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.List;
012
013import org.openstreetmap.josm.gui.NavigatableComponent;
014import org.openstreetmap.josm.plugins.PluginHandler;
015import org.openstreetmap.josm.spi.preferences.Config;
016import org.openstreetmap.josm.tools.CheckParameterUtil;
017import org.openstreetmap.josm.tools.Logging;
018
019/**
020 * <p>MapRendererFactory manages a list of map renderer classes and associated
021 * meta data (display name, description).</p>
022 *
023 * <p>Plugins can implement and supply their own map renderers.</p>
024 * <strong>Sample code in a plugin</strong>
025 * <pre>
026 * public class MyMapRenderer extends AbstractMapRenderer {
027 *    // ....
028 * }
029 *
030 * // to be called when the plugin is created
031 * MapRendererFactory factory = MapRendererFactory.getInstance();
032 * factory.register(MyMapRenderer.class, "My map renderer", "This is is a fast map renderer");
033 * factory.activate(MyMapRenderer.class);
034 *
035 * </pre>
036 * @since 4087
037 */
038public final class MapRendererFactory {
039
040    /** preference key for the renderer class name. Default: class name for {@link StyledMapRenderer}
041     *
042     */
043    public static final String PREF_KEY_RENDERER_CLASS_NAME = "mappaint.renderer-class-name";
044
045    /**
046     * An exception thrown while creating a map renderer
047     */
048    public static class MapRendererFactoryException extends RuntimeException {
049
050        /**
051         * Create a new {@link MapRendererFactoryException}
052         * @param message The message
053         * @param cause The cause
054         */
055        public MapRendererFactoryException(String message, Throwable cause) {
056            super(message, cause);
057        }
058
059        /**
060         * Create a new {@link MapRendererFactoryException}
061         * @param message The message
062         */
063        public MapRendererFactoryException(String message) {
064            super(message);
065        }
066
067        /**
068         * Create a new {@link MapRendererFactoryException}
069         * @param cause The cause
070         */
071        public MapRendererFactoryException(Throwable cause) {
072            super(cause);
073        }
074    }
075
076    /**
077     * A description of a possible renderer for the map
078     */
079    public static class Descriptor {
080        private final Class<? extends AbstractMapRenderer> renderer;
081        private final String displayName;
082        private final String description;
083
084        /**
085         * Creates a new map renderer description
086         * @param renderer The renderer
087         * @param displayName The display name for the renderer
088         * @param description The longer description that should be displayed to the user.
089         */
090        public Descriptor(Class<? extends AbstractMapRenderer> renderer, String displayName, String description) {
091            this.renderer = renderer;
092            this.displayName = displayName;
093            this.description = description;
094        }
095
096        /**
097         * Get the class of the renderer
098         * @return The class
099         */
100        public Class<? extends AbstractMapRenderer> getRenderer() {
101            return renderer;
102        }
103
104        /**
105         * Get the display name
106         * @return The name
107         */
108        public String getDisplayName() {
109            return displayName;
110        }
111
112        /**
113         * Get the description
114         * @return The description
115         */
116        public String getDescription() {
117            return description;
118        }
119    }
120
121    private static MapRendererFactory instance;
122
123    /**
124     * Replies the unique instance
125     * @return instance of map rending class
126     */
127    public static synchronized MapRendererFactory getInstance() {
128        if (instance == null) {
129            instance = new MapRendererFactory();
130        }
131        return instance;
132    }
133
134    private static Class<?> loadRendererClass(String className) {
135        for (ClassLoader cl : PluginHandler.getResourceClassLoaders()) {
136            try {
137                return Class.forName(className, true, cl);
138            } catch (final NoClassDefFoundError | ClassNotFoundException e) {
139                Logging.trace(e);
140            }
141        }
142        Logging.error(tr("Failed to load map renderer class ''{0}''. The class wasn''t found.", className));
143        return null;
144    }
145
146    private final List<Descriptor> descriptors = new ArrayList<>();
147    private Class<? extends AbstractMapRenderer> activeRenderer;
148
149    private MapRendererFactory() {
150        registerDefaultRenderers();
151        String rendererClassName = Config.getPref().get(PREF_KEY_RENDERER_CLASS_NAME, null);
152        if (rendererClassName != null) {
153            activateMapRenderer(rendererClassName);
154        } else {
155            activateDefault();
156        }
157    }
158
159    private void activateMapRenderer(String rendererClassName) {
160        Class<?> c = loadRendererClass(rendererClassName);
161        if (c == null) {
162            Logging.error(tr("Can''t activate map renderer class ''{0}'', because the class wasn''t found.", rendererClassName));
163            Logging.error(tr("Activating the standard map renderer instead."));
164            activateDefault();
165        } else if (!AbstractMapRenderer.class.isAssignableFrom(c)) {
166            Logging.error(tr("Can''t activate map renderer class ''{0}'', because it isn''t a subclass of ''{1}''.",
167                    rendererClassName, AbstractMapRenderer.class.getName()));
168            Logging.error(tr("Activating the standard map renderer instead."));
169            activateDefault();
170        } else {
171            Class<? extends AbstractMapRenderer> renderer = c.asSubclass(AbstractMapRenderer.class);
172            if (!isRegistered(renderer)) {
173                Logging.error(tr("Can''t activate map renderer class ''{0}'', because it isn''t registered as map renderer.",
174                        rendererClassName));
175                Logging.error(tr("Activating the standard map renderer instead."));
176                activateDefault();
177            } else {
178                activate(renderer);
179            }
180        }
181    }
182
183    private void registerDefaultRenderers() {
184        register(
185                WireframeMapRenderer.class,
186                tr("Wireframe Map Renderer"),
187                tr("Renders the map as simple wire frame.")
