Develop Reference

C# winforms. Drag events

I need to run code when I dismiss(end) dragging click. How this event is called?
Here is main example, please find the below screenshot for more information:
I made that I can drag the car on other picture boxes like below this:
Repeat again - I need to know what EVENT is then you dismiss to drag on picture box?

There is no event for when the drag is released on a control, but you don't really need one. This is what I did to simulate what (I think) you're looking for. I used code courtesy of this stackoverflow answer
private Point? _mouseLocation;
private void Form1_Load(object sender, EventArgs e)
{
this.pictureBox1.MouseDown += this.pictureBox1_MouseDown;
this.pictureBox1.MouseUp += this.pictureBox1_MouseUp;
this.pictureBox1.MouseMove += this.pictureBox1_MouseMove;
}
void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if ( this._mouseLocation.HasValue)
{
this.pictureBox1.Left = e.X + this.pictureBox1.Left - this._mouseLocation.Value.X;
this.pictureBox1.Top = e.Y + this.pictureBox1.Top - this._mouseLocation.Value.Y;
}
}
void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
this._mouseLocation = null;
}
void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
//Check if you've left-clicked if you want
this._mouseLocation = e.Location;
}
Setting the mouse location to null with this._mouseLocation = null; is your "drag released" code.

I guess you talking about DragDrop. You can find example here: How to: Enable Drag-and-Drop Operations with the Windows Forms RichTextBox Control

custom tooltip in c# .net win forms

I am looking to simulate a custom tooltip the like of you see in websites using c# .NET 4.5 windows forms.This tooltip will basically show status of some Tasks like how many tasks are pending,tasks in process, completed etc.To do this i am using a borderless win form.This winform will have some texts, images etc.I want it to reveal itself on button's mouseHover event and disappear on MouseLeave event.My problem is that on Mousehover event numerous instances of that tooltip form is getting generated and on MouseLeave they are not getting closed.My code is
private void B_MouseHover(object sender, EventArgs e)
{
frmSecQStatToolTipDlg tooltip = new frmSecQStatToolTipDlg();
tooltip.Location = this.PointToScreen(new Point(this.Left, this.Bottom));
tooltip.Show();
}
private void B_MouseLeave(object sender, EventArgs e)
{
frmSecQStatToolTipDlg tooltip = new frmSecQStatToolTipDlg();
tooltip.Close();
}
My code is not working, hence please tell me how to do this the correct way.Thanks

You're generating a new instance of the form class every time you get a hover event, and every time you get a leave event. If you want to continue to use this approach I would recommend you use a variable on your main form object to store the reference to your tooltip form. Secondly, you need to not generate a new instance whenever the event handler is called, but only when necessary. I would create your instance the first time your Hover event is called for a particular control, and then dispose of it when your Leave handler is called -- this is under the assumption that the tooltip dialog's constructor loads up different information for each control being hovered over. Like so:
frmSecQStatToolTipDlg f_tooltip;
private void B_MouseHover(object sender, EventArgs e)
{
if(frmSecQStatToolTipDlg == null)
{
f_tooltip = new frmSecQStatToolTipDlg();
}
tooltip.Location = this.PointToScreen(new Point(this.Left, this.Bottom));
tooltip.Show();
}
private void B_MouseLeave(object sender, EventArgs e)
{
if(f_tooltip != null)
{
f_tooltip.Close();
f_tooltip = null;
}
}

You should keep a global field for this form, and should not dispose or close it. Just hide it on some events and show again.
Sample Code:
frmSecQStatToolTipDlg tooltip;
private void B_MouseHover(object sender, EventArgs e)
{
if(frmSecQStatToolTipDlg == null)
{
tooltip = new frmSecQStatToolTipDlg();
}
tooltip.Location = this.PointToScreen(new Point(this.Left, this.Bottom));
tooltip.Show();
}
private void B_MouseLeave(object sender, EventArgs e)
{
if(frmSecQStatToolTipDlg != null)
{
tooltip.Hide();
}
}
With this logic you'll not have to create tooltip instance again and again and it will not take time to popup if you frequently do this activity.

Declare your tooltip once as readonly and use it without asking anytime if it is null or not.
If you need to Dispose it, implement the IDisposable pattern:
https://msdn.microsoft.com/en-us/library/b1yfkh5e(v=vs.110).aspx
private readonly frmSecQStatToolTipDlg _tooltip = new frmSecQStatToolTipDlg() ;
private void B_MouseHover(object sender, EventArgs e)
{
_tooltip.Location = this.PointToScreen(new Point(this.Left, this.Bottom));
_tooltip.Show();
}
private void B_MouseLeave(object sender, EventArgs e)
{
_tooltip.Hide();
}

How to Cancel an Event (EventArgs e) that is not bound to a WindowsForm

I have a code to detect keyboard input on a plugin
private void Plugin_Load(object sender, EventArgs e)
{
mouse = new MouseInput();
mouse.MouseMoved += mouse_MouseMoved;
}
void mouse_MouseMoved(object sender, EventArgs e)
{
if (testBool== true)
{
return; // Trying to cancel mouse event
}
}
I need to cancel event e(EventArgs), but return does not seems to work.
MouseEventArgs is a Winform event so doesn't works on my code.
Kindly suggest on how to cancel the event.
Thanks

