lazarus-ccr/components/rx/ex_rx_bin_datapacket.pas

{
    TBinaryRxDatapacketReader implementation

    See the file COPYING.FPC, included in this distribution,
    for details about the copyright.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

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

unit ex_rx_bin_datapacket;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, dom, db, ex_rx_datapacket;

type
  TChangeLogEntry = record
       UpdateKind : TUpdateKind;
       OrigEntry  : integer;
       NewEntry   : integer;
  end;
  TChangeLogEntryArr = array of TChangeLogEntry;

type
  { TBinaryRxDatapacketReader }

  TBinaryRxDatapacketReader = class(TRxDataPacketReader)
  public
    procedure LoadFieldDefs(AFieldDefs : TFieldDefs); override;
    procedure StoreFieldDefs(AFieldDefs : TFieldDefs); override;
    function GetRecordRowState(out AUpdOrder : Integer) : TRowState; override;
    procedure FinalizeStoreRecords; override;
    function GetCurrentRecord : boolean; override;
    procedure GotoNextRecord; override;
    procedure InitLoadRecords; override;
    procedure RestoreRecord(ADataset : TDataset); override;
    procedure StoreRecord(ADataset : TDataset; ARowState : TRowState; AUpdOrder : integer = 0); override;
    class function RecognizeStream(AStream : TStream) : boolean; override;
  end;

implementation

uses
  dbconst;

{ TBinaryRxDatapacketReader }

const
  RxBinaryIdent = 'BinRxDataset';

procedure TBinaryRxDatapacketReader.LoadFieldDefs(AFieldDefs: TFieldDefs);
var
  FldCount : word;
  i : integer;
begin

  if not RecognizeStream(Stream) then
    DatabaseError(SStreamNotRecognised);

  FldCount:=Stream.ReadWord;
  AFieldDefs.Clear;
  for i := 0 to FldCount -1 do with TFieldDef.create(AFieldDefs) do
    begin
    Name := Stream.ReadAnsiString;
    Displayname := Stream.ReadAnsiString;
    Size := Stream.ReadWord;
    DataType := TFieldType(Stream.ReadWord);

    if Stream.ReadByte = 1 then
      Attributes := Attributes + [faReadonly];
    end;

end;

procedure TBinaryRxDatapacketReader.StoreFieldDefs(AFieldDefs: TFieldDefs);
var i : integer;
begin
  Stream.Write(RxBinaryIdent[1],length(RxBinaryIdent));

  Stream.WriteWord(AFieldDefs.Count);
  for i := 0 to AFieldDefs.Count -1 do with AFieldDefs[i] do
    begin
    Stream.WriteAnsiString(Name);
    Stream.WriteAnsiString(DisplayName);
    Stream.WriteWord(size);
    Stream.WriteWord(ord(DataType));

    if faReadonly in Attributes then
      Stream.WriteByte(1)
    else
      Stream.WriteByte(0);
    end;

end;

function TBinaryRxDatapacketReader.GetRecordRowState(out AUpdOrder: Integer
  ): TRowState;
var Buf : byte;
begin
  Buf := 0;
  AUpdOrder := 0;

  Stream.Read(Buf,1);
  Result := ByteToRowState(Buf);
  if Result<>[] then
    Stream.ReadBuffer(AUpdOrder,sizeof(integer));

end;

procedure TBinaryRxDatapacketReader.FinalizeStoreRecords;
begin
//  Do nothing
end;

function TBinaryRxDatapacketReader.GetCurrentRecord: boolean;
var
  Buf : byte;
begin
  Buf := 0;
  Result := (Stream.Read(Buf,1)=1) and (Buf=$fe);
end;

procedure TBinaryRxDatapacketReader.GotoNextRecord;
begin
//  Do Nothing
end;

procedure TBinaryRxDatapacketReader.InitLoadRecords;
begin
//  Do Nothing
end;

procedure TBinaryRxDatapacketReader.RestoreRecord(ADataset: TDataset);
begin
  Stream.ReadBuffer(ADataset.ActiveBuffer^,ADataset.RecordSize);
end;

procedure TBinaryRxDatapacketReader.StoreRecord(ADataset: TDataset;
  ARowState: TRowState; AUpdOrder: integer);
begin
  Stream.WriteByte($fe);
  Stream.WriteByte(RowStateToByte(ARowState));
  if ARowState<>[] then
    Stream.WriteBuffer(AUpdOrder,sizeof(integer));
  Stream.WriteBuffer(ADataset.ActiveBuffer^,ADataset.RecordSize);
end;

class function TBinaryRxDatapacketReader.RecognizeStream(AStream: TStream
  ): boolean;
var s        : string;
    len      : integer;
begin
  Len := length(RxBinaryIdent);
  setlength(s,len);
  if (AStream.Read (s[1],len) = len)
  and (s=RxBinaryIdent) then
    Result := True
  else
    Result := False;

end;

initialization
  RegisterDatapacketReader(TBinaryRxDatapacketReader,dfBinary);
end.