How to add serialization support to WTL CRichEditCtrl class






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Small class that adds a serialization support to CRichEditCtrl class
Introduction
WTL comes with many control classes that provide standard elements of the
user interface. One of them is CRichEditCtrl
- a rich edit control
that understands some basic RTF formatting and allows multiple fonts, colors,
and so on. But some useful features that it's MFC counterpart has are missing in
the WTL implementation, one of them being able to serialize
CRichEditCtrl
.
So I wrote a small class CRichEditEx
that adds a serialization
support to CRichEditCtrl
class. This class is using CXArchive class
[^] also developed by me and, basically, a port of MFC code.
CRichEditEx
template <class T> class CRichEditEx : public CWindowImpl<T, CRichEditCtrl> { private: bool m_bRTF; // when true, indicates // that CRichEditCtrl should store paragraph // and character-formatting characteristics. /************************************************************ * Function......: Stream * Parameters....: Ar - archive class * bSelection - indicates whether only selected text should * be saved or read * Returns.......: None * Description...: Transfers data into or out of a rich edit control ************************************************************/ void Stream(CXArchive& Ar, bool bSelection) { ATLASSERT(::IsWindow(m_hWnd)); int nFormat; // indicates whether stream I/O should include formatting EDITSTREAM es = {0, 0, EditStreamCallBack}; es.dwCookie = (DWORD)&Ar; if (m_bRTF) // rich edit control maintains formatting information nFormat = SF_RTF; else // rich edit control does not maintain formatting information nFormat = SF_TEXT; if (bSelection) nFormat |= SFF_SELECTION; if (Ar.IsStoring()) // Store text from the rich edit control into an output stream StreamOut(nFormat, es); else { // Insert text from an input stream into the rich edit control StreamIn(nFormat, es); Invalidate(); } } /****************************************************************** * Function......: EditStreamCallBack * Parameters....: dwCookie - application-defined value * pbBuff - data buffer * cb - number of bytes to read or write * pcb - number of bytes transferred * Returns.......: Returns 0 if no error, otherwise return error code * Description...: Application defined callback function * used to transfer a stream of data into or out of a rich edit control ******************************************************************/ static DWORD CALLBACK EditStreamCallBack(DWORD dwCookie, LPBYTE pbBuff, LONG cb, LONG *pcb) { ATLASSERT(dwCookie != 0); ATLASSERT(pcb != NULL); DWORD dwRet = 0; // Retrieve an archive object CXArchive * pAr = (CXArchive*)dwCookie; pAr->Flush(); *pcb = cb; try { if (pAr->IsStoring()) // Save text pAr->GetFile()->Write(pbBuff, cb); else // Load test *pcb = pAr->GetFile()->Read(pbBuff, cb); } catch(CXException& e) { *pcb = 0; dwRet = e.GetErrorNumber(); } return dwRet; } public: DECLARE_WND_SUPERCLASS(NULL, CRichEditCtrl::GetWndClassName()) /****************************************************************** * Function......: Constructor * Parameters....: None * Returns.......: None * Description...: Initializes a class object *******************************************************************/ CRichEditEx() { m_bRTF = true; } BOOL PreTranslateMessage(MSG* pMsg) { pMsg; return FALSE; } BEGIN_MSG_MAP(CRichEditEx) END_MSG_MAP() /***************************************************************** * Function......: SetStreamFormat * Parameters....: Formatting flag value * Returns.......: None * Description...: Sets a formatting flag ****************************************************************/ void SetStreamFormat(bool bRTF) { m_bRTF = bRTF; } /***************************************************************** * Function......: GetStreamFormat * Parameters....: None * Returns.......: Formatting flag * Description...: Gets a formatting flag ***************************************************************/ bool GetStreamFormat() { return m_bRTF; } /**************************************************************** * Function......: Serialize * Parameters....: Ar - archive class * Returns.......: None * Description...: Reads/writes CRichEditCtrl object from/to archive ****************************************************************/ void Serialize(CXArchive& Ar) { ATLASSERT(::IsWindow(m_hWnd)); Stream(Ar, false); } };
Using the code
1. Derive your class from CRichEditEx
like so:
class CRichEditDemoView : public CRichEditEx<CRichEditDemoView> { ... };2. Add
CXFile
and CXArchive
classes to your
project: #include "File.h" #include "Archive.h"3. Somewhere in your code where you want to save the contents of the rich edit control add the following code:
LRESULT OnFileSave(WORD /*wNotifyCode*/, WORD /*wID*/, HWND /*hWndCtl*/, BOOL& /*bHandled*/) { string strFile = "demo.txt"; try { CXFile file; file.Open(strFile, GENERIC_WRITE | GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL); CXArchive ar(&file, CXArchive::store); m_view.Serialize(ar); ar.Close(); } catch (CXException& Ex) { MessageBox(Ex.GetErrorDesc().c_str(), _T("Richedit Demo"), MB_OK); } catch (...) { MessageBox(_T("Unexpected error"), _T("Richedit Demo"), MB_OK); } return 0; }4. Somewhere in your code where you want to load the contents of the rich edit control from the file add the following code:
LRESULT OnFileOpen(WORD /*wNotifyCode*/, WORD /*wID*/, HWND /*hWndCtl*/, BOOL& /*bHandled*/) { string strFile = "demo.txt"; try { CXFile file; file.Open(strFile, GENERIC_WRITE | GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL); CXArchive ar(&file, CXArchive::load); m_view.Serialize(ar); ar.Close(); } catch (CXException& Ex) { MessageBox(Ex.GetErrorDesc().c_str(), _T("Richedit Demo"), MB_OK); } catch (...) { MessageBox(_T("Unexpected error"), _T("Richedit Demo"), MB_OK); } return 0; }
Demo project
Demo project contains the CRichEditEx
, CXArchive
,
CXFile
classes implementations and example how to use
them.
Selecting File->Save will store the contents of the rich edit control into the file and File->Open will insert text into the rich edit control.
History
- October 12, 2004 - initial release.
- October 13, 2004 - bug fix, where methods of the class derived from
CRichEditEx
can't be called byCWindowImpl
. Thanks to Stuart Dootson for pointing it out.
Disclaimer
THIS SOFTWARE AND THE ACCOMPANYING FILES ARE DISTRIBUTED "AS IS" AND WITHOUT ANY WARRANTIES WHETHER EXPRESSED OR IMPLIED. NO RESPONSIBILITIES FOR POSSIBLE DAMAGES CAN BE TAKEN. THE USER MUST ASSUME THE ENTIRE RISK OF USING THIS SOFTWARE.