| /* ZoneView.java -- An effective BoxView subclass |
| Copyright (C) 2006 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package javax.swing.text; |
| |
| import java.awt.Shape; |
| import java.util.ArrayList; |
| import java.util.LinkedList; |
| |
| import javax.swing.event.DocumentEvent; |
| |
| /** |
| * A View implementation that delays loading of sub views until they are |
| * needed for display or internal transformations. This can be used for |
| * editors that need to handle large documents more effectivly than the |
| * standard {@link BoxView}. |
| * |
| * @author Roman Kennke (kennke@aicas.com) |
| * |
| * @since 1.3 |
| */ |
| public class ZoneView |
| extends BoxView |
| { |
| |
| /** |
| * The default zone view implementation. The specs suggest that this is |
| * a subclass of AsyncBoxView, so do we. |
| */ |
| static class Zone |
| extends AsyncBoxView |
| { |
| /** |
| * The start position for this zone. |
| */ |
| private Position p0; |
| |
| /** |
| * The end position for this zone. |
| */ |
| private Position p1; |
| |
| /** |
| * Creates a new Zone for the specified element, start and end positions. |
| * |
| * @param el the element |
| * @param pos0 the start position |
| * @param pos1 the end position |
| * @param axis the major axis |
| */ |
| Zone(Element el, Position pos0, Position pos1, int axis) |
| { |
| super(el, axis); |
| p0 = pos0; |
| p1 = pos1; |
| } |
| |
| /** |
| * Returns the start offset of the zone. |
| * |
| * @return the start offset of the zone |
| */ |
| public int getStartOffset() |
| { |
| return p0.getOffset(); |
| } |
| |
| /** |
| * Returns the end offset of the zone. |
| * |
| * @return the end offset of the zone |
| */ |
| public int getEndOffset() |
| { |
| return p1.getOffset(); |
| } |
| } |
| |
| /** |
| * The maximumZoneSize. |
| */ |
| private int maximumZoneSize; |
| |
| /** |
| * The maximum number of loaded zones. |
| */ |
| private int maxZonesLoaded; |
| |
| /** |
| * A queue of loaded zones. When the number of loaded zones exceeds the |
| * maximum number of zones, the oldest zone(s) get unloaded. |
| */ |
| private LinkedList loadedZones; |
| |
| /** |
| * Creates a new ZoneView for the specified element and axis. |
| * |
| * @param element the element for which to create a ZoneView |
| * @param axis the major layout axis for the box |
| */ |
| public ZoneView(Element element, int axis) |
| { |
| super(element, axis); |
| maximumZoneSize = 8192; |
| maxZonesLoaded = 3; |
| loadedZones = new LinkedList(); |
| } |
| |
| /** |
| * Sets the maximum zone size. Note that zones might still become larger |
| * then the size specified when a singe child view is larger for itself, |
| * because zones are formed on child view boundaries. |
| * |
| * @param size the maximum zone size to set |
| * |
| * @see #getMaximumZoneSize() |
| */ |
| public void setMaximumZoneSize(int size) |
| { |
| maximumZoneSize = size; |
| } |
| |
| /** |
| * Returns the maximum zone size. Note that zones might still become larger |
| * then the size specified when a singe child view is larger for itself, |
| * because zones are formed on child view boundaries. |
| * |
| * @return the maximum zone size |
| * |
| * @see #setMaximumZoneSize(int) |
| */ |
| public int getMaximumZoneSize() |
| { |
| return maximumZoneSize; |
| } |
| |
| /** |
| * Sets the maximum number of zones that are allowed to be loaded at the |
| * same time. If the new number of allowed zones is smaller then the |
| * previous settings, this unloads all zones the aren't allowed to be |
| * loaded anymore. |
| * |
| * @param num the number of zones allowed to be loaded at the same time |
| * |
| * @throws IllegalArgumentException if <code>num <= 0</code> |
| * |
| * @see #getMaxZonesLoaded() |
| */ |
| public void setMaxZonesLoaded(int num) |
| { |
| if (num < 1) |
| throw new IllegalArgumentException("Illegal number of zones"); |
| maxZonesLoaded = num; |
| unloadOldestZones(); |
| } |
| |
| /** |
| * Returns the number of zones that are allowed to be loaded. |
| * |
| * @return the number of zones that are allowed to be loaded |
| * |
| * @see #setMaxZonesLoaded(int) |
| */ |
| public int getMaxZonesLoaded() |
| { |
| return maxZonesLoaded; |
| } |
| |
| /** |
| * Gets called after a zone has been loaded. This unloads the oldest zone(s) |
| * when the maximum number of zones is reached. |
| * |
| * @param zone the zone that has been loaded |
| */ |
| protected void zoneWasLoaded(View zone) |
| { |
| loadedZones.addLast(zone); |
| unloadOldestZones(); |
| } |
| |
| /** |
| * This unloads the specified zone. This is implemented to simply remove |
| * all child views from that zone. |
| * |
| * @param zone the zone to be unloaded |
| */ |
| protected void unloadZone(View zone) |
| { |
| zone.removeAll(); |
| } |
| |
| /** |
| * Returns <code>true</code> when the specified zone is loaded, |
| * <code>false</code> otherwise. The default implementation checks if |
| * the zone view has child elements. |
| * |
| * @param zone the zone view to check |
| * |
| * @return <code>true</code> when the specified zone is loaded, |
| * <code>false</code> otherwise |
| */ |
| protected boolean isZoneLoaded(View zone) |
| { |
| return zone.getViewCount() > 0; |
| } |
| |
| /** |
| * Creates a zone for the specified range. Subclasses can override this |
| * to provide a custom implementation for the zones. |
| * |
