001// License: GPL. For details, see LICENSE file.
002package org.openstreetmap.josm.data.osm.visitor.paint;
003
004import static org.openstreetmap.josm.tools.I18n.tr;
005
006import java.awt.Graphics2D;
007import java.lang.reflect.Constructor;
008import java.lang.reflect.InvocationTargetException;
009import java.text.MessageFormat;
010import java.util.ArrayList;
011import java.util.Collections;
012import java.util.Iterator;
013import java.util.List;
014
015import org.openstreetmap.josm.Main;
016import org.openstreetmap.josm.gui.NavigatableComponent;
017import org.openstreetmap.josm.plugins.PluginHandler;
018import org.openstreetmap.josm.tools.CheckParameterUtil;
019
020/**
021 * <p>MapRendererFactory manages a list of map renderer classes and associated
022 * meta data (display name, description).</p>
023 *
024 * <p>Plugins can implement and supply their own map renderers.</p>
025 * <strong>Sample code in a plugin</strong>
026 * <pre>
027 * public class MyMapRenderer extends AbstractMapRenderer {
028 *    // ....
029 * }
030 *
031 * // to be called when the plugin is created
032 * MapRendererFactory factory = MapRendererFactory.getInstance();
033 * factory.register(MyMapRenderer.class, "My map renderer", "This is is a fast map renderer");
034 * factory.activate(MyMapRenderer.class);
035 *
036 * </pre>
037 * @since 4087
038 */
039public final class MapRendererFactory {
040
041    /** preference key for the renderer class name. Default: class name for {@link StyledMapRenderer}
042     *
043     */
044    public static final String PREF_KEY_RENDERER_CLASS_NAME = "mappaint.renderer-class-name";
045
046    public static class MapRendererFactoryException extends RuntimeException {
047
048        public MapRendererFactoryException(String message, Throwable cause) {
049            super(message, cause);
050        }
051
052        public MapRendererFactoryException(String message) {
053            super(message);
054        }
055
056        public MapRendererFactoryException(Throwable cause) {
057            super(cause);
058        }
059    }
060
061    public static class Descriptor {
062        private final Class<? extends AbstractMapRenderer> renderer;
063        private final String displayName;
064        private final String description;
065
066        public Descriptor(Class<? extends AbstractMapRenderer> renderer, String displayName, String description) {
067            this.renderer = renderer;
068            this.displayName  = displayName;
069            this.description = description;
070        }
071
072        public Class<? extends AbstractMapRenderer> getRenderer() {
073            return renderer;
074        }
075
076        public String getDisplayName() {
077            return displayName;
078        }
079
080        public String getDescription() {
081            return description;
082        }
083    }
084
085    private static MapRendererFactory instance;
086
087    /**
088     * Replies the unique instance
089     * @return instance of map rending class
090     */
091    public static synchronized MapRendererFactory getInstance() {
092        if (instance == null) {
093            instance = new MapRendererFactory();
094        }
095        return instance;
096    }
097
098    private static Class<?> loadRendererClass(String className) {
099        for (ClassLoader cl : PluginHandler.getResourceClassLoaders()) {
100            try {
101                return Class.forName(className, true, cl);
102            } catch (final NoClassDefFoundError | ClassNotFoundException e) {
103                Main.trace(e.getMessage());
104            }
105        }
106        Main.error(tr("Failed to load map renderer class ''{0}''. The class wasn''t found.", className));
107        return null;
108    }
109
110    private final List<Descriptor> descriptors = new ArrayList<>();
111    private Class<? extends AbstractMapRenderer> activeRenderer;
112
113    private MapRendererFactory() {
114        registerDefaultRenderers();
115        String rendererClassName = Main.pref.get(PREF_KEY_RENDERER_CLASS_NAME, null);
116        if (rendererClassName != null) {
117            activateMapRenderer(rendererClassName);
118        } else {
119            activateDefault();
120        }
121    }
122
123    private void activateMapRenderer(String rendererClassName) {
124        Class<?> c = loadRendererClass(rendererClassName);
125        if (c == null) {
126            Main.error(tr("Can''t activate map renderer class ''{0}'', because the class wasn''t found.", rendererClassName));
127            Main.error(tr("Activating the standard map renderer instead."));
128            activateDefault();
129        } else if (!AbstractMapRenderer.class.isAssignableFrom(c)) {
130            Main.error(tr("Can''t activate map renderer class ''{0}'', because it isn''t a subclass of ''{1}''.",
131                    rendererClassName, AbstractMapRenderer.class.getName()));
132            Main.error(tr("Activating the standard map renderer instead."));
133            activateDefault();
134        } else {
135            Class<? extends AbstractMapRenderer> renderer = c.asSubclass(AbstractMapRenderer.class);
136            if (!isRegistered(renderer)) {
137                Main.error(tr("Can''t activate map renderer class ''{0}'', because it isn''t registered as map renderer.", rendererClassName));
138                Main.error(tr("Activating the standard map renderer instead."));
139                activateDefault();
140            } else {
141                activate(renderer);
142            }
143        }
144    }
145
146    private void registerDefaultRenderers() {
147        register(
148                WireframeMapRenderer.class,
149                tr("Wireframe Map Renderer"),
150                tr("Renders the map as simple wire frame.")
151        );
152        register(
153                StyledMapRenderer.class,
154                tr("Styled Map Renderer"),
155                tr("Renders the map using style rules in a set of style sheets.")
156        );
157    }
158
159    /**
160     * <p>Replies true, if {@code Renderer} is already a registered map renderer
161     * class.</p>
162     *
163     * @param renderer the map renderer class. Must not be null.
