Could someone clarify what's the difference between these three events for the TreeView control in .NET?
Everyone of them is triggered when a node is clicked.
In practice, when should I use each of them over the others?
Private Sub TreeView_Devices_NodeMouseClick(sender As Object, e As TreeNodeMouseClickEventArgs) _
Handles TreeView_Devices.NodeMouseClick
DisplaySignals(e.Node, Me)
End Sub
Private Sub TreeView_Devices_MouseClick(sender As Object, e As MouseEventArgs) _
Handles TreeView_Devices.MouseClick
If e.Button = MouseButtons.Right Then
MsgBox("Right Click")
ElseIf e.Button = MouseButtons.Left Then
MsgBox("Left Click")
End If
End Sub
Private Sub TreeView_Devices_Click(sender As Object, e As EventArgs) _
Handles TreeView_Devices.Click
End Sub
thanks.
.NET distinguishes between Click and MouseClick because some controls allow firing a logical click with the keyboard. Buttons and checkboxes for example, you click them with the space-bar. Of course there's no mouse information available when the user operates the keyboard so that's why the Click event has a plain EventArgs instead of a MouseEventArgs. You need to use MouseClick only when you care about the mouse location for some reason.
It doesn't apply to TreeView, it doesn't support "clicking" a node with the keyboard.
Next thing that matters is exactly where the user clicks. Only some of the locations in a TreeView co-incide with a node. So that's why there's NodeMouseClick, it only fires when the user clicked a node. And doesn't fire when he clicked anywhere else, when expanding or collapsing a node for example.
It is a convenience event, it isn't actually necessary. Because MouseClick is already good enough to also detect that the click was on a node. But it requires more code, you have to use the HitTest() method. The event helps you avoid having to write that code. Convenient.
Since you very rarely care about the user clicking on anything but nodes, you'd normally always favor NodeMouseClick.
Related
I want to close my form when Alt + Tab is pressed. However, The form is somehow not registering the key combination.
i have tried to use the Me.KeyUp event to detect the keys
Private Sub Menu_KeyUp(sender As Object, e As KeyEventArgs) Handles Me.KeyUp
Select Case e.KeyData
Case (Keys.Alt + Keys.Tab)
Close()
End Select
End Sub
How can it be done ?
Try this: As in my comment Alt+Tab would not work. So try something else like Alt+Q. Put this code under the Form's keydown event.
Private Sub Form1_KeyDown(sender As Object, e As KeyEventArgs) Handles MyBase.KeyDown
If (e.KeyCode = Keys.Q AndAlso e.Modifiers = Keys.Alt) Then
Me.Close()
End If
End Sub
You need to set the form's Set KeyPreview to True for it to respond to the key events, but since Alt + Tab is a special windows combination the key events will not be fired.
Try in this way
Dim myval As Integer 'this is global variable declare
Private Sub Menu_KeyUp(sender As Object, e As KeyEventArgs) Handles Me.KeyUp
Select Case e.KeyData
Case (Keys.Alt)
myval = 1
Case (Keys.Tab)
If myval = 1 Then
Me.Close()
End If
End Select
End Sub
May be my syntax in not correct, please edit it if anything is notok.
I managed to work around this problem using this method-
That's usually the ESC key. One key press. A common one. Maybe you want to handle the Form's deactivate event, instead. – Jimi
I used the forms deactivate event to close it, since Alt+Tab is basically deactivating the form!
(A workaround because Alt+Tab as keystrokes were not detected by any means, as mentioned by
the last two answers.)
My final code looks like this -
Private Sub Menu_Deactivate(sender As Object, e As EventArgs) Handles Me.Deactivate
If loaded = true Then
Close()
End If
End Sub
I had to check if loaded (a boolean i declared to be set to true when everything is loaded)
to be true because my form opens one other form while loading, which inadvertently deactivated the main form and closed it!
Thank you so much for helping me everyone!!
Edit: I needed to clarify that the second form is always behind my main form so it is never really clicked on. I did this as a workaround to have aero blur in my application without a bug i experienced while applying it to the main form - it is too light, so text is unreadable. So i set another form to show aero blur and always stay behind my main form, whose opacity I have set to 0.88. This gives me a lot of control over the look of the blur.
