Add watcher on sketch files

Reloads sketch content if the Editor is not in foreground and isomething happens in the backing storage files.

Note that no confirmation dialog is displayed (same behaviour as SublimeText, differs from other IDEs)

Fixes #4551 and #5345

app/src/processing/app/Editor.java

@@ -110,6 +110,15 @@ import processing.app.syntax.SketchTextArea;
 import processing.app.tools.MenuScroller;
 import processing.app.tools.Tool;
 
+import processing.app.tools.WatchDir;
+import static java.nio.file.StandardWatchEventKinds.*;
+import java.nio.file.WatchService;
+import java.nio.file.WatchKey;
+import java.nio.file.WatchEvent;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.io.File;
+
 /**
  * Main editor panel for the Processing Development Environment.
  */
@@ -124,6 +133,7 @@ public class Editor extends JFrame implements RunnerListener {
   private final Box upper;
   private ArrayList<EditorTab> tabs = new ArrayList<>();
   private int currentTabIndex = -1;
+  private static boolean watcherDisable = false;
 
   private static class ShouldSaveIfModified
       implements Predicate<SketchController> {
@@ -238,6 +248,8 @@ public class Editor extends JFrame implements RunnerListener {
   private Runnable timeoutUploadHandler;
 
   private Map<String, Tool> internalToolCache = new HashMap<String, Tool>();
+  protected Thread watcher = null;
+  protected Runnable task = null;
 
   public Editor(Base ibase, File file, int[] storedLocation, int[] defaultLocation, Platform platform) throws Exception {
     super("Arduino");
@@ -263,12 +275,20 @@ public class Editor extends JFrame implements RunnerListener {
     // When bringing a window to front, let the Base know
     addWindowListener(new WindowAdapter() {
         public void windowActivated(WindowEvent e) {
+          if (watcher != null) {
+            watcher.interrupt();
+            watcher = null;
+          }
           base.handleActivated(Editor.this);
         }
 
         // added for 1.0.5
         // http://dev.processing.org/bugs/show_bug.cgi?id=1260
         public void windowDeactivated(WindowEvent e) {
+          if (watcher == null) {
+            watcher = new Thread(task);
+            watcher.start();
+          }
           List<Component> toolsMenuItemsToRemove = new LinkedList<>();
           for (Component menuItem : toolsMenu.getMenuComponents()) {
             if (menuItem instanceof JComponent) {
@@ -383,7 +403,6 @@ public class Editor extends JFrame implements RunnerListener {
     EditorConsole.setCurrentEditorConsole(console);
   }
 
-
   /**
    * Handles files dragged & dropped from the desktop and into the editor
    * window. Dragging files into the editor window is the same as using
@@ -1542,7 +1561,7 @@ public class Editor extends JFrame implements RunnerListener {
    *          the given file.
    * @throws IOException
    */
-  protected void addTab(SketchFile file, String contents) throws IOException {
+  public synchronized void addTab(SketchFile file, String contents) throws IOException {
     EditorTab tab = new EditorTab(this, file, contents);
     tab.getTextArea().getDocument()
         .addDocumentListener(new DocumentTextChangeListener(
@@ -1551,9 +1570,12 @@ public class Editor extends JFrame implements RunnerListener {
     reorderTabs();
   }
 
-  protected void removeTab(SketchFile file) throws IOException {
+  public synchronized void removeTab(SketchFile file) throws IOException {
     int index = findTabIndex(file);
     tabs.remove(index);
+    if (index == currentTabIndex) {
+      currentTabIndex = currentTabIndex -1;
+    }
   }
 
   // . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
@@ -1829,6 +1851,25 @@ public class Editor extends JFrame implements RunnerListener {
     // Disable untitled setting from previous document, if any
     untitled = false;
 
+    if (watcherDisable == true) {
+      return true;
+    }
+
+    // Add FS watcher for current Editor instance
+    Path dir = file.toPath().getParent();
+
+    Editor instance = this;
+
+    task = new Runnable() {
+      public void run() {
+        try {
+          new WatchDir(dir, true).processEvents(instance);
+        } catch (IOException x) {
+          watcherDisable = true;
+        }
+      }
+    };
+
     // opening was successful
     return true;
   }

app/src/processing/app/EditorTab.java

@@ -49,6 +49,14 @@ import javax.swing.text.PlainDocument;
 import javax.swing.text.DefaultCaret;
 import javax.swing.text.Document;
 
+import static java.nio.file.StandardWatchEventKinds.*;
+import java.nio.file.WatchService;
+import java.nio.file.WatchKey;
+import java.nio.file.WatchEvent;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.io.File;
+
 import org.apache.commons.lang3.StringUtils;
 import org.fife.ui.rsyntaxtextarea.RSyntaxDocument;
 import org.fife.ui.rsyntaxtextarea.RSyntaxTextAreaEditorKit;
@@ -63,6 +71,7 @@ import processing.app.syntax.PdeKeywords;
 import processing.app.syntax.SketchTextArea;
 import processing.app.syntax.SketchTextAreaEditorKit;
 import processing.app.tools.DiscourseFormat;
+import processing.app.tools.WatchDir;
 
