MouseLeave e MouseEnter

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Magallo - 18 Dec 2006 11:10 GMT

Hi all,
I've got a problem using the MouseLeave/MouseEnter events. What I would like
to do is something like that: I have a panel and a button inside it.. Using
the MouseEnter/MouseLeave events on the panel, I dinamically show/hide the
button so that when I enter the panel, the button is shown, and when I leave
the panel the button is hidden.

It works correctly. The problem occurs when I pass the mouse over the
button. Also in this case the panel MouseLeave event occurs, so that the
button disappears. So the effect is that: I enter the panel, the button is
shown, I pass the mouse over it to click it but it disappears.

What I should do is changing the behaviour of the MouseLeave events
implementation so that I hide the button only if the mouse is effectively
outside the panel and not when it is over a control that is a child of the
panel.

Is there a way to do this?

I hope I have been clear.

Thanks.

Magallo

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Torsten Kerz - 18 Dec 2006 13:37 GMT

> I've got a problem using the MouseLeave/MouseEnter events. What I would
> like
> to do is something like that: I have a panel and a button inside it..
> Using the MouseEnter/MouseLeave events on the panel, I dinamically
> show/hide the button so that when I enter the panel, the button is shown,
> and when I leave the panel the button is hidden.

The behavior of the events is right, because only the control under the
cursor counts.

I would ...:
Take also mouseenter and leave of the button,

start a shorttime-timer in both leave-events,
stop this timer in the enter-events and
hide the frame in the timer-event.

that's it.

Greetings,
Torsten.

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Oliver Sturm - 18 Dec 2006 14:42 GMT

Hello Torsten,

>I would ...:
>Take also mouseenter and leave of the button,
>
>start a shorttime-timer in both leave-events,
>stop this timer in the enter-events and
>hide the frame in the timer-event.

Interesting idea, but it sounds rather complicated (for example, assuming
the UI may be a little more complex than that described in the OP's post).
I guess it would be an awful lot easier to check whether the mouse cursor
is really outside the bounds of the panel before actually making the
button invisible. Something like

if (!myPanel.ClientRectangle.Contains(MousePosition))
// hide button

Oliver Sturm

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http://www.sturmnet.org/blog

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Torsten Kerz - 18 Dec 2006 18:00 GMT

Hi Oliver.

> Interesting idea, but it sounds rather complicated (for example, assuming
> the UI may be a little more complex than that described in the OP's post).

You're right. :)

> I guess it would be an awful lot easier to check whether the mouse cursor
> is really outside the bounds of the panel before actually making the
> button invisible.

This doesn't give a garantie, that the inner controls will be hidden. Mouse
enter
and leave of the panel can fail, if the pointer is moved to fast or if an
other application
(for example: mouse driver and "automatic pointer to dialog-movement") moves
the
mousepointer.

On the other side it wouldn't be to much work, to set the handlers of
subcontrols
automaticly. Something like this:

Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
Timer1.Enabled = False
Timer1.Interval = 50

For Each control As Control In Panel1.Controls
AddHandler control.MouseEnter, AddressOf Panel1_MouseEnter
AddHandler control.MouseLeave, AddressOf Panel1_MouseLeave
control.Visible = False
Next
End Sub

Private Sub Panel1_MouseEnter(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Panel1.MouseEnter
Timer1.Stop()
For Each control As Control In Panel1.Controls
control.Visible = True
Next
End Sub

Private Sub Panel1_MouseLeave(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Panel1.MouseLeave
Timer1.Start()
End Sub

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Timer1.Tick
Timer1.Stop()
For Each control As Control In Panel1.Controls
control.Visible = False
Next
End Sub
End Class

Greetings,
Torsten.

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Oliver Sturm - 18 Dec 2006 18:10 GMT

Hello Torsten,

>>I guess it would be an awful lot easier to check whether the mouse cursor
>>is really outside the bounds of the panel before actually making the
[quoted text clipped - 7 lines]
>moves the
>mousepointer.

Yeah - my suggestion doesn't have to do with which events to listen for.
But the decision of whether or not the "correct" state (i.e. the one where
the button must be hidden/shown) has been reached, can easily be made by
looking at the position of the mouse again. Given the complexity of the
sequence of leave/enter events that may come up, it seems much easier to
me to make that check before doing anything to the button, than it would
be to try and track the events themselves reliably.

