Dialog in taskbar steals focus from children - C / C++ / MFC Discussion Boards

amigaguy12-Sep-04 6:07

12-Sep-04 6:07

I'm having problem getting double buffering to work in MFC.

I have tried to implement it based on the information found on this page http://codeproject.com/gdi/flickerfree.asp

The problem is that I don't really understand how to "override" the OnDraw method. There are no OnDraw method in the code that was generated when I created the project, and I have tried to just add the method in there but it's never called.

I'm using Visual C++ 7.0 (.net) and the ClassWizard that is mentioned on a lot of examples regarding this issue seems to be removed from the new version of Visual Studio.

I would be greatfull for some pointers on how to do this.

Re: Double buffering in MFC

Antti Keskinen12-Sep-04 10:33

Antti Keskinen

12-Sep-04 10:33

What is the project type you created ? A MDI application ? An SDI application ? A dialog project ? The OnDraw method is only there if you are handling a class based on CView. CView::OnDraw is a virtual function that you can override in order to define custom behaviour.

The concept of overriding is related to the object-oriented programming model. Consider that you have a class, call it class Alpha, for now. Class Alpha has a member function called Func1 that is declared as virtual. If you derive a class called Class Beta from Alpha, and write a function called Func1 in there, this new function will override the old Func1 from Alpha.

In the MFC world, the class thinking is at large. What OnDraw does is answer to WM_PAINT windows message.

The Visual Studio .NET doesn't boast ClassWizard anymore. It is replaced by a more functioning event list in the Properties of the class. I assume you know how to use the Class View, which shows all the classes your project contain. In this view, right-click on the class name you wish to write a message handler to, then select 'Properties'. In the properties view, look for a row of buttons in the top section. From these, find one which gives a tooltip 'Messages' or 'Events'. Click on it. A list of Windows messages you can react to is displayed. Find 'WM_PAINT', and write 'OnPaint' into the box next to it and press enter.

Now write the code to first create a CMemDC, and draw your stuff there. Then destroy the CMemDC or let it go out of scope, and it will blit the new graphic into the target device context.

-Antti Keskinen

----------------------------------------------
The definition of impossible is strictly dependant
on what we think is possible.

Re: Double buffering in MFC

Anonymous12-Sep-04 11:50

Anonymous

12-Sep-04 11:50

It's a dialog project. Basicly I have a bitmap image that stretches as the background when the window is resized,
and I don't want it to flicker when I resize the window. The bitmap is drawn in the OnEraseBkgnd method, I dont know if that is all that clever but... Smile | :)

I have moved the drawing to the OnPaint() method. Should I call Invalidate() in the OnResize() method to for an WM_ONPAINT event?

CDaoDatabase connection string in Windows XP

olis12-Sep-04 5:36

olis

12-Sep-04 5:36

Hello.

I try to Open CDaoDatabase object in Windows XP (the user has the Excel
2000), and I use the "Excel 8.0" connect string. It returns the following
error "Couldn't Find Installable ISAM". BUT the same code works in Windows
2000. I tried the "Excel 9.0" and "Excel 10.0", but without success...

CDaoDatabase* p_daoDB = NULL;

p_daoDB = new CDaoDatabase;
p_daoDB->Open(_T("SCCardOS.XLS"), // file name
FALSE, // exclusive
FALSE, // read only
_T("Excel 8.0;")); // connect string

I found the post with the same problem, but without solution ;(
I need some tips for solving...

Thank you in advance.

Process help

swarup12-Sep-04 4:40

swarup

12-Sep-04 4:40

Hi there,

i want to know some things regarding process in windows. how to hide a process name. i know there is a sample in codeproject. i want to know what are the steps or what is logic behind it. what is the process difference in windows 95 series and windows nt series.

and how to hide my appication icon that comes up when you press alt+tab. in that small dialog your app icon shows up if there is more then one app running. can i remove my icon from there.

reagrds
swarup

Toolbar in views

Jens Christiansen12-Sep-04 3:26

Jens Christiansen

12-Sep-04 3:26

Hi,

how can I add a toolbar on a view, and not the mainframe ?

