How to implement a Slider control by win32

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Hi all:
In my win32 dialog application,there is check box and two slider control.what i want is when checking the check box will enable the two slider control.when drag the slider control,it can get the pos and display int a edit control.But when i debug the code,it can't get the message.

C++

case WM_INITDIALOG:
	{
	   HWND sliderConLo = GetDlgItem(hwndDlg,IDC_SLIDERLOWER);
	   HWND sliderConHi = GetDlgItem(hwndDlg,IDC_SLIDERHIGHER);
	   SendMessage(sliderConLo,TBM_SETRANGE, (WPARAM)1,(LPARAM)MAKELONG(0,100));
           SendMessage(sliderConHi,TBM_SETRANGE, (WPARAM)1,(LPARAM)MAKELONG(0,100));
           SendMessage(sliderConLo,TBM_SETPOS, (WPARAM)1,0);
           SendMessage(sliderConHi,TBM_SETPOS, (WPARAM)1,0);
	}
	break;
case WM_HSCROLL:
        {
                 //how to implement it
        }

Please help,thanks.

Posted 26-Feb-12 23:52pm

Member 8450542

Updated 27-Feb-12 0:08am

Jochen Arndt

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2 solutions

Solution 2

See here[^] for information about the notification messages generated by a Trackbar control.

Posted 27-Feb-12 2:26am

Richard MacCutchan

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Jochen Arndt · Accepted Answer · 2012-02-27T00:28:00

Solution 1

To perform actions when checking or unchecking a check box, use the BN_CLICKED notification send to the parent window of the button (your dialog). According to the state of the check box, you can than enable or disable the slider controls.

To handle mouse drag events for the slider controls, use the TB_THUMBTRACK notification. To handle also keyboard events, use the other TB_* notifications.

Posted 27-Feb-12 0:28am

Jochen Arndt

Comments

Member 8450542 27-Feb-12 6:49am

i have try the below method,but failed.
case WM_HSCROLL:
{
switch(LOWORD(wParam))
{
case TB_THUMBTRACK:
{
LowerNum = HIWORD (wParam);
SendMessage(GetDlgItem(hwndDlg, IDC_LOWER), WM_SETTEXT, 0, LPARAM(pos));
}
}
}
break;
there is no actions as if the dialog have not get the message which the slider sents.

Jochen Arndt 27-Feb-12 7:14am

You may add a TRACE command or set a breakpoint to see if the WM_HSCROLL message arrives.

Member 8450542 27-Feb-12 7:37am

I set a breakpoint to debug the code and find that it can't even step to the line “case TB_THUMBTRACK”.I have no idea about it.
thanks a lot.can u help to write a demo about what i means.

Jochen Arndt 27-Feb-12 8:00am

It is difficult to locate the problem without seeing your code. At least you should check the creation code of the sliders: The parent window handle must be those of your dialog and it must be created using the WS_CHILD and TBS_HORZ styles.

Member 8450542 1-Mar-12 7:18am

Thanks，i have solved it.but i get another question. what's the difference between the follow codes.
case WM_HSCROLL :
dwPos = SendMessage(hWndSlider,TBM_GETPOS,0,0);
_itoa(dwPos,tmp,10);
SendMessage(hEdit,WM_SETTEXT,0,(LPARAM)tmp);
break;

case WM_HSCROLL :
dwPos = HIWORD(wParam);
_itoa(dwPos,tmp,10);
SendMessage(hEdit,WM_SETTEXT,0,(LPARAM)tmp);
break;

Jochen Arndt 1-Mar-12 7:28am

Using the TBM_GETPOS message, you get the actual position of the slider. The high word of wParam contains the (same) position only with the TB_THUMBTRACK notification. With other notifications (keyboard events), it is null. I suggest to use the first version, to support also changing the slider position by keyboard.

Member 8450542 1-Mar-12 8:55am

thank u very much.i have finished it..^-^