<?php // content="text/plain; charset=utf-8"
// Example on how to treat and format timestamp as human readable labels
require_once 'jpgraph/jpgraph.php';
require_once 'jpgraph/jpgraph_line.php';

// Number of "fake" data points
DEFINE('NDATAPOINTS', 500);

// Assume data points are sample every 10th second
DEFINE('SAMPLERATE', 10);

// Callback formatting function for the X-scale to convert timestamps
// to hour and minutes.
function TimeCallback($aVal)
{
    return Date('H:i', $aVal);
}

// Get start time
$start = time();
// Set the start time to be on the closest minute just before the "start" timestamp
$adjstart = floor($start / 60);

// Create a data set in range (20,100) and X-positions
// We also apply a simple low pass filter on the data to make it less
// random and a little smoother
$data = array();
$xdata = array();
$data[0] = rand(20, 100);
$xdata[0] = $adjstart;
for ($i = 1; $i < NDATAPOINTS; ++$i) {
    $data[$i] = rand(20, 100) * 0.2 + $data[$i - 1] * 0.8;
    $xdata[$i] = $adjstart + $i * SAMPLERATE;
}

// Assume that the data points represents data that is sampled every 10s
// when determing the end value on the scale. We also add some extra
// length to end on an even label tick.
$adjend = $adjstart + (NDATAPOINTS + 10) * 10;

$graph = new Graph\Graph(500, 250);
$graph->SetMargin(40, 20, 30, 50);

// Now specify the X-scale explicit but let the Y-scale be auto-scaled
$graph->SetScale("intlin", 0, 0, $adjstart, $adjend);
$graph->title->Set("Example on TimeStamp Callback");

// Setup the callback and adjust the angle of the labels
$graph->xaxis->SetLabelFormatCallback('TimeCallback');
$graph->xaxis->SetLabelAngle(90);

// Set the labels every 5min (i.e. 300seconds) and minor ticks every minute
$graph->xaxis->scale->ticks->Set(300, 60);

$line = new Plot\LinePlot($data, $xdata);
$line->SetColor('lightblue');
$graph->Add($line);

$graph->Stroke();
