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uMAIN.pas
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{*******************************************************************************}
{* *}
{* ANALYSIS OF COMPARISON LEMPEL ZIV WELCH, ARITHMETIC CODING, AND RUN-LENGTH *}
{* ENCODING COMPRESSION ALGORITHMS ON TEXT FILE *}
{* *}
{* Author : Plipus Telaumbanua *}
{* 061401006 *}
{* philipstel@gmail.com *}
{* http://www.plipustel.com *}
{* *}
{* Computer Science *}
{* University of North Sumatera *}
{* 2010-2011 *}
{* *}
{*******************************************************************************}
unit uMAIN;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, Menus, ComCtrls, ToolWin, ImgList, Grids, ValEdit,
ExtCtrls, StdCtrls, DBGrids, functions, XPMan, uOPTION, Buttons, uAbout;
type
TArrayInt = array of Integer;
TArrayChar = array[chr(0)..chr(255)] of integer;
TfrmMAIN = class(TForm)
StatusBar1: TStatusBar;
ImageList1: TImageList;
MainMenu1: TMainMenu;
File1: TMenuItem;
Customize1: TMenuItem;
CoolBar2: TCoolBar;
Open1: TMenuItem;
SaveAs1: TMenuItem;
N1: TMenuItem;
Exit1: TMenuItem;
Compression1: TMenuItem;
Decompression1: TMenuItem;
N2: TMenuItem;
Settings1: TMenuItem;
Option1: TMenuItem;
N8Bits1: TMenuItem;
N9Bits1: TMenuItem;
N10Bits1: TMenuItem;
N11Bits1: TMenuItem;
N12Bits1: TMenuItem;
Help1: TMenuItem;
HelpTopic1: TMenuItem;
About1: TMenuItem;
CoolBar3: TCoolBar;
GroupBox1: TGroupBox;
Label1: TLabel;
Label2: TLabel;
Label3: TLabel;
Label4: TLabel;
Label5: TLabel;
Label6: TLabel;
Label7: TLabel;
Label8: TLabel;
LblFileName: TLabel;
LblFileType: TLabel;
LblFileSize: TLabel;
LblFileSource: TLabel;
CompressLZW: TButton;
CompressAC: TButton;
CompressRLEBWT: TButton;
DecompressLZW: TButton;
DecompressAC: TButton;
DecompressRLEBWT: TButton;
SaveDialog1: TSaveDialog;
OpenDialog1: TOpenDialog;
XPManifest1: TXPManifest;
StringGrid1: TStringGrid;
OpenDialog2: TOpenDialog;
CoolBar1: TCoolBar;
Panel1: TPanel;
SpeedButton1: TSpeedButton;
SpeedButton2: TSpeedButton;
SpeedButton3: TSpeedButton;
SpeedButton4: TSpeedButton;
SpeedButton5: TSpeedButton;
SpeedButton6: TSpeedButton;
SpeedButton7: TSpeedButton;
SaveDialog2: TSaveDialog;
SpeedButton8: TSpeedButton;
Loading: TStaticText;
procedure FormCreate(Sender: TObject);
procedure CompressLZWClick(Sender: TObject);
procedure Exit1Click(Sender: TObject);
procedure N8Bits1Click(Sender: TObject);
procedure N9Bits1Click(Sender: TObject);
procedure N10Bits1Click(Sender: TObject);
procedure N11Bits1Click(Sender: TObject);
procedure N12Bits1Click(Sender: TObject);
procedure Option1Click(Sender: TObject);
procedure DecompressLZWClick(Sender: TObject);
procedure SpeedButton5Click(Sender: TObject);
procedure SettingDictionary(BitLength: Integer);
procedure GridTitle(WhatType: string);
procedure CompressActive();
procedure DecompressActive();
procedure OpenFile();
procedure SaveAs();
procedure SaveAutomatically(Res, Properties: String; Compress: Boolean);
procedure Compression1Click(Sender: TObject);
procedure Decompression1Click(Sender: TObject);
procedure SpeedButton3Click(Sender: TObject);
procedure SpeedButton4Click(Sender: TObject);
procedure SpeedButton1Click(Sender: TObject);
procedure Open1Click(Sender: TObject);
procedure SaveAs1Click(Sender: TObject);
procedure SpeedButton2Click(Sender: TObject);
procedure SpeedButton7Click(Sender: TObject);
procedure SpeedButton8Click(Sender: TObject);
procedure CompressRLEBWTClick(Sender: TObject);
procedure DecompressRLEBWTClick(Sender: TObject);
procedure CompressACClick(Sender: TObject);
procedure DecompressACClick(Sender: TObject);
procedure About1Click(Sender: TObject);
procedure HelpTopic1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
