ScrollPane. Objects of this class are
* returned by ScrollPane methods.
*
* @since 1.4
*/
public class ScrollPaneAdjustable implements Adjustable, Serializable {
/**
* The ScrollPane this object is a scrollbar of.
* @serial
*/
private ScrollPane sp;
/**
* 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
*
* @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.
*
* @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.
*
* @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.
*
* @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 #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.
*
* @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.
*
* @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.
*/
private static final String SCROLLPANE_ONLY =
"Can be set by scrollpane only";
/**
* 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.
*/
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.
* @param sp ScrollPane
* @param l AdjustmentListener to add upon creation.
* @param orientation specifies which scrollbar this object represents,
* can be either Adjustable.HORIZONTAL
* or Adjustable.VERTICAL.
*/
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.
*/
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.
* @return the orientation of this scrollbar, either
* Adjustable.HORIZONTAL or
* Adjustable.VERTICAL
*/
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.
*/
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.
*/
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.
*/
public void setVisibleAmount(int v) {
throw new AWTError(SCROLLPANE_ONLY);
}
public int getVisibleAmount() {
return visibleAmount;
}
/**
* Sets the valueIsAdjusting 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.
*
* @return the value of the valueIsAdjusting 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. * * @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.
*
* @param v the new value of the scrollbar
* @param type the type of the scrolling operation occured
*/
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.
*
* @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.
*
* @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.
*
* @return all of this ScrollPaneAdjustable's
* AdjustmentListeners
* 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.
* @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.
*
* @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);
}
}