userpointpanel.java

一个一元曲线多项式数值演示例子

package numbercruncher.pointutils;

import java.awt.*;
import java.awt.event.*;

import numbercruncher.graphutils.*;

/**
 * The base panel for all demo panels that allow
 * the user to set data points with the mouse.
 */
public abstract class UserPointPanel
    extends GraphPanel {
  private static final float INIT_X_MIN = -0.5f;
  private static final float INIT_X_MAX = 11.5f;
  private static final float INIT_Y_MIN = -0.75f;
  private static final float INIT_Y_MAX = 9.5f;

  /** control panel */
  protected Panel controlPanel = new Panel();
  /** n label */
  protected Label nLabel = new Label();
  /** n text */
  protected Label nText = new Label();
  /** action button 1 */
  protected Button actionButton1 = new Button();
  /** action button 2 */
  protected Button actionButton2 = new Button();

  /** count of data points */
  protected int n;

  /** array of data point coordinates */
  private Point data[];
  /** maximum number of data points */
  private int maxPoints;
  /** true if OK to set data points */
  private boolean dotOK = true;

  /** initial plot properties */
  protected static PlotProperties plotProps =
      new PlotProperties(INIT_X_MIN, INIT_X_MAX, INIT_Y_MIN, INIT_Y_MAX);

  /**
   * Constructor.
   * @param maxPoints the maximum number of data points
   * @param nLabelText the text of the n label
   * @param actionButton1Label the label for action button 1
   * @param actionButton2Label the label for action button 2
   */
  protected UserPointPanel(int maxPoints, String nLabelText,
                           String actionButton1Label,
                           String actionButton2Label) {
    super(" ", plotProps);
    this.maxPoints = maxPoints;

    Font labelFont = getLabelFont();
    Font textFont = getTextFont();

    // Controls.
    nLabel.setFont(labelFont);
    nLabel.setAlignment(Label.RIGHT);
    nLabel.setText(nLabelText);
    nText.setFont(textFont);
    nText.setAlignment(Label.LEFT);
    nText.setText(" ");
    actionButton1.setLabel(actionButton1Label);
    actionButton2.setLabel(actionButton2Label);

    // Action button 1 handler.
    actionButton1.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent ev) {
        doButton1Action();
      }
    });

    // Action button 2 handler.
    actionButton2.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent ev) {
        doButton2Action();
      }
    });

    // Data points.
    data = new Point[maxPoints];
  }

  /**
   * Perform the dot action.  (Do nothing here.)
   * @param r the dot's row
   * @param c the dot's column
   */
  protected void doDotAction(int r, int c) {}

  /**
   * Perform the button 1 action 1.  (Do nothing here.)
   */
  protected void doButton1Action() {}

  /**
   * Perform the button 2 action 2.  (Do nothing here.)
   */
  protected void doButton2Action() {}

  /**
   * Mouse pressed on the plot:  Add an interpolation point.
   * @param ev the mouse event
   */
  public void mousePressedOnPlot(MouseEvent ev) {
    if (!dotOK()) {
      return;
    }
    if (n == maxPoints) {
      return;
    }

    int c = ev.getX();
    int r = ev.getY();

    // Record the new data point.
    data[n] = new Point(c, r);

    ++n;
    drawDots();
    nText.setText(Integer.toString(n));
    doDotAction(r, c);
  }

  /**
   * Return true if it is OK to add another data point.
   * @return true or false
   */
  public boolean dotOK() {
    return dotOK;
  }

  /**
   * Draw the data points.
   */
  protected void drawDots() {
    if (n > 0) {
      plotDots(data, n, 8, Color.red);
    }
  }

  /**
   * Reset.
   */
  protected void reset() {
    n = 0;
    dotOK = true;

    // Initialize n in the control panel.
    nText.setText(Integer.toString(n));
  }

  //------------------//
  // Method overrides //
  //------------------//

  /**
   * Notification that the plot bounds changed.
   * Redraw the panel.
   */
  public void plotBoundsChanged() {
    reset();
    draw();
  }

  /**
   * Notification that the panel was resized.  (Callback from DemoFrame.)
   */
  public void panelResized() {
    reset();
    draw();
  }

  /**
   * Notification that a user input error occurred.
   * Disable the action1 button and enable the action2 button.
   */
  protected void userErrorOccurred() {
    dotOK = false;
    actionButton1.setEnabled(false);
    actionButton2.setEnabled(true);
  }

  /**
   * Redraw the dots.
   */
  public void draw() {
    super.draw();
    drawDots();

    // Set the focus to an action button to avoid spurious
    // repaints caused by the text losing focus later.
    actionButton2.requestFocus();
  }
}