C# Discussion Boards - CodeProject

1-Apr-04 12:04

Hi,

I have a rather simple problem, yet I can't find an acceptable solution. It isn't much of a problem for users running my application at high resolution (1280x1024 for example), but it really is for 800x600 users (too bad they still exist!)

My application is a MDI and I use FormStartPosition.WindowsDefaultBounds for each child form in order for them to open underneath the previous one (cascade).

The problem is that if I open 3 or 4 windows, a scrollbar shows up on my MDI form and the user needs to scroll to see the new windows. It happens even when no windows are open (ie: 4 windows were opened, then closed, the user will need to scroll to see the next opened window because it is not positionned at the top of the screen like it should).

Is there an easy solution to this? Anyone else having this problem?

Thanks!

Carl

Dave Kreskowiak1-Apr-04 13:10

Dave Kreskowiak

1-Apr-04 13:10

You would have to track the position of the last form you opened. Then add whatever offsets you need in order to keep the next window inside the client area. You would be managing the position and size of the child forms yourself. Simply create a new instance of your child form, set its position and size properties, then show it.

RageInTheMachine9532

Carl Mercier1-Apr-04 17:03

1-Apr-04 17:03

Isn't supposed to be done automatically for me???

Dave Kreskowiak2-Apr-04 4:56

Dave Kreskowiak

2-Apr-04 4:56

The Default behavior doesn't take into account the size of the child window your opening... so no, it won't do it for you.

The Default behavior will walk down the parent window's client area adding up to 10 child windows stepping down and to the right until the new child window's title bar is half way down the client area of the parent window. It will then start at the top-left corner of the parent client area again and start over. It will do this without any reguard to the size of the child windows...

So if you want the entire child window inside the parent client area, you're goin got have to supply your own code for placing the child windows with reguard to it's size.

RageInTheMachine9532

Carl Mercier2-Apr-04 6:12

2-Apr-04 6:12

Urg! Pain in the neck... Let's code! Smile | :)

Dave Kreskowiak2-Apr-04 6:22

Dave Kreskowiak

2-Apr-04 6:22

What? You want Microsoft to do everything for you, just the way you want it? Poke tongue | ;-P

That's why we write code! We want it done OUR way!! Big Grin | :-D

RageInTheMachine9532

Carl Mercier2-Apr-04 6:35

Problem with web browser control in Windows Form

2-Apr-04 6:35

We want it our way, but we also want some free time to chill out and watch tv Smile | :)

Tim Kohler1-Apr-04 11:23

Tim Kohler

1-Apr-04 11:23

I'm having a problem with using the Web Browser ActiveX control in a C# windows form app. The circumstance is easily reproducable:

Create the boiler plate example of this using the VS toolbox to create the ActiveX wrapper and add then drag it into your C# form.

Now, open up a web page with your forms app. For instance, mail.yahoo.com. Click in the user name entry field so that focus is there. Now minimize your form app and then bring it right back up. All of a sudden that entry field no longer has the focus.

I have another example using this control through a VC++ 6 MFC SDI app and ironically, it works fine there (the entry field still has focus).

Any ideas on what to look at? I thought it might have to do with message routing differences between windows forms and MFC SDI but hooking the app up to Spy++ didn't reveal anything. Now I'm thinking it's a problem with the .NET generated wrapper but I'm at a loss as to what to do about it.

???

any help appreciated!

ComboBox on a ToolBar Menu

adam.southerland@oscn.net1-Apr-04 11:22

adam.southerland@oscn.net

1-Apr-04 11:22

I'm wanting to create a ToolBarMenu with a few combo boxes... I'm having problems on figuring this out.

Does anyone have any sample code to do this? (for .Net Framwork 1.1)

problem with the project reference

dizzyha1-Apr-04 10:35

dizzyha

1-Apr-04 10:35

I have multiple projects in a solution and I am trying to create dependencied, but when i was trying to add a project reference i got the following message:

A reference to NDMUI could not be added. An assembly must have a "dll" extension in order to be referenced.

I do not not how to resolve it......may someone please help!

Tryin' my best

Re: problem with the project reference

Heath Stewart1-Apr-04 10:40

Re: CreateGraphics Problem

1-Apr-04 10:40

VS.NET doesn't let you reference a .exe. It is possible, but you'll have to use the command line compiler (csc.exe) or a build tool like NAnt[^].

Microsoft MVP, Visual C#
My Articles

CreateGraphics Problem

Tristan Rhodes1-Apr-04 10:25

Tristan Rhodes

1-Apr-04 10:25

I figure that to draw my little windows style borders, i need to actualy have a valid handle to the grahics device for the control.

Now, I have this section of code i have included in my component constructor that causes a problem:

Graphics clientDC = this.CreateGraphics(); <br />
IntPtr hdc = clientDC.GetHdc(); <br />
pDC = ThemeAPI.CreateCompatibleDC(hdc);<br />
clientDC.Dispose();

That throws the following error on run time:

An unhandled exception of type 'System.InvalidOperationException' occurred in system.drawing.dll

Additional information: The object is currently in use elsewhere.

