delphi 加载大文件显示进度条

procedure TForm1.Button1Click(Sender: TObject);

const

FName = 'about.txt'; // use a file larger than 2048 bytes to make it interesting.

var

F: File;

MyData: array[1..2048] of byte;

BytesRead: LongInt;

begin

AssignFile(F, FName);

try

Reset(F, 1);

ProgressBar1.Max := FileSize(F);

if (ProgressBar1.Max > 10) then

begin

// amount to move when StepIt method called

ProgressBar1.Step := ProgressBar1.Max div 10;

ProgressBar1.Step := Min(ProgressBar1.Step, 2048);

end

else

ProgressBar1.Step := ProgressBar1.Max;

while (ProgressBar1.Position < ProgressBar1.Max) do

begin

// read one Step size chunk of data to buffer

BlockRead(F, MyData, ProgressBar1.Step, BytesRead);

// move the ProgressBar Position using StepIt

ProgressBar1.StepIt; // move by Step amount

// Do this or the read will wrap and start over!

ProgressBar1.Step :=

Min(ProgressBar1.Step, ProgressBar1.Max - ProgressBar1.Position);

end;

finally;

CloseFile(F);

end;

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