压缩后的图片大小为0k了

Question

var
opendlg:topendialog;
 Jpeg:TjpegImage;
begin
opendlg:=topendialog.create(application);
try
opendlg.filename:=editimagepath.text;
opendlg.Filter:='image(*.jpg)|*.jpg|*.jpg';
opendlg.Options:=opendlg.Options+[ofpathmustexist];
if opendlg.Execute then
begin
editimagepath.text:=opendlg.filename;if not(editimagepath.text='') then
begin
if fileexists(editimagepath.text) then
       begin
       image1.picture.loadfromfile(editimagepath.text) ;
    jpeg:=TjpegImage.Create()   ;
      //image1.picture.LoadFromFile(editimagepath.text);
    jpeg.LoadFromFile(editimagepath.text);
    //jpeg.Assign(image1.Picture.Graphic);
   //application.messagebox(inttostr(jpeg.width),'错误',mb_ok)
jpeg.CompressionQuality:=30;   //压缩率1～100
jpeg.Compress;                               //执行压缩
jpeg.SaveToFile('c:\a.jpg');
image2.Picture.loadfromfile('c:\a.jpg');
jpeg.Free;
   opendlg.Free;
 //保存新图像
editimagepath.text:=''end
   else
application.messagebox('指定图片文件不存在','错误',mb_ok);
 end  elseapplication.messagebox('没有指定jpg图片文件','错误',mb_ok) ;
end  else
begin
application.messagebox('没有指定jpg图片文件','错误',mb_ok) ;
 end ;        finally
end ; end;

Answer 1

//try these code
//-----------
var
  Jpeg : TJPEGImage;
  Bmp : TBitmap;
begin
  Bmp := TBitmap.Create;
  try
    Bmp.LoadFromFile('c:\1.bmp');
    Jpeg := TJPEGImage.Create;
    try
      Jpeg.Assign(bmp);
      jpeg.CompressionQuality := 30;
      Jpeg.Compress;
      //保存图片
      Jpeg.SaveToFile('c:\a.jpg');
    finally
      Jpeg.Free;
    end;
  finally
     Bmp.Free;
  end;
end;