PointToScreen problem in UserControl

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A Nonymous - 21 Mar 2008 20:19 GMT

I created a PopUp edit based on a UserControl. It has a TextBox and a
button and works like a DateTimePicker except that in addition to date
and time, you can pick repeat intervals, days of the week, second
Tuesday, etc.

The problem is with the positioning of the PopUp. Basically the first
time I call PointToScreen I don't get the correct coordinates. The code
fragment I am using is shown below:

private void btnPick_Click(object sender, EventArgs e)
{
Point P = this.PointToScreen(Point.Empty);
if (P.Y + this.Height + editWhen.Height <=
SystemInformation.WorkingArea.Bottom)
P.Y += this.Height;
else
P.Y -= editWhen.Height;
editWhen.Location = P;
editWhen.Show();
}

What happens is the first time I click the drop down button the edit
window appears usually somewhere near the upper left corner of the
screen, but some times still on my app but near the upper corner of the
client area. The location is not completely consistent.

Now if I click the button again the dialog goes away, as designed, and
if I click it again it appears in the correct position. In fact from
then on I can just keep clicking on the button and it is always in the
correct location. I can even move the main form that contains my custom
edit and it is still correct.

It is only wrong, the first time I click the drop down button after the
form is created.

Any ideas on what is causing this, or how to fix it?

Reply to this Message

Peter Duniho - 21 Mar 2008 20:37 GMT

> [...]
> It is only wrong, the first time I click the drop down button after the
> form is created.
>
> Any ideas on what is causing this, or how to fix it?

I'm not entirely clear on what you're trying to do. However, the code you
posted appears to be using screen coordinates to try to position a
control/menu relative to another control (perhaps your form?).

I don't know why you're converting to screen coordinates in the first
place, and I don't know why the code you posted should ever work, but
given that you are using screen coordinates, you need to convert back to
client coordinates for the containing control so that they are correct
when you assign the Location property.

Pete

Reply to this Message

Fred Hebert - 21 Mar 2008 20:52 GMT

> I don't know why you're converting to screen coordinates in the first
> place, and I don't know why the code you posted should ever work, but
[quoted text clipped - 3 lines]
>
> Pete

editWhen is a form. Yes controls on a form use coordinates that are
relitave to the uuiper left of the parent form client area. Forms,
however, use screen relitave coordinates. PointToScreen Translates the
control cordinates on a form, say (10, 10) to screen coordinates like (273,
489).

To get a ComboBox or DateTime picker behaviour where a small frameless
window appears directly below the edit, I use the above code. I have used
thie technique before to position forms below edits. The difference was in
the past I would start with a new control based on say a TextBox, then
override the paint to draw the drop down button and a bunch of other things
to make it work. This time I tried the "easier" method that I got from the
MSDN site and started with a UserControl.

When the control is based on a UserControl it doesn't seem to work the
first time.

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Peter Duniho - 21 Mar 2008 21:17 GMT

> editWhen is a form.

An important piece of information left out of your original post. A good
example of why it's so important to provide a complete code sample, if not
a complete description of what you're doing.

Anyway, I still don't have an answer as to why you are (apparently?)
getting different return values from PointToScreen() for subsequent
calls. Without a concise-but-complete code sample that reliably
demonstrates the problem, it's hard to know where to even start with
suggestions. I've never had trouble with PointToScreen() before, but then
I've never tried to use it from within a UserControl.

There may be some sort of initialization that you need to perform, and
which is done implicitly between the first time you call PointToScreen()
and the second time. Without knowing everything you're doing between
those two moments in time though, I can't offer an alternative. Unless
someone else has seen this exact issue and already has a workaround,
you're going to have to provide more information.

Please note that the "concise" is just as important as the "complete".

