Handle containers inside containers in for each control vb 2008 - vb.net

I have created a function to translate my forms. I can loop through every control in a form to call this function, but I have made a situation, I cannot handle.
In one of my forms, I have groupbox in a groupbox.
This source works if I only have one groupbox.
Public Function translate_form(ByVal form As Form)
Dim control As Object
Dim controlname As String
form.Text = Get_Control_Name(form.Name, "Form")
Try
For i = 0 To form.Controls.Count - 1
control = form.Controls(i)
If TypeOf (control) Is MenuStrip Then
For j = 0 To control.items.count - 1
control.items(j).text = Get_Control_Name(form.Name, "MenuItem" & j)
Next
Else
controlname = Get_Control_Name(form.Name, control.Name)
control.Text = IIf(controlname Is Nothing, control.Text, controlname)
If TypeOf (control) Is GroupBox Then
For j = 0 To control.Controls.Count - 1
controlname = Get_Control_Name(form.Name, control.Controls(j).Name)
control.Controls(j).Text = IIf(controlname Is Nothing, control.Controls(j).Text, controlname)
If TypeOf (control.Controls(j)) Is Button Then
control.Controls(j).AutoSize = True
End If
Next
End If
If TypeOf (control) Is Button And UCase(control.Text) <> "X" Then
control.AutoSize = True
End If
End If
Next
Catch ex As Exception
MsgBox(ex.Message, MsgBoxStyle.Critical)
End Try
End Function
But in some cases I want to sperate controls inside a container. I could have one more loop if the
control.Controls(j)
is a groupbox but I want to make this function to handle any kind of "container pyramid", if you know what I mean. Maybe I will have a container which has one also and that one too etc... Or is there any control I can use as a groupbox but it doesn't count as a contaier, so I can see it with:
form.Controls
Any suggestions?
Thanks in advance.

The reason why your code does not deliver what you want is that you are not performing a recursive search of controls. Bear in mind that Form.Controls contains only the parent controls (not the children controls eventually contained by the parents; like the situation you refer of controls contained by a GroupBox). Additionally, I see various not-too-right issues (you should writeOption Strict On on the top of your file) and that's why this answer intends to provide you with a somehow better framework to work with (you have just to fill in the blanks with your code):
Public Sub translate_form2(ByVal form As Form)
Try
For Each ctrl As Control In form.Controls
actionsCurrentControl(ctrl)
recursiveControls(ctrl)
Next
Catch ex As Exception
End Try
End Sub
'Accounting for all the child controls (if any)
Public Sub recursiveControls(parentControl As Control)
If (parentControl.HasChildren) Then
For Each ctrl As Control In parentControl.Controls
actionsCurrentControl(ctrl)
recursiveControls(ctrl)
Next
End If
End Sub
Public Sub actionsCurrentControl(curControl As Control)
If TypeOf curControl Is MenuStrip Then
Else
If TypeOf (curControl) Is GroupBox Then
End If
If TypeOf (curControl) Is Button And UCase(curControl.Text) <> "X" Then
End If
End If
End Sub
translate_form2 iterates through all the parent controls as in your code (but by relying on a set of Subs (you are wrongly using a Function without returning any value, what is wrong), making the structure more adaptable); it also calls recursiveControls (which also calls itself for each control it analyses) to take care of any child control which might be present. I am also including actionsCurrentControl which contains all the actions to perform for each control (you have to populate it with your code).

Related

Change Label Text with Controls in VB

I'm trying to change a Label Text with Controls command, using this line
Controls("C_" & 0).Text = "Conta:"
But I get this error
"System.NullReferenceException"
If I delete this label and change it for a textbox (with same name "C_0"), it works! But I need to do this with a Label not a textbox...
This is because you do not have a control named C_0. I would suggest using ControlCollection.Find to get your control and then use a conditional If statement to check if the returned control exists:
Dim desiredControls() As Control = Me.Controls.Find("C_" & 0, True)
If desiredControls.Count = 0 Then
'No controls named C_0 found
ElseIf desiredControls.Count > 1 Then
'Multiple controls named C_0 found
Else
desiredControls(0).Text = "Conta:"
End If
Or if you simply wanted a one-liner then you would use:
Me.Controls.Find("C_" & 0, True).First().Text = "Conta:"
However, I would highly recommend that you use the conditional If statements so that you an exception isn't thrown if 0 controls are found.
Ok, I find the problem... This command wasn't working because it was inside a GroupBox.
Then the right code is
Me.Controls("GroupBox1").Controls("C_" & 0).Text = "123"
Thanks for everyone help!
Your problem is control.Controls only returns the controls directly inside the control. So you can use these extension methods. Put this in a Module:
<Extension>
Public Function ChildControls(parent As Control) As IEnumerable(Of Control)
Return ChildControls(Of Control)(parent)
End Function
<Extension>
Public Function ChildControls(Of TControl As Control)(parent As Control) As IEnumerable(Of TControl)
Dim result As New List(Of TControl)
For Each ctrl As Control In parent.Controls
If TypeOf ctrl Is TControl Then result.Add(CType(ctrl, TControl))
result.AddRange(ctrl.ChildControls(Of TControl)())
Next
Return result
End Function
Here is how you would use it:
' general option to return all controls, filter on name
Me.ChildControls().Single(Function(c) c.Name = "C_" & 0)).Text = "Conta:"
' generic option to return only Labels, filter on name
Me.ChildControls(Of Label)().Single(Function(c) c.Name = "C_" & 0)).Text = "Conta:"
This will work whether the Label is in the GroupBox or not, and if you move it to a different GroupBox, Panel, or back to the Form, without needing to change your code.

