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<?php
/** Libchart - PHP chart library
*
* Copyright (C) 2005-2006 Jean-Marc Tr�meaux (jm.tremeaux at gmail.com)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
/**
* Automatic axis boundaries and ticks calibration
*
* @author Jean-Marc Tr�meaux (jm.tremeaux at gmail.com)
*/
class Axis
{
/**
* Creates a new axis formatter
*
* @access public
* @param integer minimum value on the axis
* @param integer maximum value on the axis
*/
function Axis($min, $max)
{
$this->min = $min;
$this->max = $max;
$this->guide = 10;
}
/**
* Computes value between two ticks
*
* @access private
*/
function quantizeTics()
{
// Approximate number of decades, in [1..10[
$norm = $this->delta / $this->magnitude;
// Approximate number of tics per decade
$posns = $this->guide / $norm;
if ($posns > 20)
$tics = 0.05; // e.g. 0, .05, .10, ...
else
if ($posns > 10)
$tics = 0.2; // e.g. 0, .1, .2, ...
else
if ($posns > 5)
$tics = 0.4; // e.g. 0, 0.2, 0.4, ...
else
if ($posns > 3)
$tics = 0.5; // e.g. 0, 0.5, 1, ...
else
if ($posns > 2)
$tics = 1; // e.g. 0, 1, 2, ...
else
if ($posns > 0.25)
$tics = 2; // e.g. 0, 2, 4, 6
else
$tics = ceil($norm);
$this->tics = $tics * $this->magnitude;
}
/**
* Computes automatic boundaries on the axis
*
* @access public
*/
function computeBoundaries()
{
// Range
$this->delta = abs($this->max - $this->min);
// Check for null distribution
if($this->delta == 0)
$this->delta = 1;
// Order of magnitude of range
$this->magnitude = pow(10, floor(log10($this->delta)));
$this->quantizeTics();
$this->displayMin = floor($this->min / $this->tics) * $this->tics;
$this->displayMax = ceil($this->max / $this->tics) * $this->tics;
$this->displayDelta = $this->displayMax - $this->displayMin;
// Check for null distribution
if($this->displayDelta == 0)
$this->displayDelta = 1;
}
/**
* Set boundaries on the axis. Theses values override the automatic values.
*
* @access public
*/
function setBoundaries($sampleCount, $yMinValue, $yMaxValue)
{
$this->sampleCount = $sampleCount;
$this->yMinValue = $yMinValue;
$this->yMaxValue = $yMaxValue;
}
/**
* Get the lower boundary on the axis
*
* @access public
* @return integer lower boundary on the axis
*/
function getLowerBoundary()
{
return $this->displayMin;
}
/**
* Get the upper boundary on the axis
*
* @access public
* @return integer upper boundary on the axis
*/
function getUpperBoundary()
{
return $this->displayMax;
}
/**
* Get the value between two ticks
*
* @access public
* @return integer value between two ticks
*/
function getTics()
{
return $this->tics;
}
}
?>
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