C / C++ / MFC Discussion Boards

Re: Returning large objects from a function without unnecessarily invoking the constructor !

Nemanja Trifunovic24-Jul-09 8:58

24-Jul-09 8:58

paolosh wrote:
The intention is to create a MyClass instance in foo, and return it without onvoking the constructor on exit.

instead of

return *p;

call

return p;

(of course, you need to declare foo to return a pointer)

and than in the caller do something like:

std::auto_ptr<MyClass> p(foo());

This way the object will be automatically destroyed on exit of your test, and you won't have a memory leak.

Programming Blog

utf8-cpp

flickering issues with GDI+

Adassus24-Jul-09 3:26

Adassus

24-Jul-09 3:26

Hi all,

I'm trying to animate something using GDI+. At the moment, to prevent smearing when my picture moves on the screen, I clear the screen before redrawing each picture with drawimage(hdc).

Of course, that causes the screen to flicker.

Is there a way to stop that using GDI+? With GDI, I was able to stop the flickering by BITBLTing the pictures in a buffer HDC before BITBLTing in the window HDC. However, it doesnt look like BITBLT works with GDI+ (unless I'm doing something wrong).

I tried using drawimage to draw to a buffer HDC and then using BITBLT to copy the buffer HDC to the window HDC, but that doesn't work.

Does anyone know an alternative way? Or a way to draw in a buffer hdc and then copying that buffer to the window hdc using GDI+, not GDI.

Re: flickering issues with GDI+

Iain Clarke, Warrior Programmer24-Jul-09 3:35

Iain Clarke, Warrior Programmer

24-Jul-09 3:35

The only way I know how (and the way I use) is to use GDI+ to draw on a memory HDC (in xp at least, GDI+ is not accelerated, so you're not losing much), then Blt that using classic GDI to the main screen.

So...

void CMyView::OnDraw (CDC *dc)
{
   CMemDC MemDC (dc); // See Keith Rule's class CMemDC article

   Graphics gfx (MemDC);

   // Do your GDI+ stuff, and let destructors tidy up after! Neat, eh?

  ....
}

See Flicker Free Drawing In MFC[^] for the article I refer to. I use it in 83% of my drawing code.

Iain.

I have now moved to Sweden for love (awwww).
If you're in Scandinavia and want an MVP on the payroll (or happy with a remote worker), or need cotract work done, give me a job! http://cv.imcsoft.co.uk/[^]

Re: flickering issues with GDI+

Randor 24-Jul-09 9:12

Randor

24-Jul-09 9:12

I recommend doing all of your drawing into a memory Bitmap and then use DrawImage. Something like this:

void YourClass::OnPaint()
{
	CPaintDC dc(this);
	Graphics g(dc.m_hDC);
	CRect r;
	GetClientRect(r);
	Bitmap memBitmap(r.Width(), r.Height());
	Graphics memGraphics(&memBitmap);
	
	//Do all your drawing on the memGraphics object

	g.DrawImage(&memBitmap, 0, 0);
}

How To Draw on a Memory Bitmap in GDI+[^]

I also highly recommend using the CachedBitmap Class[^]. Draw your background/pictures a single time and store them in a CachedBitmap object.

Best Wishes,
-David Delaune

Remote Desktop Access by using client/server architecture

Madhu_Rani24-Jul-09 3:20

Madhu_Rani

24-Jul-09 3:20

I have a two very simple client server applications that work well. Client can communicate with Server and Server too can communicate with Client.

My goal is to access the applications of servers from client like TeamViewer. For that purpose, I have created a client/server application. Now what next I should do?

Re: Remote Desktop Access by using client/server architecture

Moak25-Jul-09 0:04

Moak

25-Jul-09 0:04

What is 'TeamViewer'? Could you elaborate on your requirements or technical C++ problems?

My webchat in Europe Java | [Coffee]

Re: Remote Desktop Access by using client/server architecture

Bacon Ultimate Cheeseburger25-Jul-09 16:20

Bacon Ultimate Cheeseburger

25-Jul-09 16:20

It sounds like you are attempting to create a remote desktop viewer which is not a trivial task. If so I suggest that you look at something like TightVNC.

