eqGraph

Equation Graph.

Defined (1)

The class is defined in the following location(s).

/deprecated/includes/eos.class.php  
  1. class eqGraph extends eqEOS { 
  2.     private $width; 
  3.     private $height; 
  4.     //GD Image reference 
  5.     private $image; 
  6.  
  7.     /** 
  8.      * Constructor 
  9.      * 
  10.      * Sets up the Graph class with an image width and height defaults to 
  11.      * 640x480 
  12.      * 
  13.      * @param Integer $width Image width 
  14.      * @param Integer $height Image height 
  15.      */ 
  16.     public function __construct($width=640, $height=480) { 
  17.         // default width and height equal to that of a poor monitor (in early 2000s) 
  18.         $this->width = $width; 
  19.         $this->height = $height; 
  20.         //initialize main class variables 
  21.         parent::__construct(); 
  22.     } //end function eqGraph 
  23.  
  24.  
  25.     /** 
  26.      * Create GD Graph Image 
  27.      * 
  28.      * Creates a GD image based on the equation given with the parameters that are set 
  29.      * 
  30.      * @param String $eq Equation to use.  Needs variable in equation to create graph, all variables are interpreted as 'x' 
  31.      * @param Integer $xLow Lower x-bound for graph 
  32.      * @param Integer $xHigh Upper x-bound for graph 
  33.      * @param Float $xStep Stepping points while solving, the lower, the better precision. Slow if lower than .01 
  34.      * @param Boolean $xyGrid Draw gridlines? 
  35.      * @param Boolean $yGuess Guess the upper/lower yBounds? 
  36.      * @param Integer $yLow Lower y-bound 
  37.      * @param Integer $yHigh Upper y-bound 
  38.      * @return Null 
  39.      */ 
  40.     public function graph($eq, $xLow, $xHigh, $xStep, $xyGrid = false, $yGuess = true, $yLow=false, $yHigh=false) { 
  41.         //create our image and allocate the two colors 
  42.         $img = ImageCreate($this->width, $this->height); 
  43.         $white = ImageColorAllocate($img, 255, 255, 255); 
  44.         $black = ImageColorAllocate($img, 0, 0, 0); 
  45.         $grey = ImageColorAllocate($img, 220, 220, 220); 
  46.         $xStep = abs($xStep); 
  47.         //DEVELOPER, UNCOMMENT NEXT LINE IF WANTING TO PREVENT SLOW GRAPHS 
  48.         //$xStep = ($xStep > .01) ? $xStep : 0.01; 
  49.         if($xLow > $xHigh) 
  50.             list($xLow, $xHigh) = array($xHigh, $xLow);    //swap function 
  51.          
  52.         $xScale = $this->width/($xHigh-$xLow); 
  53.         $counter = 0; 
  54.         if(DEBUG) { 
  55.             $hand=fopen("eqgraph.txt", "w"); 
  56.             fwrite($hand, "$eq\n"); 
  57.         } 
  58.         for($i=$xLow;$i<=$xHigh;$i+=$xStep) { 
  59.             $tester = sprintf("%10.3f", $i); 
  60.             if($tester == "-0.000") $i = 0; 
  61.             $y = $this->solveIF($eq, $i); 
  62.             //eval('$y='. str_replace('&x', $i, $eq).";"); /* used to debug my eqEOS class results */ 
  63.             if(DEBUG) { 
  64.                 $tmp1 = sprintf("y(%5.3f) = %10.3f\n", $i, $y); 
  65.                 fwrite($hand, $tmp1); 
  66.             } 
  67.  
  68.             // If developer asked us to find the upper and lower bounds for y...  
  69.             if($yGuess==true) { 
  70.                 $yLow = ($yLow===false || ($y<$yLow)) ? $y : $yLow; 
  71.                 $yHigh = ($yHigh===false || $y>$yHigh) ? $y : $yHigh; 
  72.             } 
  73.             $xVars[$counter] = $y; 
  74.             $counter++;             
  75.         } 
  76.         if(DEBUG) 
  77.             fclose($hand); 
  78.         // add 0.01 to each side so that if y is from 1 to 5, the lines at 1 and 5 are seen  
  79.         $yLow-=0.01;$yHigh+=0.01; 
  80.  
  81.         //Now that we have all the variables stored...find the yScale 