Pete

Reply to this Message

A Nonymous - 24 Mar 2008 16:24 GMT

Here are the simplest steps to reproduce:

1. Create a new windows forms project called "WhenPickerTest".

2. Add a UserControl called "clsWhenPicker" set the Size to 120,20.

3. To the user control add a TextBox and set the Location to 0,0, Size
to 100,20, Anchor to all 4 sides.

4. Next add a Button to the project and set its Location to 100,0, Size
to 20,20.

5. In the source of the UserControl just above the constructor add the
following line:
    private Form Picker;

6. In the constructor after InitializeComponent add the following lines:
    Picker = new Form();
    Picker.BorderStyle = BorderStyle.None;
    Picker.BackColor = Color.Green;
    Picker.Size = new Size(200, 200);
    Picker.Hide();

7. Go back to the designer and double click on the button. In the
Button1_Click add the following code:
    If (Picker.Visible)
    Picker.Hide();
    else
    {
    Point P = this.PointToScreen(Point.Empty);
if (P.Y + this.Height + Picker.Height <=
SystemInformation.WorkingArea.Bottom)
P.Y += this.Height;
else
P.Y -= Picker.Height;
Picker.Location = P;
Picker.Show();
    }

8. Compile, then go to the project main for designer. you should be
able to drop a clsWhenPicker on the form.

I think that will do it. If you compile and run you should get the form
with the clsWhenPicker. If you click the drop down button, the first
time the Picker form will probably be located somewhere near the upper
left corner of your screen. Click the button again to close the drop
down, then again to reopen. The second and subsequent times the Picker
form should be in the correct place which is immediately below the
TextBox.

Now this is missing a lot of code but I wanted to keep it simple. In
the actual control I created the "Picker" form is much more complex. I
hide the form when it looses focus and subclass the main form so the
title bar does not lose focus when the Picker is visible, and other
niceties, but this is good enough to demonstrate the problem.

Reply to this Message

Peter Duniho - 24 Mar 2008 18:22 GMT

> Here are the simplest steps to reproduce:

No, actually the simplest steps to reproduce would be if you'd posted a
concise-but-complete sample of code that reliably demonstrates the problem.

Given that I already wrote that and you seem to have misunderstood, you
may find Jon Skeet's article helpful:
http://www.yoda.arachsys.com/csharp/complete.html

Reply to this Message

A Nonymous - 24 Mar 2008 19:00 GMT

>> Here are the simplest steps to reproduce:
>
[quoted text clipped - 5 lines]
> you may find Jon Skeet's article helpful:
> http://www.yoda.arachsys.com/csharp/complete.html

Yea, I thought this would be a waste of time...

Have a nice day!

Reply to this Message

A Nonymous - 24 Mar 2008 19:25 GMT

Peter,

Your responses seem terse and condescending. If you don't want to help and
you see everyone that is asking a question as dumber than you, then why do
you bother.

I thought my initial question was sufficient in that I wanted to know if
anyone was aware of any quirks when using PoiintToScreen in a UserControl.

If you don't know, don't answer.

I don't want to upload a zipped project to the newsgroup, and because of
the type of problem you can't express it in a single file.

Apart from a few clicks I included all of the source needed to recreate a
project to demonstrate the problem. I thought I was doing you a favor
because you might learn something, when someone else answered the problem.

I think my impression of you based on your first response was accurate.
You are completely unfamiliar with this problem and this technique. Have
you ever created a control with DateTimePicker or ComboBox like drop down
behavior? (It's a rhetorical question...)

Please don't bother trying to help with this problem, I have already
decided that it is easer to do it the way I have always done it. There is
definitely something different about using the UserControl.

Thanks for the effort.

Reply to this Message

Peter Duniho - 24 Mar 2008 19:59 GMT

> Your responses seem terse and condescending. If you don't want to help
> and
> you see everyone that is asking a question as dumber than you, then why
> do
> you bother.

You are completely misinterpreting the situation. If I'm terse, it's
because I have nothing more to offer. There's certainly nothing in any of
the messages I posted that you have any valid reason to perceive as being
condescending.

As for your actual question, if you don't want any help, that's fine. My
replies were aimed at helping you understand better how to get an answer
to your question, but if you don't care about that you are free to ignore
what I wrote.

That said:

> [...]
> I don't want to upload a zipped project to the newsgroup, and because of
> the type of problem you can't express it in a single file.

