Re: How to reduce Flickering ? - C / C++ / MFC Discussion Boards

002comp23-Mar-11 22:47

23-Mar-11 22:47

Hello Friends
I am using drawImage from GDIPLUS in OnPaint().And Mine image is getting flickered too much.How can i reduce it?

Thanks & Regards
Yogesh

Re: How to reduce Flickering ?

CPallini23-Mar-11 23:00

CPallini

23-Mar-11 23:00

You may use double buffering technique. Have a look at (one of) the following CodeProject articles:
http://www.codeproject.com/info/search.aspx?artkw=double+buffering&sbo=kw[^].
Smile | :)

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-- Alfonso the Wise, 13th Century King of Castile.

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[My articles]

Re: How to reduce Flickering ?

Maximilien24-Mar-11 2:56

Maximilien

24-Mar-11 2:56

+1 for using the CP search instead of google! Big Grin | :-D

Watched code never compiles.

Re: How to reduce Flickering ?

CPallini24-Mar-11 4:27

CPallini

24-Mar-11 4:27

Thanks.

Re: How to reduce Flickering ? [modified]

Cool_Dev24-Mar-11 0:22

Cool_Dev

24-Mar-11 0:22

in addition, handle WM_ERASEBACKGROUND message and simply return TRUE from there without calling base class's message handler. This will discard the flickering due to background painting. Remember, you have to paint the background from OnPaint (use double buffering Smile | :)

)

modified on Thursday, March 24, 2011 9:13 AM

Re: How to reduce Flickering ?

Nitheesh George24-Mar-11 2:02

Nitheesh George

24-Mar-11 2:02

Hi
Also create a memory DC and select this image to this DC. And use this DC as the Source in API BitBlt, StretchBitBlt etc.

Hope this helps

Nitheesh George

http://www.simpletools.co.in

Re: How to reduce Flickering ?

Albert Holguin24-Mar-11 4:26

Albert Holguin

24-Mar-11 4:26

this method works very well for drawing at high rates

Re: How to reduce Flickering ?

Stephen Hewitt24-Mar-11 2:14

Stephen Hewitt

24-Mar-11 2:14

The first step (before investigating possible solutions, such as double buffering) is to figure out why the flicking is occuring. Can you provide any more details? When does it flicker? Does the image resize if the window size is altered? Are you using the CS_HREDRAW and CS_VREDRAW[^] class styles?

Steve

Re: How to reduce Flickering ?

002comp24-Mar-11 18:47

002comp

24-Mar-11 18:47

hi,Its Flickering whenever some update happen like if i zoom,scroll etc.
It looks like tht OnPaint is calling and that is makeing flickering bcoz onpaint m using drawimage().

Regards
Yogesh

Variable In SQL String

Mike Certini23-Mar-11 19:11

Mike Certini

23-Mar-11 19:11

I am trying to insert a variable in a SQL string but am not having any success in finding the proper sytax. I am coding in C++. Listed below is code section I am trying to figure out. This code is part of an ADO routine that adds a field in an Access Database.

char Value[40];
printf("Input A String");
scanf("%s",Value);
sSQLCommand = L"ALTER TABLE TableIn ADD @Value nvarchar(20)";
com->CommandText = sSQLCommand;

Unfortunately what gets added to the database as a field is @Value.

Re: Variable In SQL String

«_Superman_»23-Mar-11 19:21

«_Superman_»

23-Mar-11 19:21

wchar_t sqlCommand[1024];
wsprintf(sqlCommand, L"ALTER TABLE TableIn ADD %s nvarchar(20)", Value);

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

Microsoft MVP (Visual C++)

Polymorphism in C

Re: Variable In SQL String

Mike Certini23-Mar-11 20:05

Mike Certini

23-Mar-11 20:05

Superman,

Excellent! You pointed me in the right direction. After some modifications, the following code works:

char sSQLCommand[100];                            
char TempField[50];                               
printf("Input Field");
scanf("%s",TempField);
sprintf_s(sSQLCommand,"ALTER TABLE TableIn ADD %s nvarchar(20)",TempField);

Re: Variable In SQL String

markkuk23-Mar-11 20:29

markkuk

23-Mar-11 20:29

Next, read about SQL injection[^] to understand why code like that is dangerous.

Re: Variable In SQL String

Pravin Patil, Mumbai23-Mar-11 22:16

Pravin Patil, Mumbai

23-Mar-11 22:16

You should avoid this coding style as it may lead to some serious problems. Google SQL Injection, you yourself will understand.

Is there a linkable chat control?

includeh1023-Mar-11 3:48

includeh10

23-Mar-11 3:48

I need an existing linkable chat control for client/server communication, which is readonly and text-only.

When users say something, chat contents are added to the control.
Texts displayed on the control have multiple types of links, such as user-name, comments, advertisements and something else. If clicking on those links, related events or messages are submitted to the control's parent or itself, so that I can show further info by types of those links, i.e. show pop-up menu or show some windows.

