GDLib Graphing Class

[dclamp]

Intro
I made this class because i could not, for the life of me, find a basic x/y axis graph for php. With this class you can do the following:

Graph Multiple Objects
Graph unlimited X/Y Cooridnate Pairs
Choose Color for each Object


The Class

header("Content-type: image/png");
header("Cache-Control: no-cache, must-revalidate");
header("Expires: Sat, 26 Jul 1997 05:00:00 GMT");

class graph {

var $imgx;
var $imgy;
//var $scale;
var $mult;
var $xorigin;
var $yorigin;
var $image;
var $clrWhite;
var $clrBlack;
var $clrRed;
var $currentColor;

function __construct() {
$this->imgx = 400;
$this->imgy = 400;
$this->mult = 10;

$this->xorigin = ($this->imgx/2);
$this->yorigin = ($this->imgy/2);

$this->image = imagecreate($this->imgx, $this->imgy);
$this->clrWhite = imagecolorallocate($this->image, 255, 255, 255);
$this->clrBlack = imagecolorallocate($this->image, 0, 0, 0);
$this->clrRed = imagecolorallocate($this->image, 255, 0, 0);

$this->buildAxis();

}

function buildAxis() {
// CREATE X-AXIS
imageline($this->image, 0, $this->yorigin, $this->imgx, $this->yorigin, $this->clrBlack);

// CREATE Y-AXIS
imageline($this->image, $this->xorigin, 0, $this->xorigin, $this->imgy, $this->clrBlack);
}

function makeGraph($grapharray) {
$parabolacount = count($grapharray);

$p = 0;
for ($p; $p <= $parabolacount; $p++) {
if (count($grapharray[$p][2])!= 3) {
$red = rand(0,255);
$green = rand(0,255);
$blue = rand(0,255);
} else {
if ($grapharray[$p][2][0] > 255 || $grapharray[$p][2][0] < 0) {
$red = 0;
} else {
$red = $grapharray[$p][2][0];
}
if ($grapharray[$p][2][1] > 255 || $grapharray[$p][2][1] < 0) {
$green = 0;
} else {
$green = $grapharray[$p][2][1];
}
if ($grapharray[$p][2][2] > 255 || $grapharray[$p][2][2] < 0) {
$blue = 0;
} else {
$blue = $grapharray[$p][2][2];
}
}
$this->currentColor = imagecolorallocate($this->image, $red, $green, $blue);
$this->drawLines($grapharray[$p][0], $grapharray[$p][1], $this->currentColor);
}

}

function drawLines($x, $y, $color) {
//print_r($x);

$xcount = count($x);
$i = 0;
for ($i; $i<=$xcount; $i++) {
if ($i != $xcount-1) {
imageline($this->image, ($this->xorigin+($x[$i])*$this->mult), ($this->yorigin-($y[$i])*$this->mult), ($this->xorigin+($x[$i+1])*$this->mult), ($this->yorigin-($y[$i+1])*$this->mult), $color);
} else {
imageline($this->image, ($this->xorigin+($x[$i])*$this->mult), ($this->yorigin-($y[$i])*$this->mult), ($this->xorigin+($x[$i])*$this->mult), ($this->yorigin-($y[$i])*$this->mult), $color);
}
}
}

function __destruct() {
imagepng($this->image);
imagedestroy($this->image);
}
}


Usage
Create a graph.php page. The following is an example:

include ('class.graph.php');
$graph = new graph;

$graph->makeGraph(
array(
//parabola 1
array(
//x point
array(-3,-2,-1,0,1,2,3),
//y points
array(9,4,1,0,1,4,9),
//color RGB
array(255, 0, 0)
),
//parabola 2
array(
//x point
array(-3,-2,-1,0,1,2,3),
//y points
array(-9,-4,-1,0,-1,-4,-9),
//color RGB
array(0, 0, 255)
)
)
);


Then, where ever you want that graph to show, use the Image Tag:

<img src="graph.php">


http://development.subsoft.net/math/quadratic_formula/graph.php?example=true


Here is another example, allowing you to set the points through $_GET. Although, this only allows 1 object At the moment.

if ($_GET['x'] != "" && $_GET['y'] != "") {
$xa = explode(',', $_GET['x']);
$ya = explode(',', $_GET['y']);

include ('class.graph.php');
$graph = new graph;

$graph->makeGraph(
array(
//parabola 1
array(
//x point
$xa,
//y points
$ya,
//color RGB
array(255, 0, 0)
)
)
);

}



The IMG tag:

<img src="graph.php?x=-3,-2,-1,0,1,2,3&y=-9,-4,-1,0,-1,-4,-9">


http://development.subsoft.net/math/quadratic_formula/graph.php?x=-3,-2,-1,0,1,2,3&y=-9,-4,-1,0,-1,-4,-9