How to hide a DataGridViewButtonCell - vb.net

I have a DataGridViewButtonCell in my DataGridView and I wanted to set the property Visible to True.
I have tried:
DataGridView1.Rows("number of row i want").Cells("number of cell i want").Visible = True
Unfortunately it says that the property visible is read only.
Here is the code:
Private Sub DataGridView1_CellClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellClick
'does not work
DataGridView1.Rows(e.RowIndex).Cells(6).Visible = True
End Sub
Does anyone knows how I can achieve this?
Thanks.

There is no actual way to hide a DataGridViewButtonCell. Currently I can only see two options:
Use padding to move the button over as shown here. I will provide similar VB.NET code
Set the Cell to a DataGridViewTextBoxCell and set the ReadOnly property to True
Use Padding:
Private Sub DataGridView1_CellClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellClick
If DataGridView1.Rows(e.RowIndex).Cells(6).GetType() Is GetType(DataGridViewButtonCell) Then
Dim columnWidth As Integer = DataGridView1.Columns(e.ColumnIndex).Width
Dim newDataGridViewCellStyle As New DataGridViewCellStyle With {.Padding = New Padding(columnWidth + 1, 0, 0, 0)}
DataGridView1.Rows(e.RowIndex).Cells(6).Style = newDataGridViewCellStyle
End If
End Sub
Use DataGridViewTextBoxCell:
Private Sub DataGridView1_CellClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellClick
If DataGridView1.Rows(e.RowIndex).Cells(6).GetType() Is GetType(DataGridViewButtonCell) Then
Dim newDataGridViewCell As New DataGridViewTextBoxCell
DataGridView1.Rows(e.RowIndex).Cells(6) = newDataGridViewCell
newDataGridViewCell.ReadOnly = True
End If
End Sub
Both of these should give you the effect of not showing the button.

This is really a perspective issue. From a programmer’s perspective, simply ignoring the button clicks on the buttons I want to disable is very easy to do and takes just a few lines of code.
From a user perspective, this situation would play out like this… the user clicks what appears to be a valid enabled button, and nothing happens. The user did not write the code for this… so at best the user will think the computer is not responding to the button click or at the worst… would think your coding skills are dubious!
The same situation happens if the button is missing. The user is not going to know why it is missing… but will most likely come to the same conclusion described above with a non-working button.
In another very simple approach, let say that all the buttons are enabled and we have a list of the button indexes we want to disable. The users presses one of the buttons, we check the disabled button list and if the clicked button is one that is disabled, simply display a message box to indicate why this button is disabled. This approach says to the user… “Here are a bunch of buttons, guess which ones are enabled”…
The DataGridViewDisableButtonCell and DataGridViewDisableButtonColumn wrappers solve all of the above issues… the button is visible so the user wont question where the button went if you set it to invisible and it is greyed out. “Greyed out” is something most users understand and will relieve the user of having to “guess” which buttons are enabled.
You can create a wrapper for two classes: the DataGridViewButtonCell and the DataGridViewButtonColumn.
The link How to: Disable Buttons in a Button Column in the Windows Forms DataGridView Control to the MS example is one I have used before using C#, however there is a VB implementation at the link also.
Below is a picture of the result of using the two wrappers described in the MS link. For testing, the picture below uses the check boxes to left of the button to disable the button on the right.
IMHO, using this strategy is user friendly. If you simply make the button invisible or read only, then the user is possibly going to think your code is messed up and not have a clear understanding of WHY the button is missing or doesn’t work. A disabled button indicates to the user that the button is not available for that item. An option would be to have a mouse roll-over indicating why the button is disabled.

