.ds f. AtAxis.man
.\"  $Header: /afs/athena.mit.edu/astaff/project/atdev/spec/man/RCS/AtAxis.man,v 3.2 91/02/20 19:52:36 crcraig Exp Locker: crcraig $
.\"  Copyright (C) 1990 by the Massachusetts Institute of Technology
.\"
.TH AtAxis 3X
.SH NAME
.B AtAxis -- the Axis widget class
.SH SYNOPSIS
.B #include <At/Axis.h>

.SH DESCRIPTION

The AtAxis widget is an Xt object that displays an axis in an existing
widget or window.  An axis may be oriented horizontally or vertically.
An axis has an optional label, and can have tics and subtics.  Tics
can be labeled with numbers or user-supplied strings.  Both linear and
log axes are supported.

Two (or three, if a Y2 axis is desired) axes are automatically created
by the AtPlotter widget.  If the Axis object is used outside of the
AtPlotter widget, the programmer is responsible for resizing and
redisplaying the AtAxis object (see USAGE).

.SH CLASSES
The class pointer is atAxisObjectClass, and the class name is
AtAxis.

.SH RESOURCES

The AtAxis widget inherits all the resources from the Object widget
class.  In addition, it has the following new resources:

.TS
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.IP XtNlabel
Specifies the string to display as the axis label.

.IP XtNlabelFontFamily
Specifies the font family to use for the axis label.

.IP XtNlabelSize
Specifies the font size for the axis label.

.IP XtNlabelColor
Specifies the color of the axis label.

.IP XtNnumberFontFamily
Specifies the font family to number the axes with.  

.IP XtNnumberSize
Specifies the font size used for numbering the axes.

.IP XtNnumberStyle
Specifies the font style used for numbering the axes.

.IP XtNnumberColor
Specifies the color of the numbers on the axis.

.IP XtNaxisColor
Specifies the color to use to draw the axes, and the tics.

.IP XtNmin
Specifies the minimum value to be displayed on the axis.

.IP XtNmax
Specifies the maximum value to be displayed on the axis.

.IP XtNtransform
Specifies the transform to be used for the axis.  The options are
AtTransformLINEAR and AtTransformLOG.  The default is linear.

.IP XtNvertical
Specifies whether the axis is to be drawn vertically.  If this resource
is set to false, the axis will be drawn horizontally.  The AtPlotter
widget forces the value of this resource as appropriate.

.IP XtNmirror
Specifies whether the axis should be drawn as a mirror image of its
"normal" configuration.  A "normal" axis is drawn on the left or bottom
of the plotting region, with the label on the "outside".  An axis with
this resource set to True would be appropriate for the top or right of a
a plotting area.  The AtPlotter widget forces the value of this resource
as appropriate.

.IP XtNdrawNumbers
Specifies whether the axis should be numbered.

.IP XtNdrawGrid 
Specifies whether dotted lines should be drawn at each tic mark
perpendicular to the axis across the plotting region.  If True, it
creates a "graph paper" effect.

.IP XtNautoNumber
Specifies whether the location of tic marks and subtics should be
calculated by the widget.  If True (the default) the resources
XtNticDensity and XtNsubticDensity are hints to the widget about how
many tics and subtics are desired.  If False, the resource
XtNticInterval specifies the spacing between tics and XtNsubtics
specifies the number of subtics between each tic.

.IP XtNticInterval
If XtNautoNumber is False, this resource directly specifies the interval
(in the user coordinate system, not pixels) between tics.  If
XtNautoNumber is True, this resource can be queried to get the current
spacing between tics.

.IP XtNsubtics
If XtNautoNumber is False, this resource directly specifies the number
of subtics between every two tics.  Note that the number of subtics is
one less than the number of sub-intervals that the space is partitioned
into.  Thus to divide the space between tics into quarters, specify
three tics.  If XtNautoNumber is True, this resource can be queried to
get the current number of subtics.

.IP XtNticDensity
If XtNautoNumber is True, this resource provides a hint as to how many
tics the user wants.  The default of zero will cause the axis to
produce an "optimal" number of tics, based on the length of the axis,
and the font size.  To get more tics, specify a value of 1 to 5 for this
resource.  To get fewer tics, specify a value from -1 to -5.

.IP XtNsubticDensiy
If XtNautoNumber is true, this resource provides a hint to the widget
about how many subtics should be drawn between tics.  The default of
zero will produce an "optimal" number of subtics.  A positive value
between 1 and 5 will produce more subtics, and a negative value between
-1 and -5 will produce fewer subtics.

