Here is an example
import java.awt.*; // Graphics, Color, ...
import javax.swing.*; // JFrame, JPanel, ...
import java.text.DecimalFormat;
import java.util.ArrayList;
public class Plotter extends JFrame {
/** Default constructor (8 x 8 coordinate system)
* Postcondition: my lower left corner is (-4, -4) &&
* my upper right corner is (4, 4) &&
* my title is "PointPlotter"
*/
public Plotter() {
this(0, 0, -4.0, -4.0, 4.0, 4.0, "Plotter");
centerFrame();
}
/** Explicit value constructor using x-y values
* @param minX, a double
* @param minY, a double
* @param maxX, a double
* @param maxY, a double
* Postcondition: my lower left corner is (minX, minY) &&
* my upper right corner is (maxX, maxY) &&
* my title is "PointPlotter"
*/
public Plotter(double minX, double minY, double maxX, double maxY) {
this(0, 0, minX, minY, maxX, maxY, "Plotter");
centerFrame();
}
/** Explicit value constructor using x-y values
* @param minX, a double
* @param minY, a double
* @param maxX, a double
* @param maxY, a double
* Postcondition: my lower left corner is (minX, minY) &&
* my upper right corner is (maxX, maxY) &&
* my title is "PointPlotter"
*/
public Plotter(double minX, double minY, double maxX, double maxY, String title) {
this(0, 0, minX, minY, maxX, maxY, title);
centerFrame();
}
/** Explicit value constructor using x-y values
* @param screenX, an int
* @param screenY, an int
* @param minX, a double
* @param minY, a double
* @param maxX, a double
* @param maxY, a double
* @param title, a String
* Postcondition: I have been drawn at (screenX, screenY) &&
* my lower left corner is (minX, minY) &&
* my upper right corner is (maxX, maxY) &&
* my title is title
*/
public Plotter(int screenX, int screenY, double minX, double minY, double maxX, double maxY,
String title) {
super();
setDefaultCloseOperation(EXIT_ON_CLOSE);
setTitle(title);
myPanel = new PlotPanel(minX, minY, maxX, maxY);
this.setContentPane(myPanel);
this.setLocation(screenX, screenY);
this.pack();
this.setVisible(true);
}
private void centerFrame() {
Toolkit kit = Toolkit.getDefaultToolkit();
Dimension screenSize = kit.getScreenSize();
int screenWidth = (int)screenSize.getWidth();
int screenHeight = (int)screenSize.getHeight();
this.setLocation(((screenWidth / 2) - (this.getWidth()/2)),
((screenHeight / 2) - (this.getHeight()/2)));
}
/** Draw a point at (x,y)
* @param x, a double
* @param y, a double
* Postcondition: I now have a point at (x,y)
*/
public void drawPoint(double x, double y) {
myPanel.plotPoint(x, y);
}
/** draw a Line from (x1, y1) to (x2, y2).
* @param x1, a double
* @param y1, a double
* @param x2, a double
* @param y2, a double
* Postcondition: I contain a line from (x1, y1) to (x2, y2).
*/
public void drawLine(double x1, double y1, double x2, double y2) {
myPanel.drawLine(x1, y1, x2, y2);
}
/** draw an Oval at (xCenter, yCenter), of the given width and height
* @param xCenter, a double
* @param yCenter, a double
* @param width, a double
* @param height, a double
* Postcondition: I contain an oval whose width is width, whose height
* is height, and whose center is at (xCenter, yCenter).
*/
public void drawOval(double xCenter, double yCenter,
double width, double height) {
myPanel.drawOval(xCenter, yCenter, width, height);
}
/** Hide the axes
* Postcondition: the axes in myPanel are hidden.
*/
public void hideAxes() {
myPanel.hideAxes();
}
/** Make axes visible
* Postcondition: the axes in myPanel are visible.
