JDK14/Java14源码在线阅读
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package java.awt;
import java.awt.peer.ScrollbarPeer;
import java.awt.event.*;
import java.util.EventListener;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import javax.accessibility.*;
/**
* The {@code Scrollbar} class embodies a scroll bar, a
* familiar user-interface object. A scroll bar provides a
* convenient means for allowing a user to select from a
* range of values. The following three vertical
* scroll bars could be used as slider controls to pick
* the red, green, and blue components of a color:
* <p>
* <img src="doc-files/Scrollbar-1.gif" alt="Image shows 3 vertical sliders,
* side-by-side." style="margin: 7px 10px;">
* <p>
* Each scroll bar in this example could be created with
* code similar to the following:
*
* <hr><blockquote><pre>
* redSlider=new Scrollbar(Scrollbar.VERTICAL, 0, 1, 0, 255);
* add(redSlider);
* </pre></blockquote><hr>
* <p>
* Alternatively, a scroll bar can represent a range of values. For
* example, if a scroll bar is used for scrolling through text, the
* width of the "bubble" (also called the "thumb" or "scroll box")
* can be used to represent the amount of text that is visible.
* Here is an example of a scroll bar that represents a range:
* <p>
* <img src="doc-files/Scrollbar-2.gif"
* alt="Image shows horizontal slider with starting range of 0 and ending range
* of 300. The slider thumb is labeled 60." style="margin: 7px 10px;">
* <p>
* The value range represented by the bubble in this example
* is the <em>visible amount</em>. The horizontal scroll bar
* in this example could be created with code like the following:
*
* <hr><blockquote><pre>
* ranger = new Scrollbar(Scrollbar.HORIZONTAL, 0, 60, 0, 300);
* add(ranger);
* </pre></blockquote><hr>
* <p>
* Note that the actual maximum value of the scroll bar is the
* {@code maximum} minus the {@code visible amount}.
* In the previous example, because the {@code maximum} is
* 300 and the {@code visible amount} is 60, the actual maximum
* value is 240. The range of the scrollbar track is 0 - 300.
* The left side of the bubble indicates the value of the
* scroll bar.
* <p>
* Normally, the user changes the value of the scroll bar by
* making a gesture with the mouse. For example, the user can
* drag the scroll bar's bubble up and down, or click in the
* scroll bar's unit increment or block increment areas. Keyboard
* gestures can also be mapped to the scroll bar. By convention,
* the <b>Page Up</b> and <b>Page Down</b>
* keys are equivalent to clicking in the scroll bar's block
* increment and block decrement areas.
* <p>
* When the user changes the value of the scroll bar, the scroll bar
* receives an instance of {@code AdjustmentEvent}.
* The scroll bar processes this event, passing it along to
* any registered listeners.
* <p>
* Any object that wishes to be notified of changes to the
* scroll bar's value should implement
* {@code AdjustmentListener}, an interface defined in
* the package {@code java.awt.event}.
* Listeners can be added and removed dynamically by calling
* the methods {@code addAdjustmentListener} and
* {@code removeAdjustmentListener}.
* <p>
* The {@code AdjustmentEvent} class defines five types
* of adjustment event, listed here:
*
* <ul>
* <li>{@code AdjustmentEvent.TRACK} is sent out when the
* user drags the scroll bar's bubble.
* <li>{@code AdjustmentEvent.UNIT_INCREMENT} is sent out
* when the user clicks in the left arrow of a horizontal scroll
* bar, or the top arrow of a vertical scroll bar, or makes the
* equivalent gesture from the keyboard.
* <li>{@code AdjustmentEvent.UNIT_DECREMENT} is sent out
* when the user clicks in the right arrow of a horizontal scroll
* bar, or the bottom arrow of a vertical scroll bar, or makes the
* equivalent gesture from the keyboard.
* <li>{@code AdjustmentEvent.BLOCK_INCREMENT} is sent out
* when the user clicks in the track, to the left of the bubble
* on a horizontal scroll bar, or above the bubble on a vertical
* scroll bar. By convention, the <b>Page Up</b>
* key is equivalent, if the user is using a keyboard that
* defines a <b>Page Up</b> key.