const
DEFAULT_ASCII_SIZE = 255; { for initial dictionary }
DEFAULT_BUFFER_SIZE = 2000000; { buffer size 2 mb ( 2 million bytes) }
END_OF_HEADER = '$'; { stop if this found while reading the header }
END_OF_FILE = Chr($FF);
RLE_MARKER_BYTE = '#';
var
frmMAIN: TfrmMAIN;
{ File Handling Declaration }
IntFileSize, NumRead: Integer; { file size (num bytes) and indicator }
StrFileName: String; { file name}
FileHandling: File; { for untyped file instead of textFile }
Buffer: Array[0..DEFAULT_BUFFER_SIZE] of Char;
{ LZW Properties }
SetDictionaryLength, SetBitsLength: Integer; { for dictionary arbitary length }
Dictionary: Array Of String;
{ AC Properties }
SymbolLow, SymbolHigh, Frequency: TArrayChar;
Factor, TotalScaled: Integer;
ACFileType: String;
HeadMod, HeadFSize : Integer;
{ BWT Properties }
Buffer2: String; { Buffer2 holds the copy of Buffer for F building }
{ Others }
{ Simply go to option menu to understand this }
CompressSavingPath, DecompressSavingPath: String;
EncodedStream, DecodedStream: String; { used for LZW, AC, and RLE+BWT }
CompressGridCounter, DecompressGridCounter, HeaderIndexPosition: Integer;
OpenDialogType: Boolean; { true for compression's openDialog and false for
decompression's OpenDialog }
implementation
{$R *.dfm}
{**
* This function is used to search the string characters in the dictionary using
* by sequential search.
* @Param 1 : <string> Str : symbol being searched
* @Param 2 : <array> Dict : dictionary
* @Return : <boolean> return TRUE if it's found, otherwise FALSE.
* @Effect : None
**}
function IsInDictionary(Str: string): Boolean;
var
I : Integer;
Found : Boolean;
begin
Found := False;
if Length(Str) = 1 then begin
Found := True;
end else begin
for I := 256 to Length(Dictionary) - 1 do begin
if Str = Dictionary[I] then begin
Found := True;
Break; { stop searching if it's found }
end;
Found := False;
end;
end;
Result := Found;
end;
{**
* This function is used to take the 'index' for current symbol from the dictionary
* @Param 1 : <string> Str : symbol searched
* @Return : <integer> return the index for its symbol
* @Effect : None
**}
function GetIndex(Str: string): Integer;
var
I, Index : Integer;
begin
Index := 0;
for I := 0 to Length(Dictionary) - 1 do begin
if Str = Dictionary[I] then begin
Index := I;
Break;
end;
end;
Result := Index;
end;
{**
* This function is used to change the 'CodeWord' in binary to be 'ASCII' characters
* that fix in 8 bits for each character. (Used for Compresssion)
* @Param 1 : <string> CW : CodeWord in binary. Ex: 011011100...
* @Return : <string> return the 'CodeWord' to ASCII characters as a final encoding.
* @Effect : Make the length of 'CodeWord' MOD 8 is 0
**}
function CodewordToAscii(CW: String): String;
var
AfterRestRemoved, ActualRest, ActualCodeword, AsciiOutput: String;
Rest: Integer;
I: LongInt;
begin
ActualCodeword := CW;
{ It turns out that the length of CW mod 8 is not 0. Wow that's bad! we need to pad it }
if Length(CW) mod 8 <> 0 then begin
Rest := Length(CW) mod 8;
AfterRestRemoved := SubStr(CW, 1, Length(CW) - Rest);
ActualRest := BitPadding(SubStr(CW, (Length(CW) - Rest) + 1, Rest), 8, 'RIGHT');
ActualCodeword := AfterRestRemoved + ActualRest; { finally it mod 8 is 0}
end;
{ It turns out that the length of CW mod 8 is 0. So feel free to change it to ASCII character }
I := 1;
while I <= Length(ActualCodeWord) do begin
AsciiOutput := AsciiOutput + Chr(BinerToDecimal(SubStr(ActualCodeWord, I, 8)));
Inc(I, 8);
end;
Result := AsciiOutput;
end;
{**
* This function is used for decoding. This function works by changing the ASCII characters
* (encoded stream) to a sequence of biner. (Used for Decompression)
* that fix in 8 bits for each character.
