feat: extract SpinnerAnimator for loading animations in AgentStatusLabel

Author: ethanyhou

com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/AgentStatusLabel.java

@@ -10,30 +10,26 @@
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.Composite;
-import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Label;
 import org.eclipse.ui.ISharedImages;
 import org.eclipse.ui.PlatformUI;
 import org.osgi.service.event.EventHandler;
 
 import com.microsoft.copilot.eclipse.core.events.CopilotEventConstants;
 import com.microsoft.copilot.eclipse.ui.swt.CssConstants;
+import com.microsoft.copilot.eclipse.ui.swt.SpinnerAnimator;
 import com.microsoft.copilot.eclipse.ui.utils.AccessibilityUtils;
 import com.microsoft.copilot.eclipse.ui.utils.UiUtils;
 
 /**
  * A label with icon that displays the running status of the agent.
  */
 public class AgentStatusLabel extends Composite {
-  private static final int TOTAL_FRAMES = 8; // Adjust based on actual number of spinner images
-
-  private Image runningIcon;
   private Image completedIcon;
   private Image cancelledIcon;
   private Label iconLabel;
   private ChatMarkupViewer textLabel;
-  private int currentFrame = 1;
-  private Runnable animationRunnable;
+  private SpinnerAnimator spinner;
   private Status status;
   private EventHandler cancelStatusHandler;
   private IEventBroker eventBroker;
@@ -47,14 +43,12 @@ public class AgentStatusLabel extends Composite {
   public AgentStatusLabel(Composite parent, int style) {
     super(parent, style);
     GridLayout layout = new GridLayout(2, false);
+    layout.marginWidth = 0;
+    layout.marginHeight = 0;
     layout.horizontalSpacing = 0;
     setLayout(layout);
     setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
     this.addDisposeListener(e -> {
-      stopAnimation();
-      if (this.runningIcon != null && !this.runningIcon.isDisposed()) {
-        this.runningIcon.dispose();
-      }
       if (this.completedIcon != null && !this.completedIcon.isDisposed()) {
         this.completedIcon.dispose();
       }
@@ -66,6 +60,7 @@ public AgentStatusLabel(Composite parent, int style) {
       }
     });
     iconLabel = new Label(this, SWT.LEFT);
+    spinner = new SpinnerAnimator(iconLabel);
 
     this.status = Status.RUNNING;
     this.cancelStatusHandler = new EventHandler() {
@@ -84,7 +79,7 @@ public void handleEvent(org.osgi.service.event.Event event) {
    * @param statusText the text to display when the agent is completed
    */
   public void setCompletedStatus(String statusText) {
-    stopAnimation();
+    spinner.stop();
 
     if (this.completedIcon == null) {
       this.completedIcon = UiUtils.buildImageFromPngPath("/icons/complete_status.png");
@@ -101,11 +96,7 @@ public void setCompletedStatus(String statusText) {
    * @param statusText the text to display when the agent is running
    */
   public void setRunningStatus(String statusText) {
-    // Stop any existing animation
-    stopAnimation();
-
-    // Start new animation
-    startAnimation();
+    spinner.start();
 
     setText(statusText);
     this.status = Status.RUNNING;
@@ -116,7 +107,7 @@ public void setRunningStatus(String statusText) {
    */
   public void setErrorStatus() {
     if (this.status == Status.RUNNING) {
-      stopAnimation();
+      spinner.stop();
     }
     iconLabel.setImage(PlatformUI.getWorkbench().getSharedImages().getImage(ISharedImages.IMG_OBJS_ERROR_TSK));
     this.status = Status.ERROR;
@@ -127,7 +118,7 @@ public void setErrorStatus() {
    */
   public void setCancelledStatus() {
     if (this.status == Status.RUNNING) {
-      stopAnimation();
+      spinner.stop();
 
       if (this.cancelledIcon == null) {
         this.cancelledIcon = UiUtils.buildImageFromPngPath("/icons/cancel_status.png");
@@ -138,47 +129,6 @@ public void setCancelledStatus() {
     }
   }
 