*/
public void showAxes() {
myPanel.showAxes();
}
/** Set pen color for graphics
* @param col, a Color
* Postcondition: whatever I draw next will be done in col.
*/
public void setPenColor(Color col) {
myPanel.setPenColor(col);
}
/** Get the delta value for 1 column
* @return delta x for the given window size
*/
public double deltaX() {
return myPanel.deltaX();
}
/** Get the delta value for 1 row
* @return delta y for the given window size
*/
public double deltaY() {
return myPanel.deltaY();
}
/** Minimum x-value accessor
* @return my minimum x-value
*/
public double minX() {
return myPanel.minX();
}
/** Minimum y-value accessor
* @return my minimum y-value
*/
public double minY() {
return myPanel.minY();
}
/** Maximum x-value accessor
* @return my maximum x-value
*/
public double maxX() {
return myPanel.maxX();
}
/** Maximum y-value accessor
* @return my maximum y-value
*/
public double maxY() {
return myPanel.maxY();
}
/** Rounding utility method
* @param number, a double
* @return the int nearest to number.
*/
public static int round(double number) {
return (int) (number + 0.5);
}
// --- PlotPanel does most of the hard work ---
private class PlotPanel extends JPanel {
public final static int AXIS_MARGIN = 40, // rows/columns at edge of axis
AXIS_GAP = 50; // rows/columns btwn axis markings
/** Default constructor
* Postcondition: I have been initialized:
* lower-left == (-4.0, -4.0);
* upper-right == (4.0, 4.0).
*/
public PlotPanel() {
this(-4.0, -4.0, 4.0, 4.0);
}
/** Explicit coordinate constructor
* Receive: minX, minY, maxX, maxY, four double values.
* Postcondition: I have been initialized:
* lower-left == (minX, minY);
* upper-right == (maxX, maxY).
*/
public PlotPanel(double minX, double minY, double maxX, double maxY) {
xMin = minX;
yMin = minY;
xMax = maxX;
yMax = maxY;
myXRange = xMax - xMin;
myYRange = yMax - yMin;
mySizeFactor = 400;
int width, height;
if (myXRange < myYRange) {
width = round(mySizeFactor * myXRange / myYRange) + 2
* AXIS_MARGIN;
height = mySizeFactor + 2 * AXIS_MARGIN;
} else {
width = mySizeFactor + 2 * AXIS_MARGIN;
height = round(mySizeFactor * myYRange / myXRange) + 2
* AXIS_MARGIN;
}
setSize(width, height);
setPreferredSize(new Dimension(width, height));
setMaximumSize(new Dimension(width, height));
setBackground(Color.WHITE);
setSizeDependentAttributes();
myFont = new Font("Serif", Font.PLAIN, 12);
setFont(myFont);
myFontMetrics = getFontMetrics(myFont);
myFormatter.setMaximumFractionDigits(3);
myFormatter.setMinimumFractionDigits(0);
// myFormatter.setPositivePrefix("+");
myPointList = new ArrayList<Point>();
myLineList = new ArrayList<Line>();
myOvalList = new ArrayList<Oval>();
}
/** Utility to initialize size-dependent attributes
* Precondition: I have a height accessible via getHeight(),
* and a width accessible via getWidth().
* Postcondition: My size-dependent attributes:
* myRows, myLastRow, myColumns, myColumnsPerX,
* myRowsPerY, xInterval, and yInterval
* have been initialized.