* @Param 1 : <array> Buffer : Buffer (encoded stream) which containts human unreadable characters
* @Parm 2 : <LongInt) IntFileSize : The file size
* @Return : <string> Collection of biners which fix with 'Bits' length.
* @Effect : Make ASCII characters to biners and fix with 'Bits' length.
**}
function AsciiToCodeword(var Buffer: Array of Char; intFSize: LongInt): String;
var
InBiner, EightBits, RemovePadding: String;
Rest, Bits: Integer;
I: LongInt;
begin
{ get the header information }
Bits := SetBitsLength;
{ read buffer from this position, add one since buffer from 0, while HeaderIndexPosition from 1 }
I := HeaderIndexPosition + 1;
{ read the ASCII character (encoded stream). Read one byte at a time }
while I < IntFSize - 1 do begin
InBiner := DecimalToBiner(Ord(Buffer[I])); { change to biner per character }
EightBits := EightBits + BitPadding(InBiner, 8, 'LEFT'); { make every character fix in 8 bits }
Inc(I);
end;
{ we need to check it again if it's fix in 'Bits' size }
if Length(EightBits) mod Bits <> 0 then begin
Rest := Length(EightBits) mod Bits;
RemovePadding := SubStr(EightBits, 1, Length(EightBits) - Rest);
Result := RemovePadding;
end else begin
Result := EightBits;
end;
end;
{**
* This procedure is used to set the arbitary dictionary length
* @Param 1 : <integer> BitLength : the bit length being used
* @Return : None
* @Effect : Change the bit and dictionary being used
**}
procedure TfrmMAIN.SettingDictionary(BitLength: Integer);
begin
case (BitLength) of
8: begin
N8Bits1.Checked := True;
N9Bits1.Checked := False;
N10Bits1.Checked := False;
N11Bits1.Checked := False;
N12Bits1.Checked := False;
end;
9: begin
N8Bits1.Checked := False;
N9Bits1.Checked := True;
N10Bits1.Checked := False;
N11Bits1.Checked := False;
N12Bits1.Checked := False;
end;
10: begin
N8Bits1.Checked := False;
N9Bits1.Checked := False;
N10Bits1.Checked := True;
N11Bits1.Checked := False;
N12Bits1.Checked := False;
end;
11: begin
N8Bits1.Checked := False;
N9Bits1.Checked := False;
N10Bits1.Checked := False;
N11Bits1.Checked := True;
N12Bits1.Checked := False;
end;
12: begin
N8Bits1.Checked := False;
N9Bits1.Checked := False;
N10Bits1.Checked := False;
N11Bits1.Checked := False;
N12Bits1.Checked := True;
end;
end;
end;
{** This function is used to get the opposite bits due to the underflow
* @param1 : <string> Bit : bit input '0' or '1'
* @return : <string> '0' to '1', '1' to '0'
**}
function OppositeBit(Bit: String): String;
begin
if Bit = '0' then begin
Result := '1';
end else begin
Result := '0';
end;
end;
{** This function is used to shift out the msb as well as shift in lsb
* @param1 : <string> Biner : 110011
* @param2 : <string> ShiftIn : '0' or '1'
* @return : ShiftMSB('abcde', '0') would return 'bcde0'
**}
function ShiftMSB(Biner: String; ShiftIn: String): String;
begin
Result := Copy(Biner, 2, Length(Biner) - 1) + ShiftIn;
end;
{** this function is used to revomve the 2nd bit and then shift in
* the 'shiftIn' bit in the most left of 'Biner'
**}
function ShiftUnderflow(Biner: String; ShiftIn: String): String;
var
FirstBit, ThirdBit: String;
begin
FirstBit := Copy(Biner, 1, 1);
ThirdBit := Copy(Biner, 3, Length(Biner) - 1);
Result := FirstBit + ThirdBit + ShiftIn;
end;
{** This function is used to build the model for counting the lower and
* upper bound of symbol.