* <li>{@code AdjustmentEvent.BLOCK_DECREMENT} is sent out
* when the user clicks in the track, to the right of the bubble
* on a horizontal scroll bar, or below the bubble on a vertical
* scroll bar. By convention, the <b>Page Down</b>
* key is equivalent, if the user is using a keyboard that
* defines a <b>Page Down</b> key.
* </ul>
* <p>
* The JDK 1.0 event system is supported for backwards
* compatibility, but its use with newer versions of the platform is
* discouraged. The five types of adjustment events introduced
* with JDK 1.1 correspond to the five event types
* that are associated with scroll bars in previous platform versions.
* The following list gives the adjustment event type,
* and the corresponding JDK 1.0 event type it replaces.
*
* <ul>
* <li>{@code AdjustmentEvent.TRACK} replaces
* {@code Event.SCROLL_ABSOLUTE}
* <li>{@code AdjustmentEvent.UNIT_INCREMENT} replaces
* {@code Event.SCROLL_LINE_UP}
* <li>{@code AdjustmentEvent.UNIT_DECREMENT} replaces
* {@code Event.SCROLL_LINE_DOWN}
* <li>{@code AdjustmentEvent.BLOCK_INCREMENT} replaces
* {@code Event.SCROLL_PAGE_UP}
* <li>{@code AdjustmentEvent.BLOCK_DECREMENT} replaces
* {@code Event.SCROLL_PAGE_DOWN}
* </ul>
* <p>
* <b>Note</b>: We recommend using a {@code Scrollbar}
* for value selection only. If you want to implement
* a scrollable component inside a container, we recommend you use
* a {@link ScrollPane ScrollPane}. If you use a
* {@code Scrollbar} for this purpose, you are likely to
* encounter issues with painting, key handling, sizing and
* positioning.
*
* @author Sami Shaio
* @see java.awt.event.AdjustmentEvent
* @see java.awt.event.AdjustmentListener
* @since 1.0
*/
public class Scrollbar extends Component implements Adjustable, Accessible {
/**
* A constant that indicates a horizontal scroll bar.
*/
public static final int HORIZONTAL = 0;
/**
* A constant that indicates a vertical scroll bar.
*/
public static final int VERTICAL = 1;
/**
* The value of the {@code Scrollbar}.
* This property must be greater than or equal to {@code minimum}
* and less than or equal to
* {@code maximum - visibleAmount}
*
* @serial
* @see #getValue
* @see #setValue
*/
int value;
/**
* The maximum value of the {@code Scrollbar}.
* This value must be greater than the {@code minimum}
* value.<br>
*
* @serial
* @see #getMaximum
* @see #setMaximum
*/
int maximum;
/**
* The minimum value of the {@code Scrollbar}.
* This value must be less than the {@code maximum}
* value.<br>
*
* @serial
* @see #getMinimum
* @see #setMinimum
*/
int minimum;
/**
* The size of the {@code Scrollbar}'s bubble.
* When a scroll bar is used to select a range of values,
* the visibleAmount represents the size of this range.
* Depending on platform, this may be visually indicated
* by the size of the bubble.
*
* @serial
* @see #getVisibleAmount
* @see #setVisibleAmount
*/
int visibleAmount;
/**
* The {@code Scrollbar}'s orientation--being either horizontal
* or vertical.
* This value should be specified when the scrollbar is created.<BR>
* orientation can be either : {@code VERTICAL} or
* {@code HORIZONTAL} only.
*
* @serial
* @see #getOrientation
* @see #setOrientation
*/
int orientation;
/**
* The amount by which the scrollbar value will change when going
* up or down by a line.
* This value must be greater than zero.
*
* @serial
* @see #getLineIncrement
* @see #setLineIncrement
*/
int lineIncrement = 1;
/**
* The amount by which the scrollbar value will change when going
* up or down by a page.
* This value must be greater than zero.
*
* @serial
* @see #getPageIncrement
* @see #setPageIncrement
*/
int pageIncrement = 10;
/**
* The adjusting status of the {@code Scrollbar}.
* 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
*/
transient boolean isAdjusting;
transient AdjustmentListener adjustmentListener;
private static final String base = "scrollbar";
private static int nameCounter = 0;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = 8451667562882310543L;
/**
* Initialize JNI field and method IDs.
*/
private static native void initIDs();
static {
/* ensure that the necessary native libraries are loaded */
Toolkit.loadLibraries();
if (!GraphicsEnvironment.isHeadless()) {
initIDs();
}
}
/**
* Constructs a new vertical scroll bar.