Re: Remote Desktop Access by using client/server architecture

Madhu_Rani26-Jul-09 20:10

Madhu_Rani

26-Jul-09 20:10

YES. U are right. I have studied the VNC source code and could not grasp it completely. I would apprecaite if you guide me step by step.

eg , as I have already developed the client/server application. so what I should do next. How to capture the remote machine applications and then how to transmitt using client/server application.

Even I am not sure , either I need the client/server application or not?

I can guees that might be I capture the remote machine desktop by using printscreen function and then transmitt this image to viewer application (client) but then the question arises , how I may perform functions over an image, like mouse click to start/close the application.

THANKS for earlier help.

Re: Remote Desktop Access by using client/server architecture

Bacon Ultimate Cheeseburger29-Jul-09 18:35

Bacon Ultimate Cheeseburger

29-Jul-09 18:35

Madhu_Rani wrote:
I have studied the VNC source code and could not grasp it completely

I would go back and study it a bit more. There is a wealth of information available in open source remote desktop apps and not just in the source code. Review the change logs and the SVN history of files responsible for the functionality that you are particularly interested in. Seeing the problems they have had to deal with can give you an idea of what you might encounter during the development process. You can even go back to very early versions which might be a bit primitive but will be easier to understand.

Madhu_Rani wrote:
I would apprecaite if you guide me step by step.

At a very basic level most of what you are trying to accomplish is fairly straight forward. You might approach this by having your remote desktop server capture the desktop as an image, prepare the image data and then transmit it to the client. On the client you would then simply process the incoming image data and display it in a window. Without compression however you will be transmitting a significant amount of data for each screen update.

Re: Remote Desktop Access by using client/server architecture

Madhu_Rani29-Jul-09 19:46

Madhu_Rani

29-Jul-09 19:46

THANKS for the detailed reply.

I am trying to capture the desktop as an image and then I would send the captured image to the client and if delay is on higher side, then I would do compression by using some built-in-API..

I am little confused, how a transmitted image ( from server) would responds to mouse clicks. eg If I have a click over START button of transmitted image, how server would open the START menu ... as it is an image, so how clicks would trigger the corresponding events...

I can capture these events on client machine but how these events would be mapped to server sides...

THANKS.

Re: Remote Desktop Access by using client/server architecture

Bacon Ultimate Cheeseburger29-Jul-09 20:40

Bacon Ultimate Cheeseburger

29-Jul-09 20:40

Madhu_Rani wrote:
If I have a click over START button of transmitted image, how server would open the START menu

Well this is pretty straight forward as well. If you click on the image representing the remote desktop you will receive a button message (e.g. WM_LBUTTONDOWN) which includes the mouse coordinates. The message and it's associated parameters (wParam/lParam) are simply transmitted to the remote desktop server which simulates the event. Since the mouse coordinates supplied are relative to the upper left hand corner of the window client area (on the remote client side) you shouldn't have to do any conversion. To simulate mouse and keyboard events on the server side you can make a call to SendInput().

Re: Remote Desktop Access by using client/server architecture

Madhu_Rani30-Jul-09 3:55

Madhu_Rani

30-Jul-09 3:55

This was my biggest fear Smile | :)

and now I got the idea. Any how today I gained knowledge about DC and how to capture desktop and now I am integrating all these pieces of code with client server application. Then after integration I would do the final stuff that you mentioned in your reply. THANKS

Menu deletion

transoft24-Jul-09 3:13

transoft

24-Jul-09 3:13

Hi
I tried to delete the one menu from the main menu bar. I did following:

CMenu MainMenu = ((CMainFrame*)AfxGetMainWnd())->GetMenu();
CMenu toolmenu = MainMenu ->GetSubMenu(1);
while( toolmenu->GetMenuItemCount() > 0 )
{
  ret = toolmenu->DeleteMenu(0,MF_BYPOSITION);

}

I checked the "ret" value. it is "1".