**}
procedure BuildProbabilities(var Lower, Upper: TArrayChar);
var
Temp: Char;
I: Integer;
begin
Upper[Temp] := 0;
for I := 0 to 255 do begin
Lower[Chr(I)] := Upper[Temp];
Upper[Chr(I)] := Frequency[Chr(I)] + Upper[Temp];
Temp := Chr(I);
end;
end;
{** This padding will divide all bits in 'padding'
* this is obvious different with bitpadding() function
**}
function OutputBits(Biner: String; Padding: Integer): String;
var
N, Modulus, Ins: Integer;
begin
N := Length(Biner);
Modulus := N mod Padding;
if Modulus <> 0 then begin
Ins := N + (Padding - Modulus);
Biner := BitPadding(Biner, Ins, 'RIGHT');
end;
Result := Biner;
end;
{ read AC header }
procedure ReadACHeader();
var
I: Integer;
Dexp : TStringList;
begin
Dexp := Explode('|', Buffer);
ACFileType := Dexp[0];
if ACFileType = 'ac' then begin
TotalScaled := 0;
for I := 1 to 256 do begin
Frequency[Chr(I - 1)] := StrToInt(Dexp[I]);
TotalScaled := TotalScaled + StrToInt(Dexp[I]);
end;
HeadMod := StrToInt(Dexp[257]);
HeadFSize := StrToInt(Dexp[258]);
// now we have low and high range for each symbol
BuildProbabilities(SymbolLow, SymbolHigh);
// Get the buffer's index of end of header character position, so that we can start from there.
HeaderIndexPosition := 0;
for I := 0 to IntFileSize - 1 do begin
if Buffer[I] = END_OF_HEADER then begin
HeaderIndexPosition := I;
Break;
end;
end;
end;
end;
function WriteString(Chr: Char; Long: Integer): String;
var
I: Integer;
Output: String;
begin
Output := '';
for I := 1 to Long do begin
Output := Output + Chr;
end;
Result := Output;
end;
{** This function is used to rotate a string starting from I index
* to look the effect cuased by it, simply run this Rotate('PHILIPS_TEL', 3) it will
* give you 'LIPS_TELPHI'
**}
function Rotate(Str: String; I: Integer): String;
var
RotatedStrings: String;
N: Integer;
begin
N := IntFileSize;
RotatedStrings := Copy(Str, I + 1, N - (I * 1)) + Copy(Str, 1, (I * 1) );
Result := RotatedStrings;
end;
{** This function is used to compare a byte with the next byte, comparing will be continue
* until the difference is found. (Theorically and practically this will be always occurs, since
* there is an unique EOF (indicator)...hehe..nice!
* @param : <integer> x, y: indicies to be compared
* @return :<boolean> (try guess, what is it??? lol....)
**}
function Compare(X, Y: Integer): Boolean;
begin
while Buffer[X] = Buffer[Y] do begin
Inc(X);
Inc(Y);
end;
if Buffer[X] < Buffer[Y] then begin
Result:= True;
end else begin
Result:= False;
end;
end;
{** This is used to ConcatArray two sorted arrays in to an sorted array as well.
