Class CanvasGraph

Class CanvasGraph

Warning, links to the API class, i.e., java.awt.*, java.lang.*, etc., do not exist. Only links to Poggendoff class exists: the "see also" links.
java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.Canvas
                   |
                   +----CanvasGraph

class CanvasGraph
extends Canvas
implements DialogClient
This class draws the psychometric curve.

Constructor Index

 o CanvasGraph(double[], int[], int)
The constructor copies the parameters objects into class objects.

Method Index

 o DrawCurve(Graphics)
This method draws the graph
 o PtoC_X(double)
This method converts graph model points (i.e., the graph defined in an abstract, right-handed coordinate system) to points in the canvas coordinate system.
 o PtoC_Y(double)
This method converts graph model points (i.e., the graph defined in an abstract, right-handed coordinate system) to points in the canvas coordinate system.
 o dialogDismissed(Dialog)
This interface method is called when an error dialog box is dismissed (the error being that the results window is too small.
 o getOffset()
This method returns the 50% offset value
 o paint(Graphics)
When paint is called for the first time, we have access to the bounds of the canvas at that time.

Constructors

 o CanvasGraph
  public CanvasGraph(double o[],
                     int p[],
                     int m)
The constructor copies the parameters objects into class objects.
Parameters:
o - is an array of comparision line offsets
p - is an array of y-component curve points
m - is the maximum index value for the offset and percent arrays

Methods

 o dialogDismissed
  public void dialogDismissed(Dialog d)
This interface method is called when an error dialog box is dismissed (the error being that the results window is too small. This implementation feature is part of the MessageDialog class in the gjt package: it is called from the 'action' method of MessageDialog.class.
Returns:
void
 o paint
  public void paint(Graphics g)
When paint is called for the first time, we have access to the bounds of the canvas at that time. This is important because the features of the lines, at the beginning of each trial, require this info. The paint routine first checks to see if the experiment has started (i.e., the variable that keeps track of the number of trials is greater than 0)--if not, a trial initialization routine is called and based on the info. in the first trial object, features of the lines are initialized. It also calls the drawing methods of all graphics objects
Parameters:
g - is the Graphics objects attached to the current canvas
Returns:
void
Overrides:
paint in class Canvas
 o DrawCurve
  public void DrawCurve(Graphics g)
This method draws the graph
Parameters:
g - is the Graphics object attached to the class of this method
Returns:
void
 o getOffset
  public double getOffset()
This method returns the 50% offset value
Parameters:
Null - no parameters
Returns:
double the offset value
 o PtoC_X
  public double PtoC_X(double p)
This method converts graph model points (i.e., the graph defined in an abstract, right-handed coordinate system) to points in the canvas coordinate system. In the graph model, the x-axis values run from the largest negative value, which represents a comparison line below the true connect point, to the largest positive value, which represents a comparison line above the true connect point. To convert the graph model points into the canvas coordinate, I need the largest negative offset to coorespond to where the graph origin will be in canvas coor. sys., i.e., xOffset% of way from the left hand side of the canvas (the xOffset*w factor). Each graph model x value needs to be shifted to the right (i.e., it's value must be reduced by a factor "shiftX" which is equal to the absolute value of the largest offset). This value must then be scaled into the range of the x-axis (which is specificed in canvas coor. sys. values).
Parameters:
p - is a graph model x-value
Returns:
double a cooresponding canvas coordinate system x-value
 o PtoC_Y
  public double PtoC_Y(double p)
This method converts graph model points (i.e., the graph defined in an abstract, right-handed coordinate system) to points in the canvas coordinate system. In the graph model, the y-axis values run from 0, which represents zero "above" responses, to 100, which represents 100% "above" responses. To convert the graph model points into the canvas coordinate, I need the 0% to be ploted at the origin of the graph in the canvas cor. system (which is yOffset% of the canvas height from the bottom of the canvas--this is the yOffset*h factor). All model percentage points must then be scaled into the lenght of the y-axis, which is specified in canvas coor. sys. values, i.e., pixels (this is the "scaleY" factor). Finally, I need to take into account the left-handed nature of the canvas (i.e., y values increase as one goes DOWN the screen). For example, if the graph model specifies a percentage of 100%, directly ploting that value will result in a point towards the bottom of the canvas rather than towards the top where you would expect it. In order to move that point up, I need to take -100 and add it to the height of the canvas. In short, model y values where directly ploted, the graph would be upside down.
Parameters:
p - is a graph model x-value
Returns:
double a cooresponding canvas coordinate system x-value

Back to Results class documentation