(Delphi DLL) File Read Blocks

Demonstrates how to read a file in fixed-size blocks (except for the very last block).

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, CkByteData, FileAccess;

...

procedure TForm1.Button1Click(Sender: TObject);
var
dataBlock: HCkByteData;
facSrc: HCkFileAccess;
facDest: HCkFileAccess;
srcPath: PWideChar;
destPath: PWideChar;
success: Boolean;
numBlocks: Integer;
i: Integer;
bEqual: Boolean;

begin
// Demonstrates how to read a file in blocks,
// which can be useful when uploading to cloud storage
// services such as Azure, S3, Google, etc.

// For this example, we're simply writing the blocks
// to an output file, and then checking to see if the
// resulting file contents equals the original file contents.

dataBlock := CkByteData_Create();

facSrc := CkFileAccess_Create();
facDest := CkFileAccess_Create();

srcPath := 'qa_data/xml/hamlet.xml';
destPath := 'qa_output/hamletOut.xml';

success := CkFileAccess_OpenForRead(facSrc,srcPath);
success := CkFileAccess_OpenForWrite(facDest,destPath);
// Assuming success for the example..

// How many 1024-byte blocks?  (Including 1 for the last partial block)
numBlocks := CkFileAccess_GetNumBlocks(facSrc,1024);

i := 0;
while (i < numBlocks) do
  begin
    success := CkFileAccess_ReadBlock(facSrc,i,1024,dataBlock);
    if (CkFileAccess_getLastMethodSuccess(facSrc) <> True) then
      begin
        Memo1.Lines.Add(CkFileAccess__lastErrorText(facSrc));
        Exit;
      end;
    success := CkFileAccess_FileWrite(facDest,dataBlock);
    if (success <> True) then
      begin
        Memo1.Lines.Add(CkFileAccess__lastErrorText(facDest));
        Exit;
      end;
    i := i + 1;
  end;

CkFileAccess_FileClose(facSrc);
CkFileAccess_FileClose(facDest);

bEqual := CkFileAccess_FileContentsEqual(facSrc,srcPath,destPath);
if (bEqual <> True) then
  begin
    Memo1.Lines.Add('Something went wrong!');
    Exit;
  end;

Memo1.Lines.Add('File successfully copied by blocks.');

CkByteData_Dispose(dataBlock);
CkFileAccess_Dispose(facSrc);
CkFileAccess_Dispose(facDest);

end;