PHP histogram generation code (imagefilledrectugle function example)

/**
* php histogram imagefilledrectugle function use case
* by bbs.it-home.org
*/
function createImage($data,$twidth,$tspace,$height){
header("Content-Type:image/ jpeg");
$dataname = array();
$datavalue = array();//The value in data
$i = 0;
$j = 0;
$k = 0;
$num = sizeof( $data);
foreach($data as $key => $val){
$dataname[] = $key;
$datavalue[] = $val;
}< /p>
$width = $num * ($twidth + $tspace) + 20 ;//Get the width of the image
$im = imagecreate($width,$height);//Create image
$bgcolor = imagecolorallocate($im,255,255,255);//Background color
$jcolor = imagecolorallocate($im,255,255,0);//Background color of the rectangle
$acolor = imagecolorallocate($im ,0,0,0);//The color of the line
imageline($im,25,$height-20,$width-5,$height -20,$acolor);/ /X-axis
imageline($im,25,$height-20,25,2,$acolor);//Y-axis
while($i< $num){
imagefilledrectangle($im,$i*($tspace+ $twidth)+40,$height-$datavalue[$i]-20,$i*($twidth+$tspace)+$tspace+40,$height-20,$jcolor);//Draw a rectangle
imagestring($ im,3,$i*($tspace+$twidth)+40+$twidth/2,$height-$datavalue[$i]-35,$datavalue[$i],$acolor);//Write on the pillar Output value
imagestring($im,3,$i*($tspace+$twidth)+40+$twidth/2,$height-15,$dataname[$i],$acolor);//Write it below the column Value
$i ++;
}
while($j < 400/10){
imageline($im,25,($height-20)-$j*8, 28,($height-20)-$j*8,$acolor);//Draw the scale
imagestring($im,2,5,($height-30)-$j*8,$j*10, $acolor);//Mark the scale value
$j = $j +10;
}
imagejpeg($im);
}
$data =array("1"=>25,"2"=> 30,"3" =>21 );
createImage($data,40,40,300);
?>