Of course you can. You can always create it in a single file. There's no
need to post the code as an attachment, just create a single .cs file that
includes everything needed, and post the text of that file as part of the
message.

> Apart from a few clicks I included all of the source needed to recreate a
> project to demonstrate the problem. I thought I was doing you a favor
> because you might learn something, when someone else answered the
> problem.

I don't need or want you to do me any favors. However, if you want help
with your question, I _do_ need you to not waste my time, nor the time of
anyone else who might decide they want to try to help.

What do you think would take a would-be helper less time? Copying the
entire source code you've posted intact? Or trying to recreate from
scratch your project using the step-by-step instructions you've provided?
And which do you think is a more reliable way for someone to be
_absolutely sure_ that they have the exact same code you're using?

If you expect to receive useful help from forums such as these, you are
going to need to adjust your attitude. Your hostility and selfishness is
unwarranted and it's a sure-fire way to guarantee that no one will ever
want to help you.

Pete

Reply to this Message

A Nonymous - 25 Mar 2008 16:38 GMT

Pete,

Here again, you obviously misunderstood me.

I don't want you to check my code. I just want to know if anyone else
has seen this problem and knows how to fix it.

And by the way I spent some time with Google and discovered the source
of the problem. It is not actually the PointToScreen at all, but the
StartPosition setting of the form being popped up. If it is not set to
Manual, the first time the form is shown any location that was set is
overridden. Normally when I create a create components like this I hard
code everything. Using a UserControl and dropping components on it is
easier but it is also easy to miss something.

This was the first time I used this technique, and I am relatively new
to C# (but not new to programming). It was a dumb mistake but I have
learned.

So less time? Well I wasn't asking anyone to check my code and if you
knew the answer you could just answer as above. (Did you check the
Form.StartPosition?)

I apologize if everything is not what you expected or exactly the way
you would like it to be.

So relax, Please.

Sorry I can't resist, my hostility and selfishness makes me do it, and I
just like poking at pompous people.

Actually I didn't think I was hostile by pointing out that you seemed
terse and condescending. And as far as selfish, how is asking for help
selfish? I do give back, and post solutions when I find them even if
the solution was not provided here. I do help others, albeit
anonymously.

Even though I have been programming for many years I don't assume I am
superior to anyone. I listen to everyone even novices because anyone can
have a good idea, and even the smartest person can't know everything.

I know you probably think you know more than anyone here. I think you
are probably under 30, been programming for a few years and are fairly
sharp, but not necessarily the smartest one here. I am glad that you
try to help, but now that I have looked at some of your other posts to
other people, I see a pattern. Get over yourself.

I bet you blood pressure is shooting up as you read this...

Have a nice day. ;-)

Reply to this Message

Peter Duniho - 25 Mar 2008 17:48 GMT

> [...]
> Actually I didn't think I was hostile by pointing out that you seemed
> terse and condescending.

If you had approached just those two perceptions, and from an analytic,
helpful point of view, you wouldn't have been. But you didn't. You
presented them in an accusatory way, and the rest of your post was hostile
as well.

> And as far as selfish, how is asking for help
> selfish?

Asking for help isn't selfish. Expecting people who want to help you to
do more work than they should have to is. Everyone here is volunteering
their time, and when you intentionally and pointlessly force someone to
invest more time than is needed in order to try to help you, you're being
selfish (as well as foolish...after all, if my choice is to waste my time
or not, I tend to go with "not", which means if you create a situation
where someone can only help you by wasting their time, they usually will
choose not to waste their time).

> [...]
> I know you probably think you know more than anyone here. I think you
> are probably under 30, been programming for a few years and are fairly
> sharp, but not necessarily the smartest one here.

You are only correct about the last two points...your future employment as
a psychic is very much in question, as you are way off on all the other
two.

> [...]
> I bet you blood pressure is shooting up as you read this...

Another example of your selfishness. Only a selfish person would
intentionally write something intended to raise someone else's blood
pressure. I don't keep a blood pressure monitor by my desk, so I can
neither confirm nor deny your bet. But I don't feel any different, so I
doubt you won the bet.

Pete

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PointToScreen problem in UserControl

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