188        );
189        register(
190                StyledMapRenderer.class,
191                tr("Styled Map Renderer"),
192                tr("Renders the map using style rules in a set of style sheets.")
193        );
194    }
195
196    /**
197     * <p>Replies true, if {@code Renderer} is already a registered map renderer class.</p>
198     *
199     * @param renderer the map renderer class. Must not be null.
200     * @return true, if {@code Renderer} is already a registered map renderer class
201     * @throws IllegalArgumentException if {@code renderer} is null
202     */
203    public boolean isRegistered(Class<? extends AbstractMapRenderer> renderer) {
204        CheckParameterUtil.ensureParameterNotNull(renderer);
205        return descriptors.stream().anyMatch(d -> d.getRenderer().equals(renderer));
206    }
207
208    /**
209     * <p>Registers a map renderer class.</p>
210     *
211     * @param renderer the map renderer class. Must not be null.
212     * @param displayName the display name to be displayed in UIs (i.e. in the preference dialog)
213     * @param description the description
214     * @throws IllegalArgumentException if {@code renderer} is null
215     * @throws IllegalStateException if {@code renderer} is already registered
216     */
217    public void register(Class<? extends AbstractMapRenderer> renderer, String displayName, String description) {
218        CheckParameterUtil.ensureParameterNotNull(renderer);
219        if (isRegistered(renderer))
220            throw new IllegalStateException(
221                    // no I18n - this is a technical message
222                    MessageFormat.format("Class ''{0}'' already registered a renderer", renderer.getName())
223            );
224        Descriptor d = new Descriptor(renderer, displayName, description);
225        descriptors.add(d);
226    }
227
228    /**
229     * <p>Unregisters a map renderer class.</p>
230     *
231     * <p>If the respective class is also the active renderer, the renderer is reset
232     * to the default renderer.</p>
233     *
234     * @param renderer the map renderer class. Must not be null.
235     *
236     */
237    public void unregister(Class<? extends AbstractMapRenderer> renderer) {
238        if (renderer == null) return;
239        if (!isRegistered(renderer)) return;
240        descriptors.removeIf(d -> d.getRenderer().equals(renderer));
241        if (activeRenderer != null && activeRenderer.equals(renderer)) {
242            activateDefault();
243        }
244    }
245
246    /**
247     * <p>Activates a map renderer class.</p>
248     *
249     * <p>The renderer class must already be registered.</p>
250     *
251     * @param renderer the map renderer class. Must not be null.
252     * @throws IllegalArgumentException if {@code renderer} is null
253     * @throws IllegalStateException if {@code renderer} isn't registered yet
254     */
255    public void activate(Class<? extends AbstractMapRenderer> renderer) {
256        CheckParameterUtil.ensureParameterNotNull(renderer);
257        if (!isRegistered(renderer))
258            throw new IllegalStateException(
259                    // no I18n required
260                    MessageFormat.format("Class ''{0}'' not registered as renderer. Can''t activate it.", renderer.getName())
261            );
262        this.activeRenderer = renderer;
263        Config.getPref().put(PREF_KEY_RENDERER_CLASS_NAME, activeRenderer.getName());
264
265    }
266
267    /**
268     * <p>Activates the default map renderer.</p>
269     *
270     * @throws IllegalStateException if the default renderer {@link StyledMapRenderer} isn't registered
271     */
272    public void activateDefault() {
273        Class<? extends AbstractMapRenderer> defaultRenderer = StyledMapRenderer.class;
274        if (!isRegistered(defaultRenderer))
275            throw new IllegalStateException(
276                    MessageFormat.format("Class ''{0}'' not registered as renderer. Can''t activate default renderer.",
277                            defaultRenderer.getName())
278            );
279        activate(defaultRenderer);
280    }
281
282    /**
283     * <p>Creates an instance of the currently active renderer.</p>
284     * @param g Graphics
285     * @param viewport Navigable component
286     * @param isInactiveMode {@code true} if the paint visitor shall render OSM objects such that they look inactive
287     * @return an instance of the currently active renderer
288     *
289     * @throws MapRendererFactoryException if creating an instance fails
290     * @see AbstractMapRenderer#AbstractMapRenderer(Graphics2D, NavigatableComponent, boolean)
291     */
292    public AbstractMapRenderer createActiveRenderer(Graphics2D g, NavigatableComponent viewport, boolean isInactiveMode) {
293        try {
294            Constructor<?> c = activeRenderer.getConstructor(Graphics2D.class, NavigatableComponent.class, boolean.class);
295            return AbstractMapRenderer.class.cast(c.newInstance(g, viewport, isInactiveMode));
296        } catch (ReflectiveOperationException | IllegalArgumentException e) {
297            throw new MapRendererFactoryException(e);
298        }
299    }
300
301    /**
302     * <p>Replies the (unmodifiable) list of map renderer descriptors.</p>
303     *
304     * @return the descriptors
305     */
306    public List<Descriptor> getMapRendererDescriptors() {
307        return Collections.unmodifiableList(descriptors);
308    }
309
310    /**
311     * <p>Replies true, if currently the wireframe map renderer is active. Otherwise, false.</p>
312     *
313     * <p>There is a specific method for {@link WireframeMapRenderer} for legacy support.
314     * Until 03/2011 there were only two possible map renderers in JOSM: the wireframe
315     * renderer and the styled renderer. For the time being there are still UI elements
316     * (menu entries, etc.) which toggle between these two renderers only.</p>
317     *
318     * @return true, if currently the wireframe map renderer is active. Otherwise, false
319     */
320    public boolean isWireframeMapRendererActive() {
321        return WireframeMapRenderer.class.equals(activeRenderer);
322    }
323}