C / C++ / MFC Discussion Boards

Re: strange grammar about volatile and operator overload

Rajkumar R29-Jan-08 19:08

Rajkumar R

29-Jan-08 19:08

Maxwell Chen wrote:
This does not compile.

What man you are not passing the reference to pointer rather you passing the pointer that is why it is not compiling

Maxwell Chen wrote:

class I { } m;
const I* operator &()
{
printf("const I* operator & \n");
return &m;
}

I guess what will be your implementation for the typecast operator from the above code

public:  
class I  { } m;  
operator const I* &() 
{    
printf("const I* operator & \n");    
return &m;  
}

here you are not returning the reference you are returning the pointer, if you modify it as

class I  { } 
	const *m;  

	operator const I*  &()  
	{    printf("const I* typecast operator & \n");    
	return m;  
	}

it will compile

Maxwell Chen wrote:
This compiles, but the member operator function is not invoked.

This i agree

Re: strange grammar about volatile and operator overload

Maxwell Chen29-Jan-08 19:30

Maxwell Chen

29-Jan-08 19:30

Rajkumar_R wrote:
class I { } const *m;
operator const I* &() {
printf("const I* typecast operator & \n");
return m;
}

My modification below. Big Grin | :-D

class O
{
public:
  class I
  {} const* m;
  O() : m(new I()) {}
  operator const I* &() {
    printf("operator const I* & \n");
    return m;
  }
};
void main()
{
  O v;
  const O::I* &p = v; // got it!
  const O::I* &q = (const O::I* & )v; // the same.
}

Maxwell Chen

Re: strange grammar about volatile and operator overload

Rajkumar R29-Jan-08 19:37

Rajkumar R

29-Jan-08 19:37

So now you can compile without error

Re: strange grammar about volatile and operator overload

Maxwell Chen29-Jan-08 19:45

Maxwell Chen

29-Jan-08 19:45

Rajkumar_R wrote:
So now you can compile without error

Yes!

Maxwell Chen

Shell Contet Menu

john563228-Jan-08 23:45

john5632

28-Jan-08 23:45

Hi Experts,

I want to add my command at the right click of file and folder. So I have to make some changes in registry entry. Could anyone tell what steps to follow?

I do not have any idea of shell menu.

Regards.
Pther

Re: Shell Contet Menu

Iain Clarke, Warrior Programmer28-Jan-08 23:55

Iain Clarke, Warrior Programmer

28-Jan-08 23:55

pther wrote:
I do not have any idea of shell menu.

Then doing a search for tutorials on shell extensions would be a good idea...

Look under desktop development, shell and ie programming, beginners for a good start.

(I'm not being unhelpful - everything I know about shell extensions came from Michael Dunn)

Iain.

How to capture shutdown notification when Windows Shutdown

Abhijit A28-Jan-08 23:37

Abhijit A

28-Jan-08 23:37

Hello Friends,
I need to do some checking when user clicks turnoff windows.
I am trying to capture windows shutdown event in my Win32 Console Applicaton.
In MFC application WM_ENDSESSION work well upto some extent but Win32 Application doesn't provide that message handler.
Please give some suggestions.
Waiting for the reply

abhi

Re: How to capture shutdown notification when Windows Shutdown

Maxwell Chen28-Jan-08 23:42

Maxwell Chen

28-Jan-08 23:42

SetWindowsHookEx to hook WM_ENDSESSION or WM_QUERYENDSESSION?

Maxwell Chen

Re: How to capture shutdown notification when Windows Shutdown

Abhijit A29-Jan-08 0:37

Abhijit A

29-Jan-08 0:37

But SetwindowHook creates problem in terms of performance and extra load of dll will be there.
Is there any other way.

abhi

Re: How to capture shutdown notification when Windows Shutdown

Mark Salsbery29-Jan-08 5:51

Mark Salsbery

29-Jan-08 5:51

AbhijitAkude wrote:
Win32 Application doesn't provide that message handler

What do you mean by that?

