C / C++ / MFC

Re: How to SetWindowPos correctly? Actually confused with GetClientRect,GetWindowRect,ScreenToClient and ClientToScreen etc.

20-Nov-07 18:36

when create a dialog based MFC project defaultly, we have the OK, cancel buttons in the topright corner, I want to create a CListBox dynamicly and place it in the position relative to the IDOK button( the top cordination of CListBox is the same as IDOK), so I write my code like below:

first, construct a CListBox in the .h file
CListBox m_ctlBox;

then, within the OnInitDialog

BOOL CMyDialog::OnInitDialog()
{
  CDialog::OnInitDialog();
  m_ctlBox.Create(STYLE, CRect(0, 0, 0, 0), rightcode);
  m_ctlBox.ShowWindow(SW_HIDE);

  //below code to set the position for the CListBox
  CRect rcOK;
  GetDlgItem(IDOK)->GetWindowRect(&rcOK);
  int nBoxWidth = 30;
  int nBoxHeight = 40;
  int nxMargin = 10;
  int nBoxTop = rcOK.top;
  int nBoxLeft = rcOK.left - nxMargin - nBoxWidth;
  m_ctlBox.SetWindowPos(&CWnd::wndTop, nBoxLeft, nBoxTop, nBoxWidth, nBoxHeight, SWP_SHOWWINDOW);
  m_ctlBox.ShowWindow(SW_SHOW);
  return TRUE;
}

but the m_ctlBox's top is not as IDOK's. Really confused with how to use GetClientRect 、GetWindowRect、ScreenToClient and ClientToScreen correctly to set window position correctly.
So I can't write my code to deal with WM_SIZE correctly.

Mark Salsbery20-Nov-07 19:01

Mark Salsbery

20-Nov-07 19:01

GetWindowRect() gets coords relative to the screen.
SetWindowPos() is expecting coords relative to the parents client area.

BOOL CMyDialog::OnInitDialog()
{
  CDialog::OnInitDialog();
  m_ctlBox.Create(STYLE, CRect(0, 0, 0, 0), <font color="Red">this</font>);
  m_ctlBox.ShowWindow(SW_HIDE); <font color="Green">//<-- you could create the window without the WS_VISIBLE style to avoid potential flash doing this</font>

  //below code to set the position for the CListBox
  CRect rcOK;
  GetDlgItem(IDOK)->GetWindowRect(&rcOK);
  int nBoxWidth = 30;
  int nBoxHeight = 40;
  int nxMargin = 10;
<font color="Red">  CPoint BoxUpperLeft;
  BoxUpperLeft.y = rcOK.top;
  BoxUpperLeft.x = rcOK.left - nxMargin - nBoxWidth;
  ScreenToClient(&BoxUpperLeft);  <font color="Green">//<-- converts screen coords to coords relative to this window</font>
</font>  m_ctlBox.SetWindowPos(&CWnd::wndTop, <font color="Red">BoxUpperLeft.x</font>, <font color="Red">BoxUpperLeft.y</font>, nBoxWidth, nBoxHeight, SWP_SHOWWINDOW);
  m_ctlBox.ShowWindow(SW_SHOW);
  return TRUE;
}

Mark

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

Re: How to SetWindowPos correctly? Actually confused with GetClientRect,GetWindowRect,ScreenToClient and ClientToScreen etc. [modified]

fantasy121520-Nov-07 20:34

Re: How to SetWindowPos correctly? Actually confused with GetClientRect,GetWindowRect,ScreenToClient and ClientToScreen etc.

20-Nov-07 20:34

Question NO.1

BOOL CMyDialog::OnInitDialog()
{  
  CDialog::OnInitDialog();  
  m_ctlBox.Create(STYLE, CRect(0, 0, 0, 0),this);    
  m_ctlBox.ShowWindow(SW_HIDE); //<-- you could create the window without the WS_VISIBLE style to avoid potential flash doing this  
  //below code to set the position for the CListBox  
  CRect rcOK;  
  GetDlgItem(IDOK)-><big><font color="red">GetWindowRect</font></big>(&rcOK);  
  int nBoxWidth = 30;  
  int nBoxHeight = 40;  
  int nxMargin = 10;  
  CPoint BoxUpperLeft;  
  BoxUpperLeft.y = rcOK.top;  
  BoxUpperLeft.x = rcOK.left - nxMargin - nBoxWidth;   
  
