Opaque Controls - C# Discussion Boards

James T. Johnson6-Jul-02 8:59

6-Jul-02 8:59

XOR mode drawing isn't supported in GDI+ because its use was considered a hack since you couldn't control the color that was output from its operation.

The recommended solution is to do your drawing so that you don't need XOR mode; or emulate it.

For instance if you were creating a progress bar control that showed the percentage in the middle (ala most setup programs) you would draw the text twice; once with the clipping set to just the area that is being filled; again with it set to the area not being filled choosing appropriate colors both times.

This is a GOOD thing though; because then font features such as antialising and cleartype will work; where as they won't if you blit to a bitmap then xor the bitmap onto another one.

James
"Java is free - and worth every penny." - Christian Graus

Re: XOR mode...

Vu Truong7-Jul-02 2:48

Vu Truong

7-Jul-02 2:48

Hi James,

Do you think that I can use the Region class for this issue? I want to build a drawing application which use mouse to draw a shape. But when I drag the mouse I can't clear the previous shape. Can you show me a solution?

Thanks.

Re: XOR mode...

Oyvind Bratland7-Jul-02 21:03

Oyvind Bratland

7-Jul-02 21:03

Check out this link:
http://support.microsoft.com/directory/article.asp?ID=KB;EN-US;Q314945&

This works only with rectangles and lines.

Øyvind

WinXP-style Balloon Tips in WinForms

JoelDKraft5-Jul-02 17:58

JoelDKraft

5-Jul-02 17:58

I am trying to use the new XP ballon-style notification tooltip from C# on a WinForms control. I thought I had a pretty good handle on the interop stuff, but am still having some problems.

I've defined the interop pieces I need as follows:
[ StructLayout( LayoutKind.Sequential )]
public struct EDITBALLOONTIP
{
public int cbStruct;
[MarshalAs(UnmanagedType.LPWStr)]
public string pszTitle;
[MarshalAs(UnmanagedType.LPWStr)]
public string pszText;
public int ttiIcon;
};

public const uint EM_SHOWBALLOONTIP = 0x1500 + 3;
public const uint EM_HIDEBALLOONTIP = 0x1500 + 4;
public const int TTI_NONE = 0;
public const int TTI_INFO = 1;
public const int TTI_WARNING = 2;
public const int TTI_ERROR = 3;

[DllImport
("user32.dll",CharSet=CharSet.Unicode,SetLastError=true)]
private static extern int SendMessage(
IntPtr _WindowHandler,
uint _WM_USER,
int _data,
[In] ref EDITBALLOONTIP _id);

So then I create a textbox and place the following in a button click handler:

EDITBALLOONTIP ebt = new EDITBALLOONTIP();
ebt.cbStruct = Marshal.SizeOf(typeof(EDITBALLOONTIP));
ebt.pszTitle = "TITLE TEXT";
ebt.pszText = "This is the text of the balloon.";
ebt.ttiIcon = TTI_ERROR;

MessageBox.Show(
SendMessage(textBox1.Handle,
EM_SHOWBALLOONTIP,0,ref ebt).ToString());
MessageBox.Show(
Marshal.GetLastWin32Error().ToString());

I've used this basic structure to send some other messages around, but this one gives me errors. The first time I click the button when I run the program, I get error 127 (The specified procedure could not be found.), and every time after that, I get 1421 (Control ID not found.).

Any insights are appreciated!
Joel

How to search the Message Boards?

Juergen5-Jul-02 6:40

Juergen

5-Jul-02 6:40

Perhaps a stupid question, but how can I search in the message board?
(The normal search only works for articles)

Re: How to search the Message Boards?

Nnamdi Onyeyiri5-Jul-02 7:01

Nnamdi Onyeyiri

5-Jul-02 7:01

i noticed that, the text box that you used to be able to use is now gone. but i never used it anyway, the one time i wanted to use it, was the moment after it was gone. Mad | :mad:

Green Alien | [Alien] Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk

Re: How to search the Message Boards?

