.NET (Core and Framework)

12-Jul-06 5:02

I have a control that is derived from the standard ComboBox. I have an override for the OnPaint method that paints a border, drop down arrow button, background, and foreground. The only problem is that something (some other event/subcontrol) is drawing a black text box with a large font over top of the text box region of the combo box control.

I am drawing a background in my OnPaint event, and it is being draw on top of. I can see that the background is drawn because there is a border around the text box region. My code looks like the following:

<br />
protected override void OnPaint(PaintEventArgs e)<br />
{<br />
	base.OnPaint(e);<br />
<br />
	DrawBorder();<br />
	DrawBackground();<br />
	DrawArrowButton();<br />
	DrawForegroundText();<br />
}<br />

What am I missing here??? By the way, this control works just fine if the DropDownStyle is set to DropDownList, however I'm need it to work as a DropDown (being able to edit the text box).

--Ian;

Dave Kreskowiak12-Jul-06 5:16

12-Jul-06 5:16

In calling all of your painting functions, are you passing the Graphics object sent inside the PaintEventArgs or are you creating another one?? You should be passing the Graphics given to you by the PaintEventArgs.

Dave Kreskowiak
Microsoft MVP - Visual Basic

--Ian12-Jul-06 6:42

12-Jul-06 6:42

Sorry for my simple example. Yes, I am passing the PaintEventArgs that is passed to the event. So the GC is being used to do all the painting.

--Ian;

Dave Kreskowiak12-Jul-06 12:09

Re: ComboBox Custom OnPaint -- CODE

12-Jul-06 12:09

That's why we always suggest Copy-'n-Paste the code instead of retyping it.

You said that this text is being painted OVER what your code painted?

Dave Kreskowiak
Microsoft MVP - Visual Basic

--Ian12-Jul-06 12:27

Re: ComboBox Custom OnPaint -- CODE

12-Jul-06 12:27

I'm painting the background a green with a FillRectangle, and when it is displayed to the screen, I see a 2 or 3 pixel border of green surrounding a black text box region (that was not drawn by me). This is what I mean when I say that it was drawn over top of what I had drawn.

The sample class below does not contain all the code, however it will give you an idea of the problem. Just drop this class into your a project, compile, and drop it the ComboDraw control onto a form.

<br />
using System;<br />
using System.Collections.Generic;<br />
using System.Drawing;<br />
using System.Text;<br />
using System.Windows.Forms;<br />
<br />
namespace ComboTest<br />
{<br />
	class ComboDraw : ComboBox<br />
	{<br />
		public ComboDraw()<br />
		{<br />
			DrawMode = DrawMode.OwnerDrawFixed;<br />
			DropDownStyle = ComboBoxStyle.DropDown;<br />
			FlatStyle = FlatStyle.Flat;<br />
			SetStyle(ControlStyles.UserPaint, true);<br />
		}<br />
<br />
		protected override void OnPaint(PaintEventArgs e)<br />
		{<br />
			base.OnPaint(e);<br />
<br />
			e.Graphics.FillRectangle(new SolidBrush(Color.Green), ClientRectangle);<br />
		}<br />
	}<br />
}<br />

--Ian;

-- modified at 9:19 Thursday 13th July, 2006

Dave Kreskowiak13-Jul-06 6:18

13-Jul-06 6:18

OK. I see what you're looking at.

You're seeing the TextBox being drawn by the underlying ComboBox class. The bad news is, as far as I can tell, you can't get rid of it and can't override it. It's completely hidden behind "private" everything.

I've also never had to custom draw the entire Combobox. I've only done the drop down list and that turned out to be pretty easy.

Why are you trying to custom paint the entire thing?

Dave Kreskowiak
Microsoft MVP - Visual Basic

--Ian13-Jul-06 7:02

13-Jul-06 7:02

Why? I ask myself that question all the time. The answer is the same old story of having all controls behave consistently to the color scheme that has been chosen. Sometimes you can't choose your battles, you just have to fight. I have a few more hacks to try in the meantime.

--Ian;

Dave Kreskowiak13-Jul-06 12:23

Re: DropDown Button in C#

13-Jul-06 12:23

I have no idea how to get past this one. If it wasn't such a PITA composite control, it'd be real easy!

Dave Kreskowiak
Microsoft MVP - Visual Basic

DropDown Button in C#

wasife12-Jul-06 4:57

wasife

12-Jul-06 4:57

Hi,
How can add a dropdown button in a Windows Application?

Regards,
Wasif Ehsan.

Guffa12-Jul-06 12:58

Guffa

12-Jul-06 12:58

What do you mean by a dropdown button?

---
b { font-weight: normal; }

Re: DropDown Button in C#

Josh Smith14-Jul-06 5:31

Josh Smith

14-Jul-06 5:31

A dropdown button is a normal button with a separate section on the right (or left) side with an arrow image. When you click on the arrow, a little dropdown container pops open. The container can provide other options related to action performed by clicking the button.

:josh:
My WPF Blog[^]

Re: DropDown Button in C#

Josh Smith14-Jul-06 5:28

Josh Smith

14-Jul-06 5:28

The Infragistics NetAdvantage suite has the UltraDropDownButton control. Other than that, there's no dropdown button control in WinForms that I know of.

