Class FreehandFunction

java.lang.Object
  |
  +--FreehandFunction

class FreehandFunction

extends java.lang.Object

implements Function

Allows the user tp "draw" a function. Internally, a finite number of values will be stored, for regularly spaced x-coordinates. If the function is evaluated at any other x-coordinate, linear interpolation will be applied to derive a value.

Field Summary

protected int	lastX The last x coordinate the mouse pointer was seen at
protected double	maxX
protected double	minX
protected double[]	vals An array of values, for evenly spaced x coordinate between minX and maxX.

Constructor Summary

FreehandFunction(double minX, double maxX, int steps)
Creates a new freehand function, for which a number (steps) of values between minX and maxX may be set.

Method Summary

double	evaluate(double x) Uses linear interpolation to determine the value of the function at x
void	update(double x, double y, boolean mouseDown) Called to add a point to the function.
int	xToIndex(double x) Helper method to convert an x coordinate from graph space to an array index.

Methods inherited from class java.lang.Object

, clone, equals, finalize, getClass, hashCode, notify, notifyAll, registerNatives, toString, wait, wait, wait

Field Detail

lastX

protected int lastX

The last x coordinate the mouse pointer was seen at

minX

protected double minX

maxX

protected double maxX

vals

protected double[] vals

An array of values, for evenly spaced x coordinate between minX and maxX.

Constructor Detail

FreehandFunction

public FreehandFunction(double minX,
                        double maxX,
                        int steps)

Creates a new freehand function, for which a number (steps) of values between minX and maxX may be set.

Method Detail

evaluate

public double evaluate(double x)

Uses linear interpolation to determine the value of the function at x

Specified by:

evaluate in interface Function

update

public void update(double x,
                   double y,
                   boolean mouseDown)

Called to add a point to the function.

Parameters:

x - The x coordinate (in screen space)

y - The y coordinate (in screen space)

mouseDown - true if this is the first point to be added in this mouse gesture (ie. the first position reported since the mouse button was depressed)

xToIndex

public int xToIndex(double x)

Helper method to convert an x coordinate from graph space to an array index.