How can I export my class in "Regular DLL that statically linked MFC"?

Behzad Ebrahimi12-Sep-04 3:20

Behzad Ebrahimi

12-Sep-04 3:20

How can I export my class in "Regular DLL that statically linked MFC"?

My class does NOT inheritance from CObject.
But it use MFC class such as CString.

Also if my class inheritance from CObject, how can I do it?

Thanks Hmmm | :|

Dialog in taskbar steals focus from children

PEK12-Sep-04 1:49

PEK

12-Sep-04 1:49

I have a dialog in my application that I want to be shown in the taskbar (it's not the main window). I do this by calling this in OnInitDialog:

::SetWindowLong( m_hWnd, 
 GWL_EXSTYLE,
 GetWindowLong(m_hWnd, GWL_EXSTYLE)|WS_EX_APPWINDOW
 );

This works quite well but there is one minor bug. If that dialog has a children, for example a message box, the message box doesn't get the focus when the user click on the button in the taskbar. Instead the dialog receive the focus. If the user use Alt+Tab or trying to click on the dialog, the message box gets the focus as expected. Any suggestion how to solve this?

I'm using VC6 and have tested this in NT4.

Re: Dialog in taskbar steals focus from children

Gary R. Wheeler12-Sep-04 2:44

Gary R. Wheeler

12-Sep-04 2:44

You need to ensure that the parent window of the message box is the dialog.

Software Zen: delete this;

Re: Dialog in taskbar steals focus from children

PEK12-Sep-04 4:55

PEK

12-Sep-04 4:55

Thanks, but I get it same result if I do this:

::MessageBox( m_hWnd, "Bla bla bla", NULL, MB_OK);

I have checked with Spy++ and the handles are set up correctly.

However, I have found a workaround. I handle the WM_SETFOCUS message in the dialog. If the dialog gets focus and the window isn't enabled, it tries to change the focus to the popup window:

LRESULT CDialog2::OnSetfocus(WPARAM wParam, LPARAM lParam)
{
  //Window is not enabled if popup window
  if(!IsWindowEnabled())
  {
    HWND child = ::GetWindow(m_hWnd, GW_HWNDPREV);
    if(child != NULL)
    {
       TRACE(_T("Has child!\n"));
       ::SetFocus(child);
    }
  }

  return 0;
}

I don't like this solution sense I doesn't understand what's going on, but I guess I could live with that.

background color

Joerg Warthemann12-Sep-04 1:42

Joerg Warthemann

12-Sep-04 1:42

Hi,

i'm developing an MDI-application with mfc .net . Now i have the question how to change the Background-Color, so that Menu, Toolbar and Statusbar - even everything - has the same style.
I first thought that updating the Function AfxRegisterWndClass(...) with my own background-brush will help. But it doesn't work. Than I tried CWinApp::SetDialogBkColor() but its not available in Visual C++ 7.
Handling the WM_CTLCOLOR or WM_ERASEBKGND messages also did no effect.

Is there any way or am i hit with blindness?

Thanx
Jo

Getting the -REAL- printable area of a page

Ernesto D.11-Sep-04 21:48

Ernesto D.

11-Sep-04 21:48

Hi all, to get the real printable area of a page (on a printer of course)
is it correct to do it like this?
assuming that i want to use HIMETRIC, mydc is a device context (CDC class), and it has allready been "opened" to my printer...

dc.SetMapMode(MM_HIMETRIC);
CSize pagesize;
// get the "physical" size of the page...
pagesize.cx=dc.GetDeviceCaps(PHYSICALWIDTH);
pagesize.cy=dc.GetDeviceCaps(PHYSICALHEIGHT);

// now take off the non printable area
pagesize.cx-=dc.GetDeviceCaps(PHYSICALOFFSETX);
pagesize.cy-=dc.GetDeviceCaps(PHYSICALOFFSETY);

// returned values were in device units, we need himetric
dc.DPtoHIMETRIC(&pagesize);

// pagesize now has the real printable area of the page

is this correct? is there a better way?
thanks!

