Delphi :Transferring Image - image

Question

Delphi 2010
I'm Transferring Image via custom TCP Socket control uses UTF-8
Client Side
var
TSS: TStringStream;
STR :String;
JPG:TJPEGImage;
BMP:TBitmap;
begin
Try
BMP.LoadFromFile('C:\1.bmp');
JPG.Assign(BMP);
JPG.CompressionQuality:=80;
JPG.Compress;
TSS:=TStringStream.Create;
JPG.SaveToStream(TSS);
STR:=TSS.DataString;
MyTCPSocket.SendString(STR);
finally
BMP.free;
JPG.free;
TSS.free;
end;
end;
Server Side
Var
TSS: TStringStream;
TSS:=TStringStream.Create;
TSS.WriteString(STR);
TSS.SaveToFile('C:\2.jpg');
This code working on the same pc great.
The problem when I send the image to other pc that uses different encoding
it receive the image but I see many wrong characters in the data "?????"
I think when TStringStream writes the bytes to the file it fails to convert the unicode characters to bytes so it appears like "?"
Any idea is much appreciated

Answer 1

You are trying to send binary data as if it were UTF-8 encoded text. It is not, so do not try to do that! Send the binary data in its original binary form, eg:
var
MS: TMemoryStream;
JPG: TJPEGImage;
BMP: TBitmap;
begin
MS := TMemoryStream.Create;
try
JPG := TJPEGImage.Create;
try
BMP := TBitmap.Create;
try
BMP.LoadFromFile('C:\1.bmp');
JPG.Assign(BMP);
finally
BMP.Free;
end;
JPG.CompressionQuality := 80;
JPG.Compress;
JPG.SaveToStream(MS);
finally
JPG.Free;
end;
MS.Position := 0;
MyTCPSocket.SendStream(MS);
finally
MS.free;
end;
end;
var
MS: TMemoryStream;
begin
MS := TMemoryStream.Create;
try
MyTCPSocket.ReadStream(MS);
MS.Position := 0;
MS.SaveToFile('C:\2.jpg');
finally
MS.Free;
end;
end;
If you must send binary data as text, you need to encode the data using a real binary-to-text encoding algorithm, such as base64 or yEnc, not UTF-8 (which is designed for only encoding Unicode text, not binary data), eg:
// TIdEncoderMIME and TIdDecoderMIME are part of Indy,
// which ships with Delphi, but you can use whatever
// you want...
uses
..., IdCoderMIME;
var
S: String;
MS: TMemoryStream;
JPG: TJPEGImage;
BMP: TBitmap;
begin
MS := TMemoryStream.Create;
try
JPG := TJPEGImage.Create;
try
BMP := TBitmap.Create;
try
BMP.LoadFromFile('C:\1.bmp');
JPG.Assign(BMP);
finally
BMP.Free;
end;
JPG.CompressionQuality := 80;
JPG.Compress;
JPG.SaveToStream(MS);
finally
JPG.Free;
end;
MS.Position := 0;
S := TIdEncoderMIME.EncodeStream(MS);
finally
MS.free;
end;
MyTCPSocket.SendString(S);
end;
uses
..., IdCoderMIME;
var
S: string;
MS: TMemoryStream;
begin
S := MyTCPSocket.ReadString;
MS := TMemoryStream.Create;
try
TIdDecoderMIME.DecodeStream(S, MS);
MS.Position := 0;
MS.SaveToFile('C:\2.jpg');
finally
MS.Free;
end;
end;