PDF《Part II》

s Dual Context Extensions. Select Primary Font FN1 Select Secondary Font LB Label LO Label Origin SA Select Alternate Font SB Scalable or Bitmap Fonts SD Standard Font Definition SI Absolute Character Size SL Character Slant SR Relative Character Size SS Select Standard font TD Transparent Data 17-6 An Introduction to HP-GL/2 Vector Graphics EN As shown in the tables above, each HP-GL/2 command is a two-letter mnemonic code designed to remind you of its function. For example, IN is the Initialize command, SP is the Select Pen command, and CI is the Circle command. Parameters are used with certain HP-GL/2 commands to tell the printer to complete the command in a particular way. Understanding HP-GL/2 Syntax HP-GL/2 commands have four components: a mnemonic, parameter(s), separator(s), and a terminator. Refer to the following illustration of a typical HP-GL/2 command and the description of its components. Table 17-5 The HP-GL/2 Commands by Group (5 of 5) LINE AND FILL ATTRIBUTES GROUP AC Anchor Corner FT Fill Type LA Line Attributes LT Line Type PW Pen Width RF Raster Fill Definition SM Symbol Mode SP Select Pen SV1 1. These commands are part of the Palette Extensions to HP-GL/2. Screened Vectors TR1 Transparency Mode UL User-defined Line Type WU Pen Width Unit Selection EN HP-GL/2 Commands and Syntax 17-7 Figure 17-1 Typical HP-GL/2 Command z Mnemonic--The two-letter mnemonic reminds you of the command'

s function. The mnemonic can be uppercase or lowercase. z Parameter(s)--Some commands have no parameters;

for those commands which have them, parameters can be either required or optional (as indicated in the description of that command). z Separator(s)--When you use parameters, you must separate them with a comma or space, or in the case of a numeric parameter, with a + or - sign. (Commas are recommended because some computers eliminate spaces, especially when sending variables.) z Terminator--All commands require a terminator. Most HP-GL/2 commands are terminated by a semicolon or the first letter of the next mnemonic, a white space, or a tab (exceptions: LB uses a user-defined terminator;

PE cannot use the first letter of the next mnemonic). The last command prior to exiting HP-GL/2 mode must be terminated with a semicolon. The following illustration shows the flexibility of the syntax. Each variation of the two-command sequence is permissible;

however, the method shown on the left is recommended in most instances. The recommended method uses the first letter of the next mnemonic to terminate commands, uses no space between the mnemonic and its parameters, and separates parameters with a comma. (For clarity, examples in this HP-GL/2 section of the manual use semicolons as terminators, as shown in the middle example below.) Figure 17-2 Illustration of Syntax Flexibility 17-8 An Introduction to HP-GL/2 Vector Graphics EN The next section explains how the syntax of individual commands is presented. Notations Used to Express Syntax The following describes the notations used in the syntax section of each command description: Mnemonic For readability, the mnemonic is shown in uppercase and separated from the parameters and/or terminator. parameters Parameters are shown in italic. [ ] Parameters in square brackets are optional. [param1,param2...[,param1,param2]] These optional parameters must be paired. params...params These parameters may be given the number of times specified in the command description. text...text This parameter indicates that you can type in a range of ASCII characters, such as in the Label (LB) command. (....) Indicates that you can use a range of the previous parameter;