  //you use 
  <big>this->ScreenToClient(&BoxUpperLeft)</big>
  <font color=blue>//why not m_ctlBox.ScreenToClient(&BoxUpperLeft); ?
  </font>
  m_ctlBox.SetWindowPos(&CWnd::wndTop, BoxUpperLeft.x, BoxUpperLeft.y, nBoxWidth, nBoxHeight, SWP_SHOWWINDOW); 
  m_ctlBox.ShowWindow(SW_SHOW);  
  return TRUE;
}

Question NO.2
and how to do it with GetClientRect()?

BOOL CMyDialog::OnInitDialog()
{  
  CDialog::OnInitDialog();  
  m_ctlBox.Create(STYLE, CRect(0, 0, 0, 0),this);    
  m_ctlBox.ShowWindow(SW_HIDE); //<-- you could create the window without the WS_VISIBLE style to avoid potential flash doing this  
  //below code to set the position for the CListBox  
  CRect rcOK;  
  GetDlgItem(IDOK)-><big><font color="red">GetClientRect</font></big>(&rcOK);  
  int nBoxWidth = 30;  
  int nBoxHeight = 40;  
  int nxMargin = 10;  
  CPoint BoxUpperLeft;  
  BoxUpperLeft.y = rcOK.top;  
  BoxUpperLeft.x = rcOK.left - nxMargin - nBoxWidth;   
  
  m_ctlBox.SetWindowPos(&CWnd::wndTop, BoxUpperLeft.x, BoxUpperLeft.y, nBoxWidth, nBoxHeight, SWP_SHOWWINDOW); 
  m_ctlBox.ShowWindow(SW_SHOW);  
  return TRUE;
}

-- modified at 2:40 Wednesday 21st November, 2007

Parthi_Appu21-Nov-07 0:25

Parthi_Appu

21-Nov-07 0:25

Before going into your question,

GetWindowRect(..) will return the window rect with respect to screen cooridates.

GetClientRect(..) will return the client area of the window, that is regardless of its position the top left point is 0, 0 and right, bottom point is its width and height respectivly

Now for Question 1:
You got the screen coordinate of OK button, now you have to find its coordinate with respect to the dialog and not with the listbox.

For Question 2:
As i said earlier, if you use GetClientRect(..), simply it will return width and height. By knowing only the width and height you can't find its starting (top,left) coordinate.

Do your Duty and Don't expect the Result

Re: How to SetWindowPos correctly? Actually confused with GetClientRect,GetWindowRect,ScreenToClient and ClientToScreen etc. [Understood clearly]

fantasy121521-Nov-07 13:59

Re: How to SetWindowPos correctly? Actually confused with GetClientRect,GetWindowRect,ScreenToClient and ClientToScreen etc.

21-Nov-07 13:59

When I see the explaination of the API ::ScreenToClient(), I understand clearly.
GetDlgItem(IDOK)->GetWindowRect(&rcOK);

First, rcOK's coordinates are relative to the upper left of the display screen.

Then compulate the position of the CListBox to the coordinates relative to display screen.

Next we need convert the screen coordinates of the CListBox to the coordinates in the main Dialog's client coordinates.

<br />
BOOL ScreenToClient(<br />
  HWND hWnd,        // handle to window<br />
  LPPOINT lpPoint   // screen coordinates<br />
);<br />
hWnd <br />
[in] Handle to the window <big><font color="red">whose client area will be used </font></big> for the conversion.

so we should pass the dialog's hWnd.