I'm trying to setup global shortcut using mouse button and scrolling combination, (scrolling up (or down) whlie pressing right mouse button).
I'm thinking I should try to react to mouse scroll, but I have no idea how to detect mouse wheel outside of form.
Right now I got it to react to mouse click with timer and setting form to always on top (no prolem with it being always on top), but no idea how to progress with it.
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
If MouseButtons.HasFlag(MouseButtons.Right) = True Then
TextBox1.Text = "YES"
Else
TextBox1.Text = "NO"
End If
End Sub
Goal is to make it minimize aplications set by user with that shortcut, just in case that info is helpful. I have rest of the code just cant figure that part out.
EDIT:
It works inside form with this:
Private Sub ListBoxCHOWAJ_MouseWheel(sender As Object, e As MouseEventArgs) Handles ListBoxCHOWAJ.MouseWheel
If MouseButtons.HasFlag(MouseButtons.Right) = True Then
If e.Delta > 0 Then
TextBox1.Text = "up"
Else
TextBox1.Text = "down"
End If
End If
End Sub
You need a mouse hook to detect scrolling outside your application. Have a look at my InputHelper library and its low-level mouse hook.
To include it in your project, download the compiled DLL and add it as a reference:
Right-click your project in the Solution Explorer and press Add Reference...
Go to the Browse tab.
Locate the InputHelper DLL-file, select it and press OK.
You can do all your logic in the hook's MouseWheel event handler, no need for the timer any longer:
Imports InputHelperLib
Public Class Form1
Dim WithEvents MouseHook As New InputHelper.Hooks.MouseHook
Private Sub MouseHook_MouseWheel(sender As Object, e As InputHelperLib.InputHelper.Hooks.MouseHookEventArgs) Handles MouseHook.MouseWheel
If MouseButtons.HasFlag(MouseButtons.Right) = True Then
'Do something...
End If
End Sub
End Class
There's no need to check e.Delta like you did because it will never be 0.
I'm quite new to programming, so I'm facing a lot of problems such as this one:
After clicking button1, the program should assign the next pushed key(ctrl, for example) to button1.text.
For example: Click button1 -> push key X -> button1.text = X
What I have so far:
Private Sub btnTaste1_keydown(sender As Object, e As System.Windows.Forms.KeyEventArgs) Handles btnTaste1.KeyDown
btnTaste1.Text = e.KeyCode.ToString
End Sub
But that assigns a pushed key at any time, not only after clicking the button.
I think the best way to do this would be to dynamically add and remove the KeyDown handler.
Change your KeyDown to look like this (remove the Handles clause):
Private Sub btnTaste1_keydown(sender As Object, e As System.Windows.Forms.KeyEventArgs)
That will stop that code from automatically being run on every key press.
Now in your button click code, add this:
addhandler btnTaste1.Keydown, addressof(btnTaste1_keydown)
After you "handle" the key press you should detach the handler so it doesn't get called again (until the button click attaches it again), like this:
btnTaste1.Text = e.KeyCode.ToString
removeHandler btnTaste1.Keydown, addressof(btnTaste1_keydown)
Eventually you may want to investigate using the Form's KeyPreview property and attach the event to the form instead so that you don't need to worry about the complexities of input focus.
I write this code for tab-like behavior when user presses ENTER on textboxes for every form, which works fine.
If e.KeyChar = Microsoft.VisualBasic.ChrW(Keys.Return) Then
SendKeys.Send("{TAB}")
e.Handled = True
End If
However, I need to write the code once, perhaps as a sub or function in a module so that I do not have to write the same for every form. I have checked various forums including
Detecting Enter keypress on VB.NET and
Tab Key Functionality Using Enter Key in VB.Net
BUT all I get is either to write code for each textbox or for every individual form.