* The default properties of the scroll bar are listed in
* the following table:
*
* <table class="striped">
* <caption>Scrollbar default properties</caption>
* <thead>
* <tr>
* <th scope="col">Property
* <th scope="col">Description
* <th scope="col">Default Value
* </thead>
* <tbody>
* <tr>
* <th scope="row">orientation
* <td>indicates whether the scroll bar is vertical or horizontal
* <td>{@code Scrollbar.VERTICAL}
* <tr>
* <th scope="row">value
* <td>value which controls the location of the scroll bar's bubble
* <td>0
* <tr>
* <th scope="row">visible amount
* <td>visible amount of the scroll bar's range, typically represented
* by the size of the scroll bar's bubble
* <td>10
* <tr>
* <th scope="row">minimum
* <td>minimum value of the scroll bar
* <td>0
* <tr>
* <th scope="row">maximum
* <td>maximum value of the scroll bar
* <td>100
* <tr>
* <th scope="row">unit increment
* <td>amount the value changes when the Line Up or Line Down key is
* pressed, or when the end arrows of the scrollbar are clicked
* <td>1
* <tr>
* <th scope="row">block increment
* <td>amount the value changes when the Page Up or Page Down key is
* pressed, or when the scrollbar track is clicked<br>on either side of
* the bubble
* <td>10
* </tbody>
* </table>
*
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public Scrollbar() throws HeadlessException {
this(VERTICAL, 0, 10, 0, 100);
}
/**
* Constructs a new scroll bar with the specified orientation.
* <p>
* The {@code orientation} argument must take one of the two
* values {@code Scrollbar.HORIZONTAL},
* or {@code Scrollbar.VERTICAL},
* indicating a horizontal or vertical scroll bar, respectively.
*
* @param orientation indicates the orientation of the scroll bar
* @exception IllegalArgumentException when an illegal value for
* the {@code orientation} argument is supplied
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public Scrollbar(int orientation) throws HeadlessException {
this(orientation, 0, 10, 0, 100);
}
/**
* Constructs a new scroll bar with the specified orientation,
* initial value, visible amount, and minimum and maximum values.
* <p>
* The {@code orientation} argument must take one of the two
* values {@code Scrollbar.HORIZONTAL},
* or {@code Scrollbar.VERTICAL},
* indicating a horizontal or vertical scroll bar, respectively.
* <p>
* The parameters supplied to this constructor are subject to the
* constraints described in {@link #setValues(int, int, int, int)}.
*
* @param orientation indicates the orientation of the scroll bar.
* @param value the initial value of the scroll bar
* @param visible the visible amount of the scroll bar, typically
* represented by the size of the bubble
* @param minimum the minimum value of the scroll bar
* @param maximum the maximum value of the scroll bar
* @exception IllegalArgumentException when an illegal value for
* the {@code orientation} argument is supplied
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see #setValues
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public Scrollbar(int orientation, int value, int visible, int minimum,
int maximum) throws HeadlessException {
GraphicsEnvironment.checkHeadless();
switch (orientation) {
case HORIZONTAL:
case VERTICAL:
this.orientation = orientation;
break;
default:
throw new IllegalArgumentException("illegal scrollbar orientation");
}
setValues(value, visible, minimum, maximum);
}
/**
* Constructs a name for this component. Called by {@code getName}
* when the name is {@code null}.
*/
String constructComponentName() {
synchronized (Scrollbar.class) {
return base + nameCounter++;
}
}
/**
* Creates the {@code Scrollbar}'s peer. The peer allows you to modify
* the appearance of the {@code Scrollbar} without changing any of its
* functionality.
*/
public void addNotify() {
synchronized (getTreeLock()) {
if (peer == null)
peer = getComponentFactory().createScrollbar(this);
super.addNotify();
}
}
/**
* Returns the orientation of this scroll bar.
*
* @return the orientation of this scroll bar, either
* {@code Scrollbar.HORIZONTAL} or
* {@code Scrollbar.VERTICAL}
* @see java.awt.Scrollbar#setOrientation
*/
public int getOrientation() {
return orientation;
}
/**
* Sets the orientation for this scroll bar.
