Theme.java

/**
 * Copyright 2014 the staff of 52°North Initiative for Geospatial Open
 * Source Software GmbH in their free time
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package spare.n52.yadarts.themes;

import java.io.File;
import java.io.FileFilter;
import java.io.FileNotFoundException;
import java.net.URISyntaxException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Display;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A theme is a set of image files that provide the
 * basic style of the UI.
 */
public abstract class Theme {
	
	private static final Logger logger = LoggerFactory.getLogger(Theme.class);
	
	protected static final String BOARD_HI = "board-hi.jpg";
	protected static final String BOARD_M = "board-m.jpg";
	protected static final String BOARD_LO = "board-lo.jpg";
	protected static final String BASE_DIR = "/themes";
	protected static final String DEFAULT_THEME = "plain";
	protected static final String BACKGROUND = "background.jpg";
	protected static final String BACKGROUND_ALT = "background_alt.jpg";
	protected static final String CORNER_TOP_LEFT = "corner_topleft.jpg";
	protected static final String BORDER_LEFT = "border_left.jpg";
	protected static final String CORNER_TOP_RIGHT = "corner_topright.jpg";
	protected static final String BORDER_TOP = "border_top.jpg";
	protected static final String CORNER_BOTTOM_LEFT = "corner_bottomleft.jpg";
	protected static final String BORDER_BOTTOM = "border_bottom.jpg";
	protected static final String CORNER_BOTTOM_RIGHT = "corner_bottomright.jpg";
	protected static final String BORDER_RIGHT = "border_right.jpg";

	protected static final FileFilter directoryFilter = new FileFilter() {
				
				@Override
				public boolean accept(File pathname) {
					/*
					 * use directories, but not the default. we already have that
					 */
					if (pathname.isDirectory() && !pathname.equals(DEFAULT_THEME)) {
						return true;
					}
					return false;
				}
			};
	
	private static Theme defaultTheme;
	private static Map<String, Theme> availableThemes = new HashMap<>();
	private static Theme currentTheme;
	
	static {
		try {
			defaultTheme = new ClasspathTheme(BASE_DIR + "/"+ DEFAULT_THEME);
			currentTheme = defaultTheme;
			resolveThemesFromFileSystem();
		} catch (URISyntaxException e) {
			logger.warn(e.getMessage(), e);
		}
	}

	public static Theme getDefault() {
		return defaultTheme;
	}
	
	public static void setCurrentTheme(String name) {
		if (availableThemes.containsKey(name)) {
			currentTheme = availableThemes.get(name);
		}
		else {
			logger.warn("No theme with name {} available. Using default", name);
		}
	}

	public static Theme getCurrentTheme() {
		return currentTheme;
	}
	
	
	private static void resolveThemesFromFileSystem() {
		logger.info("Resolving themes from file system...");
		File[] candidates = new File(".".concat(BASE_DIR)).listFiles(directoryFilter);
		
		if (candidates != null) {
			logger.info("Found theme candidates: {}", Arrays.toString(candidates));
			instantiateThemes(candidates);
		}
		else {
			logger.info("No theme candidates found on the file system.");
		}
		
		
	}

	private static void instantiateThemes(File[] candidates) {
		for (File c : candidates) {
			if (validateDirectoryContents(c.listFiles())) {
				try {
					FileSystemTheme fst = new FileSystemTheme(c);
					availableThemes.put(c.getName(), fst);
					logger.info("Added theme: {}", c.getName());
				}
				catch (IllegalStateException e) {
					logger.warn("Could not instantiate theme {}: {}", c.getName(), e.getMessage());
				}
			}
		}
	}
	
	private static boolean validateDirectoryContents(File[] files) {
		boolean hasHi = false;
		boolean hasM = false;
		boolean hasLo = false;
		
		for (File file : files) {
			switch (file.getName()) {
			case BOARD_HI:
				hasHi = true;
				break;
			case BOARD_M:
				hasM = true;
				break;
			case BOARD_LO:
				hasLo = true;
				break;
			default:
				break;
			}
		}
		
		return hasHi && hasM && hasLo;
	}

	public abstract Image getBoardM(Display display) throws FileNotFoundException;

	public abstract Image getBoardHi(Display display) throws FileNotFoundException;

	public abstract Image getBoardLo(Display display) throws FileNotFoundException;

	public abstract Image getBackground(Display display) throws FileNotFoundException;

	public abstract Image getBackgroundAlt(Display display) throws FileNotFoundException;

	public abstract Image getCornerTopLeft(Display display) throws FileNotFoundException;

	public abstract Image getBorderLeft(Display display) throws FileNotFoundException;

	public abstract Image getCornerTopRight(Display display) throws FileNotFoundException;

	public abstract Image getBorderTop(Display display) throws FileNotFoundException;
	
	public abstract Image getCornerBottomLeft(Display display) throws FileNotFoundException;

	public abstract Image getBorderBottom(Display display) throws FileNotFoundException;
	
	public abstract Image getCornerBottomRight(Display display) throws FileNotFoundException;

	public abstract Image getBorderRight(Display display) throws FileNotFoundException;
}