The Initial Developer of the Original Code is Arnaud Bouchez.

  Portions created by the Initial Developer are Copyright (C) 2013
  the Initial Developer. All Rights Reserved.

  Contributor(s):

  
  Alternatively, the contents of this file may be used under the terms of
  either the GNU General Public License Version 2 or later (the "GPL"), or
  the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  in which case the provisions of the GPL or the LGPL are applicable instead
  of those above. If you wish to allow use of your version of this file only
  under the terms of either the GPL or the LGPL, and not to allow others to
  use your version of this file under the terms of the MPL, indicate your
................................................................................
function TSynVirtualDataSet.AllocRecordBuffer: TRecordBuffer;
begin
  result := AllocMem(sizeof(TRecInfo));
end;

procedure TSynVirtualDataSet.FreeRecordBuffer(var Buffer: TRecordBuffer);
begin
  if Buffer=nil then
    exit;
  FreeMem(Buffer);
  Buffer := nil;
end;

procedure TSynVirtualDataSet.GetBookmarkData(Buffer: TRecordBuffer; Data: Pointer);
begin
  if Data<>nil then
    PRecInfoIdentifier(Data)^ := PRecInfo(Buffer)^.Bookmark;
end;

function TSynVirtualDataSet.GetBookmarkFlag(Buffer: TRecordBuffer): TBookmarkFlag;
begin
  if Buffer<>nil then
    result := PRecInfo(Buffer)^.BookmarkFlag else
    result := bfEOF;
end;

function TSynVirtualDataSet.GetCanModify: Boolean;
begin
  result := false; // we define a READ-ONLY TDataSet
end;

................................................................................
{$endif}
{$else}
function TSynVirtualDataSet.GetFieldData(Field: TField; Buffer: Pointer): Boolean;
{$endif}
var Data, Dest: pointer;
    RowIndex, DataLen, MaxLen: integer;
    Temp: RawByteString;

begin
  result := false;

  RowIndex := PRecInfo(ActiveBuffer).RowIndentifier;
  Data := GetRowFieldData(Field,RowIndex,DataLen,(Buffer=nil));
  if Data=nil then // on success, points to Int64,Double,Blob,UTF8
    exit;
  result := true;
  if Buffer=nil then // =nil is just to test for not null
    exit;
  Dest := pointer(Buffer); // works also if Buffer is [var] TValueBuffer
  case Field.DataType of
  ftBoolean:
    PWORDBOOL(Dest)^ := PBoolean(Data)^;
  ftInteger:
    PInteger(Dest)^ := PInteger(Data)^;
................................................................................
    {$ifdef ISDELPHI2007ANDUP} // here Dest = PWideChar[] of DataSize bytes
    UTF8ToWideChar(Dest,Data,(Field.DataSize-2)shr 1,DataLen);
    {$else}          // here Dest is PWideString
    UTF8ToWideString(Data,DataLen,WideString(Dest^));
    {$endif}
  end;
  // ftBlob,ftMemo,ftWideMemo should be retrieved by CreateBlobStream()
  else raise EDatabaseError.CreateFmt('GetFieldData DataType=%d',[ord(Field.DataType)]);

  end;
end;

function TSynVirtualDataSet.CreateBlobStream(Field: TField; Mode: TBlobStreamMode): TStream;
var Data: pointer;
    DataLen: integer;
begin
  if Mode<>bmRead then
    raise EDatabaseError.Create('BLOB should be ReadOnly');
  Data := GetRowFieldData(Field,PRecInfo(ActiveBuffer).RowIndentifier,DataLen,false);
  if Data=nil then // should point to Blob or UTF8 data
    result := nil else
    case Field.DataType of
    ftBlob:
      result := TSynMemoryStream.Create(Data,DataLen);
    ftMemo:
      result := TRawByteStringStream.Create(CurrentAnsiConvert.UTF8BufferToAnsi(Data,DataLen));
    {$ifdef ISDELPHI2007ANDUP}
    ftWideMemo:
      result := TRawByteStringStream.Create(Utf8DecodeToRawUnicode(Data,DataLen));
    {$endif}
    else raise EDatabaseError.CreateFmt('CreateBlobStream DataType=%d',[ord(Field.DataType)]);

    end;
end;

function TSynVirtualDataSet.GetRecNo: Integer;
begin
  result := fCurrentRow+1;
end;
................................................................................
procedure TSynVirtualDataSet.InternalFirst;
begin
  fCurrentRow := -1;
end;

procedure TSynVirtualDataSet.InternalGotoBookmark(Bookmark: Pointer);
begin
  if Bookmark<>nil then
    fCurrentRow := PRecInfoIdentifier(Bookmark)^;
end;

procedure TSynVirtualDataSet.InternalHandleException;
begin
  Application.HandleException(Self);
end;