164     * @return true, if {@code Renderer} is already a registered map renderer
165     * class
166     * @throws IllegalArgumentException if {@code renderer} is null
167     */
168    public boolean isRegistered(Class<? extends AbstractMapRenderer> renderer) {
169        CheckParameterUtil.ensureParameterNotNull(renderer);
170        for (Descriptor d: descriptors) {
171            if (d.getRenderer().getName().equals(renderer.getName())) return true;
172        }
173        return false;
174    }
175
176    /**
177     * <p>Registers a map renderer class.</p>
178     *
179     * @param renderer the map renderer class. Must not be null.
180     * @param displayName the display name to be displayed in UIs (i.e. in the preference dialog)
181     * @param description the description
182     * @throws IllegalArgumentException if {@code renderer} is null
183     * @throws IllegalStateException if {@code renderer} is already registered
184     */
185    public void register(Class<? extends AbstractMapRenderer> renderer, String displayName, String description) {
186        CheckParameterUtil.ensureParameterNotNull(renderer);
187        if (isRegistered(renderer))
188            throw new IllegalStateException(
189                    // no I18n - this is a technical message
190                    MessageFormat.format("Class ''{0}'' already registered a renderer", renderer.getName())
191            );
192        Descriptor d = new Descriptor(renderer, displayName, description);
193        descriptors.add(d);
194    }
195
196
197    /**
198     * <p>Unregisters a map renderer class.</p>
199     *
200     * <p>If the respective class is also the active renderer, the renderer is reset
201     * to the default renderer.</p>
202     *
203     * @param renderer the map renderer class. Must not be null.
204     *
205     */
206    public void unregister(Class<? extends AbstractMapRenderer> renderer) {
207        if (renderer == null) return;
208        if (!isRegistered(renderer)) return;
209        Iterator<Descriptor> it = descriptors.iterator();
210        while (it.hasNext()) {
211            Descriptor d = it.next();
212            if (d.getRenderer().getName().equals(renderer.getName())) {
213                it.remove();
214                break;
215            }
216        }
217        if (activeRenderer != null && activeRenderer.getName().equals(renderer.getName())) {
218            activateDefault();
219        }
220    }
221
222    /**
223     * <p>Activates a map renderer class.</p>
224     *
225     * <p>The renderer class must already be registered.</p>
226     *
227     * @param renderer the map renderer class. Must not be null.
228     * @throws IllegalArgumentException if {@code renderer} is null
229     * @throws IllegalStateException if {@code renderer} isn't registered yet
230     */
231    public void activate(Class<? extends AbstractMapRenderer> renderer) {
232        CheckParameterUtil.ensureParameterNotNull(renderer);
233        if (!isRegistered(renderer))
234            throw new IllegalStateException(
235                    // no I18n required
236                    MessageFormat.format("Class ''{0}'' not registered as renderer. Can''t activate it.", renderer.getName())
237            );
238        this.activeRenderer = renderer;
239        Main.pref.put(PREF_KEY_RENDERER_CLASS_NAME, activeRenderer.getName());
240
241    }
242
243    /**
244     * <p>Activates the default map renderer.</p>
245     *
246     * @throws IllegalStateException if the default renderer {@link StyledMapRenderer} isn't registered
247     */
248    public void activateDefault() {
249        Class<? extends AbstractMapRenderer> defaultRenderer = StyledMapRenderer.class;
250        if (!isRegistered(defaultRenderer))
251            throw new IllegalStateException(
252                    MessageFormat.format("Class ''{0}'' not registered as renderer. Can''t activate default renderer.",
253                            defaultRenderer.getName())
254            );
255        activate(defaultRenderer);
256    }
257
258    /**
259     * <p>Creates an instance of the currently active renderer.</p>
260     * @param g Graphics
261     * @param viewport Navigatable component
262     * @param isInactiveMode {@code true} if the paint visitor shall render OSM objects such that they look inactive
263     * @return an instance of the currently active renderer
264     *
265     * @throws MapRendererFactoryException if creating an instance fails
266     * @see AbstractMapRenderer#AbstractMapRenderer(Graphics2D, NavigatableComponent, boolean)
267     */
268    public AbstractMapRenderer createActiveRenderer(Graphics2D g, NavigatableComponent viewport, boolean isInactiveMode)
269            throws MapRendererFactoryException {
270        try {
271            Constructor<?> c = activeRenderer.getConstructor(new Class<?>[]{Graphics2D.class, NavigatableComponent.class, boolean.class});
272            return AbstractMapRenderer.class.cast(c.newInstance(g, viewport, isInactiveMode));
273        } catch (NoSuchMethodException | IllegalArgumentException | InstantiationException | IllegalAccessException e) {
274            throw new MapRendererFactoryException(e);
275        } catch (InvocationTargetException e) {
276            throw new MapRendererFactoryException(e.getCause());
277        }
278    }
279
280    /**
281     * <p>Replies the (unmodifiable) list of map renderer descriptors.</p>
282     *
283     * @return the descriptors
284     */
285    public List<Descriptor> getMapRendererDescriptors() {
286        return Collections.unmodifiableList(descriptors);
287    }
288
289    /**
290     * <p>Replies true, if currently the wireframe map renderer is active. Otherwise,
291     * false.</p>
292     *
293     * <p>There is a specific method for {@link WireframeMapRenderer} for legacy support.
294     * Until 03/2011 there were only two possible map renderers in JOSM: the wireframe
295     * renderer and the styled renderer. For the time being there are still UI elements
296     * (menu entries, etc.) which toggle between these two renderers only.</p>
297     *
298     * @return true, if currently the wireframe map renderer is active. Otherwise,
299     * false
300     */
301    public boolean isWireframeMapRendererActive() {
302        return activeRenderer != null && activeRenderer.getName().equals(WireframeMapRenderer.class.getName());
303    }
304}