| * @param p0 the start of the range |
| * @param p1 the end of the range |
| * |
| * @return the zone |
| */ |
| protected View createZone(int p0, int p1) |
| { |
| Document doc = getDocument(); |
| Position pos0 = null; |
| Position pos1 = null; |
| try |
| { |
| pos0 = doc.createPosition(p0); |
| pos1 = doc.createPosition(p1); |
| } |
| catch (BadLocationException ex) |
| { |
| assert false : "Must not happen"; |
| } |
| Zone zone = new Zone(getElement(), pos0, pos1, getAxis()); |
| return zone; |
| } |
| |
| // -------------------------------------------------------------------------- |
| // CompositeView methods. |
| // -------------------------------------------------------------------------- |
| |
| /** |
| * Overridden to not load all the child views. This methods creates |
| * initial zones without actually loading them. |
| * |
| * @param vf not used |
| */ |
| protected void loadChildren(ViewFactory vf) |
| { |
| int p0 = getStartOffset(); |
| int p1 = getEndOffset(); |
| append(createZone(p0, p1)); |
| checkZoneAt(p0); |
| } |
| |
| /** |
| * Returns the index of the child view at the document position |
| * <code>pos</code>. |
| * |
| * This overrides the CompositeView implementation because the ZoneView does |
| * not provide a one to one mapping from Elements to Views. |
| * |
| * @param pos the document position |
| * |
| * @return the index of the child view at the document position |
| * <code>pos</code> |
| */ |
| protected int getViewIndexAtPosition(int pos) |
| { |
| int index = -1; |
| boolean found = false; |
| if (pos >= getStartOffset() && pos <= getEndOffset()) |
| { |
| int upper = getViewCount() - 1; |
| int lower = 0; |
| index = (upper - lower) / 2 + lower; |
| int bias = 0; |
| do |
| { |
| View child = getView(index); |
| int childStart = child.getStartOffset(); |
| int childEnd = child.getEndOffset(); |
| if (pos >= childStart && pos < childEnd) |
| found = true; |
| else if (pos < childStart) |
| { |
| upper = index; |
| bias = -1; |
| } |
| else if (pos >= childEnd) |
| { |
| lower = index; |
| bias = 1; |
| } |
| if (! found) |
| { |
| int newIndex = (upper - lower) / 2 + lower; |
| if (newIndex == index) |
| index = newIndex + bias; |
| else |
| index = newIndex; |
| } |
| } while (upper != lower && ! found); |
| } |
| // If no child view actually covers the specified offset, reset index to |
| // -1. |
| if (! found) |
| index = -1; |
| return index; |
| } |
| |
| // -------------------------------------------------------------------------- |
| // View methods. |
| // -------------------------------------------------------------------------- |
| |
| public void insertUpdate(DocumentEvent e, Shape a, ViewFactory vf) |
| { |
| // TODO: Implement this. |
| } |
| |
| public void removeUpdate(DocumentEvent e, Shape a, ViewFactory vf) |
| { |
| // TODO: Implement this. |
| } |
| |
| protected boolean updateChildren(DocumentEvent.ElementChange ec, |
| DocumentEvent e, ViewFactory vf) |
| { |
| // TODO: Implement this. |
| return false; |
| } |
| |
| // -------------------------------------------------------------------------- |
| // Internal helper methods. |
| // -------------------------------------------------------------------------- |
| |
| /** |
| * A helper method to unload the oldest zones when there are more loaded |
| * zones then allowed. |
| */ |
| private void unloadOldestZones() |
| { |
| int maxZones = getMaxZonesLoaded(); |
| while (loadedZones.size() > maxZones) |
| { |
| View zone = (View) loadedZones.removeFirst(); |
| unloadZone(zone); |
| } |
| } |
| |
| /** |
| * Checks if the zone view at position <code>pos</code> should be split |
| * (its size is greater than maximumZoneSize) and tries to split it. |
| * |
| * @param pos the document position to check |
| */ |
| private void checkZoneAt(int pos) |
| { |
| int viewIndex = getViewIndexAtPosition(pos); //, Position.Bias.Forward); |
| View view = getView(viewIndex); |
| int p0 = view.getStartOffset(); |
| int p1 = view.getEndOffset(); |
| if (p1 - p0 > maximumZoneSize) |
| splitZone(viewIndex, p0, p1); |
| } |
| |
| /** |
| * Tries to break the view at the specified index and inside the specified |
| * range into pieces that are acceptable with respect to the maximum zone |
| * size. |
| * |
| * @param index the index of the view to split |
| * @param p0 the start offset |
| * @param p1 the end offset |
| */ |
| private void splitZone(int index, int p0, int p1) |
| { |
| ArrayList newZones = new ArrayList(); |
| int p = p0; |
| do |
| { |
| p0 = p; |
| p = Math.min(getPreferredZoneEnd(p0), p1); |
| newZones.add(createZone(p0, p)); |
| } while (p < p1); |
| View[] newViews = new View[newZones.size()]; |
| newViews = (View[]) newZones.toArray(newViews); |
| replace(index, 1, newViews); |
| } |
| |
| /** |
| * Calculates the positions at which a zone split is performed. This |
| * tries to create zones sized close to half the maximum zone size. |
| * |
| * @param start the start offset |
| * |
| * @return the preferred end offset |
| */ |
| private int getPreferredZoneEnd(int start) |
| { |
| Element el = getElement(); |
| int index = el.getElementIndex(start + (maximumZoneSize / 2)); |
| Element child = el.getElement(index); |
| int p0 = child.getStartOffset(); |
| int p1 = child.getEndOffset(); |
| int end = p1; |
| if (p0 - start > maximumZoneSize && p0 > start) |
| end = p0; |
| return end; |
| } |
| } |