  82.         $yScale = $this->height/(($yHigh)-($yLow)); 
  83.  
  84.         // if developer wanted a grid on the graph, add it now  
  85.         if($xyGrid==true) { 
  86.             for($i=ceil($yLow);$i<=floor($yHigh);$i++) { 
  87.                 $i0 = abs($yHigh-$i); 
  88.                 ImageLine($img, 0, $i0*$yScale, $this->width, $i0*$yScale, $grey); 
  89.             } 
  90.             for($i=ceil($xLow);$i<=floor($xHigh);$i++) { 
  91.                 $i0 = abs($xLow-$i); 
  92.                 ImageLine($img, $i0*$xScale, 0, $i0*$xScale, $this->height, $grey); 
  93.             } 
  94.         } 
  95.          
  96.         //Now that we have the scales, let's see if we can draw an x/y-axis 
  97.         if($xLow <= 0 && $xHigh >= 0) { 
  98.             //the y-axis is within our range - draw it. 
  99.             $x0 = abs($xLow)*$xScale; 
  100.             ImageLine($img, $x0, 0, $x0, $this->height, $black); 
  101.             for($i=ceil($yLow);$i<=floor($yHigh);$i++) { 
  102.                 $i0 = abs($yHigh-$i); 
  103.                 ImageLine($img, $x0-3, $i0*$yScale, $x0+3, $i0*$yScale, $black); 
  104.             } 
  105.         } 
  106.         if($yLow <= 0 && $yHigh >= 0) { 
  107.             //the x-axis is within our range - draw it. 
  108.             $y0 = abs($yHigh)*$yScale; 
  109.             ImageLine($img, 0, $y0, $this->width, $y0, $black); 
  110.             for($i=ceil($xLow);$i<=floor($xHigh);$i++) { 
  111.                 $i0 = abs($xLow-$i); 
  112.                 ImageLine($img, $i0*$xScale, $y0-3, $i0*$xScale, $y0+3, $black); 
  113.             } 
  114.         } 
  115.         $counter=2; 
  116.  
  117.         //now graph it all ;] 
  118.         for($i=$xLow+$xStep;$i<=$xHigh;$i+=$xStep) { 
  119.             $x1 = (abs($xLow - ($i - $xStep)))*$xScale; 
  120.             $y1 = (($xVars[$counter-1]<$yLow) || ($xVars[$counter-1] > $yHigh)) ? -1 : (abs($yHigh - $xVars[$counter-1]))*$yScale; 
  121.             $x2 = (abs($xLow - $i))*$xScale; 
  122.             $y2 = (($xVars[$counter]<$yLow) || ($xVars[$counter] > $yHigh)) ? -1 : (abs($yHigh - $xVars[$counter]))*$yScale; 
  123.              
  124.             // if any of the y values were found to be off of the y-bounds, don't graph those connecting lines  
  125.             if($y1!=-1 && $y2!=-1) 
  126.                 ImageLine($img, $x1, $y1, $x2, $y2, $black); 
  127.             $counter++; 
  128.         } 
  129.         $this->image = $img; 
  130.     } //end function 'graph' 
  131.  
  132.     /** 
  133.      * Sends JPG to browser 
  134.      * 
  135.      * Sends a JPG image with proper header to output 
  136.      */ 
  137.     public function outJPG() { 
  138.         header("Content-type: image/jpeg"); 
  139.         ImageJpeg($this->image); 
  140.     } 
  141.  
  142.     /** 
  143.      * Sends PNG to browser 
  144.      * 
  145.      * Sends a PNG image with proper header to output 
  146.      */ 
  147.     function outPNG() { 
  148.         header("Content-type: image/png"); 
  149.         ImagePng($this->image); 
  150.     } 
  151.      
  152.     /** 
  153.      * Output GD Image 
  154.      * 
  155.      * Will give the developer the GD resource for the graph that 
  156.      * can be used to store the graph to the FS or other media 
  157.      * 
  158.      * @return Resource GD Image Resource 
  159.      */ 
  160.     public function getImage() { 
  161.         return $this->image; 
  162.     } 
  163.      
  164.     /** 
  165.      * Output GD Image 
  166.      * 
  167.      * Alias for eqGraph::getImage() 
  168.      * 
  169.      * @return Resource GD Image resource 
  170.      */ 
  171.     public function outGD() { 
  172.         return $this->getImage(); 
  173.     } 
  174. } //end class 'eqGraph'