.IP XtNticMultiplier 
The coordinate of each tic on an axis will be multiplied by this value
before it is displayed.  This is useful when an axis is used with very
large or very small numbers, or when displaying data in different units
than it is measured in.  If XtNautoNumber is True, this multiplier is
taken into account when the interval between tics is calculated, so that
the numbers will still be on "nice" intervals.  If False, the user
specified XtNticInterval is multiplied by this amount before the tics
are calculated.

.IP XtNticFormat
This string is used as the format string to the function sprintf when
converting the numeric value of a tic to a string.  It can be modified
to alter then number of digits displayed after the decimal point.  Note
that it can also contain text, so tics like "3pi" or "5 dB" could be
generated.  

.IP XtNticLabels
Specifies labels to be used for tic labels.  Each label is separated
by a newline (i.e. '\n').  If XtNticLabels is non-NULL, these labels
are used to label the tics on the axis instead of the tics' numeric
values.  If this resource is used, XtNautoNumber should be False,
XtNticInterval should be set to an appropriate value, and XtNticFormat
and XtNticMultiplier are ignored.  If not enough tic labels are given,
the extra tics are not labeled.

.IP XtNticsOutside
Specifies whether tic marks should be drawn on the "outside" of the
axis.  The outside is the left or bottom if XtNmirror is false and the
top or right if it is true.

.IP XtNticsInside
Specifies whether tic marks should be drawn on the "inside" of the axis.

.IP XtNticLength
Specifies the length in pixels of tic.  This many pixels are drawn on
the "outside" or "inside" of the axis, or both, or neither depending on
the state of the XtNticsOutside and XtNticsInside resources.

.IP XtNsubticLength
Specifies the length of pixels of a subtic. This many pixels are drawn
on the "outside" or "inside" of the axis, or both, or neither depending
on the state of the XtNticsOutside and XtNticsInside resources.

.IP XtNaxisNeedsRedraw
Specifies procedures to be called when the axis should be redrawn
(i.e. one or more of its resources changed).

.IP XtNerrorCallback
Specifies procedures to be called when an error occurs in the axis.
If no procedures are specified, any error messages are output to
standard error using \fBXtWarning()\fP.


.SH "PUBLIC ROUTINES"
.nf
.ta 10n
void AtAxisComputeTicSpacing(\fIaxis\fP, \fIlength\fP)
	AtAxisObject \fIaxis\fP;
	int \fIlength\fP;
int AtAxisWidth(\fIaxis\fP)
	AtAxisObject \fIaxis\fP;
void AtAxisChangeBounds(\fIaxis\fP, \fImin\fP, max)
	AtAxisObject \fIaxis\fP;
	double \fImin\fP, max;
void AtAxisGetBounds(\fIaxis\fP, \fImin\fP, \fImax\fP)
	AtAxisObject \fIaxis\fP;
	double *\fImin\fP, *\fImax\fP;
void AtAxisSetLocation(\fIaxis\fP, \fIx1\fP, \fIy1\fP, \fIx2\fP, \fIy2\fP)
	AtAxisObject \fIaxis\fP;
	int \fIx1\fP, \fIx2\fP, \fIy1\fP, \fIy2\fP;
void AtAxisGetLocation(\fIaxis\fP, \fIx1\fP, \fIx2\fP, \fIy1\fP,
\fIy2\fP)
	AtAxisObject \fIaxis\fP;
	int *\fIx1\fP, *\fIx2\fP, *\fIy1\fP, *\fIy2\fP;
void AtAxisDraw(\fIdpy\fP, \fIwin\fP, \fIaxis\fP, \fIbg\fP)
	Display *\fIdpy\fP;
	Window \fIwin\fP;
	AtAxisObject \fIaxis\fP;
	Pixel \fIbg\fP;
void AtAxisDrawGrid(\fIdpy\fP, \fIwin\fP, \fIaxis\fP, \fIstart_pixel\fP, \fIend_pixel\fP)
	Display *\fIdpy\fP;
	Window \fIwin\fP;
	AtAxisObject \fIaxis\fP;
	int \fIstart_pixel\fP, \fIend_pixel\fP;
void AtAxisDrawGridRegion(\fIdpy\fP, \fIwin\fP, \fIaxis\fP, \fIstart_pixel\fP,
                          \fIend_pixel\fP, \fIregion\fP)
	Display *\fIdpy\fP;
	Window \fIwin\fP;
	AtAxisObject \fIaxis\fP;
	int \fIstart_pixel\fP, \fIend_pixel\fP;
	Region \fIregion\fP;
int AtAxisWidthPS(\fIaxis\fP)
	AtAxisObject \fIaxis\fP;
void AtAxisDrawPS(fp, \fIaxis\fP, \fIx1\fP, \fIy1\fP, \fIx2\fP, \fIy2\fP, \fIgrid_min\fP, \fIgrid_max\fP)
	FILE *fp;
	AtAxisObject \fIaxis\fP;
	int \fIx1\fP, \fIy1\fP, \fIx2\fP, \fIy2\fP, \fIgrid_min\fP, \fIgrid_max\fP;

.fi
.IP AtAxisComputeTicSpacing()
Causes \fIaxis\fP to compute its tic spacing for an approximate length
of \fIlength\fP pixels.