Has anyone tried out a single code for ALL or may be several selected forms of the application? If yes, please share with me. Writing for every form still works fine for me but i need to take advantage of OOP. Thanks
There are many ways to implement this, one of those is to create a custom textbox User Control
Adding a control to your project is very easy just right click in your project in the solution explorer ->Add->User Control
Give a name to your control ex. "tabedtextbox"
Add a textbox control to your User Control
Place the code in the keypress event of textbox1 of the UserControl
Private Sub TextBox1_KeyPress(sender As Object, e As KeyPressEventArgs) Handles TextBox1.KeyPress
If e.KeyChar = Microsoft.VisualBasic.ChrW(Keys.Return) Then
SendKeys.Send("{TAB}")
e.Handled = True
End If
End Sub
Compile once in order to update the whole project with the new user control.
Goto to your form and add your new User Control, you can locate it at the Toolbox panel.
Run your program and you will see the behavior of TAB when you press enter on each textbox.
If You wish to allow the user to press enter in a TextBox, instead of pressing a specific button,
you can use the acceptbutton property.
One good way to use it, is to change the property, on the Enter and Leave events of the TextBox. That you call Click event of the Button, when User press Enter inside the TextBox.
Try this code:
Private Sub tbProject_Enter(sender As Object, e As EventArgs) Handles tbProject.Enter
Me.AcceptButton = bSearch
End Sub
Private Sub tbProject_Leave(sender As Object, e As EventArgs) Handles tbProject.Leave
Me.AcceptButton = Nothing
End Sub
Private Sub bSearch_Click(sender As Object, e As EventArgs) Handles bSearch.Click
'.... actions to perfom
End Sub
Screen
there is a feature I'd like to implement in my application:
The user right clicks on my picturebox object. Good.
When that happens, some code of mine executes and will generate a list of options.
Then a menu appears where the mouse right-clicked, made up of these options.
When the user clicks on one of these options, the menu is deleted and some code is run given the option index as parameter.
My two problems:
How can I tell when the user right clicks? I can see an event handler for "click", but that includes left clicks....
How do I create one of these menus? I mean, go ahead and right click something. That's the kind of menu I'm looking for.
You need to implement the picturebox' MouseUp event. Check if the right button was clicked, then create a ContextMenuStrip with the menu items you want. You can use, say, the Tag property of the items you add to help identify them so you can give them a common Click event handler. Like this:
Private Sub PictureBox1_MouseUp(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
If e.Button <> Windows.Forms.MouseButtons.Right Then Return
Dim cms = New ContextMenuStrip
Dim item1 = cms.Items.Add("foo")
item1.Tag = 1
AddHandler item1.Click, AddressOf menuChoice
Dim item2 = cms.Items.Add("bar")
item2.Tag = 2
AddHandler item2.Click, AddressOf menuChoice
'-- etc
'..
cms.Show(PictureBox1, e.Location)
End Sub
Private Sub menuChoice(ByVal sender As Object, ByVal e As EventArgs)
Dim item = CType(sender, ToolStripMenuItem)
Dim selection = CInt(item.Tag)
'-- etc
End Sub
To your first question: you actually handle just the "click" event, there is no separate event for right-click. But look at the EventArgs object you get passed for the event: it includes information of which button was pressed (and would give you more info if a mouse click had anything beyond that). So you check the button within an if block, and you're good to go.
To your second question: http://msdn.microsoft.com/en-us/library/system.windows.forms.contextmenustrip.aspx. If your menu is pre-defined, just look for that component on the Designer and prepare the menu from there and call its Show() method from the click handler. If you need to decide the menu entries on the fly, the linked documentation page actually includes an example on that ;)
PS: oops, I just noticed Jon's comment on the question. The answer I gave you is for Windows Forms. If you are on WPF let us know and I'll update with the details (although the concepts ain't too different).
There is actually an easier way to do this. Double-click on the control you wish to be able to right click. Now go to the top of the page and it should say in comboboxes; 'Control' and 'Click' Click on the 'click' combobox and look for: Right-Click. Use a ContextMenuStrip for your right click menu.
Now you can choose which function you want.
Private Sub PictureBox1_RightClick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.RightClick
ContextMenuStrip1.Show()
MsgBox("Content Activated.", MsgBoxStyle.Information, "Success!")
End Sub
Hope I could help. :)
Coridex73