*/
private void setSizeDependentAttributes() {
myRows = getHeight() - 2 * AXIS_MARGIN; // - TITLE_ROWS;
myLastRow = myRows - 1;
myColumns = getWidth() - 2 * AXIS_MARGIN;
xInterval = computeInterval(xMin, xMax);
yInterval = computeInterval(yMin, yMax);
}
private double computeInterval(double min, double max) {
double range = Math.abs(max - min);
if (range < .0002) {
return 0.00001;
} else if (range < .002) {
return 0.0001;
} else if (range < .02) {
return 0.001;
} else if (range < .2) {
return 0.01;
} else if (range < 2) {
return 0.1;
} else if (range < 20) {
return 1.0;
} else if (range < 200) {
return 10.0;
} else if (range < 2000) {
return 100.0;
} else if (range < 20000){
return 1000.0;
} else {
return 10000.0;
}
}
/** Plot one point
* @param x, a double
* @param y, a double
* Postcondition: (x,y) is the last point in myPointList
*/
public void plotPoint(double x, double y) {
myPointList.add(new Point(xToColumn(x), yToRow(y),
myPenColor));
repaint();
}
public void drawLine(double x1, double y1, double x2, double y2) {
myLineList.add( new Line(xToColumn(x1), yToRow(y1),
xToColumn(x2), yToRow(y2),
myPenColor) );
repaint();
}
public void drawOval(double xCenter, double yCenter,
double width, double height) {
myOvalList.add(new Oval(xToColumn(xCenter - width/2),
yToRow(yCenter + height/2),
(int) (width/deltaX()),
(int) (height/deltaY()),
myPenColor) );
repaint();
}
/** Map x-value to a grid column
* @param x, a double
* @return the grid column corresponding to x.
*/
private int xToColumn(double x) {
return AXIS_MARGIN + round((x - xMin) * myColumns / myXRange);
}
/** Map y-value to a grid row
* @param y, a double
* @return the grid row corresponding to y.
*/
private int yToRow(double y) {
return AXIS_MARGIN + myLastRow
- round((y - yMin) * myRows / myYRange);
}
/** Get x-value corresponding to 1 grid column
* @return the change in x per column.
*/
public double deltaX() {
return myXRange / myRows;
}
/** Get y-value corresponding to 1 grid row
* @return the change in y per row.
*/
public double deltaY() {
return myYRange / myColumns;
}
/** Minimum x-value accessor
* @return my minimum x-value
*/
public double minX() {
return xMin;
}
/** Minimum y-value accessor
* @return my minimum y-value
*/
public double minY() {
return yMin;
}
/** Maximum x-value accessor
* @return my maximum x-value
*/
public double maxX() {
return xMax;
}
/** Maximum y-value accessor
* @return my maximum y-value
*/
public double maxY() {
return yMax;
}
/** Method to draw my axes and points
* @param pen, a Graphics object.
* Postcondition: I have been drawn, showing axes and points
*/
public void paintComponent(Graphics pen) {
super.paintComponent(pen);
int rows = getHeight() - 2 * AXIS_MARGIN, // - TITLE_ROWS,
columns = getWidth() - 2 * AXIS_MARGIN;
if (rows < columns)
mySizeFactor = round(mySizeFactor * (double) rows / myRows);
else
mySizeFactor = round(mySizeFactor * (double) columns
/ myColumns);
if (myXRange < myYRange)
setSize(round(mySizeFactor * myXRange / myYRange) + 2
* AXIS_MARGIN, mySizeFactor + 2 * AXIS_MARGIN);
else
setSize(mySizeFactor + 2 * AXIS_MARGIN, round(mySizeFactor
* myYRange / myXRange)
+ 2 * AXIS_MARGIN);
setSizeDependentAttributes();
drawAxes(pen);
plotData(pen);
}
private void plotData(Graphics pen) {
// draw the currently-known points
for (int i = 0; i < myPointList.size(); i++) {
Point p = myPointList.get(i);