* arr1(3, 4, 7, 9), arr2(5, 8, 9, 10) after concated: arr3(3, 4, 5, 7, 8, 9, 9, 10)
* @param1 : <array> List1 : the 1st sorted array
* @param2 : <array> List2 : the 2nd sorted array
* @param3 : <array> List3 : the concatend of 1st and 2nd array (in a sorted condition of course)
* @param4 : <boolean> Transform: TRUE belong to 'transformation' otherwise belong to 'inversing'
* @return : List3
* @effect : none
**}
function ConcatArray(List1, List2, List3: TArrayInt; Transform: Boolean): TArrayInt;
var
List1Index, List2Index, List3Index, I: Integer;
begin
List1Index := 0;
List2Index := 0;
List3Index := 0;
while (List1Index < Length(List1)) AND (List2Index < Length(List2)) do begin
if Transform then begin
if Compare(List1[List1Index], List2[List2Index]) then begin
List3[List3Index] := List1[List1Index];
Inc(List1Index);
end else begin
List3[List3Index] := List2[List2Index];
Inc(List2Index);
end;
end else begin
if Buffer[List1[List1Index]] < Buffer[List2[List2Index]] then begin
List3[List3Index] := List1[List1Index];
Inc(List1Index);
end else begin
List3[List3Index] := List2[List2Index];
Inc(List2Index);
end;
end;
Inc(List3Index);
end; { end while }
if List1Index >= Length(List1) then begin
for I := List2Index to Length(List2) - 1 do begin
List3[List3Index] := List2[I];
Inc(List3Index);
end;
end;
if List2Index >= Length(List2) then begin
for I := List1Index to Length(List1) - 1 do begin
List3[List3Index] := List1[I];
Inc(List3Index);
end;
end;
Result := List3;
end;
{**
* This function is used to slice an array from 'from' to 'max' index (it isn't simliar as substr).
* Is used for SortString algorithm due to the natural of this algorithm to divide
* recursively an array to be sorted.
* @Param 1 : <array> Arr : Array being sliced
* @Parm 2 : <integer> From, Max: Slice array from 'From' index to 'Max' index
* @Return : <array> Sliced Array
* @Effect : None
* arr[0, 2, 4, 6, 2, 9, 4, 5]: SliceArray(Arr, 2, 6) would return 4, 6, 2, 9 (4 wouldn't included
* since would be used as 'from' in the next Slicing (Upper sliced will be excluded) )
**}
function SliceArray(Arr: TArrayInt; From, Max: Integer): TArrayInt;
var
Half, I: LongInt;
NewArr: TArrayInt;
begin
Half := Max - From;
SetLength(NewArr, Half);
for I := 0 to Half - 1 do begin
NewArr[I] := Arr[From];
Inc(From);
end;
Result := NewArr;
end;
{** This is used to sort string not integer.
* @param1 : <array> : Unsorted array
* @param2 : <boolean> : Transform : TRUE for 'transformation' sorting owtherwise for 'inverse' sorting.
* @return : <array> : a sorted list
* @effect : <array> : Unsorted (parameter) will be in a sorted condition.
**}
function SortString(Unsorted: TArrayInt; Transform: Boolean): TArrayInt;
var
Cent: Integer;
First, Second: TArrayInt;
begin
if Length(Unsorted) > 1 then begin
Cent := Length(Unsorted) div 2;
First := SortString(SliceArray(Unsorted, 0, Cent), Transform);
Second := SortString(SliceArray(Unsorted, Cent, Length(Unsorted)), Transform);
Result := ConcatArray(First, Second, Unsorted, Transform);
end else begin
Result := Unsorted;
end;
end;
function ArraySearch(FChr: Char): Integer;
var
I, Found: Integer;
begin
for I := 1 to IntFileSize do begin
if FChr = Buffer2[I] then begin
Found := I - 1;
Buffer2[I] := Chr($00);
Break;
end;
end;
Result := Found;
end;
function BWTTransform(): String;
var
I, N: Integer;
Ranged: TArrayInt;
Last: String;
begin
N := IntFileSize;
SetLength(Ranged, N);
for I := 0 to N - 1 do begin
Ranged[I] := I;
end;
SortString(Ranged, TRUE); { Ranged now in a sorted array }
for I := 0 to N - 1 do begin
Last := Last + Copy(Rotate(Buffer, Ranged[I]), N, 1);
end;
Result := Last;
end;
function BWTReversing(): String;
var
FirstColumn, LastColumn, Vector: TArrayInt;
I, Index: Integer;
Last: String;
begin
SetLength(FirstColumn, IntFileSize);
SetLength(LastColumn, IntFileSize);
SetLength(Vector, IntFileSize);
Buffer2 := Buffer;
for I := 0 to IntFileSize - 1 do begin
LastColumn[I] := I; { containts indicies 0 - n}
end;
{ FirstColumn now sorted in lexicographically. Remember its indicies = values.
