/* * @(#)ZoneView.java 1.17 03/12/19 * * Copyright 2004 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package javax.swing.text; import java.util.Vector; import java.awt.*; import javax.swing.event.*; /** * ZoneView is a View implementation that creates zones for which * the child views are not created or stored until they are needed * for display or model/view translations. This enables a substantial * reduction in memory consumption for situations where the model * being represented is very large, by building view objects only for * the region being actively viewed/edited. The size of the children * can be estimated in some way, or calculated asynchronously with * only the result being saved. *
* ZoneView extends BoxView to provide a box that implements * zones for it's children. The zones are special View implementations * (the children of an instance of this class) that represent only a * portion of the model that an instance of ZoneView is responsible * for. The zones don't create child views until an attempt is made * to display them. A box shaped view is well suited to this because: *
* The default behavior is controled by two properties, maxZoneSize
* and maxZonesLoaded. Setting maxZoneSize to Integer.MAX_VALUE would
* have the effect of causing only one zone to be created. This would
* effectively turn the view into an implementation of the decorator
* pattern. Setting maxZonesLoaded to a value of Integer.MAX_VALUE would
* cause zones to never be unloaded. For simplicity, zones are created on
* boundaries represented by the child elements of the element the view is
* responsible for. The zones can be any View implementation, but the
* default implementation is based upon AsyncBoxView which supports fairly
* large zones efficiently.
*
* @author Timothy Prinzing
* @version 1.17 12/19/03
* @see View
* @since 1.3
*/
public class ZoneView extends BoxView {
int maxZoneSize = 8 * 1024;
int maxZonesLoaded = 3;
Vector loadedZones;
/**
* Constructs a ZoneView.
*
* @param elem the element this view is responsible for
* @param axis either View.X_AXIS or View.Y_AXIS
*/
public ZoneView(Element elem, int axis) {
super(elem, axis);
loadedZones = new Vector();
}
/**
* Get the current maximum zone size.
*/
public int getMaximumZoneSize() {
return maxZoneSize;
}
/**
* Set the desired maximum zone size. A
* zone may get larger than this size if
* a single child view is larger than this
* size since zones are formed on child view
* boundaries.
*
* @param size the number of characters the zone
* may represent before attempting to break
* the zone into a smaller size.
*/
public void setMaximumZoneSize(int size) {
maxZoneSize = size;
}
/**
* Get the current setting of the number of zones
* allowed to be loaded at the same time.
*/
public int getMaxZonesLoaded() {
return maxZonesLoaded;
}
/**
* Sets the current setting of the number of zones
* allowed to be loaded at the same time. This will throw an
* IllegalArgumentException
if mzl
is less
* than 1.
*
* @param mzl the desired maximum number of zones
* to be actively loaded, must be greater than 0
* @exception IllegalArgumentException if mzl
is < 1
*/
public void setMaxZonesLoaded(int mzl) {
if (mzl < 1) {
throw new IllegalArgumentException("ZoneView.setMaxZonesLoaded must be greater than 0.");
}
maxZonesLoaded = mzl;
unloadOldZones();
}
/**
* Called by a zone when it gets loaded. This happens when
* an attempt is made to display or perform a model/view
* translation on a zone that was in an unloaded state.
* This is imlemented to check if the maximum number of
* zones was reached and to unload the oldest zone if so.
*
* @param zone the child view that was just loaded.
*/
protected void zoneWasLoaded(View zone) {
//System.out.println("loading: " + zone.getStartOffset() + "," + zone.getEndOffset());
loadedZones.addElement(zone);
unloadOldZones();
}
void unloadOldZones() {
while (loadedZones.size() > getMaxZonesLoaded()) {
View zone = (View) loadedZones.elementAt(0);
loadedZones.removeElementAt(0);
unloadZone(zone);
}
}
/**
* Unload a zone (Convert the zone to its memory saving state).
* The zones are expected to represent a subset of the
* child elements of the element this view is responsible for.
* Therefore, the default implementation is to simple remove
* all the children.
*
* @param zone the child view desired to be set to an
* unloaded state.
*/
protected void unloadZone(View zone) {
//System.out.println("unloading: " + zone.getStartOffset() + "," + zone.getEndOffset());
zone.removeAll();
}
/**
* Determine if a zone is in the loaded state.
