in my VB.Net application I am try to drag and drop a custom control. It should be dropable onto another instance of the same class. So here is the code I use:
Private Sub HandleMouseDown(ByVal sender As Object, ByVal e As MouseEventArgs) Handles Me.MouseDown
Me.DoDragDrop(Me, DragDropEffects.Copy)
End Sub
Private Sub HandleDragEnter(ByVal sender As Object, ByVal e As DragEventArgs) Handles Me.DragEnter
e.Effect = If(checkDropData(e), DragDropEffects.Copy, DragDropEffects.None)
End Sub
Private Sub HandleDragDrop(ByVal sender As Object, ByVal e As DragEventArgs) Handles Me.DragDrop
addControl(e.Data.GetData(GetType(MyControl)))
End Sub
Private Sub HandleDragLeave(ByVal sender As Object, ByVal e As DragEventArgs) Handles Me.DragLeave
Console.WriteLine("HandleDragLeave: " & sender.ToString)
End Sub
I am able to drop the control but while dragging the DragLeave event never gets called. Did I miss something?
That's very bad... I used the wrong signature but the was nothing which told me I was wrong.
I found the solution here. I used DragEventArgs instead of EventArgs as type of e. After changing the type it works like expected.
Related
I want to block the key board input when the form starts, but it is not working, please check my code:
Public Class Form2
Public Declare Function BlockInput Lib "User32" (ByVal fBlock As Integer) As Integer
Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
Private Sub Panel1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Panel1.Paint
End Sub
Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
Dim name As String
name = "12345"
If (name = TextBox1.Text) Then
Me.Close()
End If
End Sub
Private Sub Button1_Click_1(sender As Object, e As EventArgs) Handles Button1.Click
TextBox1.Visible = True
TextBox1.Focus()
End Sub
Private Sub TextBox2_Click_1(ByVal sender As Object, ByVal e As EventArgs) Handles TextBox2.MouseClick
BlockInput(1)
End Sub
Private Sub TextBox2_TextChanged(sender As Object, e As EventArgs) Handles TextBox2.TextChanged
End Sub
End Class`
I used "groupbox.enabled = False" in order to stop program users from editing anything within the groupbox on my form. You can then enable the groupbox again providing certain conditions are met. Another method I've used in my programming for VB.net was setting the read-only property (I used to to auto-populate the system date to prevent users from entering false dates) I don't know if either of those methods might help you?
I'm currently struggling with drag & drop code. I have 3 images that are at the top, and I want to add them in a random order in a flow-layout-panel.
I have this code for adding the square image into the flow-layout-panel, but I have got the feeling that this is not 100% correct. Is it possible to add these with 1 sub instead of 3?
And how do you write a sub that detects what object in being dragged? Now my sub just adds a square with each dragdrop event. But I need it to drop a Square only when a Square is being dragged and drop a Trapezium or round when it's being dragged.
Public Class Form2
Private Sub PictureBox1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
' Initiate dragging.
PictureBox1.DoDragDrop(PictureBox1, DragDropEffects.Copy)
End Sub
Private Sub PictureBox2_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox2.MouseMove
' Initiate dragging.
PictureBox2.DoDragDrop(PictureBox2, DragDropEffects.Copy)
End Sub
Private Sub PictureBox3_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox3.MouseMove
' Initiate dragging.
PictureBox3.DoDragDrop(PictureBox2, DragDropEffects.Copy)
End Sub
Private Sub FlowLayoutPanel1_DragEnter(ByVal sender As Object, ByVal e As _
System.Windows.Forms.DragEventArgs) Handles FlowLayoutPanel1.DragEnter
' Check the format of the data being dropped.
If (e.Data.GetDataPresent(GetType(PictureBox))) Then
' Display the copy cursor.
e.Effect = DragDropEffects.Copy
Else
' Display the no-drop cursor.
e.Effect = DragDropEffects.None
End If
End Sub
Private Sub FlowLayoutPanel1_DragDrop(ByVal sender As Object, ByVal e As _
System.Windows.Forms.DragEventArgs) Handles FlowLayoutPanel1.DragDrop
Dim oPB As New PictureBox()
oPB.Image = Image.FromFile("C:\Users\Jef\Desktop\square.jpg")
oPB.Visible = True
oPB.Width = 100
oPB.Height = 100
oPB.SizeMode = PictureBoxSizeMode.CenterImage
FlowLayoutPanel1.Controls.Add(oPB)
End Sub
You already got the answer in your previous question:
Private Sub FlowLayoutPanel1_DragDrop(ByVal sender As Object, ByVal e As _
System.Windows.Forms.DragEventArgs) Handles FlowLayoutPanel1.DragDrop
Dim oPB As New PictureBox()
Dim pb = CType(e.Data.GetData(GetType(PictureBox)))
oPB.Image = pb.Image
pb.Image = Nothing '' Optional
'' etc...
End Sub
You do have a bug, the probable reason why you did not use the answer:
Private Sub PictureBox3_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox3.MouseMove
' Initiate dragging.
