Command: blob

Syntax

blob <assign> {,<assign> ... }

Description

Declare (and optionally assign) one or more blob variables. A blob is a block of binary data with user-defined contents.

Parameters

• <assign>

<ident> { = <value> }

• <ident>
  The name of the identifier.

• <value>
  A blob expression, typically a function returning a blob value.

Switches

None

Notes

If no assignment is supplied, a blob identifier is initialized to an empty block of data.

Once a blob has been assigned, it may be used within the language in the same context as a file, i.e. wherever a file parameter is expected a blob identifier may be used. However a blob expression, e.g. a function returning a blob, may not be used like this anf must be assigned to a blob identifier first.

When a string value containing a file name is required, and a blob is to be used for the file, the blob name may be preceded by 'blob:' and used instead of the file name. Note, the blob name must be valid in the command frame in which the string value is to be used.

Examples

Declare a new blob identifier, initialized with a length 0 bytes.

blob b

Declare 2 new blob identifiers, both initialized by assignment. The first blob is initialized to a block of 64 zero-filled bytes, the second blob is initialzed to a block of 4 bytes containing the ascii control characters CR, LF, CR, LF.

blob b1 = zeroblob(64), b2 = datablob(13,10,13,10)

Declare and initialize a blob array.

blob bs[] = <zeroblob(128),fileblob('c:/temp/mustang.jpg'),zeroblob(256)>

Creates an image as a blob, then uses it as an image within a panel window. Because the panel assignment requires a string value, we use the 'blob:' prefix. Note how the blob is declared before using a command which writes to it.

blob b
rasdump b,-png,-iw=mygraphicwindow
mywin.mypanel.image = 'blob:b'

See Also