But the "Tool" menu is still there. Why I can not delete it?

Best regards,

Re: Menu deletion

«_Superman_»24-Jul-09 4:04

«_Superman_»

24-Jul-09 4:04

The code should not even compile.
GetMenu[^] and GetSubMenu[^] returns CMenu pointers.
So the declaration must be CMenu* MainMenu and CMenu* toolmenu.

The DeleteMenu[^] that you are calling will delete the first menu item in the second sub menu and not an entire menu unless there is a popup menu as the menu item. For example, in Visual Studio this menu item is the Undo item in the Edit submenu.

«_Superman_»
I love work. It gives me something to do between weekends.

Re: Menu deletion

transoft24-Jul-09 4:21

transoft

24-Jul-09 4:21

I typed in code here. It might have some typo. It compiles.

My "DeleteMenu" return "1". From MSDN, it means "DeleteMenu" executes successfully.

But I still saw that menu over there.

Thanks,

getting table names from MS Access (.mdb file) in MFC

suthakar5624-Jul-09 2:54

suthakar56

24-Jul-09 2:54

hi all,
i need to get the table names from .mdb file in MFC.Can any on e help in this regard.
Thanks in advance.

Re: getting table names from MS Access (.mdb file) in MFC

Rajesh R Subramanian24-Jul-09 2:57

Rajesh R Subramanian

24-Jul-09 2:57

Hi,

Did you search CodeProject or Google?

It is a crappy thing, but it's life -^ Carlo Pallini

Re: getting table names from MS Access (.mdb file) in MFC

suthakar5624-Jul-09 3:21

suthakar56

24-Jul-09 3:21

I searched from both.but i didn't get the suitable one.So that only i posted this question.

Re: getting table names from MS Access (.mdb file) in MFC

Rajesh R Subramanian24-Jul-09 4:20

Rajesh R Subramanian

24-Jul-09 4:20

suthakar56 wrote:
I searched from both.but i didn't get the suitable one.So that only i posted this question.

Strange! CP search engine returned the following article as the first result while I searched for "MFC access":

Easy way to mix the MFC Document/View and MS Access database applications.[^]

I sure did get more relevant results when I modified the search terms. Take a look at the CDatabase[^] class as well for your need.

It is a crappy thing, but it's life -^ Carlo Pallini

Re: getting table names from MS Access (.mdb file) in MFC

Muhammad Mazhar24-Jul-09 3:21

Muhammad Mazhar

24-Jul-09 3:21

try following, I didn't tried it my self just found on googling

SELECT [Name] from msysobjects where ([type] =1 and Flags = 0) or [type] = 6

Share your experience with others
Check my Blog...

CString to long

Davitor24-Jul-09 2:40

Davitor

24-Jul-09 2:40

Hi all

How can i convert CString to long.I am try this

CString Content="000995688787";
int newintval=atoi(Content);
result is
newintval=225212472
and
__int64 n64Tmp=_atoi64(Content);
result is
n64Tmp=225212472

Re: CString to long

Rajesh R Subramanian24-Jul-09 2:54

Rajesh R Subramanian

24-Jul-09 2:54

You must have used atol (or rather _ttol) instead of atoi. See CString::Format() member if you're already using CString.

It is a crappy thing, but it's life -^ Carlo Pallini

How To Reduce time for populating the Data in Graph Format

prashant_lathigara from india24-Jul-09 1:42

prashant_lathigara from india

24-Jul-09 1:42

Hello, I am prashant workign with one company and doing the Graph Designing into my application. now the issue is that i create the function for populating the graph data but it takes to much time to populate data.