Thanks

BTW: or any idea to develop the control easily?

Re: Is there a linkable chat control?

Hans Dietrich23-Mar-11 5:19

Hans Dietrich

23-Mar-11 5:19

Here is a chat control that supports links: A chat control based on the Rich Edit control[^]
All you need to do is set it to read-only.

Best wishes,
Hans

[Hans Dietrich Software]

Use Modeless Dialog inside MFC DLL

Andraw Tang22-Mar-11 11:52

Andraw Tang

22-Mar-11 11:52

Hi, dear all,

I am creating a MFC DLL utility program that will be used by client application through exported functions in DLL.

Now I have to problem about how to create a modeless dialog in MFC dll. I searched some examples about creating modeless dialog in MFC exe application. Usually they create a dialog pointer in View class and initialize it as:
m_pDlg = new CMymfc9Dialog(this);

But my program is MFC DLL, there is no CView class, how can I initialize the m_pDlg? what argument should I pass to it?

Thanks!

Re: Use Modeless Dialog inside MFC DLL

Ozer Karaagac22-Mar-11 14:14

Ozer Karaagac

22-Mar-11 14:14

You can simply pass NULL to CDialog constructor as parent window. In this case, MFC searches a proper one. If it doesn't find any, dialog's parent window is set to the main application window.

You also don't have to use above constructor for modeless dialog boxes. You can use default constructor then you can specify parent window later by Create() function.

m_pDlg = new CMymfc9Dialog();

m_pDlg->Create(IDD_MYMFC9DIALOG, NULL); // or parent wnd instead of NULL

m_pDlg->ShowWindow(SW_SHOW);

Re: Use Modeless Dialog inside MFC DLL

Andraw Tang23-Mar-11 2:40

Andraw Tang

23-Mar-11 2:40

Thanks!

Now I use pMatTable = new CMatTable(this->m_pMainWnd); pass main window as parent window, it works now.

Re: Use Modeless Dialog inside MFC DLL

Hans Dietrich22-Mar-11 14:16

Hans Dietrich

22-Mar-11 14:16

In your DLL, put this function:

void MyDLLClass::ShowDialog(CWnd *pWnd)
{
    m_pDlg = new CMymfc9Dialog(pWnd);   // m_pDlg is variable in MyDLLClass
}

In your app, call the ShowDialog() function.

Best wishes,
Hans

[Hans Dietrich Software]

Re: Use Modeless Dialog inside MFC DLL

Andraw Tang23-Mar-11 2:41

Andraw Tang

23-Mar-11 2:41

Thanks!

Re: Use Modeless Dialog inside MFC DLL

Nitheesh George22-Mar-11 23:04

Nitheesh George

22-Mar-11 23:04

Hi,

From your posting, I think that you wanted to a dialog box which is added a resource in your MFC dll. If I am right, It is a matter of simple. Please see the sample below.

extern "C" __declspec(dllexport) showMyDialog(CWnd *parent)
{
AFX_MANAGE_STATE(AfxGetStaticModuleState( ));
CDialog *myDialog = new CDialog(IDD_DIALOG1, parent);
myDialog->ShowWindow(SW_NORMAL);
}

Make sure that you release the allocated memory in WM_NCDESTROY message handler code.

Then about the code. There is a problem when we want to show a dialog from an MFC DLL. The MFC will using main application resource handle to find the specified resource. If you not specify the AFX_MANAGE_STATE(AfxGetStaticModuleState( )); at the begginig of the exported function, the MFC framework will try to find the resource in main application's resource. If the specified resource not found, then the showWindow fails and if found, MFC will try to load that resource may causing an unexpected behaviour. For more infomation see the MSDN documentation of AFX_MANAGE_STATE(AfxGetStaticModuleState( ));

Hope this helps

Thanks

Nitheesh George

Nitheesh George

http://www.simpletools.co.in

Re: Use Modeless Dialog inside MFC DLL

Andraw Tang23-Mar-11 2:42

Andraw Tang

23-Mar-11 2:42

Thanks for reminding me, I do get application crash since I didn't use AFX_MANAGE_STATE(AfxGetStaticModuleState()) at first.

convert an image (black & white) to a file (zero & one) in the VC++

Shatha8822-Mar-11 9:08

Shatha88

22-Mar-11 9:08

Hello everyone
I have a graduation project and
I need to know how to convert an image (black & white) to a file (zero & one) in the VC++
and OpenCv ?
Or in other words how can Read image as a File ??

Can anyone help me :/

Re: convert an image (black & white) to a file (zero & one) in the VC++

Niklas L22-Mar-11 20:43

Niklas L

22-Mar-11 20:43

You really need to give more input than that. What is the format of your 'image'? Is that a HBITMAP, or some other data structure? What format should the output file have? Raw/jpg/bmp/gif?

Shatha88 wrote:
Can anyone help me :/

Probably not, as it is right now.

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