* The zones are expected to represent a subset of the
* child elements of the element this view is responsible for.
* Therefore, the default implementation is to return
* true if the view has children.
*/
protected boolean isZoneLoaded(View zone) {
return (zone.getViewCount() > 0);
}
/**
* Create a view to represent a zone for the given
* range within the model (which should be within
* the range of this objects responsibility). This
* is called by the zone management logic to create
* new zones. Subclasses can provide a different
* implementation for a zone by changing this method.
*
* @param p0 the start of the desired zone. This should
* be >= getStartOffset() and < getEndOffset(). This
* value should also be < p1.
* @param p1 the end of the desired zone. This should
* be > getStartOffset() and <= getEndOffset(). This
* value should also be > p0.
*/
protected View createZone(int p0, int p1) {
Document doc = getDocument();
View zone = null;
try {
zone = new Zone(getElement(),
doc.createPosition(p0),
doc.createPosition(p1));
} catch (BadLocationException ble) {
// this should puke in some way.
throw new StateInvariantError(ble.getMessage());
}
return zone;
}
/**
* Loads all of the children to initialize the view.
* This is called by the setParent
method.
* This is reimplemented to not load any children directly
* (as they are created by the zones). This method creates
* the initial set of zones. Zones don't actually get
* populated however until an attempt is made to display
* them or to do model/view coordinate translation.
*
* @param f the view factory
*/
protected void loadChildren(ViewFactory f) {
// build the first zone.
Document doc = getDocument();
int offs0 = getStartOffset();
int offs1 = getEndOffset();
append(createZone(offs0, offs1));
handleInsert(offs0, offs1 - offs0);
}
/**
* Returns the child view index representing the given position in
* the model.
*
* @param pos the position >= 0
* @return index of the view representing the given position, or
* -1 if no view represents that position
*/
protected int getViewIndexAtPosition(int pos) {
// PENDING(prinz) this could be done as a binary
// search, and probably should be.
int n = getViewCount();
if (pos == getEndOffset()) {
return n - 1;
}
for(int i = 0; i < n; i++) {
View v = getView(i);
if(pos >= v.getStartOffset() &&
pos < v.getEndOffset()) {
return i;
}
}
return -1;
}
void handleInsert(int pos, int length) {
int index = getViewIndex(pos, Position.Bias.Forward);
View v = getView(index);
int offs0 = v.getStartOffset();
int offs1 = v.getEndOffset();
if ((offs1 - offs0) > maxZoneSize) {
splitZone(index, offs0, offs1);
}
}
void handleRemove(int pos, int length) {
// IMPLEMENT
}
/**
* Break up the zone at the given index into pieces
* of an acceptable size.
*/
void splitZone(int index, int offs0, int offs1) {
// divide the old zone into a new set of bins
Element elem = getElement();
Document doc = elem.getDocument();
Vector zones = new Vector();
int offs = offs0;
do {
offs0 = offs;
offs = Math.min(getDesiredZoneEnd(offs0), offs1);
zones.addElement(createZone(offs0, offs));
} while (offs < offs1);
View oldZone = getView(index);
View[] newZones = new View[zones.size()];
zones.copyInto(newZones);
replace(index, 1, newZones);
}
/**
* Returns the zone position to use for the
* end of a zone that starts at the given
* position. By default this returns something
* close to half the max zone size.
*/
int getDesiredZoneEnd(int pos) {
Element elem = getElement();
int index = elem.getElementIndex(pos + (maxZoneSize / 2));
Element child = elem.getElement(index);
int offs0 = child.getStartOffset();
int offs1 = child.getEndOffset();
if ((offs1 - pos) > maxZoneSize) {
if (offs0 > pos) {
return offs0;
}
}
return offs1;
}
// ---- View methods ----------------------------------------------------
/**
* The superclass behavior will try to update the child views
* which is not desired in this case, since the children are
* zones and not directly effected by the changes to the
* associated element. This is reimplemented to do nothing
* and return false.
