Re: GDI Drawing over controls - C# Discussion Boards

Luc Pattyn9-Aug-07 2:32

Luc Pattyn

9-Aug-07 2:32

Hi Martin,

I don't know what the z-order would be of existing controls and the form's own ink.
And frankly I don't care, I never paint on a Foem, I paint on a Panel, and yes if
the requirement would be to paint over existing controls, I would add a disabled
and transparant Panel in front of everything (not another Form! I try to keep things simple)

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google

Martin#9-Aug-07 2:41

Martin#

9-Aug-07 2:41

Hello Luc,

Luc Pattyn wrote:
z-order

I just wanted to say, infront: like the z-Order of Controls.
Has nothing todo with form's ink, off corse!

Luc Pattyn wrote:
(not another Form! I try to keep things simple)

It depends on the task, if this statement is valid or not, I guess.

Smile | :)

All the best,

Martin

aparsons_cp14-Aug-07 2:30

aparsons_cp

14-Aug-07 2:30

Thanks for the replies. I'm still working on it and making some progress. If I use DrawReversibleLine which draws a nice clean line down the form over everything as I want I get a problem with it painting over other windows. This happens especially when it is partially covered by other windows and they move. My application draws a moving line that is triggered by a clock tick. At the moment I am going down the path of using DrawLine. This however will require a pretty full repaint every time the pointer moves, it will however behave properly as far as Windows is concerned.
DrawReversibleLine takes screen coordinates and will draw a line on the screen using the coordinates you give it regardless of any windows that might be partially obscuring yours. I really need the extents of the unobscured window so I can give DrawReversibleLine coordinates that only fall within the visible window. Am looking at GetUpdateRect at the moment to see what that will give me.

aparsons_cp15-Aug-07 23:21

aparsons_cp

15-Aug-07 23:21

It would be helpful if I could find the part of the form/window that is actually visible at anytime and not partly obscured by other windows. DrawReversibleLine as it uses screen coordinates doesn't seems to draw right over them. Normally this would not happen but my application responds to a timer tick so paining and graphic update activity takes place when the window does not have the focus.

I have scoured the forums and sites for anything I can find on the subject but it seems that the only way to get the shape of the visible part of the window or indeed to find out if it has been partly obscured is to go through the list of all the windows on the desktop and check their details. It seems that the actual window/form itself does not know when it has been obscured.
Have found a couple of people who have had exactly the same query over the years but the thread just stopped. So perhaps they found the answer and did not log it, or realised it was insoluble (not really just complex and laborious) and did it another way.

I'm going probably going to draw on a transparent panel or directly over the form which works and politely observes the boundaries of other windows. It just involves more painting and work for the operating system whereas DrawReversibleLine just draws and undraws over the screen.

Thanks for the replies and the additional info, I feel like Edison I now know tons of ways that will not work and like Sherlock Holmes what is left is what I must use.

The couple of questions that remain are:
1) How does one get the visible region of a partly obscured window?
2) Can a window detect when it is being obscured?

Kind Regards,
Andrew Parsons (UK)

Luc Pattyn16-Aug-07 1:26

Luc Pattyn

16-Aug-07 1:26

Hi Andrew,

aparsons_cp wrote:
How does one get the visible region of a partly obscured window? Can a window detect when it is being obscured?

I see no way to get that. The Paint handler gets a Graphics which holds a clipping
rectangle (obviously not good enough to give the details), and a clip region which
is not minimal (seems to be rectangular too). I tested the clip region by feeding
some points to Region.IsVisible() and it seems to ignore cover ups.

There is no cover up event; Paint gets fired when the Control gets (partially)
uncovered, not (partially) covered.

So I am not convinced ControlPaint.DrawReversibleLine() is the right tool for you;
I understand the reversible is nice, but you clearly want to draw to a Form,
not to the screen. (Actually the whole ControlPaint class seems wrong, the
ButtonHover/Leave example also does not take into account a possible cover up).

BTW: seems like a good topic for a CP article !

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

JVilmaire19-Aug-07 15:13

JVilmaire

19-Aug-07 15:13

Hey guys,

Im having the same problem drawing on top of controls, and I tried to use the method discussed here in this thread. I created a panel that has properties of Enabled = false, and the forecolor and backcolor set to transparent. Is this what they mean by a transparent disabled panel? I have not tried to draw to it because it causes my application to crash when the visible property is set to true and it is over the area I need it to overlay... it doesnt crash the application when it is instead placed over another panel that has some different controls, it does occlude the controls though...

