How-to-store-the-contents-of-a-richedit-in-an-emf-files


            Howto store the contents of a RichEdit in an EMF files
Sometimes, you may want to store the contents of a rich edit control in a metafile. This article outlines an approach that stores this type of control's contents in enhanced metafiles, one page per metafile. The following code demonstrates one method to dump the contents of a rich edit control into EMF files (one per page):
unit RichEditEMFPrint;
interface
uses
 Windows, SysUtils, RichEdit, commdlg, classes, messages, Comctrls;
procedure RichEditToMetaFile(AControl : TRichEdit; AFileName : string);
implementation
// GetPrinterDC()
// returns a printer DC - uses Printer Common Dialog
function GetPrinterDC : HDC;
var
 pdlg : TPRINTDLG;
begin
 FillChar(pdlg, sizeof(TPRINTDLG), 0);
 pdlg.lStructSize := sizeof( TPRINTDLG );
 pdlg.Flags := PD_RETURNDC;
 PrintDlg(pdlg);
 Result := pdlg.hDC;
end;
// Get the length, in characters, of the text in the control
function GetRTFTextLength(hWndRTF : HWND) : integer;
begin
 Result := SendMessage(hWndRTF, WM_GETTEXTLENGTH, 0, 0 );
end;
// RTFToEMF - Tell the control to draw itself on the EMF
// Parameters:
// hRefDC is used to create the EMF
// pszMetaFileName is the file name of the new EMF (can be nil)
// prcMeta is the RECT used to in CreateEnhMetaFile(), in 0.01mm
// units (should not be nil)
// hWndRTF is the control of interest
// nStart is the starting character location
// pEnd is a integer which receives the position of
// the next character to print after this page 
function RTFToEMF(hRefDC : HDC; pszMetaFileName : LPCTSTR; prcMeta : TRECT;
 hWndRTF : HWND; nStart : integer; var pEnd : integer) : HENHMETAFILE;
var
 hMetaDC : HDC;
 fr : FORMATRANGE;
 nTextPrinted : integer;
begin
 // Create the EMF
 hMetaDC := CreateEnhMetaFile( hRefDC, pszMetaFileName, @prcMeta, nil );
 if( hMetaDC = 0 ) then
 begin
 Result := 0;
 Exit;
 end;
 ZeroMemory(@fr, sizeof(fr));
 // Set up the page (convert 0.01mm to twips)
 fr.rcPage.top := prcMeta.left*1440 div 2540;
 fr.rcPage.left := prcMeta.top*1440 div 2540;
 fr.rcPage.right := prcMeta.right*1440 div 2540;
 fr.rcPage.bottom := prcMeta.bottom*1440 div 2540;
 // Set up no margins all around.
 fr.rc := fr.rcPage;
 // Set up the range of text to print as nStart to end of document
 fr.chrg.cpMin := nStart;
 fr.chrg.cpMax := -1;
 fr.hdcTarget := hMetaDC;
 fr.hdc := fr.hdcTarget;
 // Tell the control to draw itself on our (meta) DC
 nTextPrinted := SendMessage(hWndRTF, EM_FORMATRANGE, 1, integer(@(fr)));
 pEnd := nTextPrinted;
 Result := CloseEnhMetaFile( hMetaDC );
end;
// DumpRTFToPagedEMFs - demonstrates using RTFToEMF() to create an EMF
// for each page in an RTF control
// Parameters:
// hWndRTFControl - the control
// szEMFFileTitleBase - base filename for EMF files, number is appended
procedure DumpRTFToPagedEMFs(hWndRTFControl : HWND; szEMFFileTitleBase : LPTSTR);
var
 szMetaName : string;
 nRTFTextLength, nStart, nPage : integer;
 hRefDC : HDC;
 rcMeta : TRECT;
 hEMF : HENHMETAFILE;
begin
 // First, determine how many chars are in the RTF
 nRTFTextLength := GetRTFTextLength( hWndRTFControl );
 // Get a reference DC (based on a printer)
 hRefDC := GetPrinterDC();
 // Set up the meta RECT for 0.01mm units
 rcMeta := Classes.Rect( 0, 0, GetDeviceCaps(hRefDC, HORZSIZE)*100,
 GetDeviceCaps(hRefDC, VERTSIZE)*100 );
 nPage := 0;
 nStart := 0;
 while nStart // Loop while we've not reached the end of the text in the control
 begin
 // construct a file name for this page
 szMetaName := Format('%s%d.EMF', [szEMFFileTitleBase, nPage]);
 // call function above to draw this portion of the RTF on the EMF
 hEMF := RTFToEMF( hRefDC, PChar(szMetaName), rcMeta, hWndRTFControl,
 nStart, nStart );
 // clean up
 DeleteEnhMetaFile( hEMF );
 inc(nPage);
 if nStart = 0 then
 break;
 end;
end;
procedure RichEditToMetaFile(AControl : TRichEdit; AFileName : string);
begin
 DumpRTFToPagedEMFs(AControl.Handle, PChar(AFileName));
end;
end.
Examples Delphi