Only sort the character not string }
FirstColumn := SortString(LastColumn, FALSE);
// Creating vector
for I := 0 to IntFileSize - 1 do begin
Vector[I] := ArraySearch(Buffer[FirstColumn[I]]);
end;
// END_OF_FILE must be always in the last index since it's chr($ff) in the original text
Index := FirstColumn[I - 1];
for I := 0 to IntFileSize - 1 do begin
Index := Vector[Index];
Last := Last + Buffer[Index]; {Buffer = LastColumn. LastColumn has been sorted. So, don't use it}
end;
Result := Last;
end;
procedure FILE_CORRUPT_ERROR(Method : String);
begin
MessageDlg('It is not a/an ' + Method + ' file type or file may be corrupt. Decompression terminated!', MtERROR, [MbOK], 0);
end;
{**
* This procedure is used to set what grid will be using (ex: compress or decomress
* @Param 1 : <string> WhatType : compression or decompress
* @Return : None
* @Effect : Grid will looks like a dynamic grid
**}
procedure TFrmMAIN.GridTitle(WhatType: String);
var
I, J: Integer;
begin
{ Tab's Title Defenition Cells[Column, Rows] }
if WhatType = 'compression' then begin
StringGrid1.Cells[0, 0] := 'Algorithm';
StringGrid1.Cells[1, 0] := 'File Name';
StringGrid1.Cells[2, 0] := 'Original Size';
StringGrid1.Cells[3, 0] := 'After Compressed';
StringGrid1.Cells[4, 0] := 'Compression Ratio';
StringGrid1.Cells[5, 0] := 'Time Consuming';
end else begin
StringGrid1.ColCount := 5;
StringGrid1.ColWidths[1] := 250;
StringGrid1.Cells[0, 0] := 'Algorithm';
StringGrid1.Cells[1, 0] := 'File Name';
StringGrid1.Cells[2, 0] := 'Compressed Size';
StringGrid1.Cells[3, 0] := 'Original Size';
StringGrid1.Cells[4, 0] := 'Time Consuming';
end;
{ clear string grid }
for I := 1 to StringGrid1.RowCount do begin
for J := 0 to StringGrid1.ColCount do begin
StringGrid1.Cells[J, I] := '';
end;
end;
end;
procedure TFrmMAIN.CompressActive();
begin
DecompressGridCounter := 1;
OpenDialogType := True; { use openDialog1 }
Settings1.Enabled := True; { dictionary change is available }
GridTitle('compression'); { the grid's column title }
Decompression1.Checked := False;
Compression1.Checked := True;
{ compression and decompression buttons state }
CompressLZW.Enabled := True;
CompressAC.Enabled := True;
CompressRLEBWT.Enabled := True;
DecompressLZW.Enabled := False;
DecompressAC.Enabled := False;
DecompressRLEBWT.Enabled := False;
end;
procedure TFrmMAIN.DecompressActive();
begin
CompressGridCounter := 1;
OpenDialogType := False;
Settings1.Enabled := False;
GridTitle('decompression');
Decompression1.Checked := True;
Compression1.Checked := False;
CompressLZW.Enabled := False;
CompressAC.Enabled := False;
CompressRLEBWT.Enabled := False;
DecompressLZW.Enabled := True;
DecompressAC.Enabled := True;
DecompressRLEBWT.Enabled := True;
end;
{**
* This function is used to identify the file type for decompressing file.
* And that file types is just known for naming the decoded stream while decoding.
* It assumes the maximum of extention's length is 4 characters.
