Implement wait cursor delay for TreeView.

 - initial delay for wait cursor change
 - adds max lifespan for reset failures
 - cancellable

Co-authored-by: Laszlo Kishalmi <[email protected]>

Author: mbien

platform/openide.explorer/src/org/openide/explorer/view/TreeView.java

@@ -68,6 +68,8 @@
 import java.util.List;
 import java.util.Set;
 import java.util.HashSet;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import javax.accessibility.AccessibleContext;
@@ -915,73 +917,82 @@ public void setAutoWaitCursor(boolean enable) {
         autoWaitCursor = enable;
     }
 
-    //
-    // showing and removing the wait cursor
-    //
-    private void showWaitCursor (boolean show) {
-        JRootPane rPane = getRootPane();
-        if (rPane == null) {
+    private void maybeShowWaitCursor(Node node) {
+        if (node == null || !autoWaitCursor) {
             return;
         }
-
-        if (SwingUtilities.isEventDispatchThread()) {
-            doShowWaitCursor(rPane.getGlassPane(), show);
-        } else {
-            SwingUtilities.invokeLater(new CursorR(rPane.getGlassPane(), show));
+        JRootPane rootPane = getRootPane();
+        if (rootPane == null) {
+            return;
         }
+        // not sure whenter throughput 1 is OK...
+        ViewUtil.uiProcessor().post(() -> {
+            try (DelayedWaitCursor cursor = new DelayedWaitCursor(rootPane)) {
+                cursor.enable();
+                node.getChildren().getNodesCount(true);
+            } catch (Exception e) {
+                LOG.log(Level.WARNING, "can't determine node count", e);
+            }
+        });
     }
 
-    private static void doShowWaitCursor (Component glassPane, boolean show) {
-        if (show) {
-            glassPane.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
-            glassPane.setVisible(true);
-        } else {
-            glassPane.setVisible(false);
-            glassPane.setCursor(null);
-        }
-    }
+    /// Shows the wait cursor after an initial delay.
+    /// Can be used in ARM-blocks.
+    private static class DelayedWaitCursor implements AutoCloseable {
 
-    private static class CursorR implements Runnable {
-        private Component glassPane;
-        private boolean show;
+        private static final RequestProcessor RP = new RequestProcessor(DelayedWaitCursor.class.getName());
 
-        private CursorR(Component cont, boolean show) {
-            this.glassPane = cont;
-            this.show = show;
-        }
+        private static final int SPAWN_DELAY = 200;
+        private static final int MAX_LIFE_SPAN = 60_000;
 
-        @Override
-        public void run() {
-            doShowWaitCursor(glassPane, show);
-        }
-    }
+        private final JRootPane root;
+        private ScheduledFuture<?> scheduled;
 
-    private void prepareWaitCursor(final Node node) {
-        // check type of node
-        if (node == null || !autoWaitCursor) {
-            return;
+        private DelayedWaitCursor(JRootPane root) {
+            this.root = root;
         }
 
-        showWaitCursor(true);
-        // not sure whenter throughput 1 is OK...
-        ViewUtil.uiProcessor().post(new Runnable() {
-            @Override
-            public void run() {
-                try {
-                    node.getChildren().getNodesCount(true);
-                } catch (Exception e) {
-                    // log a exception
-                    LOG.log(Level.WARNING, null, e);
-                } finally {
-                    // show normal cursor above all
-                    showWaitCursor(false);
+        private void enable() {
+            if (scheduled != null) {
+                return;
+            }
+            scheduled = RP.schedule(() -> {
+                if (!scheduled.isCancelled()) {
+                    // switch to wait
+                    SwingUtilities.invokeLater(() -> {
+                        if (!scheduled.isCancelled()) {
+                            root.getGlassPane().setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
+                            root.getGlassPane().setVisible(true);
+                        }
+                    });
+                    // block to limit lifespan
+                    try {
+                        Thread.sleep(MAX_LIFE_SPAN);
+                    } catch (InterruptedException cancelled) {
+                        Thread.interrupted();
+                    }
                 }
+                // reset
+                SwingUtilities.invokeLater(() -> {
+                    root.getGlassPane().setVisible(false);
+                    root.getGlassPane().setCursor(null);
+                });
+            }, SPAWN_DELAY, TimeUnit.MILLISECONDS);
+        }
+
+        private void disable() {
+            if (scheduled != null) {
+                scheduled.cancel(true);
+                scheduled = null;
             }
-        });
+        }
+
+        @Override
+        public void close() {
+            disable();
+        }
     }
-    
-   
-    
+
     /** Synchronize the selected nodes from the manager of this Explorer.
     * The default implementation does nothing.
     */
@@ -1499,7 +1510,7 @@ public void treeWillExpand(TreeExpansionEvent event)
         throws ExpandVetoException {
             // prepare wait cursor and optionally show it
             TreePath path = event.getPath();
-            prepareWaitCursor(DragDropUtilities.secureFindNode(path.getLastPathComponent()));
+            maybeShowWaitCursor(DragDropUtilities.secureFindNode(path.getLastPathComponent()));
         }
     }
      // end of TreePropertyListener