help me on GetChildAtPoint

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this is my code.every time i run the program it returns null.can you solve this?

C#

Point P = new Point(64, 46);
           Control locatecontrol =this.GetChildAtPoint(P);
           Button BTN1 = new Button();
           BTN1 = (Button)locatecontrol;
           MessageBox.Show(BTN1.Text);

i have a Button there but again null :|
help me.
i have searched for this but i could not solve my code.

Posted 20-Dec-13 21:59pm

Farshad72

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Richard MacCutchan 21-Dec-13 4:26am

I just tested this on my system and it works fine. I suggest you use your debugger to try and determine exactly what exists at that point on your form. You might also like to explain exactly what you are trying to achieve.

2 solutions

Solution 2

you use RightToLeft
change back to LeftToRight or mybe can use

C#

if(this.RightToLeft==System.Windows.Forms.RightToLeft.Yes)
   pos.x=Width-pos.x;

Posted 12-Apr-14 4:03am

farshad saeidi

v2

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OriginalGriff · Accepted Answer · 2013-12-20T22:19:00

Solution 1

It works fine for me, if there is a Button at the appropriate point.
I'd change it slightly and use as instead myself (or you could get casting exceptions):

C#

Point p = new Point(64, 46);
Control c = GetChildAtPoint(p);
Button btn1 = c as Button;
if (btn1 != null)
    {
    MessageBox.Show(btn1.Text);
    }

Assuming there is a button at the point, it should work, but put a breakpoint on the first line of the code and step through looking at the variables - you need to know what GetChildAtPoint is returning is there is a problem.

Posted 20-Dec-13 22:19pm

OriginalGriff

Comments

Farshad72 21-Dec-13 4:27am

i put break point on this line
Control c = GetChildAtPoint(p);
and after that line C is present NULL again.

OriginalGriff 21-Dec-13 4:38am

Which means there is no control at that point.
So, look at your form in the designer, and (assuming this code is in your form class) drop a new button onto the form. Pick it up with the mouse and drag it around the form - look at the bottom right of the VS window: numbers will be changing. They show you where the top left of the control is - so move it to (roughly) (60,40) and look to see what is beneath that point.
Anything?

Farshad72 21-Dec-13 4:51am

i changed my code too see that my point is the exact location of my button
Point p = B1.Location;
Control c = GetChildAtPoint(p);
Button btn1 = c as Button;
if (btn1 != null)
{
MessageBox.Show(btn1.Text);
}
agian null :|

OriginalGriff 21-Dec-13 4:58am

That means there is no control at that location.
Look at your form in the designer: drop a button onto the form, and pick it up with the mouse. Move it around, and look at the bottom right of the VS screen - there are numbers moving. Those are the coordinates of the top left corner of the new button. Move it to roughly (60,40) and look at what is below it.
Anything?

Farshad72 21-Dec-13 5:09am

Point p = B1.Location;
Control c = GetChildAtPoint(p);
Button btn1 = c as Button;
if (btn1 != null)
{
MessageBox.Show(btn1.Text);
}
again null

OriginalGriff 21-Dec-13 5:36am

And? What is at the location?

Farshad72 21-Dec-13 5:41am

B1.location returns {X=68,Y=162}
and agian GetChildAtPoint returns NULL

OriginalGriff 21-Dec-13 5:51am

Yes. So the Top Left of your button is at (68,162) and you are looking for it at (64,46).
You won't find it there, will you?
Try this:
Point p = new Point(70, 165);

Farshad72 21-Dec-13 5:48am

this is my row project for this problem
https://www.mediafire.com/?ed00mtv36vochz4

OriginalGriff 21-Dec-13 6:10am

I'm not going to download random compressed archives from a website noted as a porn host, now am I?

Farshad72 21-Dec-13 6:23am

this is mediafire!!!how can i send my project?
http://www.mediafire.com/download/ed00mtv36vochz4/find.rar

OriginalGriff 21-Dec-13 6:42am

And what do you think is the bulk of the material stored on Mediafire? And FileServe, NetLoad, etc., etc. - that's why many companies automatically ban them...

And I don't want your project! I have plenty of my own, thank you! :laugh:

Farshad72 21-Dec-13 6:48am

it is not a big project!it just has 5 line after Initialize!i just want you to see that it does not work and help me.i have to find a way!tomorrow is my deadline

OriginalGriff 21-Dec-13 7:00am

Yes, but I don't know you, so I can't trust your code. So, I have to create a new VM, with a fresh VS installation so I can "sandbox" your project in case it does anything nasty. (Not saying it would, but I don't want to take the chance).

But... did you say "5 line after Initialize" because this code is immediately after the line:
InitializeComponent();
If so, then that is probably your problem.
You don't have a form shown at that point (you are in the constructor) so you don't have any form surface to refer to when you check your point with GetChildAtPoint - so it returns null - it has to, there is nothing to look at!
Try this: Add a form Click event handler, and copy your code into that. run your app, and click on the form. Your message box will appear, I'm pretty sure!

Farshad72 21-Dec-13 7:16am

it was a little part of my project.thanks .it worked

OriginalGriff 21-Dec-13 7:21am

You're welcome!