* @Param 1 : <string> Fname: File name taken from buffer
* @Return : <string> : the file type's name
* @Effect : None
**}
function KnownFileType(Fname: String): String;
var
Exp : TStringList;
begin
Exp := Explode('.', Fname );
Result := Exp[1];
end;
{** This procedure is used to open a file to be compressed or decompressed
* accept to 'state', OpenDialogType. True for compression and False for
* decompression. Is available for LZW, AC, and RLE+BWT. 'BUFFER' is the key
**}
procedure TFrmMAIN.OpenFile();
var
FH: TextFile;
Hold: Char;
I: Integer;
begin
{ compression opendialog }
if OpenDialogType then begin
CompressSavingPath := frmOPTION.TxtSaveCompressed.Text;
if DirectoryExists(CompressSavingPath) then begin
if OpenDialog1.Execute then begin
StrFileName := OpenDialog1.FileName;
{ add EOF for BWT indicator. It's also help for AC }
AssignFile(FH, StrFileName);
Reset( FH );
while not EOF( FH ) do begin
Read( FH, Hold );
end;
if Hold <> END_OF_FILE then begin
Append(FH);
Write(FH, END_OF_FILE);
end;
CloseFile(FH);
{ read to buffer }
AssignFile(FileHandling, StrFileName);
Reset(FileHandling, 1);
IntFileSize := FileSize(FileHandling);
repeat
BlockRead(FileHandling, Buffer, SizeOf(Buffer), NumRead);
until (NumRead = 0);
CloseFile(FileHandling);
{ START PLAY WITH ARITHMETIC CODING BY CREATING A MODEL }
// Set first frequency to zero
for I := 0 to 255 do begin
Frequency[Chr(I)] := 0;
end;
// count symbols frequency
for I := 0 to IntFileSize - 1 do begin
Frequency[Buffer[I]] := Frequency[Buffer[I]] + 1;
end;
// rescale the count. Will cause upper bounds of symbol < the total symbols count
Factor := Ceil(IntFileSize / Pow(2, 14));
// If a non-zero count become zero, make it one. Thank you Michael
TotalScaled := 0;
for I := 0 to 255 do begin
if Frequency[Chr(I)] > Factor then begin
Frequency[Chr(I)] := Floor( Frequency[Chr(I)]/Factor );
end else if Frequency[Chr(I)] <> 0 then begin
Frequency[Chr(I)] := 1;
end;
TotalScaled := TotalScaled + Frequency[Chr(I)];
end;
// Build model which only contain Low and High
BuildProbabilities(SymbolLow, SymbolHigh);
{ CREATING MODEL END HERE }
// Write the file information
LblFileName.Caption := ExtractFileName(StrFileName);
LblFileType.Caption := KnownFileType(ExtractFileName(StrFileName));
LblFileSize.Caption := IntToStr(IntFileSize) + ' bytes';
LblFileSource.Caption := StrFileName;
end;
end else begin
MessageDlg('Define first the compressed/decompressed path target from the option menu.', MtWarning, [MbOK], 0);
end;
end else begin { decompress opendialog }
DecompressSavingPath := frmOPTION.TxtSaveDecompressed.Text;
if DirectoryExists(DecompressSavingPath) then begin
if OpenDialog2.Execute then begin
StrFileName := OpenDialog2.FileName;
AssignFile(FileHandling, StrFileName);
Reset(FileHandling, 1);
IntFileSize := FileSize(FileHandling);
repeat
BlockRead(FileHandling, Buffer, SizeOf(Buffer), NumRead);
until (NumRead = 0);
CloseFile(FileHandling);
// write the file information
LblFileName.Caption := ExtractFileName(StrFileName);
LblFileType.Caption := KnownFileType(ExtractFileName(StrFileName));
LblFileSize.Caption := IntToStr(IntFileSize) + ' bytes';
LblFileSource.Caption := StrFileName;
end;
end else begin
MessageDlg('Define first the compressed/decompressed path target from the option menu.', MtWarning, [MbOK], 0);
end;
end;
end;
{** This procedure is used to save the compressed or decompressed file manually
* accept two properties: 'EncodedStream' and 'DecodedStream'.
* Is available for LZW, AC, and RLE+BWT.