:josh:
My WPF Blog[^]

Need some help for merging Crystal Reports

Jats_4ru11-Jul-06 23:54

Jats_4ru

11-Jul-06 23:54

I am using Microsoft visual studio 2005
Now Bussiness objects provide 3 different kinds of merge modules....
1-> Crystal Report for .Net Framework 2.0 x86 Redistributable package(32 bit)
2-> Crystal Report for .Net Framework 2.0 IA 64 Redistributable package(64 bit)
3-> Crystal Report for .Net Framework 2.0 x64 Redistributable package(64 bit)

Now i am not able to figure out which modules will suite my application.
Can any one help me in figuring it out.
How to find wheather my .net framework is x86 (or) IA 64 (or) x64.

Thank U.

Jats

How to get the complete scrollable height and width of a control

Yash Purohit11-Jul-06 22:36

Yash Purohit

11-Jul-06 22:36

Hi,

I am hosting a browser control(framework 2.0) in a form of fixed size. Control is docked as fill in the win form.

The control navigates to some url and displays the web page. Now if the web page size exceeds the win form size scrollbars appears.

I want to calculate the complete height and width of control(complete scrollable height and width). Let me know how i can do it.

Note that i can do it using the HTMLDocument's scrollheight and scrollwidth properties but the problem is it returns correct values only when the height and width are specified. Correct values are not guaranteed through it.

Thanks,

Yash

Exceptions in .net

narasimha peta11-Jul-06 18:22

narasimha peta

11-Jul-06 18:22

Why can’t we use Exception class for handling all exceptions. Why do we use specific calsses like Arithmetic Exception, IOException etc...

Thanks
Simha

simha

Re: Exceptions in .net

Rob Philpott12-Jul-06 3:46

Rob Philpott

12-Jul-06 3:46

...you can like this (C#):

try
{
    // the thing you want to do
}
catch (Exception ex)
{
    // the code to run if an exception is raised
}

But all you get is a signal if anything fails. By using different exception types, you can perform different actions when failure occurs.

try
{
    // the thing you want to do
}
catch (ArgumentException ex)
{
    // the code to run if a bad parameter has passed
}
catch (IOException ex)
{
    // the code to run if an IO exception occurs
}

Regards,
Rob Philpott

Re: Exceptions in .net

Dan Neely12-Jul-06 4:41

Dan Neely

12-Jul-06 4:41

You should however have a blanket catcher at the end of your highest level catch blocks to do a clean shutdown when an unanticipated error occured because the app could've ended up in an incoherant state.

Re: Exceptions in .net

eggsovereasy12-Jul-06 10:44

eggsovereasy

12-Jul-06 10:44

This works because all the other exceptions inherit from System.Exception (although, not directly). A child exception should be listed before its parent in a list like above. Lets say I made two custom exceptions:

BadDataException
and
BadIntegerException : BadDataException

A BadInteger is a specific kind of BadData so I have it inheriting from BadData. This means I have to option of catching any BadData and doing something or:

<br />
catch (BadIntegerException)<br />
{<br />
  //do stuff<br />
}<br />
catch (BadDataException)<br />
{<br />
  //do other stuff<br />
}<br />

which would do something if it were an integer, but something else if it were a different kind of bad data.

This:

<br />
catch (BadDataException)<br />
{<br />
  //do stuff<br />
}<br />
catch (BadIntegerException)<br />
{<br />
  //do other stuff<br />
}<br />

Is bad because an BadIntegerExceptions that get thrown will be caught by the first catch and the code in the second block will never get executed.

Does the CLR cache .config values or tracing levels?

nicknotyet11-Jul-06 4:22

nicknotyet

11-Jul-06 4:22

It does make sense to me that it would, but when I have multiple assemblies that examine the (TraceLevelSwitch), which is configure for a different value in each assembly. However, they all seem to operate on the same value, rather than the one configured in the individual .config files.

Detail:

Assembly A - .dll
Assembly B - .dll
Assembly C - windows forms app .exe

All assemblies use the following code:

private static System.Diagnostics.TraceSwitch _TraceLevelSwitch = new System.Diagnostics.TraceSwitch("TraceLevelSwitch", "Tracing level");

All assemblies seem to pick up the value for Assembly C, which runs/loads first.

Anyone got some insight into this?

Re: Does the CLR cache .config values or tracing levels?

Dave Kreskowiak11-Jul-06 4:26

Re: Does the CLR cache .config values or tracing levels?

11-Jul-06 4:26

.DLL's can't have their own config files. They'll always use the .EXE's config in which their running.

Dave Kreskowiak
Microsoft MVP - Visual Basic

nicknotyet11-Jul-06 6:25

nicknotyet

11-Jul-06 6:25

I was afraid of that.

Perhaps I could use different explicit switches in the main app's .config?

Thanks for the reply.

Re: Does the CLR cache .config values or tracing levels?

Rob Philpott12-Jul-06 3:50

Rob Philpott

12-Jul-06 3:50

The configuration is on the AppDomain level. If you're bonkers enough you can create a new appdomain, set its base directory/config file path etc, load your satellite assemblies in to that, and call them dynamically, but its a rubbish idea and I wish I'd never said anything now.

Regards,
Rob Philpott.

Re: Does the CLR cache .config values or tracing levels?

nicknotyet12-Jul-06 4:01

nicknotyet

12-Jul-06 4:01

No Worries.

By constructing the key (value) name at run-time, based on the assembly name, I can control the behavior of each assembly individually from one .config file, which is a better solution anyway. Big Grin | :-D

Thanks for the info.

Re: Does the CLR cache .config values or tracing levels?

Dave Kreskowiak12-Jul-06 4:11