* 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: *
* 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
* @see View
* @since 1.3
*/
public class ZoneView extends BoxView {
int maxZoneSize = 8 * 1024;
int maxZonesLoaded = 3;
Vector
* 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);
}
}
}
}
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 = 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 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