In my Firebird database I have a Blob field that contain a Bitmap. I'll have to load and display in a TImage located on my Form. Subsequently I'll have to save in the same field the image selected by a OpenDialog.
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It is generally a bad idea to store images in the database. Instead, you should store only the path to your image on the file system.LightBulb– LightBulb2012-12-13 19:39:08 +00:00Commented Dec 13, 2012 at 19:39
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@LightBulb the client may just not have access to that file system. So while RDBMS are not media storage by design - sometimes it is simplifies system design in general. Of course for some cost.Arioch 'The– Arioch 'The2012-12-14 07:57:09 +00:00Commented Dec 14, 2012 at 7:57
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2@LightBulb In general, making sweeping generalizations is a bad idea ;), it really depends on the application and limitations. Pros: files are backed up together with DB, applications (fat clients) that access your db don't also need access to a central file location, the file and associated db-record are guarded by the integrity access control of the database, cons: your db (and its backup) gets really fat, serving files from a webserver gets more complicated etc.Mark Rotteveel– Mark Rotteveel2012-12-14 09:26:50 +00:00Commented Dec 14, 2012 at 9:26
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@MarkRotteveel, thank you for clearing that up because I forgot to mention pros and cons. I was hoping that OP would do some research himself :)LightBulb– LightBulb2012-12-14 10:15:20 +00:00Commented Dec 14, 2012 at 10:15
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1 Answer
Procedure LoadBitmapFromBlob(Bitmap: TBitmap; Blob: TBlobField);
var
ms, ms2: TMemoryStream;
begin
ms := TMemoryStream.Create;
try
Blob.SaveToStream(ms);
ms.Position := 0;
Bitmap.LoadFromStream(ms);
finally
ms.Free;
end;
end;
example usage
procedure TForm4.Button1Click(Sender: TObject);
var
bmp: TBitmap;
begin
bmp := TBitmap.Create;
try
LoadBitmapFromBlob(bmp, TBlobField(Dataset.FieldByName('Image')));
Image1.Picture.Assign(bmp);
bmp.SaveToFile(OpenDialog.FileName);
finally
bmp.Free;
end;
end;
8 Comments
stacker
Thanks, now I'll try to implement my code with these examples
Arioch 'The
Hey, explore class TBlobStream :-) As far as i remember you can avoid intermediate creation of TMemoryStream and get the stream directly from the field!
Ninad Avasare
@bummi does above code work with Bitmap only? What about JPG, JPEG images stored in the database? How to display them using dataset?
bummi
@NinadAvasare you will have to know which kind of TGraphic is stored in the Blob and create a suitable Class. This information is known if you only want to store JPG images, could be stored in another field in the database, or stored with the Graphic in the blob. An example for the last way is shown here. stackoverflow.com/a/14726934/1699210
bummi
You should add it as own question, instead of asking in comments. I can't see where IStream and jpg are created, just that they are free. #53 sound like a corrupted or invalid JPEG, e.g. a Bitmap an unsupported JPG a wrong saved (to BLOB) JPG. You could try (for debugging) to save the stream for debugging to a file and inspect it and try to load it to a TImage and/or a graphic program. Image1.Picture would be overritten in every loop(while not rs.EOF).
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