Class: TEgDBGridEx
property DetectBlobImages: Boolean default False;When False (the default), only a field with
DataType = ftGraphic is drawn as an image. When
True, a plain BLOB field (DataType = ftBlob,
no more specific blob type - a memo/CLOB field is unaffected) is also
tried as an image, using the same format detection as a real graphic
field (JPEG, PNG, Bitmap, Icon, GIF, Metafile).
If the BLOB’s content does not decode as a recognized image format,
this is handled silently rather than as a failure: OnGraphicError
is not fired (unlike for a true ftGraphic field). An empty
(null) field simply shows nothing; a non-null field whose content isn’t
a recognized image format falls back to showing the field’s own display
text (for example (BLOB)) instead of staying blank. OnBeforeDrawCell
can still override either the image or the fallback text.
With DetectBlobImages left False, a plain
(ftBlob) field is never tried as an image at all, and the
cell shows nothing by default either - Null or not, its
DisplayText is never shown. As with the True
case above, OnBeforeDrawCell
is the only way to put text on such a column.
Detection runs independently on each record’s own bytes, so a single
BLOB column with DetectBlobImages set can freely mix rows
that hold a recognized image (in any supported format) with rows that
hold ordinary non-image binary data - the two kinds of content coexist
in the same column without conflict, each row falling back to its own
display text (or staying empty, if null) whenever that particular row
isn’t an image.
This property can also be overridden per column - see TEgColumn.DetectBlobImages.