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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */
package java.awt;

import sun.awt.AWTAccessor;

import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import java.awt.peer.ScrollPanePeer;
import java.io.Serializable;



This class represents the state of a horizontal or vertical
scrollbar of a ScrollPane.  Objects of this class are
returned by ScrollPane methods.

Since:      1.4
/**
 * This class represents the state of a horizontal or vertical
 * scrollbar of a <code>ScrollPane</code>.  Objects of this class are
 * returned by <code>ScrollPane</code> methods.
 *
 * @since       1.4
 */
public class ScrollPaneAdjustable implements Adjustable, Serializable {

    
The ScrollPane this object is a scrollbar of.

@serial
/**
     * The <code>ScrollPane</code> this object is a scrollbar of.
     * @serial
     */
    private ScrollPane sp;

    
Orientation of this scrollbar.

See Also:
@serial
/**
     * Orientation of this scrollbar.
     *
     * @serial
     * @see #getOrientation
     * @see java.awt.Adjustable#HORIZONTAL
     * @see java.awt.Adjustable#VERTICAL
     */
    private int orientation;

    
The value of this scrollbar.
value should be greater than minimum
and less than maximum

See Also:
@serial
/**
     * The value of this scrollbar.
     * <code>value</code> should be greater than <code>minimum</code>
     * and less than <code>maximum</code>
     *
     * @serial
     * @see #getValue
     * @see #setValue
     */
    private int value;

    
The minimum value of this scrollbar.
This value can only be set by the ScrollPane.


ATTN: In current implementation
minimum is always 0.  This field can
only be altered via setSpan method and
ScrollPane always calls that method with
0 for the minimum.  getMinimum method
always returns 0 without checking this field.

See Also:
@serial
/**
     * The minimum value of this scrollbar.
     * This value can only be set by the <code>ScrollPane</code>.
     * <p>
     * <strong>ATTN:</strong> In current implementation
     * <code>minimum</code> is always <code>0</code>.  This field can
     * only be altered via <code>setSpan</code> method and
     * <code>ScrollPane</code> always calls that method with
     * <code>0</code> for the minimum.  <code>getMinimum</code> method
     * always returns <code>0</code> without checking this field.
     *
     * @serial
     * @see #getMinimum
     * @see #setSpan(int, int, int)
     */
    private int minimum;

    
The maximum value of this scrollbar.
This value can only be set by the ScrollPane.

See Also:
@serial
/**
     * The maximum value of this scrollbar.
     * This value can only be set by the <code>ScrollPane</code>.
     *
     * @serial
     * @see #getMaximum
     * @see #setSpan(int, int, int)
     */
    private int maximum;

    
The size of the visible portion of this scrollbar.
This value can only be set by the ScrollPane.

See Also:
@serial
/**
     * The size of the visible portion of this scrollbar.
     * This value can only be set by the <code>ScrollPane</code>.
     *
     * @serial
     * @see #getVisibleAmount
     * @see #setSpan(int, int, int)
     */
    private int visibleAmount;

    
The adjusting status of the Scrollbar.
True if the value is in the process of changing as a result of
actions being taken by the user.

See Also:
Since:1.4
/**
     * The adjusting status of the <code>Scrollbar</code>.
     * True if the value is in the process of changing as a result of
     * actions being taken by the user.
     *
     * @see #getValueIsAdjusting
     * @see #setValueIsAdjusting
     * @since 1.4
     */
    private transient boolean isAdjusting;

    
The amount by which the scrollbar value will change when going
up or down by a line.
This value should be a non negative integer.

See Also:
@serial
/**
     * The amount by which the scrollbar value will change when going
     * up or down by a line.
     * This value should be a non negative integer.
     *
     * @serial
     * @see #getUnitIncrement
     * @see #setUnitIncrement
     */
    private int unitIncrement  = 1;

    
The amount by which the scrollbar value will change when going
up or down by a page.
This value should be a non negative integer.

See Also:
@serial
/**
     * The amount by which the scrollbar value will change when going
     * up or down by a page.
     * This value should be a non negative integer.
     *
     * @serial
     * @see #getBlockIncrement
     * @see #setBlockIncrement
     */
    private int blockIncrement = 1;

    private AdjustmentListener adjustmentListener;

    
Error message for AWTError reported when one of
the public but unsupported methods is called.