 /**
  * Single tab, editing a single file, in the main window.
@@ -487,6 +496,10 @@ public class EditorTab extends JPanel implements SketchFile.TextStorage {
     return scrollPane.getVerticalScrollBar().getValue();
   }
 
+  public RTextScrollPane getScrollPane() {
+    return scrollPane;
+  }
+
   public void setScrollPosition(int pos) {
     scrollPane.getVerticalScrollBar().setValue(pos);
   }

app/src/processing/app/tools/WatchDir.java

@@ -0,0 +1,198 @@
+/*
+ * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   - Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *
+ *   - Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *
+ *   - Neither the name of Oracle nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package processing.app.tools;
+
+import java.nio.file.*;
+import static java.nio.file.StandardWatchEventKinds.*;
+import static java.nio.file.LinkOption.*;
+import java.nio.file.attribute.*;
+import java.io.*;
+import java.util.*;
+import processing.app.Editor;
+import processing.app.EditorTab;
+import processing.app.Sketch;
+import processing.app.SketchFile;
+import processing.app.helpers.FileUtils;
+
+/**
+ * Example to watch a directory (or tree) for changes to files.
+ */
+
+public class WatchDir {
+
+    private final WatchService watcher;
+    private final Map<WatchKey,Path> keys;
+    private final boolean recursive;
+    private boolean trace = false;
+
+    @SuppressWarnings("unchecked")
+    static <T> WatchEvent<T> cast(WatchEvent<?> event) {
+        return (WatchEvent<T>)event;
+    }
+
+    /**
+     * Register the given directory with the WatchService
+     */
+    private void register(Path dir) throws IOException {
+        WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
+        if (trace) {
+            Path prev = keys.get(key);
+            if (prev == null) {
+            } else {
+                if (!dir.equals(prev)) {
+                }
+            }
+        }
+        keys.put(key, dir);
+    }
+
+    /**
+     * Register the given directory, and all its sub-directories, with the
+     * WatchService.
+     */
+    private void registerAll(final Path start) throws IOException {
+        // register directory and sub-directories
+        Files.walkFileTree(start, new SimpleFileVisitor<Path>() {
+            @Override
+            public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs)
+                throws IOException
+            {
+                register(dir);
+                return FileVisitResult.CONTINUE;
+            }
+        });
+    }
+
+    /**
+     * Creates a WatchService and registers the given directory
+     */
+    public WatchDir(Path dir, boolean recursive) throws IOException {
+        this.watcher = FileSystems.getDefault().newWatchService();
+        this.keys = new HashMap<WatchKey,Path>();
+        this.recursive = recursive;
+
+        if (recursive) {
+            registerAll(dir);
+        } else {
+            register(dir);
+        }
+
+        // enable trace after initial registration
+        this.trace = true;
+    }
+
+    /**
+     * Process all events for keys queued to the watcher
+     */
+    public void processEvents(Editor editor) {
+        for (;;) {
+
+            // wait for key to be signalled
+            WatchKey key;
+            try {
+                key = watcher.take();
+            } catch (InterruptedException x) {
+                return;
+            }
+
+            Path dir = keys.get(key);
+            if (dir == null) {
+                continue;
+            }
+
+            for (WatchEvent<?> event: key.pollEvents()) {
+                WatchEvent.Kind kind = event.kind();
+
+                // TBD - provide example of how OVERFLOW event is handled
+                if (kind == OVERFLOW) {
+                    continue;
+                }
+
+                // Context for directory entry event is the file name of entry
+                WatchEvent<Path> ev = cast(event);
+                Path name = ev.context();
+                Path child = dir.resolve(name);
+
+                // reload the tab content
+                if (kind == ENTRY_CREATE) {
+                  try {
+                    String filename = name.toString();
+                    FileUtils.SplitFile split = FileUtils.splitFilename(filename);
+                    if (Sketch.EXTENSIONS.contains(split.extension.toLowerCase())) {
+                      SketchFile sketch = editor.getSketch().addFile(filename);
+                      editor.addTab(sketch, null);
+                    }
+                  } catch (Exception e) {
+                    return;
+                  }
+                } else if (kind == ENTRY_DELETE) {
+                  try {
+                    Thread.sleep(100);
+                    int index = editor.getSketch().findFileIndex(child.toAbsolutePath().toFile());
+                    editor.removeTab(editor.getSketch().getFile(index));
+                  } catch (Exception e1) {
+                    // Totally fine, if the sleep gets interrupted it means that
+                    // the action was executed in the UI, not externally
+                    return;
+                  }
+                }
+                editor.getTabs().forEach(tab -> {
+                  if (!tab.isModified()) {
+                      tab.reload();
+                    }
+                });
+                // if directory is created, and watching recursively, then
+                // register it and its sub-directories
+                if (recursive && (kind == ENTRY_CREATE)) {
+                    try {
+                        if (Files.isDirectory(child, NOFOLLOW_LINKS)) {
+                            registerAll(child);
+                        }
+                    } catch (IOException x) {
+                        // ignore to keep sample readbale
+                    }
+                }
+            }
+
+            // reset key and remove from set if directory no longer accessible
+            boolean valid = key.reset();
+            if (!valid) {
+                keys.remove(key);
+
+                // all directories are inaccessible
+                if (keys.isEmpty()) {
+                    break;
+                }
+            }
+        }
+    }
+}