Custom AWT Slider

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Custom AWT Slider 

    * LabeledCostSlider.java. A numeric slider class with attached label.
    * CostSlider.java. A slider class that lets you read numeric values. Used in the LabeledCostSlider class.
    * Slider.java. A slider class: a combination of Scrollbar and TextField. Used in the CostSlider class.
    * ScrollbarPanel.java A Panel with adjustable top and bottom insets, used by the Slider class to change the thickness of the Slider.
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LabeledCostSlider.java. A numeric slider class with attached label. 
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import java.awt.*;

/** A CostSlider with a label centered above it. 
 *************
 

public class LabeledCostSlider extends Panel {
  public LabeledCostSlider(String labelString,
                           Font labelFont,
                           int minValue, int maxValue,
                           int initialValue,
                           Everest app) {
    setLayout(new BorderLayout());
    Label label = new Label(labelString, Label.CENTER);
    if (labelFont != null) {
      label.setFont(labelFont);
    }
    add(label, BorderLayout.NORTH);
    CostSlider slider = new CostSlider(minValue, 
                                       maxValue, 
                                       initialValue,
                                       app);
    add(slider, BorderLayout.CENTER);
  }
}  
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CostSlider.java. A slider class that lets you read numeric values. Used in the LabeledCostSlider class. 
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/** A Slider that takes an Everest applet as an argument,
 *  calling back to its setCostField when the slider value
 *  changes.
 *
 *******************

public class CostSlider extends Slider {
  private Everest app;

  public CostSlider(int minValue, int maxValue,
                    int initialValue, Everest app) {
    super(minValue, maxValue, initialValue);
    this.app = app;
  }

  public void doAction(int value) {
    app.setCostField(value);
  }
}
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Slider.java. A slider class: a combination of Scrollbar and TextField. Used in the CostSlider class. 
>>>>>>>>>>>>>>>>>>>>>
import java.awt.*;
import java.awt.event.*;

/** A class that combines a horizontal Scrollbar and a TextField
 *  (to the right of the Scrollbar). The TextField shows the
 *  current scrollbar value, plus, if setEditable(true) is set,
 *  it can be used to change the value as well.
 *
 ********************

public class Slider extends Panel implements ActionListener,
                                             AdjustmentListener {
  private Scrollbar scrollbar;
  private TextField textfield;
  private ScrollbarPanel scrollbarPanel;
  private int preferredWidth = 250;

  /** Construct a slider with the specified min, max and initial
   *  values. The "bubble" (thumb) size is set to 1/10th the
   *  scrollbar range.
   */

  public Slider(int minValue, int maxValue, int initialValue) {
    this(minValue, maxValue, initialValue,
         (maxValue - minValue)/10);
  }

  /** Construct a slider with the specified min, max,and initial
   *  values, plus the specified "bubble" (thumb) value. This
   *  bubbleSize should be specified in the units that min and
   *  max use, not in pixels. Thus, if min is 20 and max is 320,
   *  then a bubbleSize of 30 is 10% of the visible range.
   */

  public Slider(int minValue, int maxValue, int initialValue,
                int bubbleSize) {
    setLayout(new BorderLayout());
    maxValue = maxValue + bubbleSize;
    scrollbar = new Scrollbar(Scrollbar.HORIZONTAL,
                              initialValue, bubbleSize,
                              minValue, maxValue);
    scrollbar.addAdjustmentListener(this);
    scrollbarPanel = new ScrollbarPanel(6);
    scrollbarPanel.add(scrollbar, BorderLayout.CENTER);
    add(scrollbarPanel, BorderLayout.CENTER);
    textfield = new TextField(numDigits(maxValue) + 1);
    textfield.addActionListener(this);
    setFontSize(12);
    textfield.setEditable(false);
    setTextFieldValue();
    add(textfield, BorderLayout.EAST);
  }

  /** A place holder to override for action to be taken when
   *  scrollbar changes.
   */

  public void doAction(int value) {
  }

  /** When textfield changes, sets the scrollbar */

  public void actionPerformed(ActionEvent event) {
    String value = textfield.getText();
    int oldValue = getValue();
    try {
      setValue(Integer.parseInt(value.trim()));
    } catch(NumberFormatException nfe) {
      setValue(oldValue);
    }
  }

  /** When scrollbar changes, sets the textfield */

  public void adjustmentValueChanged(AdjustmentEvent event) {
    setTextFieldValue();
    doAction(scrollbar.getValue());
  }

