Working on a DragDrop application. I have a class object (built as an object) which has a GroupBox that is enabled for DragDrop.
In the class I have set it up so that the cursor will change when it enters the groupbox, leaves the groupbox, mouse is down within the groupbox and drag/drop is working. I also set up a label in the class object and changed the text in that label as well. Basically, the text changes in the label as expected including 'FEEDBACK' appearing when I am dragging the object BUT the cursor stays stubbornly as a pointer. This is tghe state of affairs either when I debug the class or when, after I build the class, it is run as part of the main program.
Here are the subs set up in the class.
Private Sub GroupBoxSourceMouseDown(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles GroupBoxSource.MouseDown
GroupBoxSource.DoDragDrop(GroupBoxSource.Text, DragDropEffects.Copy)
lbl1.Text = "DOWN"
End Sub
Private Sub GroupBoxSourceMouseMove(ByVal sender As Object, ByVal e AsSystem.Windows.Forms.MouseEventArgs) Handles GroupBoxSource.MouseMove
If bolDragDropMouseDown Then
' Initiate dragging.
'GroupBoxSource.DoDragDrop(GroupBoxSource.Text, DragDropEffects.Copy)
End If
bolDragDropMouseDown = False
lbl1.Text = "MOVE"
End Sub
Private Sub GroupBoxSourceMouseEnter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles GroupBoxSource.MouseEnter
Windows.Forms.Cursor.Current = Cursors.Hand
lbl1.Text = "ENTER"
End Sub
Private Sub GroupBoxSourceMouseLeave(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles GroupBoxSource.MouseLeave
Windows.Forms.Cursor.Current = Cursors.Arrow
lbl1.Text = "LEAVE"
End Sub
Private Sub GroupBoxSourceDragDropFeedback(ByVal sender As Object, ByVal e As GiveFeedbackEventArgs) Handles GroupBoxSource.GiveFeedback
Windows.Forms.Cursor.Current = Cursors.SizeAll
lbl1.Text = "FEEDBACK"
End Sub
Now for the unusual stage. I decided to change the cursor during FormLoad of the main program (which has the class object defined on the form) to a hand and nothing changed. In desperation I set up a 1mS timer and coded that to change the cursor to a hand and sure enough the cursor is now a hand but momentarity flicks back to a pointer when I move the cursor so it looks as if something else is causing the cursor to revert to its default value.
You have to set e.UseDefaultCursor = False in your GiveFeedback event handler to make your cursor change visible. Without it, drag and drop always uses the default cursors.
The cursor you get when the mouse hovers a control is set by the Control.Cursor property. Changing the Cursor.Current property has no effect, the property causes the cursor to change back instantly when you move the mouse.
To easily change the cursor, click on the form and bring up the properties. Then go to Cursor and change it to whatever you want.
Related
I use the following code in my form:
Public Class Form1
Private Sub Form1_ResizeEnd(sender As Object, e As EventArgs) Handles MyBase.ResizeEnd
MsgBox("Resized")
End Sub
End Class
When I move my form, it also seems to trigger MyBase.ResizeEnd. Why is that? A move of the panel doesn't change the size, so I don't understand why.
Why does a form move trigger ResizeEnd?
Because this is the documented behavior. From the documentation:
The ResizeEnd event is also generated after the user moves a form, typically by clicking and dragging on the caption bar.
If you want an event that doesn't get triggered when the form is moved, you should use either Resize or SizeChanged. The problem with those two events is that they will be triggered while the form is being resized by the user. To work around that, you may use it with both ResizeBegin and ResizeEnd with a couple of flags to signal when the user actually finishes resizing the form.
Here's a complete example:
Private _resizeBegin As Boolean
Private _sizeChanged As Boolean
Private Sub Form1_ResizeBegin(sender As Object, e As EventArgs) Handles MyBase.ResizeBegin
_resizeBegin = True
End Sub
Private Sub Form1_SizeChanged(sender As Object, e As EventArgs) Handles MyBase.SizeChanged
' This is to avoid registering this as a resize event if it was triggered
' by another action (e.g., when the form is first initialized).