.IP AtAxisWidth()
Returns the width of \fIaxis\fP in pixels.

.IP AtAxisChangeBounds()
Change the user coordinate bounds of \fIaxis\fP to \fImin\fP and
\fImax\fP.

.IP AtAxisGetBounds()
Return the user coordinate bounds of \fIaxis\fP in \fImin\fP and
\fImax\fP.

.IP AtAxisSetLocation()
Set the pixel location of the endpoints of \fIaxis\fP to \fI(x1,
y1)"\fP (corresponding to the axis's minimum value) and \fI(x2, y2)\fP
(corresponding to the axis's maximum value).

.IP AtAxisGetLocation()
Stores the pixel location of the endpoints of \fIaxis\fP in \fI(x1,y1)"\fP
(corresponding to the axis's minimum value) and \fI(x2, y2)\fP 
(corresponding to the axis's maximum value).

.IP AtAxisDraw()
Draw \fIaxis\fP in window \fIwin\fP on the X display \fIdpy\fP with
background color \fIbg\fP.

.IP AtAxisDrawGrid()
Draw the grid for \fIaxis\fP in window \fIwin\fP on the X display
\fIdpy\fP.  The grid lines will start at pixel \fIstart_pixel\fP and
end at pixel \fIend_pixel\fP.

.IP AtAxisDrawGridRegion()
Functions like \fBAtAxisDrawGrid()\fP, but restricts the drawing of
the grid to the region indicated by \fIregion\fP.

.IP AtAxisWidthPS()
Returns the width of the Postscript representation of \fIaxis\fP in PS
points.

.IP AtAxisDrawPS()
Write the Postscript representation of \fIaxis\fP to the file pointer
\fIfp\fP.  The axis representation will be drawn inside the bounding
box described by \fI(x1, y1)\fP and \fI(x2, y2)\fP.  Grid lines will
be drawn from \fIgrid_min\fP to \fIgrid_max\fP.

.SH USAGE

.nf
axis = XtCreateWidget(\fIaxis_name\fP, AtAxisObjectClass, \fIparent\fP,
                      \fIargs\fP, \fInum_args\fP)
	String \fIaxis_name\fP;
	WidgetClass AtAxisObjectClass;
	Widget \fIparent\fP;
	ArgList \fIargs\fP;
	Cardinal \fInum_args\fP;
.fi

When AtAxis is the child of the AtPlotter widget, AtPlotter will
control the axis object, place it, and draw it.  No outside
interaction is necessary.  If the AtAxis object is being used outside
the AtPlotter widget, the programmer must set up the axis object,
place it, and draw it.  After creating the axis,
.I AtAxisComputeTicSpacing
should be called to compute the tic spacing
for the object.  Next, 
.I AtAxisSetLocation
should be called to set the axis's location.  Finally, call
.I AtAxisDraw
to actually draw the axis.

.I AtAxisWidth
will not return a valid width unless the axis's tic spacing has
already been computed
.I (AtAxisComputeTicSpacing).

.SH CALLBACK INFORMATION

The value of the call_data argument passed to XtNaxisNeedsRedraw
callback procedures is undefined.

.SH "SEE ALSO"
AtPlotter(3X), AtText(3X), AtFontFamily(3X), X(1)

.SH BUGS
Logarithmic mode still has some problems.  Upside down axes don't
always work quite right.

.SH AUTHORS
David Flanagan (MIT Project Athena), Chris Craig (MIT Project Athena)

.SH NOTES
Postscript is a trademark of Adobe Systems Incorporated.

.SH COPYRIGHT

Copyright (C) 1990 by the Massachusetts Institute of Technology

Export of this software from the United States of America is assumed
to require a specific license from the United States Government.
It is the responsibility of any person or organization contemplating
export to obtain such a license before exporting.

WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
distribute this software and its documentation for any purpose and
without fee is hereby granted, provided that the above copyright
notice appear in all copies and that both that copyright notice and
this permission notice appear in supporting documentation, and that
the name of M.I.T. not be used in advertising or publicity pertaining
to distribution of the software without specific, written prior
permission.  M.I.T. makes no representations about the suitability of
this software for any purpose.  It is provided "as is" without express
or implied warranty.