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ftGraphic

ftGraphic = 17

Example​

function IsGraphicBlob(Field: TField): Boolean;
begin
  Result := Field.DataType = ftGraphic;
end;

Usage​

ftGraphic identifies graphic-oriented blob metadata whose payload, optional Velox graphic header and decoder remain separate concerns.

Additional Technical Info​

ftGraphic is declaration ordinal 17 of TFieldType. It labels a graphic-oriented BLOB. Embarcadero describes it as a bitmap field, but the enum alone does not prove that any particular row contains a valid BMP or identify dimensions, colour model or compression.

The installed RTL maps it to TGraphicField, a TBlobField descendant. TBlobField.GraphicHeader defaults to True. Assigning an IStreamPersist graphic can prepend Delphi's TGraphicHeader; loading through the matching persistent-object path recognises and skips a valid header. Raw LoadFromStream/SaveToStream operations copy stored bytes and do not provide a general image decoder. Consequently, consumers must know whether a header is present before treating the bytes as a standard image file.

Large images should be streamed; byte-array/string access materialises the payload. Validate type, size, dimensions and decoder resource limits before rendering untrusted content. Do not rely on a filename extension or this enum as validation, and do not assume that converting the field to text is meaningful.

Use ftBlob for opaque binary content. The image manipulation functions are a separate future test-bed stream and were deliberately not exercised here.

The example only inspects metadata and was source-reviewed; no graphic decode, blob, file, stream, dataset, database, runtime or image-function test ran.

External references

Created 2026-07-15