*
* @param orientation the orientation of this scroll bar, either
* {@code Scrollbar.HORIZONTAL} or
* {@code Scrollbar.VERTICAL}
* @see java.awt.Scrollbar#getOrientation
* @exception IllegalArgumentException if the value supplied
* for {@code orientation} is not a
* legal value
* @since 1.1
*/
public void setOrientation(int orientation) {
synchronized (getTreeLock()) {
if (orientation == this.orientation) {
return;
}
switch (orientation) {
case HORIZONTAL:
case VERTICAL:
this.orientation = orientation;
break;
default:
throw new IllegalArgumentException("illegal scrollbar orientation");
}
/* Create a new peer with the specified orientation. */
if (peer != null) {
removeNotify();
addNotify();
invalidate();
}
}
if (accessibleContext != null) {
accessibleContext.firePropertyChange(
AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
((orientation == VERTICAL)
? AccessibleState.HORIZONTAL : AccessibleState.VERTICAL),
((orientation == VERTICAL)
? AccessibleState.VERTICAL : AccessibleState.HORIZONTAL));
}
}
/**
* Gets the current value of this scroll bar.
*
* @return the current value of this scroll bar
* @see java.awt.Scrollbar#getMinimum
* @see java.awt.Scrollbar#getMaximum
*/
public int getValue() {
return value;
}
/**
* Sets the value of this scroll bar to the specified value.
* <p>
* If the value supplied is less than the current {@code minimum}
* or greater than the current {@code maximum - visibleAmount},
* then either {@code minimum} or {@code maximum - visibleAmount}
* is substituted, as appropriate.
* <p>
* Normally, a program should change a scroll bar's
* value only by calling {@code setValues}.
* The {@code setValues} method simultaneously
* and synchronously sets the minimum, maximum, visible amount,
* and value properties of a scroll bar, so that they are
* mutually consistent.
* <p>
* Calling this method does not fire an
* {@code AdjustmentEvent}.
*
* @param newValue the new value of the scroll bar
* @see java.awt.Scrollbar#setValues
* @see java.awt.Scrollbar#getValue
* @see java.awt.Scrollbar#getMinimum
* @see java.awt.Scrollbar#getMaximum
*/
public void setValue(int newValue) {
// Use setValues so that a consistent policy relating
// minimum, maximum, visible amount, and value is enforced.
setValues(newValue, visibleAmount, minimum, maximum);
}
/**
* Gets the minimum value of this scroll bar.
*
* @return the minimum value of this scroll bar
* @see java.awt.Scrollbar#getValue
* @see java.awt.Scrollbar#getMaximum
*/
public int getMinimum() {
return minimum;
}
/**
* Sets the minimum value of this scroll bar.
* <p>
* When {@code setMinimum} is called, the minimum value
* is changed, and other values (including the maximum, the
* visible amount, and the current scroll bar value)
* are changed to be consistent with the new minimum.
* <p>
* Normally, a program should change a scroll bar's minimum
* value only by calling {@code setValues}.
* The {@code setValues} method simultaneously
* and synchronously sets the minimum, maximum, visible amount,
* and value properties of a scroll bar, so that they are
* mutually consistent.
* <p>
* Note that setting the minimum value to {@code Integer.MAX_VALUE}
* will result in the new minimum value being set to
* {@code Integer.MAX_VALUE - 1}.
*
* @param newMinimum the new minimum value for this scroll bar
* @see java.awt.Scrollbar#setValues
* @see java.awt.Scrollbar#setMaximum
* @since 1.1
*/
public void setMinimum(int newMinimum) {
// No checks are necessary in this method since minimum is
// the first variable checked in the setValues function.
// Use setValues so that a consistent policy relating
// minimum, maximum, visible amount, and value is enforced.
setValues(value, visibleAmount, newMinimum, maximum);
}
/**
* Gets the maximum value of this scroll bar.
*
* @return the maximum value of this scroll bar
* @see java.awt.Scrollbar#getValue
* @see java.awt.Scrollbar#getMinimum
*/
public int getMaximum() {
return maximum;
}
/**
* Sets the maximum value of this scroll bar.
* <p>
* When {@code setMaximum} is called, the maximum value
* is changed, and other values (including the minimum, the
* visible amount, and the current scroll bar value)
* are changed to be consistent with the new maximum.
