This function allows you to define the bounding box that will be used for all charting function that will be called. It is mandatory to define the coordinates of this rectangular area before calling any chart drawing component.

setGraphArea($X1,$Y1,$X2,$Y2);

Where :

 /* Define the chart area*/
 $myPicture->setGraphArea(20,40,680,210);

This will define the charting area at position (20,40)-(680,210). Note that this command will not display anything, the transparent box in the sample picture is just here to help you figuring out where will be set the graph area.