/**
     * Error message for <code>AWTError</code> reported when one of
     * the public but unsupported methods is called.
     */
    private static final String SCROLLPANE_ONLY =
        "Can be set by scrollpane only";


    
Initialize JNI field and method ids.

/**
     * Initialize JNI field and method ids.
     */
    private static native void initIDs();

    static {
        Toolkit.loadLibraries();
        if (!GraphicsEnvironment.isHeadless()) {
            initIDs();
        }
        AWTAccessor.setScrollPaneAdjustableAccessor(new AWTAccessor.ScrollPaneAdjustableAccessor() {
            public void setTypedValue(final ScrollPaneAdjustable adj,
                                      final int v, final int type) {
                adj.setTypedValue(v, type);
            }
        });
    }

    
JDK 1.1 serialVersionUID.

/**
     * JDK 1.1 serialVersionUID.
     */
    private static final long serialVersionUID = -3359745691033257079L;


    
Constructs a new object to represent specified scrollabar
of the specified ScrollPane.
Only ScrollPane creates instances of this class.

Params:
  • sp –           ScrollPane
  • l –            AdjustmentListener to add upon creation.
  • orientation –  specifies which scrollbar this object represents,
                    can be either  Adjustable.HORIZONTAL
                    or Adjustable.VERTICAL.
/**
     * Constructs a new object to represent specified scrollabar
     * of the specified <code>ScrollPane</code>.
     * Only ScrollPane creates instances of this class.
     * @param sp           <code>ScrollPane</code>
     * @param l            <code>AdjustmentListener</code> to add upon creation.
     * @param orientation  specifies which scrollbar this object represents,
     *                     can be either  <code>Adjustable.HORIZONTAL</code>
     *                     or <code>Adjustable.VERTICAL</code>.
     */
    ScrollPaneAdjustable(ScrollPane sp, AdjustmentListener l, int orientation) {
        this.sp = sp;
        this.orientation = orientation;
        addAdjustmentListener(l);
    }

    
This is called by the scrollpane itself to update the
minimum, maximum and
visible values.  The scrollpane is the only one
that should be changing these since it is the source of these
values.

/**
     * This is called by the scrollpane itself to update the
     * <code>minimum</code>, <code>maximum</code> and
     * <code>visible</code> values.  The scrollpane is the only one
     * that should be changing these since it is the source of these
     * values.
     */
    void setSpan(int min, int max, int visible) {
        // adjust the values to be reasonable
        minimum = min;
        maximum = Math.max(max, minimum + 1);
        visibleAmount = Math.min(visible, maximum - minimum);
        visibleAmount = Math.max(visibleAmount, 1);
        blockIncrement = Math.max((int)(visible * .90), 1);
        setValue(value);
    }

    
Returns the orientation of this scrollbar.

Returns:   the orientation of this scrollbar, either
           Adjustable.HORIZONTAL or
           Adjustable.VERTICAL
/**
     * Returns the orientation of this scrollbar.
     * @return    the orientation of this scrollbar, either
     *            <code>Adjustable.HORIZONTAL</code> or
     *            <code>Adjustable.VERTICAL</code>
     */
    public int getOrientation() {
        return orientation;
    }

    
This method should NOT be called by user code.
This method is public for this class to properly implement
Adjustable interface.

Throws:
  • AWTError – Always throws an error when called.
/**
     * This method should <strong>NOT</strong> be called by user code.
     * This method is public for this class to properly implement
     * <code>Adjustable</code> interface.
     *
     * @throws AWTError Always throws an error when called.
     */
    public void setMinimum(int min) {
        throw new AWTError(SCROLLPANE_ONLY);
    }

    public int getMinimum() {
        // XXX: This relies on setSpan always being called with 0 for
        // the minimum (which is currently true).
        return 0;
    }

    
This method should NOT be called by user code.
This method is public for this class to properly implement
Adjustable interface.