* <p>
* Normally, a program should change a scroll bar's maximum
* value only by calling {@code setValues}.
* The {@code setValues} method simultaneously
* and synchronously sets the minimum, maximum, visible amount,
* and value properties of a scroll bar, so that they are
* mutually consistent.
* <p>
* Note that setting the maximum value to {@code Integer.MIN_VALUE}
* will result in the new maximum value being set to
* {@code Integer.MIN_VALUE + 1}.
*
* @param newMaximum the new maximum value
* for this scroll bar
* @see java.awt.Scrollbar#setValues
* @see java.awt.Scrollbar#setMinimum
* @since 1.1
*/
public void setMaximum(int newMaximum) {
// minimum is checked first in setValues, so we need to
// enforce minimum and maximum checks here.
if (newMaximum == Integer.MIN_VALUE) {
newMaximum = Integer.MIN_VALUE + 1;
}
if (minimum >= newMaximum) {
minimum = newMaximum - 1;
}
// Use setValues so that a consistent policy relating
// minimum, maximum, visible amount, and value is enforced.
setValues(value, visibleAmount, minimum, newMaximum);
}
/**
* Gets the visible amount of this scroll bar.
* <p>
* When a scroll bar is used to select a range of values,
* the visible amount is used to represent the range of values
* that are currently visible. The size of the scroll bar's
* bubble (also called a thumb or scroll box), usually gives a
* visual representation of the relationship of the visible
* amount to the range of the scroll bar.
* Note that depending on platform, the value of the visible amount property
* may not be visually indicated by the size of the bubble.
* <p>
* The scroll bar's bubble may not be displayed when it is not
* moveable (e.g. when it takes up the entire length of the
* scroll bar's track, or when the scroll bar is disabled).
* Whether the bubble is displayed or not will not affect
* the value returned by {@code getVisibleAmount}.
*
* @return the visible amount of this scroll bar
* @see java.awt.Scrollbar#setVisibleAmount
* @since 1.1
*/
public int getVisibleAmount() {
return getVisible();
}
/**
* Returns the visible amount of this scroll bar.
*
* @return the visible amount of this scroll bar
* @deprecated As of JDK version 1.1,
* replaced by {@code getVisibleAmount()}.
*/
@Deprecated
public int getVisible() {
return visibleAmount;
}
/**
* Sets the visible amount of this scroll bar.
* <p>
* When a scroll bar is used to select a range of values,
* the visible amount is used to represent the range of values
* that are currently visible. The size of the scroll bar's
* bubble (also called a thumb or scroll box), usually gives a
* visual representation of the relationship of the visible
* amount to the range of the scroll bar.
* Note that depending on platform, the value of the visible amount property
* may not be visually indicated by the size of the bubble.
* <p>
* The scroll bar's bubble may not be displayed when it is not
* moveable (e.g. when it takes up the entire length of the
* scroll bar's track, or when the scroll bar is disabled).
* Whether the bubble is displayed or not will not affect
* the value returned by {@code getVisibleAmount}.
* <p>
* If the visible amount supplied is less than {@code one}
* or greater than the current {@code maximum - minimum},
* then either {@code one} or {@code maximum - minimum}
* is substituted, as appropriate.
* <p>
* Normally, a program should change a scroll bar's
* value only by calling {@code setValues}.
* The {@code setValues} method simultaneously
* and synchronously sets the minimum, maximum, visible amount,
* and value properties of a scroll bar, so that they are
* mutually consistent.
*
* @param newAmount the new visible amount
* @see java.awt.Scrollbar#getVisibleAmount
* @see java.awt.Scrollbar#setValues
* @since 1.1
*/
public void setVisibleAmount(int newAmount) {
// Use setValues so that a consistent policy relating
// minimum, maximum, visible amount, and value is enforced.
setValues(value, newAmount, minimum, maximum);
}
/**
* Sets the unit increment for this scroll bar.
* <p>
* The unit increment is the value that is added or subtracted
* when the user activates the unit increment area of the
* scroll bar, generally through a mouse or keyboard gesture
* that the scroll bar receives as an adjustment event.
* The unit increment must be greater than zero.
* Attempts to set the unit increment to a value lower than 1
* will result in a value of 1 being set.
* <p>
* In some operating systems, this property
* can be ignored by the underlying controls.