-  private void startAnimation() {
-    final Display display = getDisplay();
-
-    animationRunnable = new Runnable() {
-      @Override
-      public void run() {
-        if (isDisposed() || iconLabel.isDisposed()) {
-          return;
-        }
-
-        // Dispose previous image
-        if (runningIcon != null && !runningIcon.isDisposed()) {
-          runningIcon.dispose();
-        }
-
-        // Load the next frame
-        String imagePath = String.format("/icons/spinner/%d.png", currentFrame);
-        runningIcon = UiUtils.buildImageFromPngPath(imagePath);
-        iconLabel.setImage(runningIcon);
-        // request layout to update the icon, otherwise the scale of the spinner will be wrong
-        iconLabel.requestLayout();
-
-        // Update frame counter
-        currentFrame = (currentFrame % TOTAL_FRAMES) + 1;
-
-        // Schedule next frame
-        display.timerExec(100, this);
-      }
-    };
-
-    // Start the animation
-    display.timerExec(0, animationRunnable);
-  }
-
-  private void stopAnimation() {
-    if (animationRunnable != null) {
-      getDisplay().timerExec(-1, animationRunnable);
-      animationRunnable = null;
-    }
-  }
-
   /**
    * Set the text to display next to the icon.
    */

com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/swt/SpinnerAnimator.java

@@ -0,0 +1,99 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+package com.microsoft.copilot.eclipse.ui.swt;
+
+import org.eclipse.swt.graphics.Image;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Label;
+
+import com.microsoft.copilot.eclipse.ui.utils.UiUtils;
+
+/**
+ * Drives a rotating spinner animation on a target {@link Label}.
+ *
+ * <p>The animator owns the lifecycle of the per-frame {@link Image} resources: each new frame is
+ * loaded, the previous one is disposed, and {@link #stop()} guarantees that the label no longer
+ * holds a reference to a disposed image. After {@link #stop()} the caller is free to swap in a
+ * final image (e.g. a "completed" icon) on the same label.
+ *
+ * <p>The animator hooks the target label's dispose listener so the animation is cancelled and the
+ * running frame is freed automatically when the label goes away.
+ */
+public final class SpinnerAnimator {
+  /** Total number of frames in the spinner animation under {@code /icons/spinner/}. */
+  private static final int TOTAL_FRAMES = 8;
+  /** Per-frame interval in milliseconds. */
+  private static final int FRAME_INTERVAL_MS = 100;
+
+  private final Label target;
+  private Image currentFrameImage;
+  private int currentFrame = 1;
+  private Runnable animationRunnable;
+
+  /**
+   * Create an animator that will rotate spinner frames on the given label.
+   *
+   * @param target the label to update with each frame; must not be {@code null}
+   */
+  public SpinnerAnimator(Label target) {
+    this.target = target;
+    target.addDisposeListener(e -> stop());
+  }
+
+  /**
+   * Start (or restart) the animation. Safe to call when already running — the existing animation
+   * is cancelled first.
+   */
+  public void start() {
+    if (target.isDisposed()) {
+      return;
+    }
+    stop();
+    final Display display = target.getDisplay();
+    animationRunnable = new Runnable() {
+      @Override
+      public void run() {
+        if (target.isDisposed()) {
+          return;
+        }
+        // Dispose the previous frame before loading the next one.
+        if (currentFrameImage != null && !currentFrameImage.isDisposed()) {
+          currentFrameImage.dispose();
+        }
+        currentFrameImage = buildFrame(currentFrame);
+        target.setImage(currentFrameImage);
+        // Request layout so the icon scale stays correct as frames change.
+        target.requestLayout();
+        currentFrame = (currentFrame % TOTAL_FRAMES) + 1;
+        display.timerExec(FRAME_INTERVAL_MS, this);
+      }
+    };
+    display.timerExec(0, animationRunnable);
+  }
+
+  /**
+   * Stop the animation and release the frame image. Detaches the image from the target label
+   * before disposing it so the label never points at a disposed image. Safe to call repeatedly.
+   */
+  public void stop() {
+    if (animationRunnable != null && !target.isDisposed()) {
+      target.getDisplay().timerExec(-1, animationRunnable);
+    }
+    animationRunnable = null;
+    // Detach the image from the label before disposing it so the label never points at a
+    // disposed image. Callers that want a final icon (completed/cancelled/error) set it
+    // immediately after stop(), avoiding any visible flicker.
+    if (!target.isDisposed() && target.getImage() == currentFrameImage) {
+      target.setImage(null);
+    }
+    if (currentFrameImage != null && !currentFrameImage.isDisposed()) {
+      currentFrameImage.dispose();
+    }
+    currentFrameImage = null;
+  }
+
+  private static Image buildFrame(int frame) {
+    return UiUtils.buildImageFromPngPath(String.format("/icons/spinner/%d.png", frame));
+  }
+}