The message is handled like any other window message.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: How to capture shutdown notification when Windows Shutdown

Stephen Hewitt29-Jan-08 12:13

Stephen Hewitt

29-Jan-08 12:13

Create a hidden window and handle the WM_ENDSESSION message.

Steve

ListView item selection

ilgale28-Jan-08 23:37

ilgale

28-Jan-08 23:37

Hi all,
I've a problem in ListView management. The problem is the following:

when the ListView looses the focus, the currently selected item in the
ListView looses the selection: the selection in the ListView is not mantained
switching from a control to another in the user interface.

How can I solve this problem ? I'd like to let the ListView to mantain
the selection.

Thanks a lot !

Re: ListView item selection

Iain Clarke, Warrior Programmer28-Jan-08 23:57

Iain Clarke, Warrior Programmer

28-Jan-08 23:57

Have a look in the styles. I'm pretty sure there's one called "show selection always".

Just peeked... LVS_SHOWSELALWAYS exists.

Iain.

Re: ListView item selection

ilgale29-Jan-08 0:21

ilgale

29-Jan-08 0:21

Thanks a lot !!!!

Urgent Help ~!! Convert Lab to RGB

azusakt28-Jan-08 23:17

azusakt

28-Jan-08 23:17

Hi all,

I have to make a library to convert the Color from Lab value to RGB value. However, I have no much idea on the calculations or algorithms.

Suppose I will receive a data (Char pointer) then convert to RGB.

Can some of you give me some hints or examples? Please Please...
I believed that this should be easy for some experts.

Thanks for your help..

Re: Urgent Help ~!! Convert Lab to RGB

Rajesh R Subramanian28-Jan-08 23:31

Rajesh R Subramanian

28-Jan-08 23:31

azusakt wrote:
I have no much idea on the calculations or algorithms.

You don't have much idea or you have absolutely no idea? Tell us what you've tried.

Nobody can give you wiser advice than yourself. - Cicero
.·´¯`·->Rajesh<-·´¯`·.
Codeproject.com: Visual C++ MVP

Re: Urgent Help ~!! Convert Lab to RGB [modified]

azusakt29-Jan-08 15:26

azusakt

29-Jan-08 15:26

Actually, I'm a beginner in writting Graphic related program. especially in C++.

I have no idea on the calculation for processing & converting the LAB to RGB. So I hope to find some examples with codings that I can easily to learn and understand .

Could you provide me some program examples if you have this experience.
Thanks a lot.

modified on Tuesday, January 29, 2008 10:04:23 PM

Re: Urgent Help ~!! Convert Lab to RGB

CPallini28-Jan-08 23:57

CPallini

28-Jan-08 23:57

azusakt wrote:
I have to make a library to convert the Color from Lab value to RGB value. However, I have no much idea on the calculations or algorithms.

But documentation exists http://en.wikipedia.org/wiki/Lab_color_space#Advantages_of_Lab[^].

There is also the very nice Guillaume Leparmentier's article [^] here at CP.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

[my articles]

Re: Urgent Help ~!! Convert Lab to RGB [modified]

Mr. Surprise29-Jan-08 7:35

Mr. Surprise

29-Jan-08 7:35

I guess, by using an array structure you can do this. For Example:

<br />
static COLORREF arColors[] = {<br />
RGB(0,255,0),<br />
RGB(0,255,255)<br />
};<br />
<br />
char* arNames[] = {<br />
"green",<br />
"cyan"<br />
};<br />
<br />
for(int i=0; i<2; i++)<br />
{<br />
arColors[i] = i;      // you can try "atof"<br />
arNames[i] = atof(i);<br />
}<br />

modified on Wednesday, January 30, 2008 4:09:09 AM

Re: Urgent Help ~!! Convert Lab to RGB

azusakt29-Jan-08 19:10

azusakt

29-Jan-08 19:10

Thanks for you reply.