Mazdak5-Jul-02 8:49

Mazdak

5-Jul-02 8:49

It disappear for unknown reason. Cry | :((

Mazy

"If I go crazy then will you still
Call me Superman
If I’m alive and well, will you be
There holding my hand
I’ll keep you by my side with
My superhuman might
Kryptonite"Kryptonite-3 Doors Down

Opaque Controls

Martin D5-Jul-02 4:34

Martin D

5-Jul-02 4:34

Hi folks

I'm trying to work out if it's possible to make controls on a form transparent or not in the sense that i would like to be able to 'see through' a label control to partially read the text on other controls behind it.

By setting the Color.Transparent property i seem to pick up the color of the parent control but this doesn't allow me to read anything on the parent control - it just sets my child control to the same color.

I know this can be done with Forms by amending the Opacity property but is there any way this can be applied to controls on forms?

Cheers

Re: Opaque Controls

Marc Clifton21-Nov-02 1:21

Marc Clifton

21-Nov-02 1:21

Hi Martin,

Did you ever figure out how to do this? I'm trying to figure out the same thing!

Thanks,

Marc

Help! I'm an AI running around in someone's f*cked up universe simulator.

Drawing Application...

Vu Truong5-Jul-02 2:20

Vu Truong

5-Jul-02 2:20

Hello all,

Please show me where I can find out a drawing application that built by C# using GDI+. The source code is enclosed certainly.

Thanks.

Re: Drawing Application...

Rüpel5-Jul-02 2:36

Rüpel

5-Jul-02 2:36

there's a C#-scribble in my MSDN-documentation. maybe you also have one...

:wq

Copy or reference?

Daniel Strigl5-Jul-02 1:57

Daniel Strigl

5-Jul-02 1:57

If I write following code:

int i = 1;
object o = i;
object a = o;

Is 'o' a reference to 'i' or
is 'o' a copy of 'i' ???

Is 'a' a reference to 'o' or
is 'a' a copy of 'o' ???

(Sorry for my bad english Wink | ;-)

)

Thanks for every answer!

Re: Copy or reference?

SimonS5-Jul-02 2:08

SimonS

5-Jul-02 2:08

jb_dani wrote:
Sorry for my bad english
It's fine. Wink | ;)

int i = 1;
object o = i;
Console.WriteLine(o.ToString());
i=10;
Console.WriteLine(o.ToString());
Console.ReadLine();

Output is: "1 \n 1"
The "i" value is copied to object "o", so there is no longer a reference between the two.

HTH

Cheers,
Simon

"Sign up for a chance to be among the first to experience the wrath of the gods.", Microsoft's home page (24/06/2002)

Re: Copy or reference?

Daniel Strigl5-Jul-02 2:23

Daniel Strigl

5-Jul-02 2:23

Thanks, but i a second question (sorry)...

What's with the following code:

Test t1 = new Test();
Test t2 = t1;

What is 't2'? Is it also a copy of t1 or a reference?

Thanks!!!

MFG Daniel.

Re: Copy or reference?

SimonS5-Jul-02 2:32

SimonS

5-Jul-02 2:32

I'm not sure what those classes are, but:

	class Test1
	{
		public int _i =-1;
		public Test1(int i)
		{_i=i;}
		public override string ToString()
		{return _i.ToString();}
	}
Test1 t1 = new Test1(100);
Test1 t2 = t1;
Console.WriteLine(t1.ToString());
t2._i=200;
Console.WriteLine(t2.ToString());
Console.WriteLine(t1.ToString());
Console.ReadLine();

Proves that t2 and t1 point to the same location in mem.

Does that help you?

Cheers,
Simon

"Sign up for a chance to be among the first to experience the wrath of the gods.", Microsoft's home page (24/06/2002)

Re: Copy or reference?

Daniel Strigl5-Jul-02 2:47

Daniel Strigl

5-Jul-02 2:47

I how can i make a full copy of a object, so that when i change the member in object 1, the member in object 2 will not be changed???? So, as a deep copy in c++!!!

