如何用Delphi将数据库里的jpg图片转换成bmp

[heiqixingyi]

做报表，想有QRDBImage，数据库存的是jpg格式的，还有ADOTable，想将数据库里的图片转换成bmp格式显示到QRDBImage中~

[JPEXE]

uses Graphic, Jpeg;

{----|
 名称: JPG2BMP
 功能: 将图片从 JPG 格式转换为 BMP 格式
 参数: JPGFile: string - JPG 图片文件
       BMPFile: string - BMP 图片文件
 返回: Boolean - 成功返回 True, 失败返回 False.
-----}
function JPG2BMP(const JPGFile, BMPFile: string): Boolean;
var
  BMP: TBitmap;
  JPG: TJpegImage;
begin
  Result := False;

  if not FileExists(JPGFile) then Exit;

  BMP := nil;
  JPG := nil;

  try
    try
      JPG := TJpegImage.Create;
      JPG.LoadFromFile(JPGFile);

      BMP := TBitmap.Create;
      BMP.Assign(JPG);
      BMP.SaveToFile(BMPFile);
    except
      Exit;
    end;
  finally
    if Assigned(BMP) then BMP.Free;
    if Assigned(JPG) then JPG.Free;
  end;

  Result := True;
end;

[lovelymelon]

procedure TForm1.BitBtn1Click(Sender: TObject);
var
  bm:TBitmap;
  jpg:TJPEGImage;
  ms:TMemoryStream;
var
  s:string;
begin
  if self.OpenDialog1.Execute then
  begin
    s:=self.OpenDialog1.FileName;
    jpg:=TJPEGImage.Create;
    jpg.LoadFromFile(s);
    bm:=TBitmap.Create;
    bm.Assign(jpg);
    self.Image1.Picture.Bitmap:=bm;
    jpg.Free;
    bm.Free;
  end;
end;

[heiqixingyi]

我界面上有Image
有三个label标签
分别写着：上传，保存，另存
我想做的效果是：点击上传时有照片出来，要无论是jpg，还是bmp都可以上传
然后:保存：点击保存将上传的照片直接存到数据库中！要求上传时jpg图片是要转换成bmp，是bmp是就原样保存到数据库！数据库中已定义好image类型的字段为（照片）
最后是另存：将数据库中的照片取出来以图片jpg保存！

[lovelymelon]

//从数据库中读取图片并显示到image中
procedure TForm1.Button1Click(Sender: TObject);
var
  ms:TStream;
begin
  ms:=TMemoryStream.Create;
  self.ADOQuery1.Close;
  self.ADOQuery1.Connection:=self.ADOConnection1;
  self.ADOQuery1.SQL.Clear;
  Self.ADOQuery1.SQL.Add('select * from pic');
  self.ADOQuery1.Open;
  self.ADOQuery1.First;
  ms:=Self.ADOQuery1.CreateBlobStream(Self.ADOQuery1.FieldByName('pic'),bmread);
  self.Image1.Picture.Bitmap.LoadFromStream(ms);
  ms.Free;
end;
//将image中图片写入数据库
procedure TForm1.Button2Click(Sender: TObject);
var
  ms:TMemoryStream;
begin
  ms:=TMemoryStream.Create;
  Self.Image1.Picture.Bitmap.SaveToStream(ms);
  ms.Position:=0;
  self.ADOQuery1.Close;
  self.ADOQuery1.Connection:=self.ADOConnection1;
  self.ADOQuery1.SQL.Clear;
  Self.ADOQuery1.SQL.Add('select * from pic');
  self.ADOQuery1.Open;
  self.ADOQuery1.Append;
  TBlobField(Self.ADOQuery1.FieldByName('pic')).LoadFromStream(ms);
  self.ADOQuery1.Post;
end;
//IMage中显示jpg或bmp图片
procedure TForm1.BitBtn1Click(Sender: TObject);
var
  bm:TBitmap;
  jpg:TJPEGImage;
  ms:TMemoryStream;
  s,s1:string;
begin
  if self.OpenDialog1.Execute then
  begin
    s:=self.OpenDialog1.FileName;
    s1:=ExtractFileExt(s);
    if s1='.bmp' then
      self.Image1.Picture.Bitmap.LoadFromFile(s)
    else
    begin
      jpg:=TJPEGImage.Create;
      jpg.LoadFromFile(s);
      bm:=TBitmap.Create;
      bm.Assign(jpg);
      self.Image1.Picture.Bitmap:=bm;
      jpg.Free;
      bm.Free;
    end
  end;
end;
将Image中图片保存成jpg图片
procedure TForm1.Button3Click(Sender: TObject);
begin
  Self.Image1.Picture.SaveToFile('f:\lzx.jpg');
end;

[plutu]

同意楼上的