**}
procedure TFrmMAIN.SaveAs();
var
Fout: TextFile;
I: Integer;
begin
if OpenDialogType then begin
if SaveDialog1.Execute then begin
AssignFile(Fout, SaveDialog1.FileName);
ReWrite(Fout);
for I := 1 to Length(EncodedStream) do begin
Write(Fout, EncodedStream[I]);
end;
CloseFile(Fout);
SaveAs1.Enabled := False;
end;
end else begin
if SaveDialog2.Execute then begin
AssignFile(Fout, SaveDialog2.FileName + '.txt');
ReWrite(Fout);
for I := 1 to Length(DecodedStream) do begin
Write(Fout, DecodedStream[I]);
end;
CloseFile(Fout);
SaveAs1.Enabled := False;
end;
end;
end;
procedure TFrmMain.SaveAutomatically(Res, Properties: String; Compress: Boolean);
var
Exp: TStringList;
Fout: TextFile;
I: Integer;
begin
CompressSavingPath := frmOPTION.TxtSaveCompressed.Text;
DecompressSavingPath := frmOPTION.TxtSaveDecompressed.Text;
Exp := Explode('.', ExtractFileName(StrFileName));
if DirectoryExists(CompressSavingPath) and DirectoryExists(DecompressSavingPath) then begin
if Compress then begin
AssignFile(Fout, CompressSavingPath + '\' + Exp[0] + '.' + Properties);
Rewrite(Fout);
for I := 1 to Length(Res) do begin
Write(Fout, Res[I]);
end;
CloseFile(Fout);
MessageDlg('Saving the compressed file is successfully in ' + CompressSavingPath, MtInformation, [MbOK], 0);
end else begin
AssignFile(Fout, DecompressSavingPath + '\' + Exp[0] + '.' + Properties + '.' + 'txt');
Rewrite(Fout);
for I := 1 to Length(Res) do begin
Write(Fout, Res[I]);
end;
CloseFile(Fout);
MessageDlg('Saving the Decompressed file is successfully in ' + DecompressSavingPath, MtInformation, [MbOK], 0);
end;
end else begin
MessageDlg('Automatic saving is failed. Save as it manually or set the new saving path from the option menu', MtError, [MbOK], 0);
end;
end;
{ write ratio in percent (%) }
function WriteRatio(Ratio: double):String;
begin
if Ratio < 1 then begin
WriteRatio := '0' + FormatFloat('#.##', Ratio) + '%';
end else begin
WriteRatio := FormatFloat('#.##', Ratio) + '%';
end;
end;
{ # --------------------------- END FOR ALL PROPERTIES ---------------------- #}
{ # --------------------- START FOR IMPLEMENTING OBJECTS --------------------- #}
procedure TfrmMAIN.FormCreate(Sender: TObject);
begin
ShowHint := True;
OpenDialogType := True;
CompressGridCounter := 1;
DecompressGridCounter := 1;
SetDictionaryLength := 2048;
SetBitsLength := 11;
GridTitle('compression');
{ Disable all components }
DecompressLZW.Enabled := False;
DecompressAC.Enabled := False;
DecompressRLEBWT.Enabled := False;
SaveAs1.Enabled := False;
end;
{ LZW Algorithm Compression }
procedure TfrmMAIN.CompressLZWClick(Sender: TObject);
var
I, J, K, Bits, OutputIndex, LastDictIndex: Integer;
CurrentChars, NextChar, ConcatStr, Header, Codeword: String;
{ counting the elapsed time }
Elapsed: String;
Start, Stop: TDateTime;
begin
Loading.Caption := 'Compressing...';
{ begin here to estimate the complexity (time complexity and running time) of
this LZW's encoding algorithm }
Start := Now;
{ Dictionary can be arbitary length: 8, 9, 10, 11 or 12 bits | 256, 512, 1024, 2048, 4096 }
SetLength(Dictionary, SetDictionaryLength);
Bits := SetBitsLength;
{ inisialization a dictionary 0 - 255 }
for I := 0 to DEFAULT_ASCII_SIZE do begin
Dictionary[I] := Chr(I);
end;
LastDictIndex := 256;
J := 0;
CurrentChars := SubStr(Buffer, 1, 1);
while J < IntFileSize do begin
NextChar := Buffer[J + 1];
ConcatStr := CurrentChars + NextChar;
if IsInDictionary(ConcatStr) then begin
CurrentChars := ConcatStr;
end else begin
OutputIndex := GetIndex(CurrentChars);
Codeword := Codeword + BitPadding(DecimalToBiner(OutputIndex), Bits, 'LEFT');
if LastDictIndex < Length(Dictionary) then begin
Dictionary[LastDictIndex] := ConcatStr;
end;
CurrentChars := NextChar;
Inc(LastDictIndex);
end;
if (J = IntFileSize - 1) then begin
OutputIndex := GetIndex(CurrentChars);
Codeword := Codeword + BitPadding(DecimalToBiner(OutputIndex), Bits, 'LEFT');
end;