fed.1

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)fed.1	8.1	9/11/90
.TH fed 1 VAX "" Unsupported
.SH Name
fed \- font editor
.SH Syntax
.B fed
[
.B \-i
]
[
.B \-q
]
name
.SH Description
The 
.PN fed
program is an editor for font files.
It is display oriented and must be used on an HP 2648 graphics terminal.
.PN fed 
does the necessary handshaking to work at 9600 baud on the 2648.
.SH Options
.IP \-i
Requests
.IR "inverse video mode" ,
where all dots are dark and the background is bright.
This provides a setting similar to the hardcopy output of
the plotter, and is useful for fonts such as the shadow
font where shading is important.
.IP \-q
Requests
.IR "quiet mode" ,
where all graphic output is suppressed.
This mode is useful on terminals other than the HP 2648
(assuming you are editing blindly) and for operations
such as the # and A commands, since 
these operations do not make essential use of graphics,
and since suppression
of the graphic output speeds of
.PN fed
considerably.
.SH Restrictions
Attempting to use the second 128 characters would be folly.
Fed has never been tested on such fonts, and at a bare minimum
there would be problems trying to input 8 bit characters.
.PP
The character DEL is interpreted by the tty driver to mean interrupt.
Hence the corresponding glyph cannot be accessed.
The
.IR start ,
.IR stop ,
and
.I quit
characters are turned off, but other characters used by the
new tty driver must be quoted with ^V.
.PP
Changed widths are not copied to the width table used by troff.
This only matters if logical widths are changed, or if
glyphs are moved around.
For these cases,
.I vwidth(1)
must be used.
.SH Fonts
A font is a collection of up to 256
.IR glyphs ,
each of which is some pattern or design.
Glyphs are represented on Unix as a rectangular array
of dots, each of which is either dark or blank.
Each location in the array is called a
.IR pixel .
There are 200 pixels per inch due to the hardware of the
Versatec and Varian plotters.
.PP
Each glyph has, in addition to its bit pattern, a
.I base
and a
.IR width .
The base is a point, typically near the lower left of the array,
that represents the logical lower left point of the glyph.
The base is not restricted to be within the array, in fact, it is usually
a few locations to the left of the edge.
The vertical position of the base defines the
.IR baseline ,
which is held constant for all glyphs when a line is typeset.
Letters with descenders, such as ``g'', go below the baseline.
Other glyphs typically rest on the baseline.
.PP
The width is used by
.I troff(1)
to determine where to place the next glyph.
It need not be the same as the width of the array, although it is usually
about the same.
.PP
The size of the array, location of the base, and the width can vary among
glyphs in a font.
Fonts where all glyphs have the same width are called
.IR "fixed width fonts" ,
others are
.IR "variable width fonts" .
.PP
Attributes which do not vary among glyphs include the
.IR "font name" ,
which can be up to 11 alphabetic characters, and the
.IR "point size" ,
which is a positive integer indicating the overall size of the font.
A point is 1/72 inch.
The point size of a font is the distance, in points, from the top of
the tallest glyph to the bottom of the lowest.
The software of troff currently restricts point sizes to
6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, 22, 24, 28, and 36 point.
Normal text is usually 10 point.
.PP
Font files conventionally have names of the form
.br
	\fIname.pointsize\fP
.br
for example, `bocklin.14' to indicate 14 point bocklin.
Fed will look for such a file in both the current directory
and /usr/lib/vfont.
Vtroff will only look in /usr/lib/vfont.
.PP
There is a correspondence between
.I glyphs
and
.I characters
in a font.
For a given font, each glyph has an ASCII character associated with it.
The glyph is obtained in troff by typing the associated character,
and in fed glyphs are also referred to by their character.
However, it is not required for all characters to have a glyph,
fonts never have more than 128 glyphs and usually have fewer.
.PP
There is usually a natural correspondence between glyphs and characters.
For example, the glyph which is a roman lower case `a' will generally
have the ascii character `a' as its corresponding character.
In the special font, the Greek lower case alpha has `a' as it's corresponding
character, upper case delta has 'D' as it's corresponding character, etc.
However, special fonts such as the chess font have glyphs that do not
appear to be related to their corresponding characters.
.PP
It is easy to confuse glyphs and characters.
Note, however, that the three glyphs
roman a, bold
.BR a ,
and italic
.IR a ,
are all different, yet all three correspond to the character `a'.
When this is multiplied by the large number of font styles and point
sizes, there are many glyphs that match a single character,
(but only one in a particular font).
.SH Fed Organization
.PP
Fed organizes the screen into 21
.I windows
in a 3 by 7 array.
Each window is 100 by 100 pixels,
meaning that the maximum height and width of a glyph is 100 pixels.
Since the HP 2648 has a resolution of 100 dots per inch, glyphs
displayed on the screen and printer will be double the actual
height and width, even when fully zoomed out.
There is a
.IR "current window" ,
which will be marked with a square border.
There are two
.IR pens ,
called
.I fine
and
.IR bold .
The fine pen is one pixel wide,
the bold pen can range from two pixels to ten pixels in diameter.
The default width of the bold pen is taken from the point size
implied by the file name.
The point size is not otherwise used.
There are also fine and bold
.IR erasers .
.PP
There are two locations in the window, called the
.I cursor
and the
.IR mark .
These tools are used to draw on glyphs.
.PP
Sometimes the cursor is on, in which case it is indicated by the
hardware graphics cursor of the terminal, a cross.  The cursor is
considered to be located at the center of the cross.
Sometimes the
.I "rubber band line"
is turned on, showing the path a line drawn would traverse.
This line runs from the mark to the cursor, and is the only
way the mark is graphically visible.
.SH Commands
Commands to fed are single characters, sometimes followed by any
needed arguments.
The commands used by fed were chosen to be as similar to
.IR vi (1)
commands as was reasonable.
Another distinction is that certain commands are in upper case.
These commands were deliberately made hard to type because they
cause a large change in the state of the editor and should not
be done by accident.
In a few cases there are both upper and lower case commands with
the same letter.
.PP
.IR "Alphanumeric Keypad" :
Note that this is the keypad on the far right.
The graphics keypad on the near right will not work.
These keys are each synonyms for other commands.
They are arranged in a manner that causes the five
arrow keys to behave sensibly,
but the others need to be memorized or stickers
placed on the keys.
They are provided for convenience only,
and the user can avoid memorization simply
by using the mnemonic letter keys instead.
.PP
The layout is as follows:
.ta 1i 2i 3i
.nf
	undo (u)	rezoom ( )	fillin (f)
	move (m)	up (k)	draw (d)
	left (h)	base (b)	right (l)
	setdot (.)	down (j)	cleardot (>)
.fi
.DT
.PP
The arrow keys move the cursor one pixel in the indicated direction.
The cursor is turned on if it was off.
Note that the alphanumeric keys (far right) must be used.
The graphics keys (near right) will appear to move the cursor but
it will not be moved internally.
The cursor cannot be moved outside the current window.
.PP
.IR "^L" :
Redraw the screen.  This is useful if an I/O error or background
process has caused the screen to get messed up.
.PP
.IR b :
Move the cursor to the base of the window.
This is the default location of the cursor.
.PP
.IR c :
If the cursor is on, turn it off.
Otherwise, turn it on.
.PP
.IR d :
Draw a line from the mark to the cursor.
The currently selected tool (fine pen, bold pen, fine eraser, bold eraser)
is used.
The cursor is turned off.
The mark is moved to the location of the cursor.
.PP
.IR f :
Fill in the current hole.
The cursor must be in a completely enclosed empty (white) area.
The area is set to black.