Как конвертировать кодовую страницу?

All Systems (Win 95+ and WinNT4+) with MS Internet Explorer 4 and newer have a library named mlang.dll in the Winnt\System32 directory. Usually you can tell Delphi to simply import these COM Libraries. This one however, Delphi did not. I started to convert the "most wanted" interface for myself. The results I present you here.

First I give you the code for the conversion unit, that allows you simply convert any text from code page interpretation into another one. Following I will shortly discuss the code and give you a sample of how to use it.

Code:

{* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

* Unit Name : uCodePageConverter

* Autor : Daniel Wischnewski

* Urheber : Daniel Wischnewski

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *}

unit uCodePageConverter;

interface

uses

Windows;

const

IID_MLangConvertCharset: TGUID = '{D66D6F98-CDAA-11D0-B822-00C04FC9B31F}';

CLASS_MLangConvertCharset: TGUID = '{D66D6F99-CDAA-11D0-B822-00C04FC9B31F}';

type

tagMLCONVCHARF = DWORD;

const

MLCONVCHARF_AUTODETECT: tagMLCONVCHARF = 1;

MLCONVCHARF_ENTITIZE: tagMLCONVCHARF = 2;

type

tagCODEPAGE = UINT;

const

CODEPAGE_Thai: tagCODEPAGE = 0874;

CODEPAGE_Japanese: tagCODEPAGE = 0932;

CODEPAGE_Chinese_PRC: tagCODEPAGE = 0936;

CODEPAGE_Korean: tagCODEPAGE = 0949;

CODEPAGE_Chinese_Taiwan: tagCODEPAGE = 0950;

CODEPAGE_UniCode: tagCODEPAGE = 1200;

CODEPAGE_Windows_31_EastEurope: tagCODEPAGE = 1250;

CODEPAGE_Windows_31_Cyrillic: tagCODEPAGE = 1251;

CODEPAGE_Windows_31_Latin1: tagCODEPAGE = 1252;

CODEPAGE_Windows_31_Greek: tagCODEPAGE = 1253;

CODEPAGE_Windows_31_Turkish: tagCODEPAGE = 1254;

CODEPAGE_Hebrew: tagCODEPAGE = 1255;

CODEPAGE_Arabic: tagCODEPAGE = 1256;

CODEPAGE_Baltic: tagCODEPAGE = 1257;

type

IMLangConvertCharset = interface

['{D66D6F98-CDAA-11D0-B822-00C04FC9B31F}']

function Initialize(

uiSrcCodePage: tagCODEPAGE; uiDstCodePage: tagCODEPAGE;

dwProperty: tagMLCONVCHARF

): HResult; stdcall;

function GetSourceCodePage(

out puiSrcCodePage: tagCODEPAGE

): HResult; stdcall;

function GetDestinationCodePage(

out puiDstCodePage: tagCODEPAGE

): HResult; stdcall;

function GetProperty(out pdwProperty: tagMLCONVCHARF): HResult; stdcall;

function DoConversion(

pSrcStr: PChar; pcSrcSize: PUINT; pDstStr: PChar; pcDstSize: PUINT

): HResult; stdcall;

function DoConversionToUnicode(

pSrcStr: PChar; pcSrcSize: PUINT; pDstStr: PWChar; pcDstSize: PUINT

): HResult; stdcall;

function DoConversionFromUnicode(

pSrcStr: PWChar; pcSrcSize: PUINT; pDstStr: PChar; pcDstSize: PUINT

): HResult; stdcall;

end;

CoMLangConvertCharset = class

class function Create: IMLangConvertCharset;

class function CreateRemote(const MachineName: string): IMLangConvertCharset;

end;

implementation

uses

ComObj;

{ CoMLangConvertCharset }

class function CoMLangConvertCharset.Create: IMLangConvertCharset;

begin

Result := CreateComObject(CLASS_MLangConvertCharset) as IMLangConvertCharset;

end;

class function CoMLangConvertCharset.CreateRemote(

const MachineName: string

): IMLangConvertCharset;

begin

Result := CreateRemoteComObject(

MachineName, CLASS_MLangConvertCharset

) as IMLangConvertCharset;

end;

end.

As you can see, I did translate only one of the many interfaces, however this one is the most efficient (according to Microsoft) and will do the job. Further I added some constants to simplify the task of finding the most important values.

When using this unit to do any code page conersions you must not forget, that the both code pages (source and destination) must be installed and supported on the computer that does the translation. OIn the computer that is going to show the result only the destination code page must be installed and supported.

To test the unit simple create a form with a memo and a button. Add the following code to the buttons OnClick event. (Do not forget to add the conversion unit to the uses clause!)

Code:

procedure TForm1.Button1Click(Sender: TObject);

var

Conv: IMLangConvertCharset;

Source: PWChar;

Dest: PChar;

SourceSize, DestSize: UINT;

begin

// connect to MS multi-language lib

Conv := CoMLangConvertCharset.Create;

// initialize UniCode Translation to Japanese

Conv.Initialize(CODEPAGE_UniCode, CODEPAGE_Japanese, MLCONVCHARF_ENTITIZE);

// load source (from memo)

Source := PWChar(WideString(Memo1.Text));

SourceSize := Succ(Length(Memo1.Text));

// prepare destination

DestSize := 0;

// lets calculate size needed

Conv.DoConversionFromUnicode(Source, @SourceSize, nil, @DestSize);

// reserve memory

GetMem(Dest, DestSize);

try

// convert

Conv.DoConversionFromUnicode(Source, @SourceSize, Dest, @DestSize);

// show

Memo1.Text := Dest;

finally

// free memory

FreeMem(Dest);

end;