MFG Daniel.

Re: Copy or reference?

SimonS5-Jul-02 9:40

SimonS

5-Jul-02 9:40

I'm pretty sure there's a copy and a clone method for this type of thing, but I have a feeling that you're going to have to implement it yourself.
I'll have a look though.
modified: do a search for ICloneable.Clone Method in MSDN. The ICloneable interface looks like what you're looking for.

HTH

Cheers,
Simon

"Sign up for a chance to be among the first to experience the wrath of the gods.", Microsoft's home page (24/06/2002)

Re: Copy or reference?

Oyvind Bratland7-Jul-02 21:39

Oyvind Bratland

7-Jul-02 21:39

To get a deep copy in C# do this:

public static object Clone(object objectToClone) 
{
	if (objectToClone == null) 
	{
		throw new ArgumentNullException("objectToClone", "Parameter can not be null.");
	}
	BinaryFormatter formatter = new BinaryFormatter();
	MemoryStream stream = new MemoryStream();
	formatter.Serialize(stream, objectToClone);
	stream.Seek(0, SeekOrigin.Begin);
	return formatter.Deserialize(stream);
}

To deep copy an object with this method, use:

MyTest originalObject = new MyTest(a, lot, of, stuff);
MyTest cloneObject = (MyTest)Clone(originalObject);

The best part is that this is generic: extend MyTest with properties and you don't have to change the clone method.

Øyvind

Re: Copy or reference?

Rama Krishna Vavilala5-Jul-02 16:08

Rama Krishna Vavilala

5-Jul-02 16:08

SimonS wrote:
"Sign up for a chance to be among the first to experience the wrath of the gods.", Microsoft's home page (24/06/2002)

Laugh | :laugh:

This beats them all.

Re: Copy or reference?

Bo Norgaard5-Jul-02 2:16

Bo Norgaard

5-Jul-02 2:16

O will be an Object that points to a new System.Int32 with the value of i, and if you change the value of O to 2, i will still be 1.

So the short answer is that it is a copy.

/Bo

Re: Copy or reference?

Daniel Strigl5-Jul-02 2:21

Daniel Strigl

5-Jul-02 2:21

And the follwing code:

Test t1 = new Test();
Test t2 = t1;

What is 't2'? Is it also a copy of t1 or a reference?

Thanks!!!

MFG Daniel.

Re: Copy or reference?

Bo Norgaard5-Jul-02 2:32

Bo Norgaard

5-Jul-02 2:32

Both t1 and t2 will be references to the new Test object created. No copy is made - and yes they are "pointers" - even if somebody tells you that C# ´don't have pointers. Wink | ;)

/Bo

Re: Copy or reference?

Rüpel5-Jul-02 2:21

Rüpel

5-Jul-02 2:21

have you heard about boxing and unboxing?

i'm not 100% but pretty sure it goes like this:
* i is an int and placed on the stack.
* o is an object and therefore placed on the heap - i is "boxed" and the boxed copy is referenced by o - i believe, o is a COPY of i
* you can check with object.ReferenceEquals(a,o) that a and o point to the same object

as said before - i'm not 100 percent sure about it...(still a beginner to C# and .NET)

:wq

Re: Copy or reference?

Nick Parker5-Jul-02 18:54

Nick Parker

5-Jul-02 18:54

Oh boy am I tired, but glad I read your post because I was just getting ready to respond with the explanation you gave.

To my knowledge, any time you instansiate an object of a class in C# you are doing so on the heap, however when you use static methods, objects aren't required for this and therefore they process on the stack. Hopefully I am not mumbling here as I have been up for way to long. Smile | :)

HTH

Nick Parker

Re: Copy or reference?

leppie5-Jul-02 4:35

leppie

5-Jul-02 4:35

my experiences and deductions lead me to believe that any class inheriting from object is passed by reference. Smile | :)

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