Can any body tell me how to reduce the time for populating data.

the following is my function from which i draw the graph data from one table.

void D_ScripGraphWnd::OnDraw(CDC *pDC)
{

CRect crect;
BOOL b;
CPen CenterPen, AxisPen, SlotPen, DrawPenRise, DrawPenFall;
CBrush brush;
CFont font;
CPen* OldPen;
CFont *OldFont;
int left, right, top, bottom, Height, Width ;
b = CenterPen.CreatePen(PS_DASH, 0, m_GraphColor_ula[REFERENCE_DATA]);
GetClientRect(crect);
Height = m_YSlots_l * m_SlotWidthY_l + 2*m_MarginY_l ;
Width = m_XSlots_l * m_SlotWidthX_l + 2*m_MarginX_l ;
crect.left = 0;
SetScaleToFitSize;
if(crect.right < Width)
crect.right = Width;
crect.top = 0;
if(crect.bottom < Height)
crect.bottom = Height;
pDC->FillRect(crect, &brush);
pDC->SetBkMode(TRANSPARENT);
left = m_MarginX_l ;
right = Width - m_MarginX_l;
top = m_MarginY_l ;
bottom = Height - m_MarginY_l;
OldPen = pDC->SelectObject(&SlotPen);
OldFont = pDC->SelectObject(&font);
char l_StartTime_ca[TIME_STAMP_LEN] = "";
char l_CurrTime_ca[TIME_STAMP_LEN] = "";
CTimeSpan l_TimeSpan_cl(0,0,30,0);
CTime l_SeriesStartTime_cl, l_SeriesCurrTime_cl;
CTime l_IndexStartTime_cl, l_IndexCurrTime_cl;
CTime l_StartTime_cl, l_CurrTime_cl;
l_SeriesStartTime_cl = l_SeriesCurrTime_cl = NULL;
l_IndexStartTime_cl = l_IndexCurrTime_cl = NULL;
ScripGraphInfo_T* l_ScripGraphInfo_stp;
l_TimeSpan_cl = CTimeSpan(0,1,00,0);
int l_i_l;
int minutes;
if(m_ScripGraphTable_clp->m_maxEntries_l != 0 && m_ScripGraphTable_clp->m_IndexQuerySuccess_b == TRUE )
{
//To find out the starting time on X-Axis.
l_ScripGraphInfo_stp = (ScripGraphInfo_T *)m_ScripGraphTable_clp->GetAt(0);
if(l_ScripGraphInfo_stp == NULL)
return;
if(l_ScripGraphInfo_stp->TimeStamp_uca[MM] >= 30)
minutes = 30;
if(l_ScripGraphInfo_stp->TimeStamp_uca[MM] < 30)
minutes = 0;
l_IndexStartTime_cl = CTime(l_ScripGraphInfo_stp->TimeStamp_uca[CC]*100 + l_ScripGraphInfo_stp->TimeStamp_uca[YY],
l_ScripGraphInfo_stp->TimeStamp_uca[MO],
l_ScripGraphInfo_stp->TimeStamp_uca[DD],
l_ScripGraphInfo_stp->TimeStamp_uca[HH],
minutes,
0);

l_ScripGraphInfo_stp = (ScripGraphInfo_T *)m_ScripGraphTable_clp->GetAt(m_ScripGraphTable_clp->m_maxEntries_l-1);
if(l_ScripGraphInfo_stp == NULL)
return;

l_IndexCurrTime_cl = CTime(l_ScripGraphInfo_stp->TimeStamp_uca[CC]*100 + l_ScripGraphInfo_stp->TimeStamp_uca[YY],
l_ScripGraphInfo_stp->TimeStamp_uca[MO],
l_ScripGraphInfo_stp->TimeStamp_uca[DD],
l_ScripGraphInfo_stp->TimeStamp_uca[HH],
l_ScripGraphInfo_stp->TimeStamp_uca[MM],
0);

