01: /*
02: * The Unified Mapping Platform (JUMP) is an extensible, interactive GUI
03: * for visualizing and manipulating spatial features with geometry and attributes.
04: *
05: * Copyright (C) 2003 Vivid Solutions
06: *
07: * This program is free software; you can redistribute it and/or
08: * modify it under the terms of the GNU General Public License
09: * as published by the Free Software Foundation; either version 2
10: * of the License, or (at your option) any later version.
11: *
12: * This program is distributed in the hope that it will be useful,
13: * but WITHOUT ANY WARRANTY; without even the implied warranty of
14: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15: * GNU General Public License for more details.
16: *
17: * You should have received a copy of the GNU General Public License
18: * along with this program; if not, write to the Free Software
19: * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
20: *
21: * For more information, contact:
22: *
23: * Vivid Solutions
24: * Suite #1A
25: * 2328 Government Street
26: * Victoria BC V8T 5G5
27: * Canada
28: *
29: * (250)385-6040
30: * www.vividsolutions.com
31: */
32:
33: package com.vividsolutions.jump.workbench.ui.snap;
34:
35: import java.util.Iterator;
36:
37: import com.vividsolutions.jts.geom.Coordinate;
38: import com.vividsolutions.jts.geom.Geometry;
39: import com.vividsolutions.jts.geom.GeometryCollection;
40: import com.vividsolutions.jts.geom.GeometryFactory;
41: import com.vividsolutions.jump.geom.InteriorPointFinder;
42: import com.vividsolutions.jump.util.Blackboard;
43: import com.vividsolutions.jump.workbench.ui.LayerViewPanel;
44:
45: public class SnapToFeaturesPolicy implements SnapPolicy {
46: private Blackboard blackboard;
47:
48: public SnapToFeaturesPolicy(Blackboard blackboard) {
49: this .blackboard = blackboard;
50: }
51:
52: public SnapToFeaturesPolicy() {
53: this (new Blackboard());
54: blackboard.put(ENABLED_KEY, true);
55: }
56:
57: public static final String ENABLED_KEY = SnapToFeaturesPolicy.class
58: .getName()
59: + " - ENABLED";
60: private InteriorPointFinder interiorPointFinder = new InteriorPointFinder();
61: //On-screen features are cached. The cache is built lazily. [Jon Aquino]
62: private GeometryFactory factory = new GeometryFactory();
63:
64: public Coordinate snap(LayerViewPanel panel,
65: Coordinate originalCoordinate) {
66: if (!blackboard.get(ENABLED_KEY, false)) {
67: return null;
68: }
69: Geometry bufferedTransformedCursorLocation;
70: bufferedTransformedCursorLocation = factory.createPoint(
71: originalCoordinate).buffer(
72: SnapManager.getToleranceInPixels(blackboard)
73: / panel.getViewport().getScale());
74: for (Iterator i = VisiblePointsAndLinesCache.instance(panel)
75: .getTree().query(
76: bufferedTransformedCursorLocation
77: .getEnvelopeInternal()).iterator(); i
78: .hasNext();) {
79: Geometry candidate = (Geometry) i.next();
80: if (!(candidate instanceof GeometryCollection)) {
81: Geometry intersection = candidate
82: .intersection(bufferedTransformedCursorLocation);
83: if (intersection.isEmpty()) {
84: continue;
85: }
86: return interiorPointFinder.findPoint(intersection);
87: }
88: }
89: return null;
90: }
91: }
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