art, art2pic - edit line-art
art [ -f font ] [ -b picture ]
Art is an interactive program to create precise line-art in the style of pic(1). It is
mostly mouse-operated, with a few commands entered from the keyboard. It divides its win-
dow into four areas: a menu bar at the top, a one-line rectangle immediately below for
echoing typed-in characters, another one-line rectangle below that for printing messages,
and a large area at the bottom for displaying the drawing. The -b option displays the
specified picture (in the format of picfile(9.6)) as a background for the drawing.
A small caret, whose apex is the current point, appears on the screen. The lines, arcs,
and other elements of a drawing are constructed by placing the caret at each of a sequence
of points that define the item. When the caret moves, two other markers (a square and a
cross) trail it, showing its previous positions. Items on the screen near the caret
attract it. Important points on items, like endpoints or intersections, pull harder than
more mundane points, making precise alignment easy.
On request, art will automatically construct alignment lines and circles, which it dis-
plays more faintly than items in the drawing. Certain lines and points in a drawing are
hot. Art constructs circles of given radii and lines of given slopes at hot points, and
parallels at given distances from hot lines and lines at given angles to their endpoints.
Menus pulled down from the menu bar control what alignment items are constructed. Items
are automatically heated when added to the drawing and will be heated or cooled on com-
The `important points' on a line segment to which the caret preferentially gravitates are
its endpoints and midpoint. On a circle, the center is important. On an arc, the end-
points are important. On a box, the corners, the midpoints of the sides and the center
are important. Likewise, on a piece of text, the corners, midpoints and center of its
bounding box are important. On a spline, the control points are important, and in a
group, the important points of the group members are important.
Whenever button 1 is pressed, the caret follows the mouse cursor. On release, the item
the caret is touching, if any, is selected and highlighted. If more than one item touches
the caret, clicking button 1 repeatedly will cycle through them.
Pressing button 2 pops up a menu of commands that add new items to the drawing. Every
item is described by several control points: a line by its endpoints, a circular arc by
its endpoints and a third point on the arc, and so forth. A new item is specified by mov-
ing the caret in turn to each control point but the last, selecting a menu entry with but-
ton two, then using button 1 to place the caret on the last control point. (Buttons 2 and
3 will cancel the command.) While the caret is being dragged to the last control point,
art displays and updates the item on the screen (``rubber-banding''). In all cases, after
making an addition to the drawing, the new item becomes the current selection. The button
2 menu operations are
line Add a line segment to the drawing. The two control points are the segment's end-
circle Add a circle to the drawing. The first control point is the center. The second is
a point on the circumference.
arc Add a circular arc to the drawing. The endpoints are the first and third control
points. The second control point is an interior point of the arc.
box Add a rectangle to the drawing. The box's sides are vertical and horizontal. The
two control points are two diagonally opposite corners.
spline Add a spline curve to the drawing, or extend an existing spline. Splines are a
little more complicated than other items because they may have any number of con-
trol points. If the current selection is not a spline, there are two control
points -- the ends of a new spline. When a spline is selected, the spline button
adds a new control point to the end of the spline closest to the selected point.
group Add a group to the drawing. The two control points are the diagonally opposite
corners of a rectangle. Any item partially or completely contained in the rectan-
gle is made part of the group. Henceforth the group acts as a monolithic item and
may be moved, deleted or copied as a unit. The open, close and flatten commands
(on button 3) allow manipulation of the items within a group. Groups may be nested
within other groups.
Button 3's menu has commands to manipulate the current selection.
delete Remove the selection from the drawing. If the whole drawing is selected, art asks
for confirmation by pressing mouse button 3. Buttons 1 and 2 cancel the command.
heat Heat the selected item.
copy Create a duplicate of the selected item. The duplicate must be dragged to its
intended position using button 1. Buttons 2 and 3 cancel the command.
edit Change the indicated point of the selected item. Button 1 adjusts the point. But-
tons 2 and 3 cancel the command. This command's behavior depends on the kind of
item and the point at which it is selected.
If a line is selected near an endpoint, that endpoint moves and the other remains
fixed. Both endpoints of a line selected near its midpoint move--its length and
slope do not change.
If a circle selected at its center, it translates without changing its radius. If
selected on its circumference, its radius changes but its center remains fixed.
The control point of an arc or spline nearest the selection point is modified.
If a box is selected near a corner, that corner moves and the other remains fixed.
If selected near the middle of an edge, the edge moves, but the opposite edge
remains fixed. If selected near its center, the whole box moves without changing
its size or shape.
A group or a piece of text translates, regardless of the selection point.
open The selection must be a group. All commands now operate on the members of the
close The most-recently opened group is closed. Any changes made while it was open are
propagated to other copies.
The selection must be a group. The items in the group are inserted in its place in
the drawing. This undoes the effect of the group command. Other copies of the
group are unaffected.
t text Add text to the drawing. The text is in the current font and is drawn centered on
f name Set the current typeface. Name is the name of a font file. Subdirectories of
/lib/font/bit contain many appropriate fonts.
D Redraw the display.
q Quit. Art exits, without asking for confirmation.
Write the drawing into a file in art format. File defaults to the last file men-
tioned in a read or write command. Art files may be converted to pic(1) format by
the art2pic command.
Read a drawing from a file. File defaults to the last file mentioned in a read or
c Cool everything. Every hot item is cooled.
a Select all items. The entire drawing is selected.
d Drop anchor. The anchor is the fixed point for the not-yet-implemented rotate and
Menus pulled down from the menu bar contain commands that alter how art responds to user
slopes Most of the entries in this menu are numbers, representing angles in degrees.
Those that are marked with a star are the inclination from horizontal of alignment
lines constructed at each hot point of the drawing. Selecting a number toggles the
star on and off. The measure button measures the slope of the line connecting the
most recent two points selected with the caret. The measurement is printed, and a
corresponding new entry is made in the menu.
angles This menu behaves much like the slopes menu. Items marked with a star are angles
at which alignment lines are drawn through the endpoints of hot lines. The measure
button measures the angle indicated by the most recent three points selected with
Items marked with a star are distances at which alignment lines are drawn parallel
to hot lines. The measure button measures the distance between the most recent two
points selected with the caret. Distances are nominally in inches, but the program
believes the display pitch to be 100 pixels per inch.
Items marked with a star are radii of alignment circles drawn with centers at hot
points. The measure button measures the distance between the most recent two
points selected with the caret.
grid Items in this menu activate a rectangular grid of gravitating points. They have
labels like 0,0+.1,.1. The first pair of numbers is the coordinate of a point on
the grid; the other pair is the x and y displacements of other points. The off
item disables the grid (the default situation). Measure creates a custom-measured
grid using the last two positions of the caret as diagonally adjacent grid-points.
The starred entry on this menu is the maximum distance that the caret will move
from the mouse cursor to snap to an item on the screen.
The heat new button toggles whether objects are automatically heated when created
or modified. The item is marked with a star if set, as it is initially.
Needs two or more bits per pixel. Doesn't compute intersections of splines with circles
or arcs. No filled regions, line styles or arrowheads. Doesn't save construction lines
in files. Because it draws in xor mode when rubber-banding, lines can momentarily disap-
pear. Tracks slowly in large drawings.