}
strcpy(l_StartTime_ca, l_IndexStartTime_cl.Format("%H:%M"));
l_StartTime_cl = l_IndexStartTime_cl;

strcpy(l_CurrTime_ca, l_IndexCurrTime_cl.Format("%H:%M"));
l_CurrTime_cl = l_IndexCurrTime_cl;

pDC->SetTextColor(m_GraphColor_ula[AXIS_LABELS]);

for(l_i_l = 0; l_i_l <= m_XSlots_l; l_i_l++)
{
pDC->MoveTo(left, top);
pDC->LineTo(left, bottom);
if(m_DisplayXScale_b)
{
if(m_InitTime_cl != NULL && (l_i_l %2 == 0))
{
CTimeSpan l_Span_cl = l_StartTime_cl - l_CurrTime_cl;
if(l_Span_cl <= l_TimeSpan_cl)
pDC->TextOut(left-10 , bottom+5, l_StartTime_ca);
l_StartTime_cl += l_TimeSpan_cl;
strcpy(l_StartTime_ca, l_StartTime_cl.Format("%H:%M"));
}
}
left += m_SlotWidthX_l;
}
char l_buff_ca[20];
int j = m_Origin_l + m_YSlots_l*SlotWidthY;
left = m_MarginX_l;
for(l_i_l=0; l_i_l<=m_YSlots_l; l_i_l++)
{
pDC->MoveTo(left, top);
pDC->LineTo(right, top);
sprintf(l_buff_ca, "%d", j);

if(m_DisplayYScale_b)
{
if ((strcmp(g_SystemInfo_st.BrokerCode_ca, "") != 0) &&
(strcmp(g_SystemInfo_st.TraderCode_ca, "") != 0))
{
if(m_ScripGraphTable_clp->m_maxEntries_l > 0 )
pDC->TextOut(left - m_MarginX_l, top-2 , l_buff_ca);

}
}
top += SlotWidthY;
j -= SlotWidthY;
}
top = m_MarginY_l ;
pDC->SelectObject(&AxisPen);
pDC->MoveTo(left, top);
pDC->LineTo(left, bottom);
pDC->MoveTo(left, bottom);
pDC->LineTo(right, bottom);
pDC->SelectObject(&CenterPen);

if ((strcmp(g_SystemInfo_st.BrokerCode_ca, "") != 0) &&
(strcmp(g_SystemInfo_st.TraderCode_ca, "") != 0))
{
PrevCloseY = int(l_ScripDayOpen1)- m_Origin_l;
PrevCloseY = bottom-PrevCloseY;
pDC->MoveTo(left, PrevCloseY);
pDC->LineTo(right,PrevCloseY);
}
CString key;
char temp[20];
int x,y;
m_tooltip.Activate(TRUE);
for(l_i_l = 0; (l_i_l < m_ScripGraphTable_clp->m_maxEntries_l && m_InitTime_cl != NULL); l_i_l++)
// for( pos = g_IndexMap_cl.GetStartPosition(); pos != NULL; )
{
if(m_MinY_l == -1 || m_MaxY_l == -1)
return;
l_ScripGraphInfo_stp = (ScripGraphInfo_T* )m_ScripGraphTable_clp->GetAt(l_i_l);
if(l_ScripGraphInfo_stp == NULL)
return;
strcpy(l_CurrTime_ca, "");
if(l_ScripGraphInfo_stp->TimeStamp_uca[HH] < 10)
strcpy(l_CurrTime_ca, "0");
sprintf(temp, "%d",l_ScripGraphInfo_stp->TimeStamp_uca[HH]);
strcat(l_CurrTime_ca, temp);

