Blobs and TPicture

[TRNelson]

I have a small snippet of code that loads a picture file and stores it in a Blob in a table.

Code: Pascal  [Select][+][-]

1. SQLQuery1.SQL.Text:= 'insert into Photos (PhotoID, FileName, Content) values (:PhotoID, :FileName, :Content)';
2. SQLQuery1.ParamByName('PhotoId').AsInteger   := cntr;
3. SQLQuery1.ParamByName('FileName').AsString   := Info.Name;
4. SQLQuery1.ParamByName('Content').LoadFromFile(FName, ftBlob);
5. SQLQuery1.ExecSQL;
6. SQLTransaction1.Commit;

It works well and does the job. 

I would like to change the code so that the picture data comes from a TPicture object instead.  I could write the TPicture to a temporary file and reuse the code but that is pretty inefficient and I would rather extract the data directly from TPicture without having to resort to an intermediate file.

I can't find an elegant way of doing this.  All suggestions are welcomed!   

[Leledumbo]

There's no direct way as far as I can find. You can use memory stream as intermediate storage, at least it won't suffer from disk I/O latency.

[TRNelson]

There's no direct way as far as I can find. You can use memory stream as intermediate storage, at least it won't suffer from disk I/O latency.

That's what I thought as well.  The picture is already loaded in a TPicture.  Time to do some research on memory streams.

[TRNelson]

Well, that turned out to be a lot easier than I thought it would be. 

Code: Pascal  [Select][+][-]

1. Thumbnail.SaveToStream(MyStream);
2. MyStream.Position := 0;
3. Image1.Picture.LoadFromStream(MyStream);

I am continually surprised on how feature rich this system is.  It is a far more sophisticated than what I used to use 40 years ago. Fortran and S/360 Assembly language on punch cards.
 

[Zath]

Is position the actual physical position of an image file in a directory ?

[howardpc]

No, Position is a stream property, a pointer to a location somewhere within the entire length of the stream (for streams where Length makes sense) where the next stream read/write will take place.
To load a picture you want to begin at Position zero, right at the beginning of the stream (otherwise you would fail to read the initial bytes).

[Zath]

Thank you howard.