BOOL CMyDialog::OnInitDialog()
{    
  CDialog::OnInitDialog();    
  m_ctlBox.Create(STYLE, CRect(0, 0, 0, 0),this); 
  m_ctlBox.ShowWindow(SW_HIDE); //<-- you could create the window without the WS_VISIBLE style to avoid potential flash doing this    
  //below code to set the position for the CListBox    
  CRect rcOK;    
  GetDlgItem(IDOK)->GetWindowRect(&rcOK);    
  int nBoxWidth = 30;    
  int nBoxHeight = 40;    
  int nxMargin = 10;    
  CPoint BoxUpperLeft;    
  BoxUpperLeft.y = rcOK.top;    
  BoxUpperLeft.x = rcOK.left - nxMargin - nBoxWidth;       

  ::ScreenToClient(this->m_hWnd, &BoxUpperLeft);
  <font color="red">//This code first compulate the CListBox screen coordinate then convert to the Dialog client coordinate</font>   
  
  
  m_ctlBox.SetWindowPos(&CWnd::wndTop, BoxUpperLeft.x, BoxUpperLeft.y, nBoxWidth, nBoxHeight, SWP_SHOWWINDOW);   
  m_ctlBox.ShowWindow(SW_SHOW);    
  return TRUE;
}

If somewhere is wrong, please correct me! thx.

-- modified at 0:17 Thursday 22nd November, 2007

Mark Salsbery21-Nov-07 5:15

Mark Salsbery

21-Nov-07 5:15

There's not an API (or CWnd method) I know of to get the rect of a window relative
to its parent, so your GetClientRect() method isn't going to give you the info you need.

Remember, the window rect is the outer bounding rect of the window. The client rect
is the interior of the window, excluding borders, title bar, menu, and other "decorations".
As Parthi mentioned, the client rect's upper left coord is always 0,0.

Controls are windows, so the same rules apply.

About Windows[^]
MapWindowPoints()[^]

Mark

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

GetWindowText in OnKeyDown not correct

followait20-Nov-07 18:26

20-Nov-07 18:26

<br />
class CMyEdit:public CEdit<br />
<br />
void CMyEdit::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)<br />
{<br />
    CEdit::OnKeyDown(nChar, nRepCnt, nFlags); // though called first<br />
    CString s;<br />
    GetWindowText(s);//But s is the previous WindowText<br />
}<br />

I want to use the WindowText as soon as the text is changed, any way?

Thanks.

Hamid_RT20-Nov-07 18:35

Hamid_RT

20-Nov-07 18:35

Why you dont use of EN_CHANGE?

followait20-Nov-07 18:40

20-Nov-07 18:40

Thanxxxxx

Haroon Sarwar20-Nov-07 18:36

Haroon Sarwar

20-Nov-07 18:36

did you try handling the EN_CHANGE message?

followait20-Nov-07 18:40

20-Nov-07 18:40

Thanxxxxx

fantasy121520-Nov-07 18:42

tchar to constant char mfc-vc++

20-Nov-07 18:42

in the cpp file write
BEGIN_MESSAGE_MAP(CYourEdit, CEdit)
ON_NOTIFY_REFLECT(EN_CHANGE, OnEnChange)
END_MESSAGE_MAP()
afx_msg void OnEnChange(NMHDR *pNMHDR , LRESULT *pResult);
void CYourEdit::OnEnChange(NMHDR *pNMHDR , LRESULT *pResult)
{
CEdit::GetWindowText(str);
//Then use the str to do your work
}

Paulraj G20-Nov-07 17:46

Paulraj G

20-Nov-07 17:46

hi how to convert tchar to const char

paulraj

followait20-Nov-07 18:33

20-Nov-07 18:33

It will not be perfect, because tchar may have 2 bytes or 1 byte,
you can't put 2 byte into 1 byte when converting,
however it may work when tchar takes 1 byte. All depends on your code, you can try it.

<br />
TCHAR t;<br />
const char c=char(t);<br />

<br />
TCHAR t;<br />
const char *pc=cosnt char*(&t);<br />

nitin320-Nov-07 20:03

nitin3

20-Nov-07 20:03

followait wrote:
tchar may have 2 bytes or 1 byte

when TCHAR takes 2 bytes ?

Confused | :confused:

Thanks

Cedric Moonen20-Nov-07 20:10

Cedric Moonen

20-Nov-07 20:10

TCHAR is a macro that resolves either to char if UNICODE is not defined (then it will be 1 byte) or to wchar if UNICODE is defined (then it will be 2 bytes).

Cédric Moonen
Software developer

Charting control [v1.2]