Re: Getting the -REAL- printable area of a page

Blake Miller13-Sep-04 6:10

Blake Miller

13-Sep-04 6:10

In some, if not most cases, I have found that the PHYSICALOFFSETX and PHYSICALOFFSETY would apply to BOTH edges of the page, so you might want to do your math like this:

// now take off the non printable area
pagesize.cx-= (2 * dc.GetDeviceCaps(PHYSICALOFFSETX));
pagesize.cy-= (2 * dc.GetDeviceCaps(PHYSICALOFFSETY));

I also don't think this accounts for any of the margins the user might have set for the printing area.

You might want to also obtain the printer device context (CreateDC) and examine the DEVMODE fields:

dmYResolution - Specifies the y-resolution, in dots per inch, of the printer. If the printer initializes this member, the dmPrintQuality member specifies the x-resolution, in dots per inch, of the printer.

Or you can get the from associated with a print job and check these fields:
Size - Specifies the width and height, in thousandths of millimeters, of the form. ImageableArea - Specifies the width and height, in thousandths of millimeters, of the form.

how to find which port is active?

anuchelvi11-Sep-04 20:55

anuchelvi

11-Sep-04 20:55

hai,
I need to find the port which is precently active and set the port settings and send date to that particular port and to receive data from that port,how am i to do it?

mithila

Re: how to find which port is active?

Mad__13-Sep-04 4:49

Mad__

13-Sep-04 4:49

What kind of ports you meen : COM, LPT, USB ? Cool | :cool:

searching for Nicholl-Lee- Nicholl C or C++ code

gledaoc11-Sep-04 18:26

gledaoc

11-Sep-04 18:26

Can enyone tell me where I can find C or C++ code for Nicholl-Lee- Nicholl, line clipping, alghoritm. If you know where i can find it or you have it please send it to my e-mail: taj_sam@yahoo.com.

Thanks in advance....

Re: searching for Nicholl-Lee- Nicholl C or C++ code

Ravi Bhavnani12-Sep-04 7:16

Ravi Bhavnani

12-Sep-04 7:16

Dunno about code, but the algorithm can be found here[^].

/ravi

My new year's resolution: 2048 x 1536
Home | Articles | Freeware | Music
ravib@ravib.com

deselecting list ctrl items

Tyrus18211-Sep-04 14:05

Tyrus182

11-Sep-04 14:05

does anyone know how to deselect a list ctrl item ive tried
list.SetItemState(i, 0, 0);

but this doesnt work
anyone have any idea
thanks

Re: deselecting list ctrl items

Branislav11-Sep-04 22:32

Branislav

11-Sep-04 22:32

You'll need to handle LVN_ITEMCHANGING and return FALSE to allow the item to be (un)checked or (de)selected and return TRUE to disallow a change.

Here's some code that might help.

Add this to your CMyListCtrl class definition as a protected function:

// Returns TRUE if the item is checked, false if it is not or uState == 0
inline BOOL IsChecked(UINT uState) {return
(uState ? ((uState & LVIS_STATEIMAGEMASK) >> 12) - 1 : FALSE);}

Here's a sample function for handling LVN_ITEMCHANGING:

void CTestListView::OnItemchanging(NMHDR* pNMHDR, LRESULT* pResult)
{
NM_LISTVIEW* pNMListView = (NM_LISTVIEW*)pNMHDR;

// If old state is unchecked and new state is checked
// then item is being checked.
if ((! IsChecked(pNMListView->uOldState)) &&
(IsChecked(pNMListView->uNewState)))
MessageBox("Item is being checked");

// If old state is checked and new state is unchecked,
// item is being unchecked
else if ((IsChecked(pNMListView->uOldState)) &&
(! IsChecked(pNMListView->uNewState)))
MessageBox("Item is being unchecked");

// return FALSE (or 0) to allow change, TRUE to prevent
*pResult = 0;
}//OnItemchanging

Select: m_ListCtrl.SetItemState(iItem, LVIS_SELECTED, LVIS_SELECTED);
Deselect: m_ListCtrl.SetItemState(iItem, 0, LVIS_SELECTED);

Focused: m_ListCtrl.SetItemState(iItem, LVIS_FOCUSED, LVIS_FOCUSED);
Unfocused: m_ListCtrl.SetItemState(iItem, 0, LVIS_FOCUSED);

Re: deselecting list ctrl items

Michael Dunn12-Sep-04 8:49

Michael Dunn

12-Sep-04 8:49

Look at your call, the 3rd param is which state bits you want to change. Since you pass 0, no bits are changed. Pass LVIS_SELECTED in that parameter to turn off that state bit.