PictureBox3.DoDragDrop(PictureBox2, DragDropEffects.Copy)
End Sub
Note how it drags the wrong control, PictureBox2 instead of PictureBox3. You avoid bugs like this by writing DRY code, Do not Repeat Yourself. The sender argument of a MouseMove event already gives you a reference to the control. So you just need one event handler for all three controls:
Private Sub PictureBox_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove, PictureBox2.MouseMove, PictureBox3.MouseMove
' Initiate dragging.
Me.DoDragDrop(sender, DragDropEffects.Copy)
End Sub
With the detail that we now let the Form support DoDragDrop(). Which only matters if you implement the GiveFeedback or QueryContinueDrag events.
I have a dgv filled by a sp everything created with the wizard. since filling takes about 10 seconds i wanna have this in a background using a backgroundworker. I tried:
Public Class frmStart
Delegate Sub updateDGV()
Private Sub frmStart_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles MyBase.Load
BackgroundWorker1.WorkerSupportsCancellation = True
BackgroundWorker1.RunWorkerAsync()
End Sub
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, _
ByVal e As System.ComponentModel.DoWorkEventArgs) _
Handles BackgroundWorker1.DoWork
Me.Invoke(New updateDGV(AddressOf UpdatingForm))
End Sub
Private Sub BackgroundWorker1_RunWorkerCompleted(ByVal sender As Object , _
ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) _
Handles BackgroundWorker1.RunWorkerCompleted
msgbox("Completed")
End Sub
Private Sub UpdatingForm()
Try
me.tableadapter.fill(me.dataset.table)
Catch ex As Exception
MsgBox("Error during loading the dgv")
Finally
BackgroundWorker1.CancelAsync()
End Try
End Sub
End Class
I just see the first row in the dgv. How can i fill my whole dgv in the background, where is the mistake in the code? Additionally, i would like to see a popup during the fill process with "please wait your dgv gets filled". any idea how to accomplish that?
before i modified the code i had only the following line, which was programatically created.
me.tableadapter.fill(me.dataset.table)
Your new code is identical to the initial version. Me.Invoke is forcing UpdatingForm to be executed in UI thread. You can split in 2 parts.
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Me.ProductsTableAdapter.Fill(Me.NorthwindDataSet.Products)
End Sub
Private Sub BackgroundWorker1_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
Me.ProductsBindingSource.ResetBindings(False)
End Sub
check as well Asynchronous Data Loading using TableAdapter with Cancel Feature
I have a background worker that calls a form, holding a gif animation. The purpose is to display the animation while process is underway but it should close when the process is done. But it does not close even after completion of the process. Please help.
Thanks
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
frmAnimation.ShowDialog()
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
BackgroundWorker1.RunWorkerAsync()
Dim sqldatasourceenumerator1 As SqlDataSourceEnumerator = SqlDataSourceEnumerator.Instance
datatable1 = sqldatasourceenumerator1.GetDataSources()
DataGridView1.DataSource = datatable1
'I have tried CancelAsync, but did not work
BackgroundWorker1.CancelAsync()
frmAnimation.Dispose()
End Sub
BackgroundWorkers are intended to actually do the "work" of the background operation, so the main UI thread can continue rendering things onto the screen. I suspect you want the GetDataSources() function call to be done within the BackgroundWorker thread.
Try switching what's in your button click function and what's in the DoWork function of your BackgroundWorker. Specifically, I mean something like this:
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Dim sqldatasourceenumerator1 As SqlDataSourceEnumerator = SqlDataSourceEnumerator.Instance
datatable1 = sqldatasourceenumerator1.GetDataSources()
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
BackgroundWorker1.RunWorkerAsync()
frmAnimation.ShowDialog()
End Sub
And in addition, add some code to the RunWorkerCompleted event to handle what should be done upon completion of your background operation.
Private Sub BackgroundWorker1_RunWorkerCompleted(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
DataGridView1.DataSource = datatable1
frmAnimation.Close()
End Sub
You may also want to consider using frmAnimation.Show() instead of frmAnimation.ShowDialog() depending on if you want the procedure to be modal or modeless. You can read more about that here.
I have built my own browser 9see attached code) however I would like to modify the code so that textbox1 reads a txt file at start and uses the contents of that text file to navigate to a URL of equal value to the text with in that text file. All this should happen at the launch of the web browser form.
Example of the text file contents would be http://www.testsite.com
Code as follows:
#Region "Webbrowser navigation"
Private Sub Go()
WebBrowser1.Navigate(TextBox1.Text)
End Sub
Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
Go()
End Sub
Private Sub TextBox1_keydown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyDown
If e.KeyCode = Keys.Enter Then
Go()
End If
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
WebBrowser1.GoBack()
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
WebBrowser1.GoForward()
End Sub
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
WebBrowser1.Stop()
End Sub
#End Region
how can I best do this?
In the event handler for the form's Load event, do something like this:
TextBox1.Text = File.ReadAllText("StartUrl.txt")
Go()
However, unless you have some good reason to use a text file, I would suggest something more flexible and standard such as XML. If you don't mind using the standard app.config file, just add one of those to your project and you can use the ConfigurationManager class to read the setting.