Loop - set Textboxes to ReadOnly in all Groupboxes

I have groupboxes that contain textboxes and I want to set all of them to ReadOnly=True. Here is what I tried (doesn't work):
EDIT (I forgot about Split container):
For Each SplitCon As Control In Me.Controls
If TypeOf SplitCon Is SplitContainer Then
For Each GBox As Control In SplitCon.Controls
If TypeOf GBox Is GroupBox Then
For Each ctrl As Control In GBox.Controls
If TypeOf (ctrl) Is TextBox Then
CType(ctrl, TextBox).ReadOnly = True
End If
Next
End If
Next
End If
Next
You can simplify things a great deal. Rather than looking thru all sorts of Control collections, create an array to act as a ToDo list. Then you can get rid of all the TypeOf and CType in the loop used.
' the ToDo list
Dim GrpBoxes = New GroupBox() {Groupbox1, Groupbox2,
Groupbox3, Groupbox4}
For Each grp In GrpBoxes
For Each tb As TextBox In grp.Controls.OfType(Of TextBox)()
tb.ReadOnly = True
Next
Next
Your code no longer depends on the form layout of the moment. The only thing you have to remember is to add any new GroupBox items to your list. You can also declare the array once ever for the whole form if you prefer (or even in the For Each statement)
Rather than working with Control objects, Controls.OfType(Of T) filters the collection and returns an object variable of that type, so there is no need to cast it or skip over controls you are not interested in. You can also tack on a Where method to further refine the list to include only do those with a certain name or Tag.

Close all controls which has specific type

I would like to create function which could take as parameter either usercontrol or windows form and then close all controls on it which are currently opened but only when type of them are either usercontrols or windows forms.
Below find my tries pseudo code:
'take as parameter either usercontrol or winform
Public Shared Sub DisposeUserControlControls(ucOrWinForm As T)
Dim type as Type = GetType(ucOrWinForm)
While type.Controls.Count > 0
'if uc.Control is type of UserControl or WindowsForms then --> close
While type.Controls(0).Controls.Count > 0
type.Controls(0).Controls(0).Dispose()
End While
type.Controls(0).Dispose()
End While
type.Controls.Clear()
End Sub
It is a bit of a code smell. No compelling reason to make it generic, it is just as valid to do this when, say, it is a Panel you want to empty. Do beware that you'll only ever run into a Form object when you set its TopLevel property to False. Since you are going to skip controls of the wrong flavor you cannot use the While-loop anymore. You instead have to iterate backwards. Like this:
Public Shared Sub DisposeUserControlControls(parent As Control)
For ix As Integer = parent.Controls.Count - 1 To 0 Step -1
Dim ctl = parent.Controls(ix)
If (TypeOf ctl Is UserControl) Or (TypeOf ctl Is Form) Then
ctl.Dispose()
End If
Next
End Sub
You don't need a Type (and it is incorrect because the Type class has no Controls property), you specify the type as a Control in the signature of your method. Both Form and UserControl derive from Control
So you can try with this code:
Public Sub DisposeUserControlControls(Of T As Control)(ucOrWinForm As T)
While ucOrWinForm.Controls.Count > 0
ucOrWinForm.Controls(0).Dispose()
End While
ucOrWinForm.Dispose()
End Sub

