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CEditLog - fast logging into an edit control with cout

, 1 Nov 2003
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Use an edit control for logging messages and redirect cout

Problem

I once wanted to use an edit control for fast, asynchronous text output. I need to log messages from a lot of threads, sometimes more than 1000 per second. And since I created already functions to dump my objects to std::cout I also wanted to use an edit control as std::ostream.

Features

  • Asynchronous, very fast output to any edit control
  • User can scroll back, select and copy text and so on during output
  • Can be used with or without MFC (Sample is a MFC project)
  • Uses window-subclassing, so you can use it even with CEdit-derived controls
  • Save to be used by multiple threads
  • Special basic_streambuf class to create or redirect a std::ostream (such as std::cout) to an edit control

Using CEditLog

Just create an Instance of CEditLog and attach an edit control to it using the SetEditControl() function. Then you can add text to the end of the edit control using one of the AddText() members:

class CEditLog : protected CSubclassWnd
{
public:
    typedef CSubclassWnd root_type;

    // Constructs the CEditLog. You can pass the edit controls handle

    // here or set it later using the SetEditCtrl() function.

    // To increase performance CEditLog repaints the edit-control

    // only if the caret resides in the last line. Otherwise the

    // control will be refreshed only every nMaxRefreshDelay msec.

    CEditLog( HWND hEdit = NULL, UINT nMaxRefreshDelay = 500 );
    
    // Adds some text to the end of the edit control. Works asynchronously

    // (using PostMessage()) and is save to be called by multiple threads.

    // If you pass true for bLFtoCRLF every LF (ASCII 10) (as it is used in

    // most cases for end-of-line) will be converted to a CR/LF (ASCII 10/13)

    // sequence as it is needed by the windows edit control. 

    virtual void AddText( LPCWSTR pwszAdd, bool bLFtoCRLF = false );
    
    // Converts pszAdd to UNICODE and calls the above

    void AddText( LPCSTR pszAdd, bool bLFtoCRLF = false );

    // Sets the edit-control to be used for logging.

    // Pass NULL to stop text logging.

    virtual void SetEditCtrl( HWND hEdit );

    HWND GetEditCtrl() const

    ...
};

The sample project

The included sample project shows the usage of CEditLog and how to use basic_editstrbuf to redirect std::cout to use the edit log.

CEditLog uses the CSubclassWnd class, written by William E. Kempf for implementation. I have included the soure of CSubclassWnd in the sample project, the complete article is also available here at CodeProject.

History

Version Comments
1.0 First Release
1.1 Minor Revision. Now uses V2.0 of SubclassWindow.
Now really works on Win9x (V1.0 used UNICODE for internal data handling and failed on Win9x systems. Now the code checks if it runs on Win9x and does the required conversions.)
1.2 Minor Revision. Now compiles fine even in VC.NET 2003.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Daniel Lohmann

Germany Germany
Daniel Lohmann (daniel@losoft.de) is Assistant Professor at the Distributed Systems and Operating Systems department at Friedrich-Alexander-University Erlangen-Nuremberg, Germany. His main research topic is the design of a highly customizable and scalable operating system product line for deeply embedded systems using static configuration and aspect-oriented techniques. Before joining Universität Erlangen he worked as a freelance trainer and consultant for NT system programming, advanced C++ programming and OOA/OOD. He is interested in upcoming programming techniques like aspect-oriented programming, generative programming and C++ meta coding and has written some nice and handy tools for Windows NT which you can download at his web site.

Comments and Discussions

 
AnswerRe: How to reduce Flicker? Pinmembergbiddison24-Jun-04 20:09 
GeneralRe: How to reduce Flicker? PinmemberRJSoft23-Aug-04 3:04 
AnswerRe: How to reduce Flicker? Pinmemberlano11064-Jul-06 18:47 
Questionwhat about printf? Pinmemberomasoud14-Jul-03 14:32 
AnswerRe: what about printf? PinmemberDaniel Lohmann14-Jul-03 21:28 
GeneralRe: what about printf? Pinmemberomasoud15-Jul-03 0:35 
GeneralRe: what about printf? PinmemberDaniel Lohmann16-Jul-03 5:32 
GeneralHi Pinmemberannum14-Jun-03 16:19 
First thanks for the great class! I have used it and it works great Smile | :)
 
What I wan't to do is add coloring capability to it, that dpending on the text I can change its color.
 
Any pointers, suggestions as I think that would be a goot addition
 
Thanks again
GeneralRe: Hi PinmemberDaniel Lohmann15-Jun-03 1:33 
GeneralRe: Hi Coloring Pinmemberpmackell17-Sep-03 9:06 
GeneralCEditLog and FormView Pinmemberabstract312-Jun-03 8:59 
GeneralRe: CEditLog and FormView PinmemberDaniel Lohmann15-Jun-03 1:40 
GeneralRe: CEditLog and FormView Pinmembersammyc6-Dec-04 14:52 
GeneralRe: CEditLog and FormView Pinmembersammyc6-Dec-04 15:13 
GeneralRe: CEditLog and FormView PinmemberDaniel Lohmann6-Dec-04 21:42 
GeneralDon't work in studio .net 2003 Pinmemberwukas15-May-03 10:29 
GeneralRe: Don't work in studio .net 2003 PinmemberDaniel Lohmann26-May-03 5:29 
GeneralRe: Don't work in studio .net 2003 PinsussAnonymous17-Jun-03 7:20 
GeneralRe: Don't work in studio .net 2003 Pinmemberajedlitschka26-Oct-03 9:50 
GeneralNow compiles fine in VC.NET 2003 :-) PinmemberDaniel Lohmann2-Nov-03 23:25 
Generalrestrict amount of text/cut first lines Pinmemberdontsmoke14-Apr-03 9:43 
GeneralRe: restrict amount of text/cut first lines PinmemberDoubleApexCa20-Aug-04 5:40 
Generalusage with CEditView, handling of WM_DESTROY message Pinmemberluedi6-Mar-03 5:14 
GeneralRe: usage with CEditView, handling of WM_DESTROY message PinmemberDaniel Lohmann6-Mar-03 7:39 
GeneralA little unrelated but... PinmemberAnthony Winters28-Feb-03 13:13 

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