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.text.MessageFormat;
009import java.util.ArrayList;
010import java.util.Collections;
011import java.util.Iterator;
012import java.util.List;
013
014import org.openstreetmap.josm.gui.NavigatableComponent;
015import org.openstreetmap.josm.plugins.PluginHandler;
016import org.openstreetmap.josm.spi.preferences.Config;
017import org.openstreetmap.josm.tools.CheckParameterUtil;
018import org.openstreetmap.josm.tools.Logging;
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    /**
047     * An exception thrown while creating a map renderer
048     */
049    public static class MapRendererFactoryException extends RuntimeException {
050
051        /**
052         * Create a new {@link MapRendererFactoryException}
053         * @param message The message
054         * @param cause The cause
055         */
056        public MapRendererFactoryException(String message, Throwable cause) {
057            super(message, cause);
058        }
059
060        /**
061         * Create a new {@link MapRendererFactoryException}
062         * @param message The message
063         */
064        public MapRendererFactoryException(String message) {
065            super(message);
066        }
067
068        /**
069         * Create a new {@link MapRendererFactoryException}
070         * @param cause The cause
071         */
072        public MapRendererFactoryException(Throwable cause) {
073            super(cause);
074        }
075    }
076
077    /**
078     * A description of a possible renderer for the map
079     */
080    public static class Descriptor {
081        private final Class<? extends AbstractMapRenderer> renderer;
082        private final String displayName;
083        private final String description;
084
085        /**
086         * Creates a new map renderer description
087         * @param renderer The renderer
088         * @param displayName The display name for the renderer
089         * @param description The longer description that should be displayed to the user.
090         */
091        public Descriptor(Class<? extends AbstractMapRenderer> renderer, String displayName, String description) {
092            this.renderer = renderer;
093            this.displayName = displayName;
094            this.description = description;
095        }
096
097        /**
098         * Get the class of the renderer
099         * @return The class
100         */
101        public Class<? extends AbstractMapRenderer> getRenderer() {
102            return renderer;
103        }
104
105        /**
106         * Get the display name
107         * @return The name
108         */
109        public String getDisplayName() {
110            return displayName;
111        }
112
113        /**
114         * Get the description
115         * @return The description
116         */
117        public String getDescription() {
118            return description;
119        }
120    }
121
122    private static MapRendererFactory instance;
123
124    /**
125     * Replies the unique instance
126     * @return instance of map rending class
127     */
128    public static synchronized MapRendererFactory getInstance() {
129        if (instance == null) {
130            instance = new MapRendererFactory();
131        }
132        return instance;
133    }
134
135    private static Class<?> loadRendererClass(String className) {
136        for (ClassLoader cl : PluginHandler.getResourceClassLoaders()) {
137            try {
138                return Class.forName(className, true, cl);
139            } catch (final NoClassDefFoundError | ClassNotFoundException e) {
140                Logging.trace(e);
141            }
142        }
143        Logging.error(tr("Failed to load map renderer class ''{0}''. The class wasn''t found.", className));
144        return null;
145    }
146
147    private final List<Descriptor> descriptors = new ArrayList<>();
148    private Class<? extends AbstractMapRenderer> activeRenderer;
149
150    private MapRendererFactory() {
151        registerDefaultRenderers();
152        String rendererClassName = Config.getPref().get(PREF_KEY_RENDERER_CLASS_NAME, null);
153        if (rendererClassName != null) {
154            activateMapRenderer(rendererClassName);
155        } else {
156            activateDefault();
157        }
158    }
159
160    private void activateMapRenderer(String rendererClassName) {
161        Class<?> c = loadRendererClass(rendererClassName);
162        if (c == null) {
163            Logging.error(tr("Can''t activate map renderer class ''{0}'', because the class wasn''t found.", rendererClassName));
164            Logging.error(tr("Activating the standard map renderer instead."));
165            activateDefault();
166        } else if (!AbstractMapRenderer.class.isAssignableFrom(c)) {
167            Logging.error(tr("Can''t activate map renderer class ''{0}'', because it isn''t a subclass of ''{1}''.",
168                    rendererClassName, AbstractMapRenderer.class.getName()));
169            Logging.error(tr("Activating the standard map renderer instead."));
170            activateDefault();
171        } else {
172            Class<? extends AbstractMapRenderer> renderer = c.asSubclass(AbstractMapRenderer.class);
173            if (!isRegistered(renderer)) {
174                Logging.error(tr("Can''t activate map renderer class ''{0}'', because it isn''t registered as map renderer.",
175                        rendererClassName));
176                Logging.error(tr("Activating the standard map renderer instead."));
177                activateDefault();
178            } else {
179                activate(renderer);
180            }
181        }
182    }
183
184    private void registerDefaultRenderers() {
185        register(
186                WireframeMapRenderer.class,
187                tr("Wireframe Map Renderer"),
188                tr("Renders the map as simple wire frame.")
189        );
190        register(
191                StyledMapRenderer.class,
192                tr("Styled Map Renderer"),
193                tr("Renders the map using style rules in a set of style sheets.")
194        );
195    }
196
197    /**
198     * <p>Replies true, if {@code Renderer} is already a registered map renderer class.</p>
199     *
200     * @param renderer the map renderer class. Must not be null.