  /** Returns the Scrollbar part of the Slider. */

  public Scrollbar getScrollbar() {
    return(scrollbar);
  }

  /** Returns the TextField part of the Slider */

  public TextField getTextField() {
    return(textfield);
  }

  /** Changes the preferredSize to take a minimum width, since
   *  super-tiny scrollbars are hard to manipulate.
   */

  public Dimension getPreferredSize() {
    Dimension d = super.getPreferredSize();
    d.height = textfield.getPreferredSize().height;
    d.width = Math.max(d.width, preferredWidth);
    return(d);
  }

  /** This just calls preferredSize */

  public Dimension getMinimumSize() {
    return(getPreferredSize());
  }

  /** To keep scrollbars legible, a minimum width is set. This
   *  returns the current value (default is 150).
   */

  public int getPreferredWidth() {
    return(preferredWidth);
  }

  /** To keep scrollbars legible, a minimum width is set. This
   *  sets the current value (default is 150).
   */

  public void setPreferredWidth(int preferredWidth) {
    this.preferredWidth = preferredWidth;
  }

  /** This returns the current scrollbar value */

  public int getValue() {
    return(scrollbar.getValue());
  }

  /** This assigns the scrollbar value. If it is below the
   *  minimum value or above the maximum, the value is set to
   *  the min and max value, respectively.
   */

  public void setValue(int value) {
    scrollbar.setValue(value);
    setTextFieldValue();
  }

  /** Sometimes horizontal scrollbars look odd if they are very
   *  tall. So empty top/bottom margins can be set. This returns
   *  the margin setting. The default is four.
   */

  public int getMargins() {
    return(scrollbarPanel.getMargins());
  }

  /** Sometimes horizontal scrollbars look odd if they are very
   *  tall. So empty top/bottom margins can be set. This sets
   *  the margin setting.
   */

  public void setMargins(int margins) {
    scrollbarPanel.setMargins(margins);
  }

  /** Returns the current textfield string. In most cases this
   *  is just the same as a String version of getValue, except
   *  that there may be padded blank spaces at the left.
   */

  public String getText() {
    return(textfield.getText());
  }

  /** This sets the TextField value directly. Use with extreme
   *  caution since it does not right-align or check if value
   *  is numeric.
   */

  public void setText(String text) {
    textfield.setText(text);
  }

  /** Returns the Font being used by the textfield.
   *  Courier bold 12 is the default.
   */

  public Font getFont() {
    return(textfield.getFont());
  }

  /** Changes the Font being used by the textfield. */

  public void setFont(Font textFieldFont) {
    textfield.setFont(textFieldFont);
  }

  /** The size of the current font */

  public int getFontSize() {
    return(getFont().getSize());
  }

  /** Rather than setting the whole font, you can just set the
   *  size (Monospaced bold will be used for the family/face).
   */

  public void setFontSize(int size) {
    setFont(new Font("Monospaced", Font.BOLD, size));
  }

  /** Determines if the textfield is editable. If it is, you can
   *  enter a number to change the scrollbar value. In such a
   *  case, entering a value outside the legal range results in
   *  the min or max legal value. A non-integer is ignored.
   */

  public boolean isEditable() {
    return(textfield.isEditable());
  }

  /** Determines if you can enter values directly into the
   *  textfield to change the scrollbar.
   */

  public void setEditable(boolean editable) {
    textfield.setEditable(editable);
  }

  // Sets a right-aligned textfield number.

  private void setTextFieldValue() {
    int value = scrollbar.getValue();
    int digits = numDigits(scrollbar.getMaximum());
    String valueString = padString(value, digits);
    textfield.setText(valueString);
  }

  // Repeated String concatenation is expensive, but this is
  // only used to add a small amount of padding, so converting
  // to a StringBuffer would not pay off.

  private String padString(int value, int digits) {
    String result = String.valueOf(value);
    for(int i=result.length(); i>>>>>>>>>>>>>>>>>>>
ScrollbarPanel.java A Panel with adjustable top and bottom insets, used by the Slider class to change the thickness of the Slider.
>>>>>>>>>>>>>>>>>>>
import java.awt.*;

/** A Panel with adjustable top/bottom insets value.
 *  Used to hold a Scrollbar in the Slider class.
 *
 *******************

public class ScrollbarPanel extends Panel {
  private Insets insets;

  public ScrollbarPanel(int margins) {
    setLayout(new BorderLayout());
    setMargins(margins);
  }

  public Insets insets() {
    return(insets);
  }

  public int getMargins() {
    return(insets.top);
  }

  public void setMargins(int margins) {
    this.insets = new Insets(margins, 0, margins, 0);
  }
}
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