................................................................................
procedure TSynVirtualDataSet.InternalLast;
begin
  fCurrentRow := GetRecordCount;
end;

procedure TSynVirtualDataSet.InternalOpen;
begin

  InternalInitFieldDefs;
  if DefaultFields then
    CreateFields;
  BindFields(true);
  fCurrentRow := -1;
  fIsCursorOpen := True;
end;
................................................................................
function TSynVirtualDataSet.IsCursorOpen: Boolean;
begin
  result := fIsCursorOpen;
end;

procedure TSynVirtualDataSet.SetBookmarkData(Buffer: TRecordBuffer; Data: Pointer);
begin
  if Buffer<>nil then
    PRecInfo(Buffer)^.Bookmark := PRecInfoIdentifier(Data)^;
end;

procedure TSynVirtualDataSet.SetBookmarkFlag(Buffer: TRecordBuffer; Value: TBookmarkFlag);
begin
  if Buffer<>nil then
    PRecInfo(Buffer)^.BookmarkFlag := Value;
end;

procedure TSynVirtualDataSet.SetRecNo(Value: Integer);
begin


  dec(Value);
  if cardinal(Value)>=cardinal(GetRecordCount) then

    raise ERangeError.CreateFmt('SetRecNo(%d) with Count=%d',[Value+1,GetRecordCount]);

  fCurrentRow := Value;



end;

constructor TSynVirtualDataSet.Create(Owner: TComponent);
begin
  inherited Create(Owner);
  inc(GlobalDataSetCount);
  Name := ClassName+IntToStr(GlobalDataSetCount); // force unique name
end;


end.

  The Initial Developer of the Original Code is Arnaud Bouchez.

  Portions created by the Initial Developer are Copyright (C) 2013
  the Initial Developer. All Rights Reserved.

  Contributor(s):
  - mingda
    
  Alternatively, the contents of this file may be used under the terms of
  either the GNU General Public License Version 2 or later (the "GPL"), or
  the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  in which case the provisions of the GPL or the LGPL are applicable instead
  of those above. If you wish to allow use of your version of this file only
  under the terms of either the GPL or the LGPL, and not to allow others to
  use your version of this file under the terms of the MPL, indicate your
................................................................................
function TSynVirtualDataSet.AllocRecordBuffer: TRecordBuffer;
begin
  result := AllocMem(sizeof(TRecInfo));
end;

procedure TSynVirtualDataSet.FreeRecordBuffer(var Buffer: TRecordBuffer);
begin


  FreeMem(Buffer);
  Buffer := nil;
end;

procedure TSynVirtualDataSet.GetBookmarkData(Buffer: TRecordBuffer; Data: Pointer);
begin

  PRecInfoIdentifier(Data)^ := PRecInfo(Buffer)^.Bookmark;
end;

function TSynVirtualDataSet.GetBookmarkFlag(Buffer: TRecordBuffer): TBookmarkFlag;
begin

  result := PRecInfo(Buffer)^.BookmarkFlag;

end;

function TSynVirtualDataSet.GetCanModify: Boolean;
begin
  result := false; // we define a READ-ONLY TDataSet
end;