Related

DataGridView resets to top when clicked after mouse scroll

I have a DataGridView control on a TabPage of a Windows Form application.
When the user moves the mouse over the DataGrid and uses the scroll wheel, the grid scrolls as expected. But when the user clicks in a cell on the screen, instead of the cell receiving focus, the DataGrid resets to the top and requires the user to scroll down again. This response is non-intuitive since it's not immediately obvious that the cell you thought you clicked on isn't there anymore.
I would be happy to prevent the DataGrid from responding to the scroll wheel until the user clicks in the grid, or preferably to maintain the current actions except not resetting to the top when first clicked.
From what I've researched here, it appears that the DataGrid is rebinding because I'm resetting the binding when the tabpage is entered (since the database might have been updated by one of the other tabs.
Private Sub TabPage1_Enter(sender As Object, e As EventArgs) Handles TabPage1.Enter
LoadTACTable()
End Sub
In LoadTACTable():
dbGetList("spSelectTACList", dtTACs, 0, 100000, Nothing) ' Record numbers are 0 based
bsTACs.DataSource = dtTACs
With gridTACs
' TOTAL Grid width = 1380
.DataSource() = bsTACs
.
.
.
(Showing only part of the code for brevity.
Is there a way to see if the TabPage is already displayed when entered? Or, is unnecessary to reset the gridTAC datasource every time I retrieve the data from the SQL database to the dtTACs datatable using my dbGetList() sub?
There are several possible solutions to your problem. One would be to not automatically rebind the datagrid but let the user do it by clicking some refresh button. That way the user would not see non-intuitive behavior.
You mentioned that the contents of one tab may need to be refreshed when the contents of other tabs are changed. Whenever the contents of a tab is changed and can affect other tabs, you could flag these other tabs (for example, by adding a star to their titles) to indicate that they no longer have the latest data. The user would then know that the tab needs to be refreshed.
There might be other solutions, but it is difficult to tell without knowing more about your use case.
With the guidance above, I believe I solved the issue:
I created a flag:
Dim TabDirty As Boolean
Then I set it in the TabPage.Leave handler:
Private Sub TabPage1_Leave(sender As Object, e As EventArgs) Handles TabPage1.Leave
dtTACs.Dispose()
TabDirty = True
End Sub
Then I just check it when I enter the TabPage:
Private Sub TabPage1_Enter(sender As Object, e As EventArgs) Handles TabPage1.Enter
If TabDirty = True Then
TabDirty = False
LoadTACTable()
End If
End Sub
So far, this appears to work - the grid is not getting reset when clicked, but I will do a bit more testing to confirm that the data is refreshed when necessary.

Retrieving the item right-clicked in a listbox for a context menu action - vb.net

In my vb.net app, I've got a list box that contains a bunch of email addresses.
There's a context menu on the list box with view contact, modify and remove options.
I'm currently stuck on how to determine which item in listbox1.items the user has right-clicked for use in the context menu actions.... So say for example a user right clicks 'johnsmith#stackoverflow.com' and clicks remove I then need to say
listbox1.items.remove(THEITEMTHATWASRIGHTCLICKED)
But how would I determine THEITEMTHATWASRIGHTCLICKED?
I tried...
itemthatwasrightclicked = listbox1.SelectedIndex
But if I right click on an item before left-clicking, I get a returned index of -1. If I left click the item to select it first and then right click I get the correct index returned, so it seems that if a user right clicks without first left clicking, the item isn't selected as such.
I'm at a loss and any help is appreciated!
I feel like this should be something simple.
Thanks in advance! :)
The listbox class provides a method for this in the MSDN. You will want to use the IndexFromPoint(Point) method. When this method is called it returns the index for the item in the list box found at the coordinates of the Point specified. You will want to capture the coordinates of the right click event by implementing this within the MouseDown event of the ListBox.
In its most basic form, the code for this would be as follows.
Private Sub ListBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles ListBox1.MouseDown
If e.Button = MouseButtons.Right Then
ListBox1.SelectedIndex = ListBox1.IndexFromPoint(e.X, e.Y)
End If
End Sub

Make a button have multiple uses

okay... How do I explain this without being totally confusing?... Alright, I have this form that has MenuScripts (top-levels and second-levels). The problem that I am having is one of the second-levels is "Add" which brings you to another form when clicked. This other form has a button ("Record") and text boxes. This other form allows the user to input data and when the record button is clicked, the inputted data is written into a text file. Ok, so back to the first form. Another second-level MenuScript is "Update" which also brings the user to the other form; but first, the user has to click an item within a listbox to proceed. How do I get the data from the selected item to appear in the appropriate textboxes and how do I get the record button to update data instead of being confused and thinking it is only a add-data button?
Is there a way to use an "if" statement to say something like "if mnuAdd is clicked then" "elseif mnuUpdate is clicked then". Would something like that work for giving the record button multiple uses?
Also, if someone can give me some pointers on making sure the user selects an item within the listbox would definitely be a plus! Thanks, guys!
Unfortunately, I cannot add images since my reputation is too low.
Here is a visual representation of my ultimate goal
Easiest way: before displaying the second form set it's Tag property to something distinct – say "Add" or "Update" – depending on which menu item is selected. Then you just test the Tag value in the button's Click event and proceed accordingly.
As for determining whether a list item is selected: well if there isn't the ListBox's SelectedIndex property will be set to -1.
You need to put a public property on the second form (Details) which specifies which mode it is in. For instance, you could create a mode enumeration like this:
Public Enum EntryModes
AddBook
UpdateBook
End Enum
Then, define a public mode property on the second form, like this:
Public Property EntryMode As EntryModes
Get
Return _entryMode
End Get
Set(ByVal value As EntryMode)
_entryMode = value
End Set
End Property
Private _entryMode As EntryMode
Then, when you show the second form from the menu, just set the property first, before showing it:
Private Sub mnuAdd_Click(sender As Object, e As EventArgs)
Dim dialog As New DetailsDialog()
dialog.EntryMode = EntryModes.AddBook
dialog.ShowDialog()
End Sub
Private Sub mnuUpdate_Click(sender As Object, e As EventArgs)
Dim dialog As New DetailsDialog()
dialog.EntryMode = EntryModes.UpdateBook
dialog.BookToUpdate = ListBox1.SelectedItem
dialog.ShowDialog()
End Sub
As you can see, in the Upate menu click, I also added a line that passes the information for which book should be updated.

