This function allows you to push a rendered picture (object) in the static cache. Caching can greatly enhance the user experience of the people browsing your web application by lowering the web server CPU / memory usage and speed up the page rendering time. Every cached object must have an unique ID, see the getHash function for more information.

writeToCache($ID,$pChartObject);

 /* Include all the classes */ 
 include("class/pDraw.class.php"); 
 include("class/pImage.class.php"); 
 include("class/pData.class.php");
 include("class/pCache.class.php");

 /* Create your dataset object */ 
 $myData = new pData(); 
 
 /* Add data in your dataset */ 
 $myData->addPoints(array(1,3,4,3,5));

 /* Create the cache object */
 $myCache = new pCache();

 /* Compute the hash linked to the chart data */
 $ChartHash = $myCache->getHash($myData);

 /* Test if we got this hash in our cache already */
 if ( $myCache->isInCache($ChartHash))
  {
   /* If we have it, get the picture from the cache! */
   $myCache->saveFromCache($ChartHash,"cache.png");
  }
 else
  {
   /* Create a pChart object and associate your dataset */ 
   $myPicture = new pImage(700,230,$myData);

   /* Choose a nice font */
   $myPicture->setFontProperties(array("FontName"=>"fonts/Forgotte.ttf","FontSize"=>11));

   /* Define the boundaries of the graph area */
   $myPicture->setGraphArea(60,40,670,190);

   /* Draw the scale, keep everything automatic */ 
   $myPicture->drawScale();

   /* Draw the scale, keep everything automatic */ 
   $myPicture->drawSplineChart();

   /* Do some cosmetics */
   $myPicture->drawGradientArea(0,0,700,20,DIRECTION_VERTICAL,array("StartR"=>0,"StartG"=>0,"StartB"=>0,"EndR"=>50,"EndG"=>50,"EndB"=>50,"Alpha"=>100));
   $myPicture->setFontProperties(array("FontName"=>"fonts/Silkscreen.ttf","FontSize"=>6));
   $myPicture->drawText(10,13,"Test of the pCache class",array("R"=>255,"G"=>255,"B"=>255));

   /* Push the rendered picture to the cache */
   $myCache->writeToCache($ChartHash,$myPicture);

   /* Render the picture */
   $myPicture->Render("cache.png");
  }

The first time that this code will be executed, the picture will be rendered and pushed in the cache, the next times, it will be retrieved from the cache directly saving CPU and execution time.