--Mike--
Personal stuff:: Ericahist | Homepage
Shareware stuff:: 1ClickPicGrabber | RightClick-Encrypt
CP stuff:: CP SearchBar v2.0.2 | C++ Forum FAQ
----
#include "witty-quote.h"
Pinky, are you pondering what I'm pondering?
I think so Brain, but how will we fit the hamster inside the accordion?

Create a flash movie from C++ Windows code

AssemblySoft11-Sep-04 13:59

AssemblySoft

11-Sep-04 13:59

Has anyone created an SWF file from code?
I have heard this can be done.

Carl

Mouse hook

0v3rloader11-Sep-04 13:26

0v3rloader

11-Sep-04 13:26

Hello,

I have an app installing a mouse hook:

The hook setup function...

BOOL CXCapture::Setup()
{
	DFUNC_DEF(CXCapture::Setup);
	BOOL bRetVal;
	//!CODE_START--->
	m_hMouse = ::SetWindowsHookEx(WH_MOUSE, &MouseProc, ::AfxGetInstanceHandle(), NULL);
	bRetVal = m_hMouse != NULL;
	DFUNC_RET(bRetVal != FALSE, DSTR("Could not initialise mouse_hook (Err#%d)", GetLastError()));
	return bRetVal;
}

The callback function...

LRESULT CALLBACK CXCapture::MouseProc(int nCode, WPARAM wParam, LPARAM lParam)
{
	DFUNC_DEF(CXCapture::MouseProc);
	//!CODE_START--->
	DTRACE(DSTR("Hook: %d::%d, %d", nCode, wParam, lParam));
	// now lets allow the message to be processed
	return ::CallNextHookEx(m_hMouse, nCode, wParam, lParam);
}

It happens that while the mouse is inside my application's (only) dialog box, the callback function (MouseProc) is called flawlessly, but when the mouse focus is out of the window, the OS simply unhooks it.

Therefore, whenever the mouse leaves the app's window focus, I am left out with no mouse hook whatsoever!!

My question is why this is happening and what should (or can) I do in order to solve this.

All feedback is greatly appreciated.

David Nimrod

Re: Mouse hook

AssemblySoft12-Sep-04 4:53

AssemblySoft

12-Sep-04 4:53

The Callback function needs to reside in a DLL. the each process can load the dll into it's own address space.

Carl Suspicious | :suss:

Re: Mouse hook

0v3rloader12-Sep-04 5:46

0v3rloader

12-Sep-04 5:46

Yeah, I've read about that just an hour ago or so and am modifying the code.

Thanks for the reply.

David

CRecordset question.

crimsongrape11-Sep-04 12:46

crimsongrape

11-Sep-04 12:46

Hello everyone, i have question that has been a problem to me for couple of days. I am new to db programming so bare with me.
I have a login dialog where the user enters a password, and i am trying to search my employee db to find out of that person is in the db..I simply do not know how to search my db and see if the person is an employee.
here is my code...if anyone could help out, it would be great.
//getting password from and edit box
CEdit *ebptr = (CEdit *) GetDlgItem(IDC_TEXTBOX);
int i;
char str[80];
i = ebptr->GetWindowText(str, sizeof str-1);
//set my password
box_password = str;
///THIS IS WHERE I DONT HAVE ANY CLUE, HOW TO SEARCH MY DB //FOR THE PASSWORD, PLUS HOW DO I KNOW IF THE PASSWORD EXITS IN THE DATABASE?????

rsEmployeeSet.m_strFilter = "password = box_password";
rsEmployeeSet.Open();

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