Now, i know it's caused by the existence of the ClientDC, but i'm not sure how to go about solving this one.

I need to get the creatgraphics for the component in question, but I guess, as i'm creating three duplicate components at initialisation, it's running three seperate threads at once, and it's not liking the use of the Device Context. If i don't dispose of it, the program runs for a while before crashing.

Should I construct a graphics handle in the parent form?

Cata

Heath Stewart1-Apr-04 10:39

Re: CreateGraphics Problem

1-Apr-04 10:39

Call clientDC.ReleaseHdc(pDC) when you're done with the HDC, then dispose your Graphics object.

Microsoft MVP, Visual C#
My Articles

Tristan Rhodes1-Apr-04 10:50

Tristan Rhodes

1-Apr-04 10:50

Okey dokey, works now.

I was trying to use P/Invoke DeleteDC(pDC). It clearly wasn't happy with that.

But i've still got nothing drawn on my background. I think i have the object values right, and i've tried a number of values for iState. So i'm not entirely sure why nothing is appearing. Here is the code

<br />
			pTHEME = ThemeAPI.OpenThemeData(this.Handle,"Window");<br />
<br />
			Graphics clientDC = this.CreateGraphics(); <br />
			IntPtr hdc = clientDC.GetHdc(); <br />
			pDC = ThemeAPI.CreateCompatibleDC(hdc);<br />
<br />
			//Build content Pane<br />
			ThemeAPI.Rect rect = new ThemeAPI.Rect();<br />
			rect.left = this.Location.X;<br />
			rect.top = this.Location.Y;<br />
			rect.right = this.Location.X + this.Size.Width;<br />
			rect.bottom = this.Location.Y + this.Size.Height;<br />
<br />
			int result;<br />
			//Draw Background<br />
			result = ThemeAPI.DrawThemeBackground(pTHEME,pDC,5,1,ref rect,IntPtr.Zero);<br />
			result = ThemeAPI.DrawThemeBackground(pTHEME,pDC,7,1,ref rect,IntPtr.Zero);<br />
			result = ThemeAPI.DrawThemeBackground(pTHEME,pDC,8,1,ref rect,IntPtr.Zero);<br />
			result = ThemeAPI.DrawThemeBackground(pTHEME,pDC,9,1,ref rect,IntPtr.Zero);<br />
<br />
			clientDC.ReleaseHdc(pDC);<br />
			clientDC.Dispose();

What do you make of it?

Re: CreateGraphics Problem

Heath Stewart2-Apr-04 8:58

Re: DragDrop registration failed - Error

2-Apr-04 8:58

Deleting the HDC that way is fine if you don't use Graphics.GetHdc to get it. The reason is that the unmanaged pointer that the Graphics references needs to be freed, otherwise the Graphics object will complain about having an invalid handle when the Graphics.Dispose method tried to delete it.

Microsoft MVP, Visual C#
My Articles

Heath Stewart1-Apr-04 8:46

Re: DragDrop registration failed - Error

1-Apr-04 8:46

You get that error when the application is not loaded into an STA (single-threaded apartment). Make sure you use the STAThreadAttribute on your entry point and that any controls in your library used in an application are created in the main thread.

Microsoft MVP, Visual C#
My Articles

Tristan Rhodes1-Apr-04 10:39

Tristan Rhodes

1-Apr-04 10:39

Too late m8!

Got to that one on my own Smile | :)

MDIChild help

robmays1-Apr-04 8:37

robmays

1-Apr-04 8:37

there are lots of examples on how to set up child form from the MainMDI but i cant find anything on how to open a form from another child form and setting the MDIParent so as it becomes child form, where am i going wrong??? Cry | :((

Re: MDIChild help

Heath Stewart1-Apr-04 8:58

1-Apr-04 8:58

So long as you're not talking about an MDI child form within another MDI child form (which isn't supported in the .NET FCL), you can simply get the parent MDI form of the first child and add the new child as an MDI child of the parent:

MDIChildForm child = new MDIChildForm(); // Or whatever your class is
if (MdiParent != null)
  MdiParent.AddOwnedForm(child);

Microsoft MVP, Visual C#
My Articles

Re: MDIChild help

robmays1-Apr-04 9:14

robmays

1-Apr-04 9:14

fantastic response and worked first time. Smile | :)

Give a panel a focus

Jonathan Slenders1-Apr-04 8:22

Jonathan Slenders

1-Apr-04 8:22

How can i make a panel that can receive a focus
I used the GotFocus and LostFocus events to turn the panel blue when focussed. But how can i set the CanReceiveFocus Property true so that you can use your keyboard (Tab and arrows) to give that control the focus. (That panel also conatains a picturebox and a label).

Thanks

Jonathan Slenders

Re: Give a panel a focus

Heath Stewart1-Apr-04 8:55