Problems when calling a public sub

I'm facing a deadend When trying to call this sub :
Public Sub backblue(ByVal frm As Form, ByVal boxname As String)
For i = 1 To 3
CType(frm.Controls(boxname & i.ToString()), TextBox).BackColor = Color.LightBlue
Next
End Sub
with button click event :
Private Sub Button1_click and bla bla....
backblue(Me, "txb1_")
End Sub
Can anybody show me a suggestion to fix the code.
It throws "Object Referrence not set to an instance bla bla" error
For information the textbox names are :
txb1_1 , txb1_2 , txb1_3
(these are some of the many textboxes in the form that i want its bakcolor changed)
and these three textboxes are already created through designer, not from execution.
i did check the textboxes names and there's nothing wrong.
the form class is also public.
if they are the only textboxs on said form you can just loop through
For Each box as Textbox In frm.Controls
box.BackColor = Color.LightBlue
Next
This error will occur if you do not declare the Form class to be public.
Also, make sure the textbox names are really correct, although this will probably cause a different error.
If you create the textboxes during execution, make sure they are initialized with New and added to the form's Controls collection.
Try this....
Public Sub backblue(ByVal frm As Form, ByVal prefix As String)
For i = 1 To 3
Dim bxName as String = prefix & i.ToString()
Dim bx as TextBox = CType(frm.Controls(bxName), TextBox)
If bx Is Nothing Then
MsgBox("Unable to find text box " +bxName)
Dim mtch() As Control = frm.Controls.Find(bxName, true)
If mtch.Length> 0 then
bx = mtch(0)
Else
Continue For
End if
End If
Bx.BackColor = Color.LightBlue
Next
End Sub
Although, a better solution would be to either create the textboxes inside a control and pass that control to BackBlue or to create an collection that has the controls and pass that in. Which brings up what is most likely yor problem your control is contained in a sub component and thus is not in the main form control collection
Alternative, you could use either the tag of the control or create a component control that implements IExtenderProvider and add it to the form --all of the above would effectively allow you to define the controls and/how they should be handled at designtime.
It may really seem that the names generated by this loop may not be the names of the original textboxes. My suggestion is before setting this Color property verify that the names generated by this loop are indeed the actual names. Maybe output this in a messagebox:
MessageBox.Show(boxname & i.ToString()) for each loop before you set the property

Looping through Controls in VB.NET

I am creating a chess program. And it is composed of sixty four picture boxes with alternating black and white background colours.
I have named them pba1, pba2, pbb1, pbb2, pbc1 and so on.
Now, I want to loop through only the black ones, for example, I want to loop through only, pba1, pbb2, pbc3 and so on.
How do I create a loop for this in VB.NET?
I know of the way to loop through similarly named controls, but I am not able to adapt that method for my problem. Can you tell me a solution?
EDIT: In pba1, pb stands for picture box, and a1 stands for the square. Just in case, you wonder why such a name.
EDIT: Check out this answer
Loop through the PictureBox's in your ControlCollection and test for BackColor. I used the Form's ControlCollection, if they are in some other type of container control use that.
For Each cntrl As Control In Me.Controls
If TypeOf cntrl Is PictureBox Then
If cntrl.BackColor = Color.Black Then
'Do Something
End If
End If
Next
Base on the additional information that you gave in your answer, the reason your example is not working is that the Controls Name is a String and you are comparing it to the PictureBox Control not the Name of the Control.
You can try using the Tag Property instead of the Name of the Control, it will be cleaner and easier to read. I just put a 1 in the PictureBox's Tag Property for Black and a 0 for White.
Private Sub OriginalColour()
For Each cntrl As Control In Me.Controls
Dim result As Integer
If TypeOf cntrl Is PictureBox Then
If Integer.TryParse(cntrl.Tag.ToString, result) Then
If result = 1 Then
cntrl.BackColor = Color.Gray
Else
cntrl.BackColor = Color.White
End If
End If
End If
Next
End Sub
Generating controls at design time via the Forms Designer only makes sense for layouts which benefit from the forms designer.
In your case, you just have 64 uniform boxes in 8 rows of 8. Don’t use the Forms Designer for this, create the controls at runtime, and don’t give them names like pba1, just put them into an appropriate data structure (such as an 8x8 array):
Private chessFields As PictureBox(8, 8)
' In Form_Load:
For i = 0 To 7
For j = 0 To 7
chessFields(i, j) = New PictureBox
' Set size, position … then, finally,
Controls.Add(chessFields(i, j))
Next
Next
That way, you can access the fields in an orderly fashion without having to go via the Form.Controls collection.
Put all the pictureboxes in an 8x8 tableLayoutPanel (also useful for scaling etc). Then
For Each pb As PictureBox In TableLayoutPanel1.Controls
Dim col As Integer = TableLayoutPanel1.GetCellPosition(pb).Column
Dim row As Integer = TableLayoutPanel1.GetCellPosition(pb).Row
If col Mod 2 = 0 Xor row Mod 2 = 0 Then
pb.BackColor = Color.Black
Else
pb.BackColor = Color.White
End If
Next
Of course you could also use an array of the squares if you have that available.
This will not affect the events (pba1.click etc).
This is fairly simple and it may be resource heavy, but it works. I have a form with 36 CheckBoxes. This takes advantage of the fact that when you copy a checkbox it just increases the number of the name. I ended up with 36 checkboxes named CheckBox1 thru Checkbox36. The Function returns a checkbox, which may be used to set or read any property.
Private Function GetCheckBox(ByVal Index As Integer) As CheckBox
Dim CKBox As checkbox
For Each cntrl As Control In Me.Controls
If TypeOf cntrl Is CheckBox Then
CKBox = cntrl
If CKBox.Name = "CheckBox" & Index Then
Exit For
End If
End If
Next
Return ckbox
End Function