*
* @param v the amount by which to increment or decrement
* the scroll bar's value
* @see java.awt.Scrollbar#getUnitIncrement
* @since 1.1
*/
public void setUnitIncrement(int v) {
setLineIncrement(v);
}
/**
* Sets the unit increment for this scroll bar.
*
* @param v the increment value
*
* @deprecated As of JDK version 1.1,
* replaced by {@code setUnitIncrement(int)}.
*/
@Deprecated
public synchronized void setLineIncrement(int v) {
int tmp = (v < 1) ? 1 : v;
if (lineIncrement == tmp) {
return;
}
lineIncrement = tmp;
ScrollbarPeer peer = (ScrollbarPeer)this.peer;
if (peer != null) {
peer.setLineIncrement(lineIncrement);
}
}
/**
* Gets the unit increment for this scrollbar.
* <p>
* The unit increment is the value that is added or subtracted
* when the user activates the unit increment area of the
* scroll bar, generally through a mouse or keyboard gesture
* that the scroll bar receives as an adjustment event.
* The unit increment must be greater than zero.
* <p>
* In some operating systems, this property
* can be ignored by the underlying controls.
*
* @return the unit increment of this scroll bar
* @see java.awt.Scrollbar#setUnitIncrement
* @since 1.1
*/
public int getUnitIncrement() {
return getLineIncrement();
}
/**
* Returns the unit increment for this scrollbar.
*
* @return the unit increment for this scrollbar
* @deprecated As of JDK version 1.1,
* replaced by {@code getUnitIncrement()}.
*/
@Deprecated
public int getLineIncrement() {
return lineIncrement;
}
/**
* Sets the block increment for this scroll bar.
* <p>
* The block increment is the value that is added or subtracted
* when the user activates the block increment area of the
* scroll bar, generally through a mouse or keyboard gesture
* that the scroll bar receives as an adjustment event.
* The block increment must be greater than zero.
* Attempts to set the block increment to a value lower than 1
* will result in a value of 1 being set.
*
* @param v the amount by which to increment or decrement
* the scroll bar's value
* @see java.awt.Scrollbar#getBlockIncrement
* @since 1.1
*/
public void setBlockIncrement(int v) {
setPageIncrement(v);
}
/**
* Sets the block increment for this scroll bar.
*
* @param v the block increment
* @deprecated As of JDK version 1.1,
* replaced by {@code setBlockIncrement()}.
*/
@Deprecated
public synchronized void setPageIncrement(int v) {
int tmp = (v < 1) ? 1 : v;
if (pageIncrement == tmp) {
return;
}
pageIncrement = tmp;
ScrollbarPeer peer = (ScrollbarPeer)this.peer;
if (peer != null) {
peer.setPageIncrement(pageIncrement);
}
}
/**
* Gets the block increment of this scroll bar.
* <p>
* The block increment is the value that is added or subtracted
* when the user activates the block increment area of the
* scroll bar, generally through a mouse or keyboard gesture
* that the scroll bar receives as an adjustment event.
* The block increment must be greater than zero.
*
* @return the block increment of this scroll bar
* @see java.awt.Scrollbar#setBlockIncrement
* @since 1.1
*/
public int getBlockIncrement() {
return getPageIncrement();
}
/**
* Returns the block increment of this scroll bar.
*
* @return the block increment of this scroll bar
*
* @deprecated As of JDK version 1.1,
* replaced by {@code getBlockIncrement()}.
*/
@Deprecated
public int getPageIncrement() {
return pageIncrement;
}
/**
* Sets the values of four properties for this scroll bar:
* {@code value}, {@code visibleAmount},
* {@code minimum}, and {@code maximum}.
* If the values supplied for these properties are inconsistent
* or incorrect, they will be changed to ensure consistency.
* <p>
* This method simultaneously and synchronously sets the values
* of four scroll bar properties, assuring that the values of
* these properties are mutually consistent. It enforces the
* following constraints:
* {@code maximum} must be greater than {@code minimum},
* {@code maximum - minimum} must not be greater
* than {@code Integer.MAX_VALUE},
* {@code visibleAmount} must be greater than zero.
* {@code visibleAmount} must not be greater than
* {@code maximum - minimum},
* {@code value} must not be less than {@code minimum},
* and {@code value} must not be greater than
* {@code maximum - visibleAmount}
* <p>
* Calling this method does not fire an
* {@code AdjustmentEvent}.