Toggling panel visibility isn't working when they are stacked

I have a form that has two views. These views are controlled by radio buttons on top of the form.
Here is the program:
http://dl.dropbox.com/u/41629841/DataCalculator/DataCalc1.PNG
Notice how the Radio button for Number Converter is selected.
Here is what it looks like when you select the Text Converter radio button:
http://dl.dropbox.com/u/41629841/DataCalculator/DataCalc2.PNG
That isn't right. I have it set to hide the panel containing the number converter and show the one containing the text converter when you click that one. It hides the number converter but doesn't show the text converter.
Here is a picture of the text converter panel:
http://dl.dropbox.com/u/41629841/DataCalculator/DataCalc4.PNG
Here is the relevant code:
Private Sub frmCalculator_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
rdoNumberConverter.Checked = True
End Sub
Private Sub rdoTextConverter_Click(sender As Object, e As System.EventArgs) Handles rdoTextConverter.Click
pnlTextConverter.Visible = True
pnlNumberConverter.Visible = False
End Sub
Private Sub rdoNumberConverter_Click(sender As Object, e As System.EventArgs) Handles rdoNumberConverter.Click
pnlNumberConverter.Visible = True
pnlTextConverter.Visible = False
End Sub
Everything seems right and I can't figure out why the text converter doesn't show up. I've determined that it has something to do with the fact that both of the panels are right on top of each other because when I move them apart, the visibility toggling works perfectly.
Here are the supporting pictures:
http://dl.dropbox.com/u/41629841/DataCalculator/DataCalc5.PNG
http://dl.dropbox.com/u/41629841/DataCalculator/DataCalc6.PNG
So how do I make it work when they are on top of each other?
I tried using BringToFront() and SendToBack() to make sure the visible panel is in the front and it didn't make a difference.
Make sure the TextConverter panel isn't "inside" the NumberConverter panel.
From the designer, move them into different places so that they do not overlap at all.
Then in code, move them into place:
textConverterPanel.Location = numConvertPanel.Location
Your visible, not visible toggling should work then.
The issue is the panels becoming embedded, as pointed out by #LarsTech. This occurs if you use the GUI to move them to the same location.
If you want to overlap them at design time, create the second panel in a different location. Then in the Properties of the panel in the final location, copy the Location, and paste it into the Location property of the second panel. This will move it to the proper location in the Designer without embedding one into another. This can be repeated for as many additional panels as needed.

Canceling a TabControl tab selection in VB.NET

Really wracking my brain here and I'm sure it's something simple I'm missing.
Basically I have a form with two tabs. I'm checking the controls on each tab to see if they're dirty and want to prevent a user from clicking a tab if there are changes on the current tab.
I had thought if I check the dirty variable and just set the tab index to the one that hasn't been selected I'd be fine but every time I programatically set a tab's property, it fires off a bunch of the tab's events that just produce an undesireable result such as the right control set is showing but the wrong tab is selected.
Here is the code for as close as I've gotten to getting it to work.
Private Sub objTabs_Selected(ByVal sender As Object, ByVal e As System.Windows.Forms.TabControlEventArgs) Handles objTabs.Selected
If bIsDirty Then
If Me.objTabs.SelectedIndex = 1 Then
Me.objTabs.SelectedTab = tabLetterofCreditBanks
Me.objTabs.SelectTab(0)
Else
Me.objTabs.SelectedTab = tabWireTransferBanks
Me.objTabs.SelectTab(1)
End If
End If
End Sub
Thanks in advance.
Try using the Selecting event instead of the Selected event - this will give you the opportunity to override the user's behavior (i.e. setting TabControlCancelEventArgs.Cancel to True).