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lazarus-tutorials/stream_visualize/main_stream.pas

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2021-11-11 15:15:54 -05:00
unit main_stream;
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils, Forms, Controls, Graphics, Dialogs, ComCtrls, StdCtrls,
Spin, Blowfish, demo_stream;
const savedFileName: TFileName = 'stream.dat';
type
{ TForm1 }
TForm1 = class(TForm)
btnDecrypt: TButton;
btnEncrypt: TButton;
btnGenerateStream: TButton;
btnLoadStream: TButton;
btnSaveStream: TButton;
edtRecord: TEdit;
lblAdjustPosition: TLabel;
lblNumRecords: TLabel;
lblPositionDesc: TLabel;
lblOrigin: TLabel;
lblRecordNo: TLabel;
lblSavedFileSize: TLabel;
lblStreamSize: TLabel;
memoDecrypted: TMemo;
memoDisplay: TMemo;
memoEncrypted: TMemo;
seCurrentRecNo: TSpinEdit;
seNoOfRecords: TSpinEdit;
tbPosition: TTrackBar;
udMover: TUpDown;
procedure btnDecryptClick(Sender: TObject);
procedure btnEncryptClick(Sender: TObject);
procedure btnGenerateStreamClick(Sender: TObject);
procedure btnLoadStreamClick(Sender: TObject);
procedure btnSaveStreamClick(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure seCurrentRecNoChange(Sender: TObject);
procedure udMoverClick(Sender: TObject; Button: TUDBtnType);
private
ds: TdemoStream;
sOriginal, sEncrypted: TStringStream;
key: string;
public
procedure DisplayStream;
end;
var
Form1: TForm1;
implementation
{$R *.lfm}
{ TForm1 }
procedure TForm1.udMoverClick(Sender: TObject; Button: TUDBtnType);
begin
if not Assigned(ds) then Exit;
case Button of
btPrev: if (ds.Position >= SizeOf(ds.rec)) then
begin
ds.Seek(- 2*SizeOf(ds.rec), sofromCurrent);
if (ds.Position < 0) then ds.Position := 0;
edtRecord.Text := ds.RecAsString;
seCurrentRecNo.Value := seCurrentRecNo.Value-1;
end;
btNext: if (ds.Position < ds.Size) then
begin
edtRecord.Text := ds.RecAsString;
seCurrentRecNo.Value := seCurrentRecNo.Value+1;
end;
end;
seCurrentRecNoChange(nil);
end;
procedure TForm1.btnEncryptClick(Sender: TObject);
var be: TBlowFishEncryptStream;
begin
if memoDisplay.Lines.Count = 0 then Exit;
key := 'example cipher key for Blowfish';
sOriginal := TStringStream.Create(EmptyStr);
be := TBlowFishEncryptStream.Create(key, sOriginal);
be.WriteAnsiString(memoDisplay.Text);
be.Free;
memoEncrypted.Text := sOriginal.DataString;
end;
procedure TForm1.btnGenerateStreamClick(Sender: TObject);
begin
ds.Free;
ds := TdemoStream.Create(seNoOfRecords.Value);
seCurrentRecNo.MaxValue := seNoOfRecords.Value -1;
DisplayStream;
seCurrentRecNoChange(nil);
btnSaveStream.Enabled := True;
lblSavedfileSize.Caption := EmptyStr;
memoEncrypted.Lines.Clear;
memoDecrypted.Lines.Clear;
end;
procedure TForm1.btnLoadStreamClick(Sender: TObject);
begin
FreeAndNil(ds);
ds := TdemoStream.Create(0);
ds.LoadFromFile(savedFileName);
seNoOfRecords.Value := ds.Size div SizeOf(ds.rec);
seCurrentRecNo.MaxValue := seNoOfRecords.Value -1;
DisplayStream;
btnLoadStream.Enabled := False;
seCurrentRecNoChange(nil);
memoEncrypted.Lines.Clear;
memoDecrypted.Lines.Clear;
end;
procedure TForm1.btnSaveStreamClick(Sender: TObject);
begin
if Assigned(ds) then
begin
memoDisplay.Lines.Clear;
edtRecord.Text := EmptyStr;
ds.SaveToFile(savedFileName);
// lblSavedFileSize.Caption := Format('Saved file size is: %d bytes', [FileSize(savedFileName)]);
btnLoadStream.Enabled := True;
btnSaveStream.Enabled := False;
FreeAndNil(ds);
end;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
ds.Free;
end;
procedure TForm1.seCurrentRecNoChange(Sender: TObject);
var L: integer;
begin
if not Assigned(ds) then Exit;
ds.Seek(seCurrentRecNo.Value * SizeOf(ds.rec), soFromBeginning);
edtRecord.Text := ds.RecAsString;
L := Length(edtRecord.Text) + Length(LineEnding);
tbPosition.Position := tbPosition.Max * ds.Position div ds.Size;
memoDisplay.SelStart := (tbPosition.Position) * L;
memoDisplay.SelLength := L;
end;
procedure TForm1.btnDecryptClick(Sender: TObject);
var bd: TBlowFishDeCryptStream;
begin
sEncrypted := TStringStream.Create(sOriginal.DataString);
bd := TBlowFishDeCryptStream.Create(key, sEncrypted);
memoDecrypted.Text := bd.ReadAnsiString;
bd.Free;
sEncrypted.Free;
sOriginal.Free;
end;
procedure TForm1.DisplayStream;
begin
lblStreamSize.Caption := Format('%d ', [ds.Size]);
tbPosition.Max := ds.Size div SizeOf(ds.rec) -1;
memoDisplay.Lines.BeginUpdate;
memoDisplay.Clear;
ds.Position := 0;
while (ds.Position < ds.Size) do
begin
memoDisplay.Lines.Add(ds.RecAsString);
tbPosition.Position := (ds.Size * tbPosition.Max) div ds.Position;
end;
memoDisplay.Lines.EndUpdate;
seCurrentRecNo.MaxValue := seNoOfRecords.Value;
ds.Seek(seCurrentRecNo.Value * SizeOf(ds.rec), soFromBeginning);
edtRecord.Text := ds.RecAsString;
tbPosition.Position := (ds.Size * tbPosition.Max) div ds.Position;
end;
end.