Final fixes completed; recently opened files can now be selected from

Jskad's file menu.

source/org/thdl/tib/input/RecentlyOpenedFilesDatabase.java

@@ -0,0 +1,155 @@
+/*
+The contents of this file are subject to the THDL Open Community License
+Version 1.0 (the "License"); you may not use this file except in compliance
+with the License. You may obtain a copy of the License on the THDL web site 
+(http://www.thdl.org/).
+
+Software distributed under the License is distributed on an "AS IS" basis, 
+WITHOUT WARRANTY OF ANY KIND, either express or implied. See the 
+License for the specific terms governing rights and limitations under the 
+License. 
+
+The Initial Developer of this software is the Tibetan and Himalayan Digital
+Library (THDL). Portions created by the THDL are Copyright 2003 THDL.
+All Rights Reserved. 
+
+Contributor(s): ______________________________________.
+*/
+
+package org.thdl.tib.input;
+
+import org.thdl.util.ThdlOptions;
+
+import java.util.Vector;
+import java.io.File;
+
+/** A database of the files most recently opened in Jskad.  The client
+    must call {@link #storeRecentlyOpenedFilePreferences()} before
+    exiting.
+    @author David Chandler
+*/
+class RecentlyOpenedFilesDatabase {
+
+    /** Tells ThdlOptions about the recently opened files.  Call this before program exit. */
+    // DLC FIXME: this doesn't keep the second-most recently opened item second if you have just three items.
+    public static void storeRecentlyOpenedFilePreferences() {
+        int n = 0;
+        // We store 2*N files in the preferences in case some are deleted.
+        for (int k = 0; k < recentlyOpenedFiles.size() && n < 2*N; k++) {
+            File f = (File)recentlyOpenedFiles.elementAt(k);
+            if (f.isFile()) {
+                ThdlOptions.setUserPreference("thdl.recently.opened.file." + n++,
+                                              f.getAbsolutePath());
+            }
+        }
+    }
+
+    /** the number of recently opened files to display on the File
+        menu */
+    private static int N;
+
+    /** the maximum number of characters to display in a label shown
+        to the user for a recently opened file */
+    private static int maxCharsToShow;
+
+    /** Returns the maximum number of recently opened files that the
+        user wishes to see in the File menu. */
+    public static int getNumberOfFilesToShow() {
+        if (uninitialized) init();
+        return N;
+    }
+
+    /** false iff we are in the process of initializing or have
+        already initialized */
+    private static boolean uninitialized = true;
+
+    /** Reads the user's preferences and fills in {@link
+        #recentlyOpenedFiles} based on them. */
+    private static void init() {
+        if (uninitialized) {
+            uninitialized = false; // must come first!
+
+            maxCharsToShow
+                = ThdlOptions.getIntegerOption("thdl.max.chars.in.recently.opened.file.name", 40);
+            N = ThdlOptions.getIntegerOption("thdl.number.of.recently.opened.files.to.show", 4);
+
+            // Add the N most recently opened files.
+
+            if (maxCharsToShow < 5)
+                maxCharsToShow = 5;
+            for (int i = 2*N - 1; i >= 0; i--) {
+                setMostRecentlyOpenedFile(getNthRecentlyOpenedFileFromPreferences(i));
+            }
+        }
+    }
+
+    /** Returns the <code>n</code>th most recently opened file, given
+        that we care about <code>N</code> recently opened files in
+        total.  When <code>n</code> is zero, the most recently opened
+        file is returned.  This file does exist.  Returns null if we
+        haven't kept track of enough files to say. */
+    public static File getNthRecentlyOpenedFile(int n) {
+        if (uninitialized) init();
+        while (n < recentlyOpenedFiles.size()) {
+            File f = (File)recentlyOpenedFiles.elementAt(n);
+            if (f.isFile())
+                return f;
+            ++n;
+        }
+        return null;
+    }
+
+    /** Returns the nth most recently opened, existing file listed in
+        the user's preferences.  Returns null if their preferences do
+        not contain n+1 existing files. */
+    private static File getNthRecentlyOpenedFileFromPreferences(int n) {
+        if (uninitialized) init();
+        for (int i = n; i < N*2; i++) {
+            String x = ThdlOptions.getStringOption("thdl.recently.opened.file." + i);
+            if (null == x)
+                return null;
+            File f = new File(x);
+            if (f.isFile())
+                return f;
+        }
+        return null;
+    }
+
+    /** Notes the fact that fileChosen was the file most recently
+        opened by Jskad. */
+    public static void setMostRecentlyOpenedFile(File fileChosen) {
+        if (null != fileChosen) {
+            if (uninitialized) init();
+            // the first element is the most recently opened.
+            int index = recentlyOpenedFiles.indexOf(fileChosen);
+            if (index > -1) {
+                recentlyOpenedFiles.remove(index);
+            }
+            recentlyOpenedFiles.add(0, fileChosen);
+        }
+    }
+
+    /** a vector with the most recently opened file at its
+        beginning, the least recently opened at its end. */
+    private static Vector recentlyOpenedFiles = new Vector();
+
+    /** Prints debugging information to System.err. */
+    public static void printDebuggingInfo() {
+        if (uninitialized) init();
+        System.err.println("<RecentlyOpenedFilesDatabase>");
+        for (int i = 0; i < recentlyOpenedFiles.size(); i++)
+            System.err.println("File " + i + " (where 0 is most recent) is " + ((File)recentlyOpenedFiles.elementAt(i)).getAbsolutePath());
+        System.err.println("</RecentlyOpenedFilesDatabase>");
+    }
+
+    /** Returns a user-friendly label for f that is not longer than
+        the user's preferences allow. */
+    public static String getLabel(File f) {
+        if (uninitialized) init();
+        String path = f.getAbsolutePath();
+        int l;
+        if ((l = path.length()) <= maxCharsToShow)
+            return path;
+        return "..." + path.substring(l - maxCharsToShow + 3);
+    }
+}