Can you provide me a sample code for converting Lab value to RGB value?
I've read some documents, they said the step should
1. convert Lab -> XYZ
2. convert XYZ -> RGB

I don't know how to write such calculations.

Re: Urgent Help ~!! Convert Lab to RGB [modified]

Mr. Surprise29-Jan-08 22:07

Mr. Surprise

29-Jan-08 22:07

This is a constant RGB macros of the COLORREF structure. Anyway, from 0 to 255 numeric values are equivalence a 24-Bit COLORREF's scope. If you want to chance only RGB macros, you can use the
typedef struct tagCOLORREF structure.
Forexample:

<br />
#define XYZ(int i1, int i2, int i3) 0<br />
<br />
int* pNewInt = new int[255];<br />
pNewInt = NULL;<br />
#ifdef COLORREF<br />
for(int i=0; i<255; i++)<br />
{<br />
// I'm not sure just as already it will be defined a XYZ macro.<br />
RGB(pNewInt[i],pNewInt[i],pNewInt[i]) = XYZ(pNewInt[i],pNewInt[i],pNewInt[i]);<br />
}<br />
delete []pNewInt;<br />
#endif

That is must be a defined tagpoint struct what own yourself.

modified on Thursday, January 31, 2008 6:05:14 AM

Storing ptint setup info

g_sandipan28-Jan-08 23:12

g_sandipan

28-Jan-08 23:12

Dear friends,

I am opening the selected printer's document property dialog from my application.
I am using the following code

PRINTER_DEFAULTS PrinterDef = {NULL, NULL, PRINTER_ALL_ACCESS};
HANDLE hPrinter;
PDEVMODEW pDevmode = NULL;
if(OpenPrinter(PRINTER_NAME, &hPrinter, &PrinterDef))
{
int nSize = DocumentProperties(this->m_hWnd, hPrinter,
PRINTER_NAME, NULL, NULL, 0);
pDevmode = (PDEVMODEW)LocalAlloc(LPTR, nSize);
DocumentProperties(this->m_hWnd, hPrinter, PRINTER_NAME,
pDevmode, NULL, DM_IN_PROMPT );
ClosePrinter(hPrinter);
}

Now I want to cature the paper size changes made by the user on document property dialog.
Please Help.

Sandip

Floating point arithmetic

User 345557728-Jan-08 23:12

User 3455577

28-Jan-08 23:12

Check out these two code paths:

float s = 1.0f + pow(2.0f,-8.0f) + pow(2.0f,-18.0f);

float fRes1 = 1024 * s;

float fRes2 = 0.0f;
for(int i=0; i<1024; ++i)
    fRes2 +=s;

now watch the results:
fRes1: 1028.0039
fRes2: 1028.0002

This was tested on Intel Dual-core, VS2005. the direct multiplication was compiled to use fmul, the accumulation was compiled to use fadd. The scalar value s was crafted to know analytically which is the correct result. it is fRes1 (the fmul result).

Can anyone shed some light on the source of the difference??

it can't be (i think) a direct precision issue - all arguments and intermediate values are *exactly* representable in single precision.

any insight would be greatly appreciated!

-Ofek

modified 23-Jan-21 21:03pm.

Re: Floating point arithmetic

Maxwell Chen28-Jan-08 23:32

Maxwell Chen

28-Jan-08 23:32

It's of float issue. Using double instead will solve this.

Maxwell Chen

Re: Floating point arithmetic

CPallini28-Jan-08 23:36

CPallini

28-Jan-08 23:36

OfekSH wrote:
it can't be (i think) a direct precision issue

I think the opposite.

OfekSH wrote:
all arguments and intermediate values are *exactly* representable in single precision.

for instance, when executing s*1023 + s sum, you cannot line up the addition arguments without precision loss.

Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

[my articles]

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