201     * @return true, if {@code Renderer} is already a registered map renderer class
202     * @throws IllegalArgumentException if {@code renderer} is null
203     */
204    public boolean isRegistered(Class<? extends AbstractMapRenderer> renderer) {
205        CheckParameterUtil.ensureParameterNotNull(renderer);
206        for (Descriptor d: descriptors) {
207            if (d.getRenderer().equals(renderer)) return true;
208        }
209        return false;
210    }
211
212    /**
213     * <p>Registers a map renderer class.</p>
214     *
215     * @param renderer the map renderer class. Must not be null.
216     * @param displayName the display name to be displayed in UIs (i.e. in the preference dialog)
217     * @param description the description
218     * @throws IllegalArgumentException if {@code renderer} is null
219     * @throws IllegalStateException if {@code renderer} is already registered
220     */
221    public void register(Class<? extends AbstractMapRenderer> renderer, String displayName, String description) {
222        CheckParameterUtil.ensureParameterNotNull(renderer);
223        if (isRegistered(renderer))
224            throw new IllegalStateException(
225                    // no I18n - this is a technical message
226                    MessageFormat.format("Class ''{0}'' already registered a renderer", renderer.getName())
227            );
228        Descriptor d = new Descriptor(renderer, displayName, description);
229        descriptors.add(d);
230    }
231
232    /**
233     * <p>Unregisters a map renderer class.</p>
234     *
235     * <p>If the respective class is also the active renderer, the renderer is reset
236     * to the default renderer.</p>
237     *
238     * @param renderer the map renderer class. Must not be null.
239     *
240     */
241    public void unregister(Class<? extends AbstractMapRenderer> renderer) {
242        if (renderer == null) return;
243        if (!isRegistered(renderer)) return;
244        Iterator<Descriptor> it = descriptors.iterator();
245        while (it.hasNext()) {
246            Descriptor d = it.next();
247            if (d.getRenderer().equals(renderer)) {
248                it.remove();
249                break;
250            }
251        }
252        if (activeRenderer != null && activeRenderer.equals(renderer)) {
253            activateDefault();
254        }
255    }
256
257    /**
258     * <p>Activates a map renderer class.</p>
259     *
260     * <p>The renderer class must already be registered.</p>
261     *
262     * @param renderer the map renderer class. Must not be null.
263     * @throws IllegalArgumentException if {@code renderer} is null
264     * @throws IllegalStateException if {@code renderer} isn't registered yet
265     */
266    public void activate(Class<? extends AbstractMapRenderer> renderer) {
267        CheckParameterUtil.ensureParameterNotNull(renderer);
268        if (!isRegistered(renderer))
269            throw new IllegalStateException(
270                    // no I18n required
271                    MessageFormat.format("Class ''{0}'' not registered as renderer. Can''t activate it.", renderer.getName())
272            );
273        this.activeRenderer = renderer;
274        Config.getPref().put(PREF_KEY_RENDERER_CLASS_NAME, activeRenderer.getName());
275
276    }
277
278    /**
279     * <p>Activates the default map renderer.</p>
280     *
281     * @throws IllegalStateException if the default renderer {@link StyledMapRenderer} isn't registered
282     */
283    public void activateDefault() {
284        Class<? extends AbstractMapRenderer> defaultRenderer = StyledMapRenderer.class;
285        if (!isRegistered(defaultRenderer))
286            throw new IllegalStateException(
287                    MessageFormat.format("Class ''{0}'' not registered as renderer. Can''t activate default renderer.",
288                            defaultRenderer.getName())
289            );
290        activate(defaultRenderer);
291    }
292
293    /**
294     * <p>Creates an instance of the currently active renderer.</p>
295     * @param g Graphics
296     * @param viewport Navigatable component
297     * @param isInactiveMode {@code true} if the paint visitor shall render OSM objects such that they look inactive
298     * @return an instance of the currently active renderer
299     *
300     * @throws MapRendererFactoryException if creating an instance fails
301     * @see AbstractMapRenderer#AbstractMapRenderer(Graphics2D, NavigatableComponent, boolean)
302     */
303    public AbstractMapRenderer createActiveRenderer(Graphics2D g, NavigatableComponent viewport, boolean isInactiveMode) {
304        try {
305            Constructor<?> c = activeRenderer.getConstructor(Graphics2D.class, NavigatableComponent.class, boolean.class);
306            return AbstractMapRenderer.class.cast(c.newInstance(g, viewport, isInactiveMode));
307        } catch (ReflectiveOperationException | IllegalArgumentException e) {
308            throw new MapRendererFactoryException(e);
309        }
310    }
311
312    /**
313     * <p>Replies the (unmodifiable) list of map renderer descriptors.</p>
314     *
315     * @return the descriptors
316     */
317    public List<Descriptor> getMapRendererDescriptors() {
318        return Collections.unmodifiableList(descriptors);
319    }
320
321    /**
322     * <p>Replies true, if currently the wireframe map renderer is active. Otherwise, false.</p>
323     *
324     * <p>There is a specific method for {@link WireframeMapRenderer} for legacy support.
325     * Until 03/2011 there were only two possible map renderers in JOSM: the wireframe
326     * renderer and the styled renderer. For the time being there are still UI elements
327     * (menu entries, etc.) which toggle between these two renderers only.</p>
328     *
329     * @return true, if currently the wireframe map renderer is active. Otherwise, false
330     */
331    public boolean isWireframeMapRendererActive() {
332        return WireframeMapRenderer.class.equals(activeRenderer);
333    }
334}