WPF event for clicking textboxes in C#

How can I raise an event while clicking a textbox? I'm having trouble finding references for events for WPF in C#.
The idea is to have textboxes fire an event when clicked. For example, let's say as soon as I click a textbox, notepad is executed.
private void textBox1_TextChanged(object sender, TextChangedEventArgs e)
{
hello = Process.Start("notepad");
}
private void Click(object sender, MouseButtonEventArgs e)
{
/* if (e.LeftButton == MouseButtonState.Pressed)
{
hello = Process.Start(#"notepad");
}*/
}

For text events use TextInput event and read entered character from e.Text
private void yourTextBox_TextInput(object sender, TextCompositionEventArgs e)
{
if (e.Text == "K")
{
}
}
for mouse events use MouseDown/MouseUp
Sometimes MouseDown/MouseUp won't work on TextBox, then use this one:
http://msdn.microsoft.com/en-us/library/system.windows.uielement.previewmouseup.aspx

MouseLeftButtonDown event can be raised when clicking on textbox. This event will not fire by default on textbox. We need to use UIElement.AddHandler().
For e.g:
XAML:
<Textbox X:Name="Name_Textbox" MouseLeftButtonDown="Name_Textbox_MouseLeftButtonDown"/>
In the class Constructor:
TextBox_Name.AddHandler(FrameworkElement.MouseLeftButtonDownEvent, new MouseButtonEventHandler("Name_Textbox_MouseLeftButtonDown"), true);
Add Event in class file:
private void Name_Textbox_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
// Your logic on textbox click
}

How to implement Drag and Drop

I am working on a project. It does with drag and drop this is the code I have right now.
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void listBox1_MouseDown(object sender, MouseEventArgs e)
{
listBox1.DoDragDrop(listBox1.SelectedItem.ToString(), DragDropEffects.Move);
}
private void listBox2_DragEnter(object sender, DragEventArgs e)
{
e.Effect = e.AllowedEffect;
}
private void listBox2_DragDrop(object sender, DragEventArgs e)
{
listBox2.Items.Add(e.Data.GetData(DataFormats.Text));
listBox1.Items.Remove(listBox1.SelectedItem.ToString());
}
It lets you add to the second list box but I am trying to get it where you can also move the item back to first listbox if you want to. Do I repeat the code for the second list box as I did for the first one or is there a line of code I could just add.Also how can you tell if your program is “unbreakable”. Thanks.

Do I repeat the code for the second list box
Pretty much, yeah. Although you can simplify it a bit since the code will be essentially identical by having both listboxes use the same handler for MouseDown, DragEnter and DragDrop and then use the sender to figure out whether it's listBox1 or listBox2.
Also, you might want to think about your MouseDown handler. Most users won't expect a single click to immediately start a drag operation. Usually you would look for the mouse down and then for a mouse move while the button is down before starting the drag.
What I usually do is something like this:
private Size dragSize = SystemInformation.DragSize;
private Rectangle dragBounds = Rectangle.Empty;
private void listBox1_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
dragBounds = new Rectangle(new Point(e.X - dragSize.Width / 2, e.Y - dragSize.Height/2), dragSize);
}
else
{
dragBounds = Rectangle.Empty;
}
}
private void listBox1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left && dragBounds != Rectangle.Empty && !dragBounds.Contains(e.X, e.Y))
{
//start drag
listBox1.DoDragDrop(listBox1.SelectedItem.ToString(), DragDropEffects.Move);
dragBounds = Rectangle.Empty;
}
}

For the main question of implementing drag & drop: yes, you would need to create handlers for listbox1 and listbox2 that mirror the functionality you already have:
A MouseDown event handler for listBox2
A DragEnter handler for listBox1
A DragDrop handler for listBox1.
Also you'd need to make sure you assign these handlers to be used for their respective events in the form designer.

You could reapeat the code, but I tend to not want to do that. Yours is an edge case; lots of methods that only have one line in them. But any time I see repetition in code, it signals to me that I need to pull that code out somewhere else. If the repetition is in the same class, move it to its own method on the class. If the repetition is in separate classes, either find another class outside the two where it makes sense to put the new method, or consider creating a new class that both classes can share. In your case, if I decided to move the code, I would do something like this:
private void listBox1_MouseDown(object sender, MouseEventArgs e)
{
HandleMouseDown(listbox1);
}
private void listBox2_DragEnter(object sender, DragEventArgs e)
{
HandleDragEnter( e );
}
private void listBox2_DragDrop(object sender, DragEventArgs e)
{
HandleDragDrop( listBox1, listBox2, e );
}
private void listBox2_MouseDown(object sender, MouseEventArgs e)
{
HandleMouseDown(listBox2);
}
private void listBox1_DragEnter(object sender, DragEventArgs e)
{
HandleDragEnter( e );
}
private void listBox1_DragDrop(object sender, DragEventArgs e)
{
HandleDragDrop( listBox2, listBox1, e );
}
private void HandleMouseDown( ListBox listBox )
{
listBox.DoDragDrop(listBox.SelectedItem.ToString(), DragDropEffects.Move);
}
private void HandleDragEnter( DragEventArgs e )
{
e.Effect = e.AllowedEffect;
}
private void HandleDragDrop( ListBox src, ListBox dst, DragEventArgs e )
{
dst.Items.Add( e.Data.GetData(DataFormats.Text) );
src.Items.Remove( src.SelectedItem.ToString() );
}
The advantage to moving the code is, if those methods grow to more than one line, you can change them in only one place. Of course, for a one line method, I would also remember that I can always move it to its own method later. My personal preference would be to leave the two one-line methods as-is, doing a copy & paste for the second listbox, and splitting out the DragDrop handler into its own method like I did above.