Throws:
  • AWTError – Always throws an error when called.
/**
     * This method should <strong>NOT</strong> be called by user code.
     * This method is public for this class to properly implement
     * <code>Adjustable</code> interface.
     *
     * @throws AWTError Always throws an error when called.
     */
    public void setMaximum(int max) {
        throw new AWTError(SCROLLPANE_ONLY);
    }

    public int getMaximum() {
        return maximum;
    }

    public synchronized void setUnitIncrement(int u) {
        if (u != unitIncrement) {
            unitIncrement = u;
            if (sp.peer != null) {
                ScrollPanePeer peer = (ScrollPanePeer) sp.peer;
                peer.setUnitIncrement(this, u);
            }
        }
    }

    public int getUnitIncrement() {
        return unitIncrement;
    }

    public synchronized void setBlockIncrement(int b) {
        blockIncrement = b;
    }

    public int getBlockIncrement() {
        return blockIncrement;
    }

    
This method should NOT be called by user code.
This method is public for this class to properly implement
Adjustable interface.

Throws:
  • AWTError – Always throws an error when called.
/**
     * This method should <strong>NOT</strong> be called by user code.
     * This method is public for this class to properly implement
     * <code>Adjustable</code> interface.
     *
     * @throws AWTError Always throws an error when called.
     */
    public void setVisibleAmount(int v) {
        throw new AWTError(SCROLLPANE_ONLY);
    }

    public int getVisibleAmount() {
        return visibleAmount;
    }


    
Sets the valueIsAdjusting property.

Params:
  • b – new adjustment-in-progress status
See Also:
Since:1.4
/**
     * Sets the <code>valueIsAdjusting</code> property.
     *
     * @param b new adjustment-in-progress status
     * @see #getValueIsAdjusting
     * @since 1.4
     */
    public void setValueIsAdjusting(boolean b) {
        if (isAdjusting != b) {
            isAdjusting = b;
            AdjustmentEvent e =
                new AdjustmentEvent(this,
                        AdjustmentEvent.ADJUSTMENT_VALUE_CHANGED,
                        AdjustmentEvent.TRACK, value, b);
            adjustmentListener.adjustmentValueChanged(e);
        }
    }

    
Returns true if the value is in the process of changing as a
result of actions being taken by the user.

See Also:
Returns:the value of the valueIsAdjusting property
/**
     * Returns true if the value is in the process of changing as a
     * result of actions being taken by the user.
     *
     * @return the value of the <code>valueIsAdjusting</code> property
     * @see #setValueIsAdjusting
     */
    public boolean getValueIsAdjusting() {
        return isAdjusting;
    }

    
Sets the value of this scrollbar to the specified value.


If the value supplied is less than the current minimum or
greater than the current maximum, then one of those values is
substituted, as appropriate.

Params:
  • v – the new value of the scrollbar
/**
     * Sets the value of this scrollbar to the specified value.
     * <p>
     * If the value supplied is less than the current minimum or
     * greater than the current maximum, then one of those values is
     * substituted, as appropriate.
     *
     * @param v the new value of the scrollbar
     */
    public void setValue(int v) {
        setTypedValue(v, AdjustmentEvent.TRACK);
    }

    
Sets the value of this scrollbar to the specified value.


If the value supplied is less than the current minimum or
greater than the current maximum, then one of those values is
substituted, as appropriate. Also, creates and dispatches
the AdjustementEvent with specified type and value.

Params:
  • v – the new value of the scrollbar
  • type – the type of the scrolling operation occurred
/**
     * Sets the value of this scrollbar to the specified value.
     * <p>
     * If the value supplied is less than the current minimum or
     * greater than the current maximum, then one of those values is
     * substituted, as appropriate. Also, creates and dispatches
     * the AdjustementEvent with specified type and value.
     *
     * @param v the new value of the scrollbar
     * @param type the type of the scrolling operation occurred
     */
    private void setTypedValue(int v, int type) {
        v = Math.max(v, minimum);
        v = Math.min(v, maximum - visibleAmount);

        if (v != value) {
            value = v;
            // Synchronously notify the listeners so that they are
            // guaranteed to be up-to-date with the Adjustable before
            // it is mutated again.
            AdjustmentEvent e =
                new AdjustmentEvent(this,
                        AdjustmentEvent.ADJUSTMENT_VALUE_CHANGED,
                        type, value, isAdjusting);
            adjustmentListener.adjustmentValueChanged(e);
        }
    }

    public int getValue() {
        return value;
    }

    
Adds the specified adjustment listener to receive adjustment
events from this ScrollPaneAdjustable.
If l is null, no exception is thrown
and no action is performed.

