0
                    checkerChip.jumped = False
                    checkerChip.selected = False
                    checkerChip.name = checkers.Name
                    checkerChip.tileColor = "red"
                    checkerChip.boardPosition = "bottom"
                    .Tag = checkerChip
                End With
                AddHandler checkers.MouseClick, AddressOf getMouseCords
                frmBoard.checkersArray(counter - 1) = checkers
                gameTile = 0
                x = 0
                y = 0
            Next

You were right J, the problem I had was with updating the wrong array but then I realized I didn't need an array of checkers AND an array of the structures that I was using for tags within the checkers. Pretty much what I was doing was updating the struct array and NOT the checker array which meant when I selected that checker through a click event the application was working with incorrect data. I solved this by completely deleting the structure array and calling, changing, and updating the struct inside the control with the following code:

Dim x As Integer
        Dim y As Integer
        detTileCords(tile, x, y)
        Dim tag As New frmBoard.structChip
        tag = CType(checker.Tag, frmBoard.structChip)
 
 
 
        If tag.kingStatus = True Then
            Select Case tile
                Case Is = tag.currentTileLoc + 7
                    checker.Location = New Point(x, y)
                Case Is = tag.currentTileLoc + 9
                    checker.Location = New Point(x, y)
                Case Is = tag.currentTileLoc - 7
                    checker.Location = New Point(x, y)
                Case Is = tag.currentTileLoc - 9
                    checker.Location = New Point(x, y)
            End Select
        ElseIf tag.kingStatus = False Then
            If tag.boardPosition = "bottom" Then
                 Select tile
                    Case Is = tag.currentTileLoc - 7
                        checker.Location = New Point(x, y)
                        Select Case tile
                            Case Is = 1
                                tag.kingStatus = True
 
                                checker.Image = Image.FromFile("..\checkerGreentileRed1.gif")
                            Case Is = 2
                                tag.kingStatus = True
                            Case Is = 3
                                tag.kingStatus = True
                            Case Is = 4
                                tag.kingStatus = True
                            Case Is = 5
                                tag.kingStatus = True
                            Case Is = 6
                                tag.kingStatus = True
                            Case Is = 7
                                tag.kingStatus = True
                            Case Is = 8
                                tag.kingStatus = True
                        End Select
                    Case Is = tag.currentTileLoc - 9
                        checker.Location = New Point(x, y)
                        Select Case tile
                            Case Is = 1
                                tag.kingStatus = True
                            Case Is = 2
                                tag.kingStatus = True
                            Case Is = 3
                                tag.kingStatus = True
                            Case Is = 4
                                tag.kingStatus = True
                            Case Is = 5
                                tag.kingStatus = True
                            Case Is = 6
                                tag.kingStatus = True
                            Case Is = 7
                                tag.kingStatus = True
                            Case Is = 8
                                tag.kingStatus = True
                        End Select
                    Case Else
                        MsgBox("Improper move: moveChip - kingStatus = false")
                End Select
            ElseIf tag.boardPosition = "top" Then
                            Select tile
                    Case Is = tag.currentTileLoc + 7
                        checker.Location = New Point(x, y)
                        Select Case tile
                            Case Is = 57
                                tag.kingStatus = True
                            Case Is = 58
                                tag.kingStatus = True
                            Case Is = 59
                                tag.kingStatus = True
                            Case Is = 60
                                tag.kingStatus = True
                            Case Is = 61
                                tag.kingStatus = True
                            Case Is = 62
                                tag.kingStatus = True
                            Case Is = 63
                                tag.kingStatus = True
                            Case Is = 64
                                tag.kingStatus = True
                        End Select
                    Case Is = tag.currentTileLoc + 9
                        checker.Location = New Point(x, y)
                        Select Case tile
                            Case Is = 57
                                tag.kingStatus = True
                            Case Is = 58
                                tag.kingStatus = True
                            Case Is = 59
                                tag.kingStatus = True
                            Case Is = 60
                                tag.kingStatus = True
                            Case Is = 61
                                tag.kingStatus = True
                            Case Is = 62
                                tag.kingStatus = True
                            Case Is = 63
                                tag.kingStatus = True
                            Case Is = 64
                                tag.kingStatus = True
                        End Select
                    Case Else
                End Select
            Else
                MsgBox("Improper move - bottom moveChip")
            End If
 
        End If
        With tag
            .previousTileLoc = .currentTileLoc
            .prevX = .currX
            .prevY = .currY
            .currentTileLoc = tile
            .currX = x
            .currY = y
            .selected = False
        End With
        checker.Tag = tag
        frmBoard.checkSelected = False

After a shitload of case statements I update the structure and then copy it into the .tag property.

[Shaggy Hiker]

What's with all those Case Is = X parts? They are all contiguous, they all appear to be integers, and they all set to the same value. Wouldn't it be easier to just write something like:

If tile > 1 AndAlso tile < 9 then
 tag.KingStatus = True
End If

[Abrium]

It sure would. These are things that I don't think of while I'm doing them. I had already went back and done that. Good looking out though.