<?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(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);
  
  $line = new LinePlot($data,$xdata);
  $line->SetColor('lightblue');
  $graph->Add($line);
  
  $graph->Stroke();
  ?>