Delphi ActiveX

File Read Blocks

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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
dataBlock: Array of Byte;
facSrc: TCkFileAccess;
facDest: TCkFileAccess;
srcPath: WideString;
destPath: WideString;
numBlocks: Integer;
i: Integer;
bEqual: Integer;

begin
success := 0;

// 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.

facSrc := TCkFileAccess.Create(Self);
facDest := TCkFileAccess.Create(Self);

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

success := facSrc.OpenForRead(srcPath);
success := facDest.OpenForWrite(destPath);
// Assuming success for the example..

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

i := 0;
while (i < numBlocks) do
  begin
    dataBlock := facSrc.ReadBlock(i,1024);
    if (facSrc.LastMethodSuccess <> 1) then
      begin
        Memo1.Lines.Add(facSrc.LastErrorText);
        Exit;
      end;
    success := facDest.FileWrite(dataBlock);
    if (success <> 1) then
      begin
        Memo1.Lines.Add(facDest.LastErrorText);
        Exit;
      end;
    i := i + 1;
  end;

facSrc.FileClose();
facDest.FileClose();

bEqual := facSrc.FileContentsEqual(srcPath,destPath);
if (bEqual <> 1) then
  begin
    Memo1.Lines.Add('Something went wrong!');
    Exit;
  end;

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