/*
* Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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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.
* <p>
* ZoneView extends BoxView to provide a box that implements
* zones for its 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:
* <ul>
* <li>
* Boxes are a heavily used view, and having a box that
* provides this behavior gives substantial opportunity
* to plug the behavior into a view hierarchy from the
* view factory.
* <li>
* Boxes are tiled in one direction, so it is easy to
* divide them into zones in a reliable way.
* <li>
* Boxes typically have a simple relationship to the model (i.e. they
* create child views that directly represent the child elements).
* <li>
* Boxes are easier to estimate the size of than some other shapes.
* </ul>
* <p>
* The default behavior is controlled 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
* @see View
* @since 1.3
*/
public class
ZoneView extends
BoxView {
int
maxZoneSize = 8 * 1024;
int
maxZonesLoaded = 3;
Vector<
View>
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<
View>();
}
/**
* 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
* <code>IllegalArgumentException</code> if <code>mzl</code> is less
* than 1.
*
* @param mzl the desired maximum number of zones
* to be actively loaded, must be greater than 0
* @exception IllegalArgumentException if <code>mzl</code> 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 implemented 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 =
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;
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 <code>setParent</code> 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<
View>
zones = new
Vector<
View>();
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.
* <p>
* 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);
}
}
}
}