Oliver Sturm

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http://www.sturmnet.org/blog

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Torsten Kerz - 18 Dec 2006 19:45 GMT

Hmm ...

> Yeah - my suggestion doesn't have to do with which events to listen for.
> But the decision of whether or not the "correct" state (i.e. the one where
> the button must be hidden/shown) has been reached, can easily be made by
> looking at the position of the mouse again.

ok - its possible, to check the mouse position and get the correct state
with it.
But i miss one thing: which event can do this check?

but - combine the idea of "check the mouseposition" with the idea of track
down the
subcontrols and add handlers for mouseleave and it will be possible, to
discard the
timer and the additional handling of mouseenter.

---

just one very simple, additional idea, which will work, if there are only
buttons and other
clickable controls inside the frame and if every click to one of this
controls should hide the
panel:

panel1.Capture = True 'in mouseenter-event of the panel

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Oliver Sturm - 18 Dec 2006 21:16 GMT

Hello Torsten,

>ok - its possible, to check the mouse position and get the correct state
>with it.
>But i miss one thing: which event can do this check?

I'm not sure I understand your question... the OP asked a question about
how to use the various events reliably for his purposes. As far as I can
see, this question has long since been answered - basically it has to be
some combination of OnMouseEnter and OnMouseLeave, possibly hooking into
child elements as well.

The important thing is that my suggestion never targeted this part of the
problem. I would even go so far to say I haven't thought about it at all -
otherwise I would have suggested also hooking into the window and possibly
Application (de-)activation events to make sure you catch the cases where
the user just alt-tabs out of the app.

Here's what my suggestion deals with: Regardless of which events the OP
ends up using to track the mouse cursor entering/leaving various parts of
his UI, that tracking is bound to be complex, and there can be situations
where the state can be difficult to track. (Imagine: A MouseEnter from the
containing panel, a MouseLeave from moving into a contained element, a
MouseEnter from entering that contained element - if you even bothered
hooking into that -, then an Application.Deactivate (or whatever it's
called) because the user hits alt-tab, ...) This was why I suggested to
complement whatever combination of event handlers with a rather simple
status check, to find out whether the mouse cursor is in the desired
region or not. My idea is that this can happen at any time, in any desired
event handler, thereby eliminating the need for elaborate state handling.

>but - combine the idea of "check the mouseposition" with the idea of track
>down the
>subcontrols and add handlers for mouseleave and it will be possible, to
>discard the
>timer and the additional handling of mouseenter.

Yes, I believe that's what I was saying.

Oliver Sturm

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Bob Powell [MVP] - 18 Dec 2006 15:12 GMT

You need to create a control based on Panel and then override the mouseleave
protected method to see if the mouse is in one of the child controls of the
panel. if not, fire the mouseleave event, of not, dont.

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Visual C#, System.Drawing

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> Hi all,
> I've got a problem using the MouseLeave/MouseEnter events. What I would
[quoted text clipped - 20 lines]
>
> Magallo

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Bob Powell [MVP] - 18 Dec 2006 15:17 GMT

You may also need to override OnMouseEnter to see if the mouse has entered
the panel from one of it's child controls and filter raising the event in
that case.

Signature

> Hi all,
> I've got a problem using the MouseLeave/MouseEnter events. What I would
[quoted text clipped - 20 lines]
>
> Magallo

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ThunderMusic - 19 Dec 2006 00:44 GMT

I did mine just like this... it's very simple and it works as expected :

void Form_MouseLeave(object sender, System.EventArgs e)
{
if (this.ClientRectangle.Contains(PointToClient(Control.MousePosition)))
return;

if (m_HoverOpacity != m_NormalOpacity)
this.Opacity = m_NormalOpacity;

m_isHovering = false;
}
void Form_MouseEnter(object sender, System.EventArgs e)
{
if (!m_isHovering)
{
m_isHovering = true;
}
}

I hope it helps

ThunderMusic

> Hi all,
> I've got a problem using the MouseLeave/MouseEnter events. What I would
[quoted text clipped - 20 lines]
>
> Magallo

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MouseLeave e MouseEnter

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