pen.setColor( p.getColor() );
pen.fillOval(p.getX(), p.getY(), 5, 5);
}
// draw the currently-known lines
for (int i = 0; i < myLineList.size(); i++) {
Line l = myLineList.get(i);
pen.setColor( l.getColor() );
pen.drawLine(l.getX1(), l.getY1(), l.getX2(), l.getY2() );
}
// draw the currently-known ovals
for (int i = 0; i < myOvalList.size(); i++) {
Oval o = myOvalList.get(i);
pen.setColor( o.getColor() );
pen.drawOval( o.getX(), o.getY(), o.getWidth(), o.getHeight() );
}
}
private void drawAxes(Graphics pen) {
if (showAxes) {
pen.setColor(Color.BLACK);
drawXAxis(pen);
drawYAxis(pen);
}
}
private void drawYAxis(Graphics pen) {
if (xMin >= 0 || xMax <= 0) { // origin not visible,
drawYAxisAtLeftEdge(pen); // plot at left edge
} else { // origin visible
drawYAxisAtOrigin(pen); // plot at origin
}
}
private void drawYAxisAtLeftEdge(Graphics pen) {
pen.drawLine(xToColumn(xMin), yToRow(yMin), // y-axis
xToColumn(xMin), yToRow(yMax));
// draw y-axis interval marks
for (double y = yMin; y < yMax; y += yInterval) {
pen.drawLine(xToColumn(xMin) - 5, yToRow(y),
xToColumn(xMin) + 5, yToRow(y));
}
// draw mark for and label xMax
drawYAxisLabelsAt(xMin, pen);
}
private void drawYAxisAtOrigin(Graphics pen) {
pen.drawLine(xToColumn(0), yToRow(yMin), // y-axis
xToColumn(0), yToRow(yMax));
// draw y-axis interval marks
for (double y = 0; y < yMax; y += yInterval) {
pen.drawLine(xToColumn(0) - 5, yToRow(y),
xToColumn(0) + 5, yToRow(y));
}
for (double y = 0; y > yMin; y -= yInterval) {
pen.drawLine(xToColumn(0) - 5, yToRow(y),
xToColumn(0) + 5, yToRow(y));
}
// draw mark for and label xMax
drawYAxisLabelsAt(0, pen);
}
private void drawYAxisLabelsAt(double xPosition, Graphics pen) {
pen.drawLine(xToColumn(xPosition) - 10, yToRow(yMax),
xToColumn(xPosition) + 10, yToRow(yMax));
String yMaxLabel = myFormatter.format(yMax);
int labelWidth = myFontMetrics.stringWidth(yMaxLabel);
int thirdHeight = myFontMetrics.getHeight() / 3;
int labelXPosition = xToColumn(xPosition) - (labelWidth+15);
pen.drawString(yMaxLabel, labelXPosition, yToRow(yMax)+ thirdHeight);
// draw mark for and label xMin
pen.drawLine(xToColumn(xPosition) - 10, yToRow(yMin),
xToColumn(xPosition) + 10, yToRow(yMin));
String yMinLabel = myFormatter.format(yMin);
labelWidth = myFontMetrics.stringWidth(yMinLabel);
pen.drawString(yMinLabel, labelXPosition, yToRow(yMin) + thirdHeight);
}
private void drawXAxis(Graphics pen) {
if (yMin >= 0 || yMax <= 0) { // origin not visible, plot at bottom edge
drawXAxisAtBottom(pen);
} else { // origin visible, plot at y = 0
drawXAxisAtOrigin(pen);
}
}
private void drawXAxisAtBottom(Graphics pen) {
pen.drawLine(xToColumn(xMin), yToRow(yMin),
xToColumn(xMax), yToRow(yMin));
// draw x-axis interval marks
for (double x = xMin; x < xMax; x += xInterval) {
pen.drawLine(xToColumn(x), yToRow(yMin) + 5,
xToColumn(x), yToRow(yMin) - 5);
}
drawXLabelsAt(yMin, pen);
}
private void drawXLabelsAt(double yPosition, Graphics pen) {
// draw mark for and label xMax
pen.drawLine(xToColumn(xMax), yToRow(yPosition) + 10,
xToColumn(xMax), yToRow(yPosition) - 10);
String xMaxLabel = myFormatter.format(xMax);
int labelWidth = myFontMetrics.stringWidth(xMaxLabel);
int halfWidth = labelWidth / 2;
int labelYPosition = yToRow(yPosition) + 25;
pen.drawString(xMaxLabel, xToColumn(xMax) - halfWidth, labelYPosition);
// draw mark for and label xMin
pen.drawLine(xToColumn(xMin), yToRow(yPosition) + 10,
