TJPEGImage.SaveToStream problem

[peterbone]

thanks, i did that and it works.
http://atlas.walagata.com/w/peterbon...veToStream.zip
I wrote 2 procedures to save and load a jpeg to a stream properly.

[pascal]// save a jpeg to a memory stream with correct positioning
procedure JPegSaveToStream(AJPG : TJPegImage ; AStream : TMemoryStream);
Var
LStart, LEnd : Int64;
begin
// store current stream position
LStart := AStream.Position;
// skip size of stream position
AStream.Seek(8, LStart);
// write the jpeg
AJPG.SaveToStream(AStream);
// store the new position
LEnd := AStream.Position;
// seek back to start position
AStream.Position := LStart;
// write jpeg end position to correct position when loading
AStream.Write(LEnd, ;
// seek back to end of stream
AStream.Position := LEnd;
end;

// load a jpeg from a memory stream with correct positioning
procedure JPegLoadFromStream(AJPG : TJPegImage ; AStream : TMemoryStream);
Var
LEnd : Int64;
begin
// load the jpeg end position
AStream.Read(LEnd, ;
// load the jpeg
AJPG.LoadFromStream(AStream);
// go to the correct end position
AStream.Position := LEnd;
end;[/pascal]

seems messy though - I wish I knew why it gets the position wrong.

Peter

[peterbone]

15 years later and I realise that my code above has an issue with loading extra data into the jpeg if the stream contains other data after the jpeg. This can cause an out of memory error if the stream is large. Fixed version is below and avoids this by copying to a new stream containing just the jpeg data.

procedure JPegLoadFromStream(AJPG : TJPegImage ; AStream : TStream);
Var
LEnd : Int64;
LMStream : TMemoryStream;
begin
// load the jpeg end position
AStream.Read(LEnd, 8 );

// Load into temporary stream as TJPeg.LoadFromStream will load to the end
LMStream := TMemoryStream.Create;
LMStream.CopyFrom(AStream, LEnd - AStream.Position);
LMStream.Seek(0, soFromBeginning);

// load the jpeg
AJPG.LoadFromStream(LMStream);

LMStream.Free;
end;