*/
protected boolean updateChildren(DocumentEvent.ElementChange ec,
DocumentEvent e, ViewFactory f) {
return false;
}
/**
* Gives notification that something was inserted into the document
* in a location that this view is responsible for. This is largely
* delegated to the superclass, but is reimplemented to update the
* relevant zone (i.e. determine if a zone needs to be split into a
* set of 2 or more zones).
*
* @param changes the change information from the associated document
* @param a the current allocation of the view
* @param f the factory to use to rebuild if the view has children
* @see View#insertUpdate
*/
public void insertUpdate(DocumentEvent changes, Shape a, ViewFactory f) {
handleInsert(changes.getOffset(), changes.getLength());
super.insertUpdate(changes, a, f);
}
/**
* Gives notification that something was removed from the document
* in a location that this view is responsible for. This is largely
* delegated to the superclass, but is reimplemented to update the
* relevant zones (i.e. determine if zones need to be removed or
* joined with another zone).
*
* @param changes the change information from the associated document
* @param a the current allocation of the view
* @param f the factory to use to rebuild if the view has children
* @see View#removeUpdate
*/
public void removeUpdate(DocumentEvent changes, Shape a, ViewFactory f) {
handleRemove(changes.getOffset(), changes.getLength());
super.removeUpdate(changes, a, f);
}
/**
* Internally created view that has the purpose of holding
* the views that represent the children of the ZoneView
* that have been arranged in a zone.
*/
class Zone extends AsyncBoxView {
private Position start;
private Position end;
public Zone(Element elem, Position start, Position end) {
super(elem, ZoneView.this.getAxis());
this.start = start;
this.end = end;
}
/**
* Creates the child views and populates the
* zone with them. This is done by translating
* the positions to child element index locations
* and building views to those elements. If the
* zone is already loaded, this does nothing.
*/
public void load() {
if (! isLoaded()) {
setEstimatedMajorSpan(true);
Element e = getElement();
ViewFactory f = getViewFactory();
int index0 = e.getElementIndex(getStartOffset());
int index1 = e.getElementIndex(getEndOffset());
View[] added = new View[index1 - index0 + 1];
for (int i = index0; i <= index1; i++) {
added[i - index0] = f.create(e.getElement(i));
}
replace(0, 0, added);
zoneWasLoaded(this);
}
}
/**
* Removes the child views and returns to a
* state of unloaded.
*/
public void unload() {
setEstimatedMajorSpan(true);
removeAll();
}
/**
* Determines if the zone is in the loaded state
* or not.
*/
public boolean isLoaded() {
return (getViewCount() != 0);
}
/**
* This method is reimplemented to not build the children
* since the children are created when the zone is loaded
* rather then when it is placed in the view hierarchy.
* The major span is estimated at this point by building
* the first child (but not storing it), and calling
* setEstimatedMajorSpan(true) followed by setSpan for
* the major axis with the estimated span.
*/
protected void loadChildren(ViewFactory f) {
// mark the major span as estimated
setEstimatedMajorSpan(true);
// estimate the span
Element elem = getElement();
int index0 = elem.getElementIndex(getStartOffset());
int index1 = elem.getElementIndex(getEndOffset());
int nChildren = index1 - index0;
// replace this with something real
//setSpan(getMajorAxis(), nChildren * 10);
View first = f.create(elem.getElement(index0));
first.setParent(this);
float w = first.getPreferredSpan(X_AXIS);
float h = first.getPreferredSpan(Y_AXIS);
if (getMajorAxis() == X_AXIS) {
w *= nChildren;
} else {
h += nChildren;
}
setSize(w, h);
}
/**
* Publish the changes in preferences upward to the parent
* view.
