Question

我正在尝试为TPicture编写一个marshaller，以便我可以通过datasnap方法发送包含TPicture的对象类。我在寻找合适的方法时遇到了困难，我试图将TMemoryStream作为TObject发送，但似乎“图片中的数据丢失了”。我试图把图片放到一个字符串中 - 但是，我想这会给我带来各种麻烦，将二进制数据放入字符串中。有没有人对如何正确编组TPicture有任何想法？

这就是我正在做的事情，到目前为止看起来我把图片放到了结果中，但是因为我创建了一个PictureMarshal类的实例，所以我得到了泄漏。不要介意FChildren，它运作正常。

type
  TPictureMarshall = class
    FPictureName : string;
    FPictureSize : Integer;
    FPictureData : TBytes;
  end;

 TPersonMar = class(TObject)

 private
   FStringList : TStringList; // complex object that needs marshalling
   FChildren: array of TPerson; // complex object that needs marshalling
   FMar : TJsonMarshal;
   FPicture : TPicture;
   procedure RegisterConverters;
   procedure SetStringlist(const Value: TStringList);
 public
   function Marshal : string;  // should handle marshalling
   property Stringlist : TStringList read FStringlist write SetStringlist;
   constructor Create;
   destructor Destroy; override;
   procedure AddChild(AKid: TPerson);
 end;



procedure TPersonMar.RegisterConverters;
begin
    FMar.RegisterConverter(ClassType, 'FPicture', function(Data: TObject; Field: String): TObject
    var
      AMemoryStream: TMemoryStream;
      APic : TPictureMarshall;

    begin
       AMemoryStream := TMemoryStream.Create;
       try
         result := TPictureMarshall.Create; // but who frees this?
         FPicture.Graphic.SaveToStream(AMemoryStream);
         TPictureMarshall(Result).FPictureName := 'Somepicturefilename.png';
         TPictureMarshall(Result).FPictureSize := AMemoryStream.Size;
         SetLength(TPictureMarshall(Result).FPictureData, TPictureMarshall(Result).FPictureSize);
         ZeroMemory(TPictureMarshall(Result).FPictureData, TPictureMarshall(Result).FPictureSize);

         AMemoryStream.Position := 0; // reset position
         AMemoryStream.ReadBuffer(TPictureMarshall(Result).FPictureData, AMemoryStream.Size);
       finally
         AMemoryStream.Free;
       end;

    end);
end;







"FMar":null,"FPicture":{"type":"TestObjU.TPictureMarshall","id":14,"fields":{"FPictureName":"Somepicturefilename.png","FPictureSize":71290,"FPictureData":[137,80,78,71,13,...snip]}}}}

Delphi XE10如何编组TPicture

0 个答案: