Class Plotter

java.lang.Object
  |
  +--Plotter

Direct Known Subclasses:

Plotter2, RotatedPlotter

class Plotter

extends java.lang.Object

Responsible for plotting graphs. As many applets require special functionality, this class has grown a little too feature-rich. The first step to improve this class would be to take out some of the specialised behaviour (such as folding the x-axis) into several subclasses (the strategy employed with RotatedPlotter).

Plotter2 went some way towards improving this class, providing extra methods to simplify common tasks; the subclassing was mostly to break up the code, rather than to separate the functionality.

Field Summary

protected static double	ABS_MAX
protected static double	ABS_MIN
protected boolean	axes true if axes will be drawn, else false
protected double	bottomMargin When scaling to fit, the upper bound of the y range will be extended by this proportion.
protected Solvable	eqn The Solvable object providing solution data
protected boolean	fold true if the x axis will be folded, else false
protected double	foldSize The size of the folding interval
protected boolean	foldSym true if the folding interval is centred on the origin, else false
boolean	infY Set this to true if the y axis is to be infinite.
protected boolean	interpolate true if values will be interpolated, else false
protected boolean	log true if the vertical scale is logarithmic, else false
protected int	majorTickSize The length of the line drawn to indicate a major tick
protected double	maxX The maximum x value for which the Solvable object will be evaluated.
protected double	maxY The maximum y value to be included on the graph
protected int	minorTickSize The length of the line drawn to indicate a minor tick
protected double	minX The minimum x value for which the Solvable object will be evaluated.
protected double	minY The minimum y value to be included on the graph
boolean	noUnitsX Set this to true to suppress numerical labels, but still draw the main label for the axis.
boolean	noUnitsY Set this to true to suppress numerical labels, but still draw the main label for the axis.
protected double	rangeX The difference maxX - minX
protected double	rangeY The difference maxY - minY
protected double[]	soln The cache of graph data to be plotted
protected int	tickRatio The number of minor ticks per major tick
protected double	topMargin When scaling to fit, the upper bound of the y range will be extended by this proportion.
protected double	viewLeft The minimum x value to be included on the graph
protected double	viewRange The difference viewRight - viewLeft
protected double	viewRight The maximum x value to be included on the graph
protected GraphLabel	xLabel The main label for the x axis
protected boolean	xScale true if the horizontal scale will be drawn, else false
protected GraphLabel	yLabel The main label for the y axis
protected boolean	yScale true if the vertical scale will be drawn, else false

Constructor Summary

Plotter(Solvable s)
Creates a new plotter to graph the specifed Solvable object.

Method Summary

protected double	chooseTickSize(double range) Attempts to calculate an approprite tick size (distance between minor ticks) based on the size of the axis.
void	copyScale(Plotter p) Sets the view range, x range and y range of this plotter according to the settings of another.
protected double	fold(double x, double f, boolean sym) Returns the folded version of an x coordinate.
double	fromScreenX(int x, int w) Converts the specified x value from screen space to graph space
double	fromScreenY(int y, int h) Converts the specified y value from screen space to graph space
protected static double	getMax(double[] vals, int left, int right) Returns the maximum value from an array
protected static double	getMin(double[] vals, int left, int right) Returns the minimum value from an array
int	getSpaceX(java.awt.FontMetrics fm) Calculates the size of the gap between the left edge of the display and the start of the actual graph area.
int	getSpaceY(java.awt.FontMetrics fm) Calculates the size of the gap between the bottom edge of the display and the start of the actual graph area.
boolean	isInterpolated() Returns true if y values between samples will be interpolated, else false
boolean	isLogarithmic() Returns whether graph data should be log()'d before plotting
void	labelAxisX(java.awt.Graphics g, int w, int h) Labels the x axis.
void	labelAxisY(java.awt.Graphics g, int w, int h) Labels the y axis.
void	paint(java.awt.Graphics g, int w, int h) Paints the graph, axes and scales.
void	paintAxes(java.awt.Graphics g, int w, int h) Paints a set of axes (the lines x=0, y=0).
void	paintGraph(java.awt.Graphics g, int w, int h) Paints the graph (without scales, labels or axes).
void	paintGraphFolded(java.awt.Graphics g, int w, int h, double fold, boolean sym) Paints the graph (without scales, labels or axes), with a folded x axis.
protected void	paintLabelBelow(java.awt.Graphics g, java.lang.String s, int x, int y) Paints a string just below the specified point, centred horizontally.
protected void	paintLabelToLeft(java.awt.Graphics g, java.lang.String s, int x, int y) Paints a string just to the left of specified point, centred vertically.
void	paintVerticalMarkers(java.awt.Graphics g, int w, int h, double[] markers) Plots vertical markers at the specified coordinates.
protected void	scaleToFit() Adjusts the minY, maxY and rangeY parameters so that the y axis range is set to the minimum interval into which all graph data falls.
protected void	scaleToFit(int left, int right) Adjusts the minY, maxY and rangeY parameters so that the y axis range is set to the minimum interval into which all graph data within the specified interval falls.
protected void	setAxes(boolean b) Set to true if axes (x = 0, y = 0) should be displayed, else false
protected void	setFold(boolean b) Used to enable or disable folding
protected void	setFold(boolean b, double size, boolean sym) Used to enable or disable folding, and sets the folding parameters.
protected void	setFold(double size, boolean sym) Enables folding, and sets the folding parameters.
void	setInterpolated(boolean b) Set to true if y values between samples should be interpolated, else false
protected void	setLabels(java.lang.String x, java.lang.String y) Sets the labels for the axes.
void	setLogarithmic(boolean b) Sets whether graph data should be log()'d before plotting
void	setRangeX(double min, double max) Sets the range for the x axis.
void	setRangeY(double min, double max) Sets the portion of the x axis displayed on the graph.
protected void	setScalesEnabled(boolean x, boolean y) Enables or disables the x and y scales
void	setView(double min, double max) Sets the portion of the x axis displayed on the graph.
void	setViewAndRange(double min, double max) Combines a call to setView() and setRangeX(), passing the same interval bounds to each.
protected double	snap(double d, double base) Helper method to round off d to the nearest multiple of base
protected void	squareValues() Convenience method to square all the y values.
int	toScreenX(double x, int w) Converts the specified x value from graph space to screen space
int	toScreenY(double y, int h) Converts the specified y value from graph space to screen space
protected java.lang.String	toString(double d) Convenience method to format a double for display.
protected void	updateSolution(int steps) Updates this plotter's cache of solution data.

Methods inherited from class java.lang.Object

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

Field Detail

minorTickSize

protected int minorTickSize

The length of the line drawn to indicate a minor tick

majorTickSize

protected int majorTickSize

The length of the line drawn to indicate a major tick

tickRatio

protected int tickRatio

The number of minor ticks per major tick

log

protected boolean log

true if the vertical scale is logarithmic, else false

interpolate

protected boolean interpolate

true if values will be interpolated, else false

axes

protected boolean axes

true if axes will be drawn, else false

xScale

protected boolean xScale

true if the horizontal scale will be drawn, else false

yScale

protected boolean yScale

true if the vertical scale will be drawn, else false

fold

protected boolean fold

true if the x axis will be folded, else false

foldSym

protected boolean foldSym

true if the folding interval is centred on the origin, else false

noUnitsX

public boolean noUnitsX

Set this to true to suppress numerical labels, but still draw the main label for the axis.

noUnitsY

public boolean noUnitsY

Set this to true to suppress numerical labels, but still draw the main label for the axis.

infY

public boolean infY

Set this to true if the y axis is to be infinite. A messy hack; if a graph is to be scaled to fit, and the data is known to become infinite, setting this flag will provide a meaningful label (eg. "Infinity") on the y axis.

xLabel

protected GraphLabel xLabel

The main label for the x axis

yLabel

protected GraphLabel yLabel

The main label for the y axis

soln

protected double[] soln

The cache of graph data to be plotted

eqn

protected Solvable eqn

The Solvable object providing solution data

foldSize

protected double foldSize

The size of the folding interval

topMargin

protected double topMargin

When scaling to fit, the upper bound of the y range will be extended by this proportion.

bottomMargin

protected double bottomMargin

When scaling to fit, the upper bound of the y range will be extended by this proportion.

minX

protected double minX

The minimum x value for which the Solvable object will be evaluated.

maxX

protected double maxX

The maximum x value for which the Solvable object will be evaluated.

viewLeft

protected double viewLeft

The minimum x value to be included on the graph

viewRight

protected double viewRight

The maximum x value to be included on the graph

minY

protected double minY

The minimum y value to be included on the graph

maxY

protected double maxY

The maximum y value to be included on the graph

viewRange

protected double viewRange

The difference viewRight - viewLeft

rangeX

protected double rangeX

The difference maxX - minX

rangeY

protected double rangeY

The difference maxY - minY

ABS_MIN

protected static double ABS_MIN

ABS_MAX

protected static double ABS_MAX

Constructor Detail

Plotter

public Plotter(Solvable s)

Creates a new plotter to graph the specifed Solvable object.

Method Detail

paintVerticalMarkers

public void paintVerticalMarkers(java.awt.Graphics g,
                                 int w,
                                 int h,
                                 double[] markers)

Plots vertical markers at the specified coordinates. Each marker will be a vertical line running across the whole y-range.

Parameters:

g - The Graphics surface on which to paint

w - The width (in pixels) of the available display area

h - The height (in pixels) of the available display area

markers - An array of x coordinates at which markers

paintAxes

public void paintAxes(java.awt.Graphics g,
                      int w,
                      int h)

Paints a set of axes (the lines x=0, y=0).

Parameters:

g - The Graphics surface on which to paint

w - The width (in pixels) of the available display area

h - The height (in pixels) of the available display area

labelAxisX

public void labelAxisX(java.awt.Graphics g,
                       int w,
                       int h)

Labels the x axis. Major and minor ticks will be drawn, with a numerical label at each major tick. The label for this axis will also be painted. Note that "axis" here refers to the scale across the bottom of the graph, rather than the line y = 0.

Parameters:

g - The Graphics surface on which to paint

w - The width (in pixels) of the available display area

h - The height (in pixels) of the available display area

labelAxisY

public void labelAxisY(java.awt.Graphics g,
                       int w,
                       int h)

Labels the y axis. Major and minor ticks will be drawn, with a numerical label at each major tick. The label for this axis will also be painted. Note that "axis" here refers to the scale to the left of the graph, rather than the line x = 0.

Parameters:

g - The Graphics surface on which to paint

w - The width (in pixels) of the available display area

h - The height (in pixels) of the available display area

paintLabelBelow

protected void paintLabelBelow(java.awt.Graphics g,
                               java.lang.String s,
                               int x,
                               int y)

Paints a string just below the specified point, centred horizontally.

paintLabelToLeft

protected void paintLabelToLeft(java.awt.Graphics g,
                                java.lang.String s,
                                int x,
                                int y)

Paints a string just to the left of specified point, centred vertically. (The right-hand end of the text will appear one pixel to the left of the specified point.)

toString

protected java.lang.String toString(double d)

Convenience method to format a double for display. Implementation is via a call to BaseApplet2.toString().

paint

public void paint(java.awt.Graphics g,
                  int w,
                  int h)

Paints the graph, axes and scales.

Parameters:

g - The Graphics surface on which to paint

w - The width (in pixels) of the available display area

h - The height (in pixels) of the available display area

getSpaceX

public int getSpaceX(java.awt.FontMetrics fm)

Calculates the size of the gap between the left edge of the display and the start of the actual graph area. In other words, the space allocated for labels and scales on the vertical axis.

Parameters:

fm - The FontMetrics with which the graph will be rendered

getSpaceY

public int getSpaceY(java.awt.FontMetrics fm)

Calculates the size of the gap between the bottom edge of the display and the start of the actual graph area. In other words, the space allocated for labels and scales on the horizontal axis.

Parameters:

fm - The FontMetrics with which the graph will be rendered

paintGraph

public void paintGraph(java.awt.Graphics g,
                       int w,
                       int h)

Paints the graph (without scales, labels or axes).

Parameters:

g - The Graphics surface on which to paint

w - The width (in pixels) of the available display area

h - The height (in pixels) of the available display area

paintGraphFolded

public void paintGraphFolded(java.awt.Graphics g,
                             int w,
                             int h,
                             double fold,
                             boolean sym)

Paints the graph (without scales, labels or axes), with a folded x axis. The folding will be on the interval [0,fold] or [-fold,fold], depending on the sym parameter.

Parameters:

g - The Graphics surface on which to paint

w - The width (in pixels) of the available display area

h - The height (in pixels) of the available display area

fold - The width (in graph units) of the interval over which to fold.

sym - true if the graph should be folded onto an interval centred at the origin, else false

fold

protected double fold(double x,
                      double f,
                      boolean sym)

Returns the folded version of an x coordinate.

Parameters:

x - The value to fold

f - The width (in graph units) of the interval over which to fold.

sym - true if the graph should be folded onto an interval centred at the origin, else false

updateSolution

protected void updateSolution(int steps)

Updates this plotter's cache of solution data.

Parameters:

steps - The number of x values at which the solution should be sampled

scaleToFit

protected void scaleToFit()

Adjusts the minY, maxY and rangeY parameters so that the y axis range is set to the minimum interval into which all graph data falls.

scaleToFit

protected void scaleToFit(int left,
                          int right)

Adjusts the minY, maxY and rangeY parameters so that the y axis range is set to the minimum interval into which all graph data within the specified interval falls.

Parameters:

left - The minimum bound for the x-axis interval

right - The maximum bound for the x-axis interval

toScreenX

public int toScreenX(double x,
                     int w)

Converts the specified x value from graph space to screen space

Parameters:

x - The value

w - The width (in pixels) of the available display area

toScreenY

public int toScreenY(double y,
                     int h)

Converts the specified y value from graph space to screen space

Parameters:

y - The value

h - The height (in pixels) of the available display area

fromScreenX

public double fromScreenX(int x,
                          int w)

Converts the specified x value from screen space to graph space

Parameters:

x - The value

w - The width (in pixels) of the available display area

fromScreenY

public double fromScreenY(int y,
                          int h)

Converts the specified y value from screen space to graph space

Parameters:

y - The value

h - The height (in pixels) of the available display area

snap

protected double snap(double d,
                      double base)

Helper method to round off d to the nearest multiple of base

setRangeX

public void setRangeX(double min,
                      double max)

Sets the range for the x axis. This is not necessarily the range of values displayed on the screen (see setView()), but does determine the range of values for which the solution is evaluated. For graphs where the values are not independed (eg. numerical integration), this is often set larger than than the view range.

setView

public void setView(double min,
                    double max)

Sets the portion of the x axis displayed on the graph. This will normally be contained within the x axis bounds (see setRange()), but may overlap or be entirely outside that interval (although it is difficult to think of a useful application of the latter).

setViewAndRange

public void setViewAndRange(double min,
                            double max)

Combines a call to setView() and setRangeX(), passing the same interval bounds to each.

setRangeY

public void setRangeY(double min,
                      double max)

Sets the portion of the x axis displayed on the graph.

copyScale

public void copyScale(Plotter p)

Sets the view range, x range and y range of this plotter according to the settings of another.

Parameters:

p - The plotter, whose example this shall follow

squareValues

protected void squareValues()

Convenience method to square all the y values.

isInterpolated

public boolean isInterpolated()

Returns true if y values between samples will be interpolated, else false

setInterpolated

public void setInterpolated(boolean b)

Set to true if y values between samples should be interpolated, else false

getMax

protected static double getMax(double[] vals,
                               int left,
                               int right)

Returns the maximum value from an array

Parameters:

vals - The data

left - The index at which to begin searching

right - The index at which to stop searching

getMin

protected static double getMin(double[] vals,
                               int left,
                               int right)

Returns the minimum value from an array

Parameters:

vals - The data

left - The index at which to begin searching

right - The index at which to stop searching

chooseTickSize

protected double chooseTickSize(double range)

Attempts to calculate an approprite tick size (distance between minor ticks) based on the size of the axis.

Bug: does not take size of display area into account

Parameters:

range - The size of the axis

setAxes

protected void setAxes(boolean b)

Set to true if axes (x = 0, y = 0) should be displayed, else false

setLabels

protected void setLabels(java.lang.String x,
                         java.lang.String y)

Sets the labels for the axes.

Parameters:

x - The label for the x axis

y - The label for the y axis

setScalesEnabled

protected void setScalesEnabled(boolean x,
                                boolean y)

Enables or disables the x and y scales

Parameters:

x - true if the x axis is to have a scale

y - true if the y axis is to have a scale

setFold

protected void setFold(boolean b)

Used to enable or disable folding

setFold

protected void setFold(boolean b,
                       double size,
                       boolean sym)

Used to enable or disable folding, and sets the folding parameters.

Parameters:

b - true if folding should be enabled, else false

size - The size of interval over which to fold

sym - true if the interval extends in both directions from the origin, else false

setFold

protected void setFold(double size,
                       boolean sym)

Enables folding, and sets the folding parameters.

Parameters:

size - The size of interval over which to fold

sym - true if the interval extends in both directions from the origin, else false

isLogarithmic

public boolean isLogarithmic()

Returns whether graph data should be log()'d before plotting

setLogarithmic

public void setLogarithmic(boolean b)

Sets whether graph data should be log()'d before plotting