................................................................................
{$endif}
{$else}
function TSynVirtualDataSet.GetFieldData(Field: TField; Buffer: Pointer): Boolean;
{$endif}
var Data, Dest: pointer;
    RowIndex, DataLen, MaxLen: integer;
    Temp: RawByteString;
    OnlyTestForNull: boolean;
begin
  result := false;
  OnlyTestForNull := (Buffer=nil);
  RowIndex := PRecInfo(ActiveBuffer).RowIndentifier;
  Data := GetRowFieldData(Field,RowIndex,DataLen,OnlyTestForNull);
  if Data=nil then // on success, points to Int64,Double,Blob,UTF8
    exit;
  result := true;
  if OnlyTestForNull then 
    exit;
  Dest := pointer(Buffer); // works also if Buffer is [var] TValueBuffer
  case Field.DataType of
  ftBoolean:
    PWORDBOOL(Dest)^ := PBoolean(Data)^;
  ftInteger:
    PInteger(Dest)^ := PInteger(Data)^;
................................................................................
    {$ifdef ISDELPHI2007ANDUP} // here Dest = PWideChar[] of DataSize bytes
    UTF8ToWideChar(Dest,Data,(Field.DataSize-2)shr 1,DataLen);
    {$else}          // here Dest is PWideString
    UTF8ToWideString(Data,DataLen,WideString(Dest^));
    {$endif}
  end;
  // ftBlob,ftMemo,ftWideMemo should be retrieved by CreateBlobStream()
  else raise EDatabaseError.CreateFmt('%s.GetFieldData DataType=%d',
         [ClassName,ord(Field.DataType)]);
  end;
end;

function TSynVirtualDataSet.CreateBlobStream(Field: TField; Mode: TBlobStreamMode): TStream;
var Data: pointer;
    DataLen: integer;
begin
  if Mode<>bmRead then
    raise EDatabaseError.CreateFmt('%s BLOB should be ReadOnly',[ClassName]);
  Data := GetRowFieldData(Field,PRecInfo(ActiveBuffer).RowIndentifier,DataLen,false);
  if Data=nil then // should point to Blob or UTF8 data
    result := nil else
    case Field.DataType of
    ftBlob:
      result := TSynMemoryStream.Create(Data,DataLen);
    ftMemo:
      result := TRawByteStringStream.Create(CurrentAnsiConvert.UTF8BufferToAnsi(Data,DataLen));
    {$ifdef ISDELPHI2007ANDUP}
    ftWideMemo:
      result := TRawByteStringStream.Create(Utf8DecodeToRawUnicode(Data,DataLen));
    {$endif}
    else raise EDatabaseError.CreateFmt('%s.CreateBlobStream DataType=%d',
      [ClassName,ord(Field.DataType)]);
    end;
end;

function TSynVirtualDataSet.GetRecNo: Integer;
begin
  result := fCurrentRow+1;
end;
................................................................................
procedure TSynVirtualDataSet.InternalFirst;
begin
  fCurrentRow := -1;
end;

procedure TSynVirtualDataSet.InternalGotoBookmark(Bookmark: Pointer);
begin

  fCurrentRow := PRecInfoIdentifier(Bookmark)^;
end;

procedure TSynVirtualDataSet.InternalHandleException;
begin
  Application.HandleException(Self);
end;

................................................................................
procedure TSynVirtualDataSet.InternalLast;
begin
  fCurrentRow := GetRecordCount;
end;

procedure TSynVirtualDataSet.InternalOpen;
begin
  BookmarkSize := SizeOf(TRecInfo)-sizeof(TRecInfoIdentifier);
  InternalInitFieldDefs;
  if DefaultFields then
    CreateFields;
  BindFields(true);
  fCurrentRow := -1;
  fIsCursorOpen := True;
end;
................................................................................
function TSynVirtualDataSet.IsCursorOpen: Boolean;
begin
  result := fIsCursorOpen;
end;

procedure TSynVirtualDataSet.SetBookmarkData(Buffer: TRecordBuffer; Data: Pointer);
begin

  PRecInfo(Buffer)^.Bookmark := PRecInfoIdentifier(Data)^;
end;

procedure TSynVirtualDataSet.SetBookmarkFlag(Buffer: TRecordBuffer; Value: TBookmarkFlag);
begin

  PRecInfo(Buffer)^.BookmarkFlag := Value;
end;

procedure TSynVirtualDataSet.SetRecNo(Value: Integer);
begin
  CheckBrowseMode;
  if Value<>RecNo then begin
    dec(Value);
    if cardinal(Value)>=cardinal(GetRecordCount) then
      raise ERangeError.CreateFmt('%s.SetRecNo(%d) with Count=%d',
        [ClassName,Value+1,GetRecordCount]);
    DoBeforeScroll;
    fCurrentRow := Value;
    Resync([rmCenter]);
    DoAfterScroll;
  end;
end;

constructor TSynVirtualDataSet.Create(Owner: TComponent);
begin
  inherited Create(Owner);
  inc(GlobalDataSetCount);
  Name := ClassName+IntToStr(GlobalDataSetCount); // force unique name
end;


end.