*
* This is reimplemented to stop the superclass behavior * if the zone has not yet been loaded. If the zone is * unloaded for example, the last seen major span is the * best estimate and a calculated span for no children * is undesirable. */ protected void flushRequirementChanges() { if (isLoaded()) { super.flushRequirementChanges(); } } /** * Returns the child view index representing the given position in * the model. Since the zone contains a cluster of the overall * set of child elements, we can determine the index fairly * quickly from the model by subtracting the index of the * start offset from the index of the position given. * * @param pos the position >= 0 * @return index of the view representing the given position, or * -1 if no view represents that position * @since 1.3 */ public int getViewIndex(int pos, Position.Bias b) { boolean isBackward = (b == Position.Bias.Backward); pos = (isBackward) ? Math.max(0, pos - 1) : pos; Element elem = getElement(); int index1 = elem.getElementIndex(pos); int index0 = elem.getElementIndex(getStartOffset()); return index1 - index0; } protected boolean updateChildren(DocumentEvent.ElementChange ec, DocumentEvent e, ViewFactory f) { // the structure of this element changed. Element[] removedElems = ec.getChildrenRemoved(); Element[] addedElems = ec.getChildrenAdded(); Element elem = getElement(); int index0 = elem.getElementIndex(getStartOffset()); int index1 = elem.getElementIndex(getEndOffset()-1); int index = ec.getIndex(); if ((index >= index0) && (index <= index1)) { // The change is in this zone int replaceIndex = index - index0; int nadd = Math.min(index1 - index0 + 1, addedElems.length); int nremove = Math.min(index1 - index0 + 1, removedElems.length); View[] added = new View[nadd]; for (int i = 0; i < nadd; i++) { added[i] = f.create(addedElems[i]); } replace(replaceIndex, nremove, added); } return true; } // --- View methods ---------------------------------- /** * Fetches the attributes to use when rendering. This view * isn't directly responsible for an element so it returns * the outer classes attributes. */ public AttributeSet getAttributes() { return ZoneView.this.getAttributes(); } /** * Renders using the given rendering surface and area on that * surface. This is implemented to load the zone if its not * already loaded, and then perform the superclass behavior. * * @param g the rendering surface to use * @param a the allocated region to render into * @see View#paint */ public void paint(Graphics g, Shape a) { load(); super.paint(g, a); } /** * Provides a mapping from the view coordinate space to the logical * coordinate space of the model. This is implemented to first * make sure the zone is loaded before providing the superclass * behavior. * * @param x x coordinate of the view location to convert >= 0 * @param y y coordinate of the view location to convert >= 0 * @param a the allocated region to render into * @return the location within the model that best represents the * given point in the view >= 0 * @see View#viewToModel */ public int viewToModel(float x, float y, Shape a, Position.Bias[] bias) { load(); return super.viewToModel(x, y, a, bias); } /** * Provides a mapping from the document model coordinate space * to the coordinate space of the view mapped to it. This is * implemented to provide the superclass behavior after first * making sure the zone is loaded (The zone must be loaded to * make this calculation). * * @param pos the position to convert * @param a the allocated region to render into * @return the bounding box of the given position * @exception BadLocationException if the given position does not represent a * valid location in the associated document * @see View#modelToView */ public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException { load(); return super.modelToView(pos, a, b); } /** * Start of the zones range. * * @see View#getStartOffset */ public int getStartOffset() { return start.getOffset(); } /** * End of the zones range. */ public int getEndOffset() { return end.getOffset(); } /** * Gives notification that something was inserted into * the document in a location that this view is responsible for. * If the zone has been loaded, the superclass behavior is * invoked, otherwise this does nothing. * * @param e the change information from the associated document * @param a the current allocation of the view * @param f the factory to use to rebuild if the view has children * @see View#insertUpdate */ public void insertUpdate(DocumentEvent e, Shape a, ViewFactory f) { if (isLoaded()) { super.insertUpdate(e, a, f); } } /** * Gives notification that something was removed from the document * in a location that this view is responsible for. * If the zone has been loaded, the superclass behavior is * invoked, otherwise this does nothing. * * @param e the change information from the associated document * @param a the current allocation of the view * @param f the factory to use to rebuild if the view has children * @see View#removeUpdate */ public void removeUpdate(DocumentEvent e, Shape a, ViewFactory f) { if (isLoaded()) { super.removeUpdate(e, a, f); } } /** * Gives notification from the document that attributes were changed * in a location that this view is responsible for. * If the zone has been loaded, the superclass behavior is * invoked, otherwise this does nothing. * * @param e the change information from the associated document * @param a the current allocation of the view * @param f the factory to use to rebuild if the view has children * @see View#removeUpdate */ public void changedUpdate(DocumentEvent e, Shape a, ViewFactory f) { if (isLoaded()) { super.changedUpdate(e, a, f); } } } }