*
* @param value is the position in the current window
* @param visible is the visible amount of the scroll bar
* @param minimum is the minimum value of the scroll bar
* @param maximum is the maximum value of the scroll bar
* @see #setMinimum
* @see #setMaximum
* @see #setVisibleAmount
* @see #setValue
*/
public void setValues(int value, int visible, int minimum, int maximum) {
int oldValue;
synchronized (this) {
if (minimum == Integer.MAX_VALUE) {
minimum = Integer.MAX_VALUE - 1;
}
if (maximum <= minimum) {
maximum = minimum + 1;
}
long maxMinusMin = (long) maximum - (long) minimum;
if (maxMinusMin > Integer.MAX_VALUE) {
maxMinusMin = Integer.MAX_VALUE;
maximum = minimum + (int) maxMinusMin;
}
if (visible > (int) maxMinusMin) {
visible = (int) maxMinusMin;
}
if (visible < 1) {
visible = 1;
}
if (value < minimum) {
value = minimum;
}
if (value > maximum - visible) {
value = maximum - visible;
}
oldValue = this.value;
this.value = value;
this.visibleAmount = visible;
this.minimum = minimum;
this.maximum = maximum;
ScrollbarPeer peer = (ScrollbarPeer)this.peer;
if (peer != null) {
peer.setValues(value, visibleAmount, minimum, maximum);
}
}
if ((oldValue != value) && (accessibleContext != null)) {
accessibleContext.firePropertyChange(
AccessibleContext.ACCESSIBLE_VALUE_PROPERTY,
Integer.valueOf(oldValue),
Integer.valueOf(value));
}
}
/**
* 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} property
* @see #setValueIsAdjusting
* @since 1.4
*/
public boolean getValueIsAdjusting() {
return isAdjusting;
}
/**
* Sets the {@code valueIsAdjusting} property.
*
* @param b new adjustment-in-progress status
* @see #getValueIsAdjusting
* @since 1.4
*/
public void setValueIsAdjusting(boolean b) {
boolean oldValue;
synchronized (this) {
oldValue = isAdjusting;
isAdjusting = b;
}
if ((oldValue != b) && (accessibleContext != null)) {
accessibleContext.firePropertyChange(
AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
((oldValue) ? AccessibleState.BUSY : null),
((b) ? AccessibleState.BUSY : null));
}
}
/**
* Adds the specified adjustment listener to receive instances of
* {@code AdjustmentEvent} from this scroll bar.
* If l is {@code null}, 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.AdjustmentEvent
* @see java.awt.event.AdjustmentListener
* @since 1.1
*/
public synchronized void addAdjustmentListener(AdjustmentListener l) {
if (l == null) {
return;
}
adjustmentListener = AWTEventMulticaster.add(adjustmentListener, l);
newEventsOnly = true;
}
/**
* Removes the specified adjustment listener so that it no longer
* receives instances of {@code AdjustmentEvent} from this scroll bar.
* If l is {@code null}, 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.AdjustmentEvent
* @see java.awt.event.AdjustmentListener
* @since 1.1
*/
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 scrollbar.
*
* @return all of this scrollbar's {@code AdjustmentListener}s
* or an empty array if no adjustment
* listeners are currently registered
* @see #addAdjustmentListener
* @see #removeAdjustmentListener
* @see java.awt.event.AdjustmentEvent
* @see java.awt.event.AdjustmentListener
* @since 1.4
*/
public synchronized AdjustmentListener[] getAdjustmentListeners() {
return getListeners(AdjustmentListener.class);
}
/**
* Returns an array of all the objects currently registered
* as <code><em>Foo</em>Listener</code>s
* upon this {@code Scrollbar}.
* <code><em>Foo</em>Listener</code>s are registered using the
* <code>add<em>Foo</em>Listener</code> method.
* <p>
* You can specify the {@code listenerType} argument
* with a class literal, such as
* <code><em>Foo</em>Listener.class</code>.
* For example, you can query a
* {@code Scrollbar c}
* for its mouse listeners with the following code:
*
* <pre>MouseListener[] mls = (MouseListener[])(c.getListeners(MouseListener.class));</pre>
*
* If no such listeners exist, this method returns an empty array.
