Скопировать файл с заполнением своего ProgressBara

Советы » Файлы » Скопировать файл с заполнением своего ProgressBara

{
Copyright © 1999 by Delphi 5 Developer's Guide - Xavier Pacheco and Steve Teixeira
}

unit

MainFrm; interface

uses

Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, ComCtrls, Gauges; type

TMainForm = class

(TForm) prbCopy: TProgressBar; btnCopy: TButton; procedure

btnCopyClick(Sender: TObject); end

; var

MainForm: TMainForm; implementation

{$R *.DFM} procedure

TMainForm.btnCopyClick(Sender: TObject); var

SrcFile, DestFile: file

; BytesRead, BytesWritten, TotalRead: Integer; Buffer: array

[1..500] of

byte; FSize: Integer; begin

{ Assign both the source and destination files to their respective file variables } AssignFile(SrcFile, 'srcfile.tst'); AssignFile(DestFile, 'destfile.tst'); // Open the source file for read access. Reset(SrcFile, 1); try

// Open destination file for write access. Rewrite(DestFile, 1); try

{ Encapsulate this into a try..except so that we can erase the file if an error occurs. } try

// Initialize total bytes read to zero. TotalRead := 0; // Obtain the filesize of the source file FSize := FileSize(SrcFile); { Read SizeOf(Buffer) bytes from the source file and add these bytes to the destination file. Repeat this process until all bytes have been read from the source file. A progress bar is provided to show the progress of the copy operation. } repeat

BlockRead(SrcFile, Buffer, SizeOf(Buffer), BytesRead); if

BytesRead > 0 then

begin

BlockWrite(DestFile, Buffer, BytesRead, BytesWritten); if

BytesRead <> BytesWritten then

raise

Exception.Create('Error copying file') else

begin

TotalRead := TotalRead + BytesRead; prbCopy.Position := Trunc(TotalRead / Fsize) * 100; prbCopy.Update; end

; end

until

BytesRead = 0; except

{ On an exception, erase the destination file as it may be corrupt. Then re-raise the exception. } Erase(DestFile); raise

; end

; finally

CloseFile(DestFile); // Close the destination file. end

; finally

CloseFile(SrcFile); // Close the source file. end

; end

; end

.

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