fix up file change detection (#2852)

app/src/processing/app/ChangeDetector.java

@@ -15,7 +15,8 @@ public class ChangeDetector implements WindowFocusListener {
   private Sketch sketch;
   private Editor editor;
 
-  private boolean enabled = true;
+  // Set true if the user selected 'no'. TODO this can't just skip once,
+  // because subsequent returns to the window w/o saving will keep firing.
   private boolean skip = false;
 
 
@@ -25,6 +26,34 @@ public class ChangeDetector implements WindowFocusListener {
   }
 
 
+  @Override
+  public void windowGainedFocus(WindowEvent e) {
+    // Keep the listener instantiated and check this to avoid a maze of
+    // adding and removing and re-adding with Preferences changes.
+    if (Preferences.getBoolean("editor.watcher")) {
+      // if they selected no, skip the next focus event
+      if (skip) {
+        skip = false;
+
+      } else {
+        new Thread(new Runnable() {
+          @Override
+          public void run() {
+            checkFileChange();
+          }
+        }).start();
+      }
+    }
+  }
+
+
+  @Override
+  public void windowLostFocus(WindowEvent e) {
+    // Shouldn't need to do anything here, and not storing anything here b/c we
+    // don't want to assume a loss of focus is required before change detection
+  }
+
+
   private void checkFileChange() {
     //check that the content of each of the files in sketch matches what is in memory
     if (sketch == null) {
@@ -143,36 +172,6 @@ public class ChangeDetector implements WindowFocusListener {
   }
 
 
-  @Override
-  public void windowLostFocus(WindowEvent e) {
-    //shouldn't need to do anything here
-  }
-
-
-  @Override
-  public void windowGainedFocus(WindowEvent e) {
-    if (enabled) {
-      //remove the detector from main if it is disabled during runtime (due to an error?)
-      //if (!enabled || !Preferences.getBoolean("editor.watcher")) {
-      //editor.removeWindowFocusListener(this);
-      //} else if (skip) {
-
-      // if they selected no, skip the next focus event
-      if (skip) {
-        skip = false;
-
-      } else {
-        new Thread(new Runnable() {
-          @Override
-          public void run() {
-            checkFileChange();
-          }
-        }).start();
-      }
-    }
-  }
-
-
   private void showErrorEDT(final String title, final String message,
                               final Exception e) {
     EventQueue.invokeLater(new Runnable() {

build/shared/lib/defaults.txt

@@ -148,7 +148,7 @@ editor.tabs.size = 2
 # automatically indent each line
 editor.indent = true
 
-# Whether to automatically reload modified tabs
+# Whether to check files to see if they've been modified externally
 editor.watcher = true
 
 # Hide the background image. Gross because this is a pref that

todo.txt

@@ -29,6 +29,8 @@ X   https://github.com/processing/processing/commit/0a14835e6f5f4766b022e73a8fe5
 X the .macosx, .linux, etc prefs should be stripped
 X   only use them on first load, and merge into preferences.txt
 X auto-insert after antlr @SuppressWarnings({ "unused", "unchecked", "cast" })
+X fix file change detection on OS X
+X   https://github.com/processing/processing/issues/2852
 
 _ editor window draws in stages (at least on OS X) on first view
 _ "sketch modified" message still happening
@@ -270,8 +272,6 @@ _ how are we going to handle fonts for other languages?
 _   two new fonts have been added, other languages will need more
 _   need a decent sans with with Unicode coverage
 _   i.e. https://github.com/processing/processing/pull/3025
-_ fix file change detection on OS X
-_   https://github.com/processing/processing/issues/2852
 _ make examples pull/build automatic during dist
 _ add span screens pref (near the display pref)
 _   add checkbox for spans to export dialog