*
* @param listenerType the type of listeners requested; this parameter
* should specify an interface that descends from
* {@code java.util.EventListener}
* @return an array of all objects registered as
* <code><em>Foo</em>Listener</code>s on this component,
* or an empty array if no such listeners have been added
* @exception ClassCastException if {@code listenerType}
* doesn't specify a class or interface that implements
* {@code java.util.EventListener}
*
* @since 1.3
*/
public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
EventListener l = null;
if (listenerType == AdjustmentListener.class) {
l = adjustmentListener;
} else {
return super.getListeners(listenerType);
}
return AWTEventMulticaster.getListeners(l, listenerType);
}
// REMIND: remove when filtering is done at lower level
boolean eventEnabled(AWTEvent e) {
if (e.id == AdjustmentEvent.ADJUSTMENT_VALUE_CHANGED) {
if ((eventMask & AWTEvent.ADJUSTMENT_EVENT_MASK) != 0 ||
adjustmentListener != null) {
return true;
}
return false;
}
return super.eventEnabled(e);
}
/**
* Processes events on this scroll bar. If the event is an
* instance of {@code AdjustmentEvent}, it invokes the
* {@code processAdjustmentEvent} method.
* Otherwise, it invokes its superclass's
* {@code processEvent} method.
* <p>Note that if the event parameter is {@code null}
* the behavior is unspecified and may result in an
* exception.
*
* @param e the event
* @see java.awt.event.AdjustmentEvent
* @see java.awt.Scrollbar#processAdjustmentEvent
* @since 1.1
*/
protected void processEvent(AWTEvent e) {
if (e instanceof AdjustmentEvent) {
processAdjustmentEvent((AdjustmentEvent)e);
return;
}
super.processEvent(e);
}
/**
* Processes adjustment events occurring on this
* scrollbar by dispatching them to any registered
* {@code AdjustmentListener} objects.
* <p>
* This method is not called unless adjustment events are
* enabled for this component. Adjustment events are enabled
* when one of the following occurs:
* <ul>
* <li>An {@code AdjustmentListener} object is registered
* via {@code addAdjustmentListener}.
* <li>Adjustment events are enabled via {@code enableEvents}.
* </ul>
* <p>Note that if the event parameter is {@code null}
* the behavior is unspecified and may result in an
* exception.
*
* @param e the adjustment event
* @see java.awt.event.AdjustmentEvent
* @see java.awt.event.AdjustmentListener
* @see java.awt.Scrollbar#addAdjustmentListener
* @see java.awt.Component#enableEvents
* @since 1.1
*/
protected void processAdjustmentEvent(AdjustmentEvent e) {
AdjustmentListener listener = adjustmentListener;
if (listener != null) {
listener.adjustmentValueChanged(e);
}
}
/**
* Returns a string representing the state of this {@code 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}.
*
* @return the parameter string of this scroll bar
*/
protected String paramString() {
return super.paramString() +
",val=" + value +
",vis=" + visibleAmount +
",min=" + minimum +
",max=" + maximum +
((orientation == VERTICAL) ? ",vert" : ",horz") +
",isAdjusting=" + isAdjusting;
}
/* Serialization support.
*/
/**
* The scroll bar's serialized Data Version.
*
* @serial
*/
private int scrollbarSerializedDataVersion = 1;
/**
* Writes default serializable fields to stream. Writes
* a list of serializable {@code AdjustmentListeners}
* as optional data. The non-serializable listeners are
* detected and no attempt is made to serialize them.
*
* @param s the {@code ObjectOutputStream} to write
* @serialData {@code null} terminated sequence of 0
* or more pairs; the pair consists of a {@code String}
* and an {@code Object}; the {@code String} indicates
* the type of object and is one of the following:
* {@code adjustmentListenerK} indicating an
* {@code AdjustmentListener} object
*
* @see AWTEventMulticaster#save(ObjectOutputStream, String, EventListener)
* @see java.awt.Component#adjustmentListenerK
* @see #readObject(ObjectInputStream)
*/
private void writeObject(ObjectOutputStream s)
throws IOException
{
s.defaultWriteObject();
AWTEventMulticaster.save(s, adjustmentListenerK, adjustmentListener);
s.writeObject(null);
}
/**
* Reads the {@code ObjectInputStream} and if
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