if(l_ScripGraphInfo_stp->TimeStamp_uca[MM] < 10)
strcat(l_CurrTime_ca, "0");
sprintf(temp, "%d",l_ScripGraphInfo_stp->TimeStamp_uca[MM]);
strcat(l_CurrTime_ca, temp);
l_CurrTime_cl = CTime(l_ScripGraphInfo_stp->TimeStamp_uca[CC]*100 + l_ScripGraphInfo_stp->TimeStamp_uca[YY],
l_ScripGraphInfo_stp->TimeStamp_uca[MO],
l_ScripGraphInfo_stp->TimeStamp_uca[DD],
l_ScripGraphInfo_stp->TimeStamp_uca[HH],
l_ScripGraphInfo_stp->TimeStamp_uca[MM],
0/*l_ScripGraphInfo_stp->TimeStamp_uca[SS]*/);
CString l_inittime_cl = m_InitTime_cl.Format("%H, %M, %S");
CString l_currtime_cl = l_CurrTime_cl.Format("%H, %M, %S");
l_TimeSpan_cl = l_CurrTime_cl - m_InitTime_cl;
CString l_timespan_cl = l_TimeSpan_cl.Format("%H, %M, %S");
x = l_TimeSpan_cl.GetTotalMinutes();
if(x < 0)
{
IF_ERROR1(1, "Invalid time rcvd.");
return;
}
y= (int)l_ScripGraphInfo_stp->ScripValue_l/10000 ;/// 100;
if(y == 0)
continue;
AdjustSlots(x, y);
y -= m_Origin_l;
if(l_i_l == 0)
{
pDC->MoveTo(left+x, bottom-y);
if(l_ScripGraphInfo_stp->ScripValue_l/10000< l_ScripDayOpen1)
pDC->SetPixel(left+x, bottom-y, m_GraphColor_ula[INDEX_FALLING]);
else
pDC->SetPixel(left+x, bottom-y, m_GraphColor_ula[INDEX_RISING]);
}

CPoint l_CurrPt_cl = pDC->GetCurrentPosition();

if(l_ScripGraphInfo_stp->ScripValue_l/10000 < l_ScripDayOpen1)//Prev Close
// if((long)indexval < m_ScripGraphTable_clp->l_ScripDayOpen1)
pDC->SelectObject(&DrawPenFall);
else
pDC->SelectObject(&DrawPenRise);

switch(m_GraphStyle_s)
{

case LINESTYLE :

//Consider origin as (left,top) of the window, so graph grows down.
if(l_CurrPt_cl.y < PrevCloseY && (bottom-y) >= PrevCloseY)
{
pDC->SelectObject(&DrawPenRise);
pDC->LineTo(left+x, PrevCloseY);
pDC->SelectObject(&DrawPenFall);
pDC->LineTo(left+x, bottom-y);

}

if(l_CurrPt_cl.y > PrevCloseY && (bottom-y) <= PrevCloseY)
{
pDC->SelectObject(&DrawPenFall);
pDC->LineTo(left+x, PrevCloseY);
pDC->SelectObject(&DrawPenRise);
pDC->LineTo(left+x, bottom-y);

}

pDC->LineTo(left+x, bottom-y);

break;

case BARSTYLE :

pDC->MoveTo(x+left, PrevCloseY);
pDC->LineTo(x+left, bottom-y);

break;

default :
if(l_ScripGraphInfo_stp->ScripValue_l/10000 < l_ScripDayOpen1)
pDC->SetPixel(x+MarginX, bottom-y, m_GraphColor_ula[INDEX_FALLING]);
else
pDC->SetPixel(x+MarginX, bottom-y, m_GraphColor_ula[INDEX_RISING]); break;
}

}
pDC->SelectObject(OldFont);
pDC->SelectObject(OldPen);

CenterPen.DeleteObject();
AxisPen.DeleteObject();
SlotPen.DeleteObject();
DrawPenRise.DeleteObject();
DrawPenFall.DeleteObject();
brush.DeleteObject();
font.DeleteObject();

return;
}
Can any body tell me how to reduce time to populating data.

Re: How To Reduce time for populating the Data in Graph Format

Cedric Moonen24-Jul-09 2:39

Cedric Moonen

24-Jul-09 2:39

Please format your code properly because as it is now, it is very difficult to read.

Now to your question: if it is that slow, it's maybe because you are redrawing EVERYTHING each time a repaint is requested. Are you displaying a kind of dynamic chart ?

If you need a standard charting control, you can also look at my sig. I've developped one which is I think pretty ok regarding to performances.

Cédric Moonen
Software developer

Charting control [v2.0]
OpenGL game tutorial in C++

Add-in

john563224-Jul-09 1:32

john5632

24-Jul-09 1:32

Hi All,

I want to create an Add-In for MS-Outlook in MFC. Please guide me how to do that?

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.