MouseEnter and MouseLeave events from a Panel and its child controls

Question

I have a Panel that contains child controls.

If I handle the Panel's MouseEnter and MouseLeave events, and its child's MouseEnter and MouseLeave events, the events are raised in this order:

Panel.MouseEnter
Panel.MouseLeave
Child1.MouseEnter
Child1.MouseLeave
Panel.MouseEnter
Panel.MouseLeave

But I need the following order:

Panel.MouseEnter
Child1.MouseEnter
Child1.MouseLeave
Panel.MouseLeave

Is that possible?

Answer 1

If you dont mind creating a usercontrol(derived from the panel or other parent container you wish), Override your parent's OnMouseLeave method to look like the following..

protected override void OnMouseLeave(EventArgs e)
{

    if(this.ClientRectangle.Contains(this.PointToClient(Control.MousePosition)))
         return;
    else
    {
        base.OnMouseLeave(e);
    }
}

Then, the event raising will be in the required order.

Answer 2

The mouse is "leaving" the panel as it enters the child control which is why it fires the event.

You could add something along the following lines in the panel MouseLeave event handler:

// Check if really leaving the panel
if (Cursor.Position.X < Location.X ||
    Cursor.Position.Y < Location.Y ||
    Cursor.Position.X > Location.X + Width - 1 ||
    Cursor.Position.Y > Location.Y + Height - 1)
{
    // Do the panel mouse leave code
}

Answer 3

The solution is to track the number of enters/leaves. In you overall control add a counter:

private int mouseEnterCount = 0;

In the MouseEnter handler do this:

if (++mouseEnterCount == 1)
{
   // do whatever needs to be done when it first enters the control.
}

In the MouseLeave handler do this:

if (--mouseEnterCount == 0)
{
   // do whatever needs to be done when it finally leaves the control.
}

and do the above MouseEnter and MouseLeave event handlers for ALL the child controls as well as the containing object.

Answer 4

Matthew's answer will not work always. Especially if the child control is set to the edge of its container and the mouse moves off the controls in that direction. You will never detect the MouseLeave event.

The best approach is to create a user control container then hook all the child controls' MouseEnter and MouseLeave events so that you can properly detect when and where the mouse is at all times. THEN if it enters your container's bounds you can fire a custom MouseEnter event and when it leaves MouseLeave event.

Answer 5

This may not be the most elegant solution, but you could set a property in the parent control panel (subclass panel) that is a bool value like "bool selected". Then when the MouseEnter for the panel fires set it to true...then stop the mouseleave logic from firing unless it is set to false.

example

bool selected;

MouseEnter(..,..)
{
 if (!selected)
   selected = true;
 else
   selected = false;

  if (selected)
   /.. Logic Here ../
}

MouseLeave()
{
  if (selected)
   return;

/.. Logic Here ../
}

In reality I would just have the MouseLeave event of the child set the parameter.

Example:

Parent:
  bool doLeave;

  MouseLeave(..,..)
  {
    if (doLeave)
    {
     /.. Logic ../
     doLeave = false;
  }

Child:
 MouseLeave(..., ...)
  {
    DerivedPanel parent = this.Parent as DerivedPanel;
    if (parent != null)
      parent.doLeave = true;
  }

Neither are elegant but it will work.

Answer 6

I believe so. A nice tool to have for verifying your WinForms application's events.

Windows.Forms Order of Events

http://missico.spaces.live.com/blog/cns!7178D2C79BA0A7E3!186.entry

• Created with EventSpy written by Urs Eichmann. (ftp://missico.net/EventSpy.zip)
• Using .NET Framework 3.5 and with Visual Basic’s Application Framework enabled.

Answer 7

This is a tricky one, and will be difficult to code reliably for. One idea is to "capture" the 3 incoming events in a list and execute your desired code once the list is complete (has the 3 desired events in the list). Then when you're done executing whatever code (or perhaps capture the combo of events in reverse), you could empty your list and have it ready for the next time that particular combo-event happens. Not ideal, but just a thought.

Of course, that doesn't overcome the potential resolution issues & possible missed events Hans raised. Perhaps more context is in order.

Answer 8

Check the child component..

if (panel1.GetChildAtPoint(panel1.PointToClient(Cursor.Position)) == null)
{
    // mouse leave panel and children
}

Answer 9

Jimmy T. is right. There will be problems if there is no (or small) space betwean Parent Control (Panel) edge and Child Control.

This is how I solve this problem in UserControl-derived class:

    public CSStackPanelItem()
    {
        InitializeComponent();

        MouseEnter += new EventHandler(CSStackPanelItem_MouseEnter);

        foreach (Control child in Controls)
        {
            child.MouseEnter += (s, e) => CSStackPanelItem_MouseEnter(s, e);
            child.MouseLeave += (s, e) => OnMouseLeave(e);
        }
    }

    protected override void OnMouseLeave(EventArgs e)
    {
        if (this.ClientRectangle.Contains(this.PointToClient(Control.MousePosition)))
            return; //suppress mouse leave event handling

        if (m_bIsHover)
        {
            m_bIsHover = false;
            Invalidate(); //actually my mouse Enter/Leave event
        }

        base.OnMouseLeave(e);
    }

    void CSStackPanelItem_MouseEnter(object sender, EventArgs e)
    {
        m_bIsHover = true;
        Invalidate(); //actually my mouse Enter/Leave event
    }