If Not _resizeBegin Then Exit Sub
_sizeChanged = True
End Sub
Private Sub Form1_ResizeEnd(sender As Object, e As EventArgs) Handles MyBase.ResizeEnd
_resizeBegin = False
If _sizeChanged Then
_sizeChanged = False
MessageBox.Show("The form has been resized.")
End If
End Sub
One thing to note is that both ResizeBegin and ResizeEnd are only triggered when the user manually resizes* the form. It does not, however, handle other situations like when the form is resized via code, when the form is maximized, or restored.
* or moves the form, which is the part that we're trying to avoid here.
Probably a simple one but a cannot figure out the correct event:
I have a vb.net WinForm with a TabControl. On every TabPage, the user can enter/modify some data and then (hopefully) save it.
To keep things clean, I want to check, if there is unsaved data, when a user changes tabs (and delete it, if not saved).
I am looking for the best event of the TabCard to do so. There is TabControl1.Selecting, .SelectedIndexChanged and .Selected which look promising but they all fire AFTER the Tab changed.
If the user wants to return to save the data, i need to figure out where he came from and show that TabPage again. Also the event would the fire again - Not practicable.
In Conlusion: I am looking for a TabControl Event, that fires after the user clicked another tabcard but before the card actually changes...
Or a better idea to solve this isse another way.
Use the Selecting event. If you don't want to change the tab page, you can cancel the event.
'Here's an example class with a tabControl
Public Class Form1
'this variable stores the currently selected tab
Private activeTab As TabPage
'this initializes the activeTab variable
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
activeTab = TabControl1.SelectedTab
End Sub
'This checks to see if the tab should change or not
Private Sub TabControl1_Selecting(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TabControlCancelEventArgs) Handles TabControl1.Selecting
If (MessageBox.Show(String.Format("Return to {0} tab?", activeTab.Name), "TabControl", MessageBoxButtons.OKCancel) = Windows.Forms.DialogResult.OK) Then
e.Cancel = True
Else
activeTab = e.TabPage
End If
End Sub
End Class
Situation:
I have a context menu in a VB.NET form with fires an event handler on ItemClicked. The auto-generated subroutine receives sender and e as parameters. As I don't reinvent the wheel multiple times, I linked this context menu to three text boxes. Let's name them Textbox1, Textbox2 and Textbox3.
Problem: How can I figure out in which textbox the menu was opened?
Okay, what did I already try?
sender contains the menu itself,
e.ClickedItem just returns the single menu item that was selected.
sender.Parent is always nothing
sender.OwnerItem is also always Nothing`
Me.Textbox1.Focused is always False, even if its the "parent" control of the menu.
Okay, I found a solution that works fine, and here's the code for all VB.NET coders that have the same problem.
The context menu is linked in TextBox1, so we need to add another event handler that saves the sending control into the menu:
Private Sub TextBox1_MouseUp(sender As Windows.Forms.Control, e As System.Windows.Forms.MouseEventArgs) Handles TextBox1.MouseUp
If e.Button = Windows.Forms.MouseButtons.Right Then
ContextMenu.Tag = sender
End If
End Sub
And this is the code of the event handler when clicking a menu item:
Private Sub ContextMenu_ItemClicked(sender As System.Object, e As System.Windows.Forms.ToolStripItemClickedEventArgs) Handles ContextMenu.ItemClicked
ContextMenu.Close()
If ContextMenu.Tag Is Nothing Then
Debug.Print("debug info: forgot to set sender? well ... KABOOM!")
Exit Sub
End If
Dim oParent As Windows.Forms.Control
Try
oParent = ContextMenu.Tag
Catch ex As Exception
Debug.Print("debug info: tag contains data other than sender control. well ... KABOOM!")
Exit Sub
End Try
' Do fancy stuff here.