Refer to AWT Threading Issues for details on AWT's threading model.

Params:
  • l –   the adjustment listener.
See Also:
/**
     * Adds the specified adjustment listener to receive adjustment
     * events from this <code>ScrollPaneAdjustable</code>.
     * If <code>l</code> is <code>null</code>, no exception is thrown
     * and no action is performed.
     * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
     * >AWT Threading Issues</a> for details on AWT's threading model.
     *
     * @param    l   the adjustment listener.
     * @see      #removeAdjustmentListener
     * @see      #getAdjustmentListeners
     * @see      java.awt.event.AdjustmentListener
     * @see      java.awt.event.AdjustmentEvent
     */
    public synchronized void addAdjustmentListener(AdjustmentListener l) {
        if (l == null) {
            return;
        }
        adjustmentListener = AWTEventMulticaster.add(adjustmentListener, l);
    }

    
Removes the specified adjustment listener so that it no longer
receives adjustment events from this ScrollPaneAdjustable.
If l is null, no exception is thrown
and no action is performed.

Refer to AWT Threading Issues for details on AWT's threading model.

Params:
  • l –     the adjustment listener.
See Also:
Since:        JDK1.1
/**
     * Removes the specified adjustment listener so that it no longer
     * receives adjustment events from this <code>ScrollPaneAdjustable</code>.
     * If <code>l</code> is <code>null</code>, no exception is thrown
     * and no action is performed.
     * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
     * >AWT Threading Issues</a> for details on AWT's threading model.
     *
     * @param         l     the adjustment listener.
     * @see           #addAdjustmentListener
     * @see           #getAdjustmentListeners
     * @see           java.awt.event.AdjustmentListener
     * @see           java.awt.event.AdjustmentEvent
     * @since         JDK1.1
     */
    public synchronized void removeAdjustmentListener(AdjustmentListener l){
        if (l == null) {
            return;
        }
        adjustmentListener = AWTEventMulticaster.remove(adjustmentListener, l);
    }

    
Returns an array of all the adjustment listeners
registered on this ScrollPaneAdjustable.

See Also:
Returns:all of this ScrollPaneAdjustable's
        AdjustmentListeners
        or an empty array if no adjustment
        listeners are currently registered
Since:1.4
/**
     * Returns an array of all the adjustment listeners
     * registered on this <code>ScrollPaneAdjustable</code>.
     *
     * @return all of this <code>ScrollPaneAdjustable</code>'s
     *         <code>AdjustmentListener</code>s
     *         or an empty array if no adjustment
     *         listeners are currently registered
     *
     * @see           #addAdjustmentListener
     * @see           #removeAdjustmentListener
     * @see           java.awt.event.AdjustmentListener
     * @see           java.awt.event.AdjustmentEvent
     * @since 1.4
     */
    public synchronized AdjustmentListener[] getAdjustmentListeners() {
        return (AdjustmentListener[])(AWTEventMulticaster.getListeners(
                                      adjustmentListener,
                                      AdjustmentListener.class));
    }

    
Returns a string representation of this scrollbar and its values.

Returns:   a string representation of this scrollbar.
/**
     * Returns a string representation of this scrollbar and its values.
     * @return    a string representation of this scrollbar.
     */
    public String toString() {
        return getClass().getName() + "[" + paramString() + "]";
    }

    
Returns a string representing the state of this scrollbar.
This method is intended to be used only for debugging purposes,
and the content and format of the returned string may vary
between implementations.  The returned string may be empty but
may not be null.

Returns:     the parameter string of this scrollbar.
/**
     * Returns a string representing the state of this scrollbar.
     * This method is intended to be used only for debugging purposes,
     * and the content and format of the returned string may vary
     * between implementations.  The returned string may be empty but
     * may not be <code>null</code>.
     *
     * @return      the parameter string of this scrollbar.
     */
    public String paramString() {
        return ((orientation == Adjustable.VERTICAL ? "vertical,"
                                                    :"horizontal,")
                + "[0.."+maximum+"]"
                + ",val=" + value
                + ",vis=" + visibleAmount
                + ",unit=" + unitIncrement
                + ",block=" + blockIncrement
                + ",isAdjusting=" + isAdjusting);
    }
}