I need help with making this transparent panel, anyone know how to do it?
James

Help regarding timer control

Luc Pattyn19-Aug-07 22:31

Luc Pattyn

19-Aug-07 22:31

Hi, you should have replied this to one of Andrews posts, not to mine, I am the
one who poiintged you to this thread!

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

anu819-Aug-07 1:42

anu81

9-Aug-07 1:42

hi all,

I am developing a windows application using C#. i am using gridview to display the records of a table. i need to display new records that comes latest at the top of a table. i am using a timer for every minute to check the table for records.

i need to display a alert saying that a new record has come.

i wrote the following code,

string display = "";

display = "select count(*) as count,fname,emp_id from emp_new where status=0 and " +
"hire_date='" + DateTime.Today + "' group by emp_id,fname order by emp_id desc";

sqlcomm = new SqlCommand(display, conn);
sread = sqlcomm.ExecuteReader();

while (sread.Read())
{
panel1.Visible = false;
count = (int)sread["count"];
employee = sread["fname"].ToString();
display_count();
}

sread.Dispose();
sqlcomm.Dispose();

and in the display_count method, i am displaying the message in a label control.

but it displays only the last new message. i need to display each record in a gap interval of 5 seconds

how to do this?

Thanks in advance. Smile | :)

Regards

Anuradha

kubben9-Aug-07 1:48

9-Aug-07 1:48

There is probably an ajax way of doing this, but I am not that familar with ajax. I would use a meta tag to auto update the page. Here is the syntax:
<meta http-equiv="Refresh" content="n;url">

n is the number of seconds to wait before loading the specified URL.

url is an absolute URL to be loaded.

This will cause your page to auto post back in which case you can run your query and update the gridview.

Hope that helps.
Ben

anu819-Aug-07 2:43

anu81

9-Aug-07 2:43

Thanks for the reply. but if you notice, i am using a windows application and not a web application..

Thanks in advance. Smile | :)

Regards

Anuradha

kubben9-Aug-07 6:04

9-Aug-07 6:04

Sorry about that. I guess I wasn't quite awake when I read your post. I saw gridview and was thinking web.

Ben

Martin#9-Aug-07 2:53

Martin#

9-Aug-07 2:53

Hello,

So you are getting the datas in the right time intervall, but only the last one will be updated?

I think you have to call
Application.DoEvents();
after
display_count();

If this is the method were you set the text of the label.

All the best,

Martin

anu819-Aug-07 3:27

anu81

9-Aug-07 3:27

hi martin,
yes,i am getting the datas in the timer. i did call the application.doevents() as you said.

but still i am getting only the last new message.

in the method display_count, i am displaying the text in the label control.

Thanks in advance. Smile | :)

Regards

Anuradha

Martin#9-Aug-07 3:35

Martin#

9-Aug-07 3:35

Hello,

Hmm,

I'm not very familiar with SQLCommands and it's possibility of a threading problem in combination with GUI interaction, but maybe the method which setts the label text, needs to be invoked. (Please correct me if this is total rubbish!)Check 'InvokeRequired'.

All the best,

Martin

kubben9-Aug-07 6:06

9-Aug-07 6:06

I think this would do it.

display_count();
//new code
Application.DoEvents();
System.Threading.Thread.Sleep(5000);
} //end of loop

Hope that helps.
Ben

COM in C#

Stevo Z9-Aug-07 1:30

Stevo Z

9-Aug-07 1:30

Hi,

I've a COM-object written in C++ (VS 6), that is used in my C# (.NET 2.0) application. Everything works fine when my program runs on my computer (where it is build). But as soon as I copy this program to another computer, register that COM using regsvr32.exe MyCOM.dll , when calling that com I get Exception - Attemp to read or write protected memory. and things stop to work...

do you have any idea what could be wrong?

thanx

comparing image

Xmen Real 9-Aug-07 1:26

Xmen Real

9-Aug-07 1:26

hi there,
i wanna compare buttons background image something like this :

if (abcBtn.BackgroundImage != Properties.Resources.abc_un)

or like this

if (xyz.BackgroundImage == global::mypro.Properties.Resources.xyz_cur)

both code arent working properly but their working are different
in first Code C# is entering in if statemen where abcBtn background image is different (eg. def image)

in second code C# isnt entering in if statement where xyz background is same as written "xyz_cur"

Becoming Programmer...

Re: comparing image

kubben9-Aug-07 1:50