plotboundspanel.java

一个一元曲线多项式数值演示例子

package numbercruncher.graphutils;

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

/**
 * The panel that contains the x-min, x-max, y-min, and y-max text controls
 * for the function plot bounds.
 */
class PlotBoundsPanel
    extends Panel {
  /** x-min
      label */private Label xMinLabel = new Label("Min x:");

  /** y-min
      label */private Label xMaxLabel = new Label("Max x:");

  /** x-max
      label */private Label yMinLabel = new Label("Min y:");

  /** y-max
      label */private Label yMaxLabel = new Label("Max y:");

  /** x-min
      textfield */private BoundsTextField xMinText = new BoundsTextField();

  /** x-max
      textfield */private BoundsTextField xMaxText = new BoundsTextField();

  /** y-min
      textfield */private BoundsTextField yMinText = new BoundsTextField();

  /** y-max
      textfield */private BoundsTextField yMaxText = new BoundsTextField();

  /** label font */
  private Font labelFont = new Font("Dialog", 1, 12);

  /** parent graph panel */
  GraphPanel graphPanel;

  /**
   * Constructor.
   * @param graphPanel the parent graph panel
   */
  PlotBoundsPanel(GraphPanel graphPanel) {
    this.graphPanel = graphPanel;

    // Bounds controls.
    xMinLabel.setFont(labelFont);
    xMinLabel.setAlignment(Label.RIGHT);
    xMaxLabel.setFont(labelFont);
    xMaxLabel.setAlignment(Label.RIGHT);
    yMinLabel.setFont(labelFont);
    yMinLabel.setAlignment(Label.RIGHT);
    yMaxLabel.setFont(labelFont);
    yMaxLabel.setAlignment(Label.RIGHT);

    // Bounds panel.
    setBackground(Color.lightGray);
    setLayout(new GridLayout(0, 4, 5, 2));
    add(xMinLabel);
    add(xMinText);
    add(yMinLabel);
    add(yMinText);
    add(xMaxLabel);
    add(xMaxText);
    add(yMaxLabel);
    add(yMaxText);
  }

  /**
   * Set the text fields from the plot properties.
   * @param plotProps the plot properties
   */
  void setTextFields(PlotProperties plotProps) {
    xMinText.setText(Float.toString(plotProps.getXMin()));
    xMaxText.setText(Float.toString(plotProps.getXMax()));
    yMinText.setText(Float.toString(plotProps.getYMin()));
    yMaxText.setText(Float.toString(plotProps.getYMax()));
  }

  /**
   * Update the plot properties from the text fields.
   * @param plotProps the plot properties
   */
  void updatePlotProperties(PlotProperties plotProps) {
    if (!boundsOK()) {
      return;
    }

    plotProps.update(Float.valueOf(xMinText.getText()).floatValue(),
                     Float.valueOf(xMaxText.getText()).floatValue(),
                     Float.valueOf(yMinText.getText()).floatValue(),
                     Float.valueOf(yMaxText.getText()).floatValue());
  }

  /**
   * Check the bounds.
   * @return true if bounds are OK, else return false
   */
  private boolean boundsOK() {
    BoundsTextField fields[] = {
        xMinText, xMaxText, yMinText, yMaxText};
    float values[] = new float[4];

    for (int i = 0; i < 4; ++i) {
      try {
        values[i] = Float.valueOf(fields[i].getText()).floatValue();
        fields[i].setForeground(Color.black);
      }
      catch (Exception ex) {
        fields[i].setForeground(Color.red);
        graphPanel.processUserError("Invalid number format.");
        return false;
      }
    }

    if (values[1] > values[0]) {
      fields[1].setForeground(Color.black);
    }
    else {
      fields[1].setForeground(Color.red);
      graphPanel.processUserError("Min x > Max x");
      return false;
    }

    if (values[3] > values[2]) {
      fields[3].setForeground(Color.black);
    }
    else {
      fields[3].setForeground(Color.red);
      graphPanel.processUserError("Min y > Max y");
      return false;
    }

    return true;
  }

  /**
   * The bounds text field class.
   */
  private class BoundsTextField
      extends TextField {
    /**
     * Constructor.
     */
    private BoundsTextField() {
      super(3);

      // Action (return key) handler.
      addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent ev) {
          if (boundsOK()) {
            graphPanel.plotBoundsChanged(); // callback
          }
        }
      });

      // Focus (tab key) handler.
      addFocusListener(new FocusAdapter() {
        public void focusLost(FocusEvent ev) {
          if (boundsOK()) {
            graphPanel.plotBoundsChanged(); // callback
          }
        }
      });
    }
  }
}