' Release sender
ContextMenu.Tag = Nothing
End Sub
The ContextMenuStrip has a SourceControl property which contains a reference to the control which opened the menu. The event fires from one of the ToolStripMenuItems in the ContextMenuStrip, so you have to get the "parent" first:
' cast sender to menuitem
Dim mi = CType(sender, ToolStripMenuItem)
' cast mi.Owner to CMS
Dim cms = CType(mi.Owner, ContextMenuStrip)
' the control which opened the menu:
Console.WriteLine(cms.SourceControl.Name)
Under certain conditions the SourceControl can get lost but you can track it yourself with a variable and the parent ContextMenuStrip Opening event:
' tracking var:
Private MenuSourceControl As Control
Private Sub cms_Opening(sender As Object, e As CancelEventArgs) Handles cms.Opening
' set reference in case/before it is lost
MenuSourceControl = CType(sender, ContextMenuStrip).SourceControl
End Sub
Private Sub CutToolStripMenuItem_Click(sender...
If MenuSourceControl IsNot Nothing Then
' do your stuff
' optionally clear the tracking var
MenuSourceControl = Nothing
End If
End Sub
It should be also easier to get the SourceControl when dealing with sub items
You can also capture the related control in the MouseDown event of the related Control in cases where the same menu is used with different controls:
Private Sub lv2_MouseDown(sender As Object,
e As MouseEventArgs) Handles lv2.MouseDown,
myLV.MouseDown, lv1.MouseDown ...
If e.Button = Windows.Forms.MouseButtons.Right Then
MenuSourceControl = DirectCast(sender, Control)
End If
End Sub
I need help to call a function in a usercontrol that is shown in a panel within the form, so far this is i tried, but no luck, i can't still get the text inputted on the textbox
Public Class Form1
Private Sub LinkLabel1_LinkClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.LinkLabelLinkClickedEventArgs) Handles LinkLabel1.LinkClicked
Dim ustudent As New StudentAdd
ustudent.Dock = DockStyle.Fill
SplitContainer1.Panel2.Controls.Add(ustudent)
End Sub
Private Sub ToolStripButton1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ToolStripButton1.Click
ustudent.SaveData()
End If
End Sub
End Class
in user control have some textbox
textbox1 and textbox2
Public Class StudentAdd
Public Sub SaveData() As Boolean
'just testing whether it could work well
' getting textbox value
MsgBox(TextBox1.Text)
End Sub
End Class
But ustudent is a local var, try to declare it outside link_clicked event. Do you want to create multiple user controls in the win or just one?
For one you could add it at design time by dragging from the your project components panel
For more, you should implement some logic to identify the selected component and make it available for save data. If you want to save all just enumerate components in Panel2 (of type StudentAdd) and call the method
I'm creating a form with a few buttons and a combobox at runtime.
dim f as new form
(blah blah)
then the buttons acceptDescription and rejectDescription are set up...
then the combobox descriptionCombo is set up...
then...
AddHandler acceptDescription.Click, AddressOf handleAcceptedDescription
AddHandler rejectDescription.Click, AddressOf handleRejectedDescription
then I have these two methods to catch the click events... but can't figure out how to reference the other runtime generated controls. (combobox if accepted, form if rejected)
Private Sub handleAcceptedDescription(ByVal sender As System.Object, ByVal e As System.EventArgs)
'stub
'will need to reference the chosen combobox value here
dim acceptedDescription as string = descriptionCombo.selectedValue .tostring
End Sub
Private Sub handleRejectedDescription(ByVal sender As System.Object, ByVal e As System.EventArgs)
'I want to close the runtime created form here, but can't reference it
f.close()
'and return user to main form
Me.Focus()
End Sub
If the code for generating the form is in your main form, then declare the Form variable at the class level of the main form class so you can access it from the event handlers. Same goes for your combobox and text field- you need to make sure the variables are declared outside the scope of the handlers so you can reference them within the handlers.
Why can't you reference it? Just save it as a module/form-level variable and you're set.
In order to avoid global definitions, the best answer is
Private Sub handleRejectedDescription(ByVal sender As System.Object, ByVal e As System.EventArgs)
'sender is a button in this case.
'get the button
dim b as new button
b = ctype(sender,button)
'now get the button's parent form
dim f as new form
f = ctype(b.parent, form)
'now close the form
f.close()
End Sub