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Description:
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fontVersionID OBJECT-TYPE
SYNTAX INTEGER(0..65535)
ACCESS read-only
STATUS mandatory
DESCRIPTION
"<Definition> Each font that has been downloaded to a sign shall have a relatively unique ID. This ID shall be calculated using the CRC-16 algorithm defined in ISO 3309 and the associated OER-encoded (as defined in NTCIP 1102) FontVersionByteStream.
The sign shall respond with the version ID value that is valid at the time.
FontVersionByteStream consists of the main font characteristics followed by n rows of CharacterInfoList, as shown by the following ASN.1 construct:
FontVersionByteStream ::= SEQUENCE {
fontInformation FontInformation,
characterInfoList CharacterInfoList}
FontInformation describes the characteristics of the font which are common to each character and defines the order in which this information appears when constructing the byte stream which will be used to calculate the CRC. There is only one row of data for this SEQUENCE for a specific font, as defined by the following ASN.1 construct:
FontInformation ::= SEQUENCE {
fontNumber INTEGER (1..255),
fontHeight INTEGER (0..255),
fontCharSpacing INTEGER (0..255),
fontLineSpacing INTEGER (0..255)}
CharacterInfoList describes the characteristics of each defined character (e.g., where characterWidth is greater than 0) for the fontNumber indicated within the fontInformation field. The CharacterInformation is ordered by the characterNumber in an increasing format per the following ASN.1 construct:
CharacterInfoList ::= SEQUENCE OF CharacterInformation
CharacterInformation describes the characteristics of a single character and defines the objects and order of the objects within one row of CharacterInfoList, per the following ASN.1 construct:
CharacterInformation SEQUENCE {
characterNumber INTEGER (1..65535),
characterWidth INTEGER (0..255),
characterBitmap OCTET STRING}
Complete definitions for these referenced objects are contained elsewhere in this document.
The following is an example of developing the FontVersionByteStream value. Assume the following values for this example, where we only have 2 characters defined:
fontNumber = 2,
fontHeight = 7,
fontCharSpacing = 1,
fontLineSpacing = 3,
characterWidth.52 = 7,
characterBitmap.52 = 1C 59 34 6F E1 83 00,
characterWidth.65 = 6,
characterBitmap.65 = 7B 3C FF CF 3C C0
The resulting string in hex would be:
FontVersionByteStream = 02 07 01 03 01 02 00 34 07 07 1C 59 34 6F E1 83 00 00 41 06 06 7B 3C FF CF 3C C0
CRC = 0x52ED
fontVersionID = 0xED52
Clarifications:
a) characterNumber is a two-byte unsigned integer.
b) characterBitmap is defined as OCTET STRING without a size constraint. (the length octets shall be present)
c) CharacterInfoList is defined as SEQUENCE-OF that requires a quantity field (unconstrained unsigned integer) ‘with a value equal to the number of times the componentType is repeated within the value field’.
The resulting graphic depictions of those 2 defined characters are:
0001110
0010110
0100110
1000110
1111111
0000110
0000110
and
011110
110011
110011
111111
110011
110011
110011
<Object Identifier> 1.3.6.1.4.1.1206.4.2.3.3.2.1.7"
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