package ac.essex.ecj.functions; 
 
import ec.gp.GPNode; 
import ec.gp.GPData; 
import ec.gp.ADFStack; 
import ec.gp.GPIndividual; 
import ec.EvolutionState; 
import ec.Problem; 
import ac.essex.ecj.data.DoubleData; 
import ac.essex.ecj.problems.PixelProblem; 
 
/** 
 * 
 * Gets the value of a given pixel, or depending on the offset values, that of a pixel around it. 
 * 
 * @author Olly Oechsle, University of Essex, Date: 17-Aug-2006 
 * @version 1.0 
 */ 
public class GetPixel extends GPNode { 
 
    public void eval(final EvolutionState state, final int thread, final GPData input, final ADFStack stack, final GPIndividual individual, final Problem problem) { 
 
        DoubleData result = ((DoubleData) (input)); 
 
        // evaluate the first child, and save the result 
        children[0].eval(state, thread, input, stack, individual, problem); 
        int offsetX = (int) result.value; 
 
        // do the same with the second child. 
        children[1].eval(state, thread, input, stack, individual, problem); 
        int offsetY = (int) result.value; 
 
        // get a reference to the problem object, through which we can access the image. 
        PixelProblem pixelProblem = (PixelProblem) problem; 
 
        // set the value of the result 
        result.value = pixelProblem.image.getBooleanPixel(pixelProblem.x + offsetX, pixelProblem.y + offsetY); 
    } 
 
    public String toString() { 
        return "getPixel"; 
    } 
 
}