GD Graph

[nuxy]

I'm creating an graph, rather simple to display cpu usage of the server the script runs on.

It is all going well, except for the fact that the graph appears to be more random that what I made it to be.

What I want to accomplish is simply showing a graph that would display the last 50 known percentages that was logged to a text file, but for some reason it is reading either a null or just making percentages up.

It will draw a line upwards when the percentage goes lower, and at random times.

 

I already found a script that reads the cpu usage, and I know for a fact it work, just because the percentage isn't random on the text I made in the upper left corner of the graph.

The script has been cut down to the part where the graph gets generated.

<?php
  $load = round(get_server_load(true), 0);
      $fp = fopen('cpustats.txt', 'a');
      fputs($fp, ':' . $load);
      fclose($fp);
      $data = explode(':', strrev(file_get_contents('cpustats.txt')), 50);
      $data[50] = explode(':', 2);
      $data[50] = $data[50][0];
      $im = imagecreate(500, 200);
      $white = imagecolorallocate($im, 0xFF, 0xFF, 0xFF);
      $gray = imagecolorallocate($im, 0xDD, 0x00, 0x00);
      $black = imagecolorallocate($im, 0x00, 0x00, 0x00);
      $whay = imagecolorallocate($im, 0xEE, 0xEE, 0xEE);
      $dark = imagecolorallocate($im, 0xBB, 0x00, 0x00);
      imagefill($im, 0, 0, $white);
      imageline($im, 50, 0, 50, 200, $whay);
      imageline($im, 100, 0, 100, 200, $whay);
      imageline($im, 150, 0, 150, 200, $whay);
      imageline($im, 200, 0, 200, 200, $whay);
      imageline($im, 250, 0, 250, 200, $whay);
      imageline($im, 300, 0, 300, 200, $whay);
      imageline($im, 350, 0, 350, 200, $whay);
      imageline($im, 400, 0, 400, 200, $whay);
      imageline($im, 450, 0, 450, 200, $whay);
      imageline($im, 0, 50, 500, 50, $whay);
      imageline($im, 0, 100, 500, 100, $whay);
      imageline($im, 0, 150, 500, 150, $whay);
      $c = 0;
      $t = 0;
      for ($i = 0; $i <= 50; $i++) {
          $c += 10;
          $point = $data[$i] * 2;
          $l = tra($point);
          imageline($im, $c - 10, tra($t), $c, $l, $dark);
          $t = $point;
      }
      imagealphablending($im, $true);
      $trans = imagecolorallocatealpha($im, 0x33, 0x33, 0x33, 90);
      imagestring($im, 3, 5, 3, $load . '%', $trans);
      imagepng($im);
      exit;
?>

 

Thanks.

[Barand]

On your graph, y=0 is at the bottom. In GD, y=0 is at the top. So you need to compensate and translate the y values.

[nuxy]

I figured that, that is why I pass the values trough the tra function.

function tra($num)
  {
      $result = 200 - $num;
      if ($result < 0) $result = 0;
      return $result;
  }

 

Thanks!

[nuxy]

*bump*