C / C++ / MFC

Re: How to handle changes to a Slider bar by Keyboard

2-Mar-07 2:20

i have a slider bar and i have used onreleasedsliderbar event to handle its changes. but it is not fired when Keyboard is used to change the bar. How could i handle changes to Slider bar by Keyboard ?

David Crow2-Mar-07 2:39

Re: How to handle changes to a Slider bar by Keyboard

2-Mar-07 2:39

What compiler are you using? Is MFC involved?

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

reza matinnejad2-Mar-07 2:46

Re: How to handle changes to a Slider bar by Keyboard

2-Mar-07 2:46

it is a visual c++ MFC project in Visual Studio .net 2003 IDE.

David Crow2-Mar-07 2:55

Re: How to handle changes to a Slider bar by Keyboard

2-Mar-07 2:55

Ok, what message are you responding to?

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

reza matinnejad2-Mar-07 3:06

Please Some Body HELP!!!!!!!!!

2-Mar-07 3:06

just OnNMReleasedCaptureSlider from slider events,
but also OnMouseMove
but not KeyStroke events.

reza matinnejad2-Mar-07 4:20

Re: How to handle changes to a Slider bar by Keyboard

2-Mar-07 4:20

I want to handle changes to a slider bar which are made by a keyboard!

David Crow2-Mar-07 4:24

Re: How to handle changes to a Slider bar by Keyboard

2-Mar-07 4:24

Why not use Spy++ to see which of the NM_xxx notification messages are being sent (when the keyboard is used with that control)?

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

reza matinnejad2-Mar-07 4:55

Re: How to handle changes to a Slider bar by Keyboard

2-Mar-07 4:55

I did use Spy, but there are just Key_Down and Key_Up Events. Would you think there is another way except handle Key_Down or Key_Up events?

Iain Clarke, Warrior Programmer2-Mar-07 5:46

Iain Clarke, Warrior Programmer

2-Mar-07 5:46

Did a quick search on MSDN, and found the following article:
Trackbar Controls[^]

Scrolling down, it tells you about the notification messages. It behaves just like a scroll bar, and sends WM_HSCROLL, or WM_VSCROLL as appropriate.

You will want to use WM_xSCROLL / TB_ENDTRACK. It is sent when you use both keyboard and mouse.

I hope this puts you on the right path,

Iain.

How to set display resolution

reza matinnejad2-Mar-07 1:27

Re: How to set display resolution

2-Mar-07 1:27

How to set display resolution (800*600,1024*...) in runtime?

prasad_som2-Mar-07 2:02

prasad_som

2-Mar-07 2:02

Use ChangeDisplaySettings.
Refer this article by maciejr[^]

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: How to set display resolution

vibindia2-Mar-07 4:18

vibindia

2-Mar-07 4:18

DEVMODE ESimSetDM;
EnumDisplaySettings (NULL, ENUM_CURRENT_SETTINGS, &ESimSetDM);
if( (ESimSetDM.dmPelsWidth != 800) || ( ESimSetDM.dmPelsHeight != 600))
{
ESimSetDM.dmPelsWidth = 800;
ESimSetDM.dmPelsHeight = 600;
ChangeDisplaySettings( &ESimSetDM,CDS_UPDATEREGISTRY );
}

this code will always keep the Display settings as 80*600:->

VIBIN

"Fool's run away,where angle's fear to tread"

const keyword

Syamlal S Nair2-Mar-07 0:54

Syamlal S Nair

2-Mar-07 0:54

Hi
What does the meaning of keyword "const" in the following declaration

CString GetItemText(int nRow, int nCol) const;

pls give a help

Thanks

SYAMLAL

Nibu babu thomas2-Mar-07 0:57

Nibu babu thomas

2-Mar-07 0:57

SyamlalS wrote:
CString GetItemText(int nRow, int nCol) const;

This means GetItemText function does not modify any of the member variables of the class to which this function belongs niether does it call any member function that modifies any member variables of the said class.

Nibu thomas
A Developer

Programming tips[^] My site[^]

Syamlal S Nair2-Mar-07 1:01

Syamlal S Nair

2-Mar-07 1:01

Will it cause any kind of errors if I take the return value to a CString variable??

SYAMLAL

Dominik Reichl2-Mar-07 1:09

Dominik Reichl

2-Mar-07 1:09

SyamlalS wrote:
Will it cause any kind of errors if I take the return value to a CString variable??

No. The const declaration of the function has nothing to do with its return value.

Too many passwords to remember? Try KeePass Password Safe!

Stephen Hewitt4-Mar-07 13:12

Stephen Hewitt

4-Mar-07 13:12

Nibu babu thomas wrote:
This means GetItemText function does not modify any of the member variables of the class to which this function belongs niether does it call any member function that modifies any member variables of the said class.

EXCPETION: mutable data members can be changed by const member functions.

Steve

prasad_som2-Mar-07 0:58

prasad_som

2-Mar-07 0:58

SyamlalS wrote:
CString GetItemText(int nRow, int nCol) const;

This function does not change state/value of member variables of class, it is function of.

Prasad
Notifier using ATL | Operator new[],delete[][^]

Roger Stoltz2-Mar-07 1:55

Roger Stoltz

2-Mar-07 1:55

In addition to what Prasad and Nibu babu thomas already said...

Consider the const keyword as a promise to the compiler that you won't change the value of the variable. If you don't honour this promise the compiler will remind you of it. This applies in al situations for the use of the const keyword.

SyamlalS wrote:
CString GetItemText(int nRow, int nCol) const;

If you try to alter member values inside a member function declared as const, you'll get a compiler error.

So what is the benefit of the const keyword in this situation?
The answer is that you can call such functions on a const declared object.
Explanation in code:

class CMyClass
{
public:
   int GetValue() { return m_nValue; }
   int GetValueConst() const { return m_nValue; }
};

// Try to use the class declared above...
void UseClass( const CMyClass theClass ) // You promise not to change the object
{
    int nTheValue;
    nTheValue = theClass.GetValue();       // Compiler error
    nTheValue = theClass.GetValueConst();  // OK
}

It's considered good practice to declare member functions that don't alter any member variables as const.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

David Crow2-Mar-07 2:51

2-Mar-07 2:51

Roger Stoltz wrote:
nTheValue = theClass.GetValue(); // Compiler error

Exactly how is this modifying a member variable?

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Roger Stoltz2-Mar-07 3:11

Roger Stoltz

2-Mar-07 3:11

Roger Stoltz wrote:
nTheValue = theClass.GetValue(); // Compiler error

DavidCrow wrote:
Exactly how is this modifying a member variable?

I never said it would and the code also shows that it doesn't.
The compiler error is due to the instance of CMyClass being a constant object and the CMyClass::GetValue() member function is not declared as constant.
I posted it as an explanation for the use of this syntax.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

toxcct2-Mar-07 1:55

toxcct

2-Mar-07 1:55

in addition, such a constness concerning a member function is allowed to modify a data member if and only if it was declared mutable.

[VisualCalc][Binary Guide updated! ][CommDialogs new! ] | [Forums Guidelines]

vibindia2-Mar-07 4:07

vibindia

2-Mar-07 4:07

class sample
{
CString s1;
mutable CString s2;
public:
CString GetItemText(int nRow, int nCol) const;
};

CString sample::GetItemTextint nRow, int nCol) const;
{
s1 = _T("abc");//error because an const function can't change the data memter
//They are only for accesing
s2 = _T("abc");//works the keyword mutable is given
return s1;
}

//U have to read more on const object too Smile | :)

VIBIN

"Fool's run away,where angle's fear to tread"