Generate an image to show environment status

zabbix_status.php

<?php
define('ZABBIX_AUTHKEY', '****');
define('FONT_PATH', '/usr/share/fonts/vlgothic/VL-PGothic-Regular.ttf');
//define('FONT_PATH', '/usr/share/fonts/dejavu/DejaVuSans.ttf');
define('FONT_SIZE', 24);
define('IMAGE_WIDTH', 300);
define('IMAGE_HEIGHT', 50);

function zabbix_query ($request) {
	$channel = curl_init();
	$options = array(
		CURLOPT_AUTOREFERER => TRUE,
		CURLOPT_FAILONERROR => FALSE,
		CURLOPT_RETURNTRANSFER => TRUE,
		CURLOPT_POST => TRUE,
		CURLOPT_HTTPHEADER => array('Content-Type: application/json-rpc'),
		CURLOPT_URL => 'http://localhost/zabbix/api_jsonrpc.php',
		CURLOPT_POSTFIELDS => $request
	);
	curl_setopt_array($channel, $options);
	$result = curl_exec($channel);
	curl_close($channel);
	return json_decode($result, true);
}

function zabbix_query_items ($itemidarray) {
	$itemids = implode(',', $itemidarray);
	$authkey = ZABBIX_AUTHKEY;
	return zabbix_query(<<<EOT
{
"method":"item.get",
"params":{"output":"extend","itemids":[$itemids]},
"id":1,
"auth":"$authkey",
"jsonrpc":"2.0"
}
EOT
	);
}

function write_as_image ($message) {
	$image = imagecreatetruecolor(IMAGE_WIDTH, IMAGE_HEIGHT);
	$foreground_color = imagecolorallocate($image, 0, 0, 0);
	$background_color = imagecolorallocate($image, 255, 255, 255);
	imagefill($image, 0, 0, $background_color);
	imagettftext($image, FONT_SIZE, 0, 0, FONT_SIZE+10, $foreground_color, FONT_PATH, $message);
	header('Content-Type: image/png');
	imagepng($image);
	imagedestroy($image);
}

$items = zabbix_query_items(array(/* item IDs: 1, 2, 3, ... */));
$message = sprintf(<<<EOT
%s W    %.1f ℃
EOT
	,
	number_format(((float) $items['result'][0]['lastvalue'])),
	(float) $items['result'][1]['lastvalue']
	);

write_as_image($message);
?>