xToColumn(xMin), yToRow(yPosition) - 10);
String xMinLabel = myFormatter.format(xMin);
labelWidth = myFontMetrics.stringWidth(xMinLabel);
halfWidth = labelWidth / 2;
pen.drawString(xMinLabel, xToColumn(xMin) - halfWidth, labelYPosition);
}
private void drawXAxisAtOrigin(Graphics pen) {
pen.drawLine(xToColumn(xMin), yToRow(0),
xToColumn(xMax), yToRow(0));
// draw positive x-axis interval marks
for (double x = 0; x < xMax; x += xInterval) {
pen.drawLine(xToColumn(x), yToRow(0) + 5,
xToColumn(x), yToRow(0) - 5);
}
// draw negative x-axis interval marks
for (double x = 0; x > xMin; x -= xInterval) {
pen.drawLine(xToColumn(x), yToRow(0) + 5,
xToColumn(x), yToRow(0) - 5);
}
drawXLabelsAt(0, pen);
}
/** Method to mutate my pen/drawing color
* @param newColor, a Color value
* Postcondition: myPenColor = newColor
*/
public void setPenColor(Color newColor) {
myPenColor = newColor;
}
/** Accessor to retrieve my current pen/drawing color
* @return myPenColor
*/
public Color getPenColor() {
return myPenColor;
}
public void hideAxes() {
showAxes = false;
repaint();
}
public void showAxes() {
showAxes = true;
repaint();
}
// --- Attribute variables, class PlotPanel
private double xMin, yMin, // minimum axis values
xMax, yMax, // maximum axis values
xInterval, yInterval, // x/y-values btwn axis markings
myXRange, myYRange; // total range of x/y values
private int myRows, myColumns, // number of rows/columns in graph
myLastRow, // # of last row
mySizeFactor; // factor for calc-ing "size" of graph
private boolean showAxes = true; // flag for showing/hiding axes
private Color myPenColor = Color.black; // drawing color
private DecimalFormat myFormatter = new DecimalFormat(); // formatter for axis labels
private Font myFont = null;
private FontMetrics myFontMetrics = null;
private ArrayList<Point> myPointList = null; // points to draw
private ArrayList<Line> myLineList = null;
private ArrayList<Oval> myOvalList = null;
private static final long serialVersionUID = 80L; // provided to elim. a warning
private class Point {
public Point(int x, int y, Color newColor) {
myX = x; myY = y;
myColor = newColor;
}
public int getX() { return myX; }
public int getY() { return myY; }
public Color getColor() { return myColor; }
private int myX, myY;
private Color myColor;
}
private class Line {
public Line(int x1, int y1, int x2, int y2, Color newColor) {
myX1 = x1; myY1 = y1; myX2 = x2; myY2 = y2;
myColor = newColor;
}
public int getX1() { return myX1; }
public int getY1() { return myY1; }
public int getX2() { return myX2; }
public int getY2() { return myY2; }
public Color getColor() { return myColor; }
private int myX1, myY1, myX2, myY2;
private Color myColor;
}
}
public class Oval {
public Oval(int centerX, int centerY, int width, int height, Color color) {
myX = centerX; myY = centerY;
myWidth = width; myHeight = height;
myColor = color;
}
public int getX() { return myX; }
public int getY() { return myY; }
public int getWidth() { return myWidth; }
public int getHeight() { return myHeight; }
public Color getColor() { return myColor; }
private int myX, myY, myWidth, myHeight;
private Color myColor;
}
// --- attribute variables, class PointPlotter
private PlotPanel myPanel = null; // the panel where I plot points
private static final long serialVersionUID = 81L; // provided to elim. a warning
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