From 06ae1c568add6495889d54f9618a64a40ff37c62 Mon Sep 17 00:00:00 2001
From: Xen0Xys <red57101@gmail.com>
Date: Wed, 31 Jul 2024 12:09:56 +0200
Subject: [PATCH] :goal_net: Add error when exporting the WCS while the widget
 is reduced when hidden

---
 js/models/event_handler.js        |  6 +++++-
 src/ipyaladin/utils/exceptions.py |  8 ++++++++
 src/ipyaladin/widget.py           | 13 ++++++++++++-
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/js/models/event_handler.js b/js/models/event_handler.js
index d5d6fc68..5bac5d24 100644
--- a/js/models/event_handler.js
+++ b/js/models/event_handler.js
@@ -160,7 +160,11 @@ export default class EventHandler {
 
     this.aladin.on("resizeChanged", (width, height) => {
       // Skip resize event when the div is hidden
-      if (width === 1 && height === 1) return;
+      if (width === 1 && height === 1) {
+        this.model.set("_is_reduced", true);
+        this.model.save_changes();
+        return;
+      } else this.model.set("_is_reduced", false);
       this.updateWCS();
       this.update2AxisFoV();
       this.model.set("_height", height);
diff --git a/src/ipyaladin/utils/exceptions.py b/src/ipyaladin/utils/exceptions.py
index a77b3e73..0de125af 100644
--- a/src/ipyaladin/utils/exceptions.py
+++ b/src/ipyaladin/utils/exceptions.py
@@ -4,3 +4,11 @@ class WidgetCommunicationError(OSError):
     def __init__(self, message: str) -> None:
         self.message = message
         super(WidgetCommunicationError, self).__init__(message)
+
+
+class WidgetReducedError(ValueError):
+    """Error raised when a widget is reduced to a point when hidden."""
+
+    def __init__(self, message: str) -> None:
+        self.message = message
+        super(WidgetReducedError, self).__init__(message)
diff --git a/src/ipyaladin/widget.py b/src/ipyaladin/widget.py
index af4f54a1..0af4a944 100644
--- a/src/ipyaladin/widget.py
+++ b/src/ipyaladin/widget.py
@@ -23,7 +23,7 @@
 import numpy as np
 import traitlets
 
-from .utils.exceptions import WidgetCommunicationError
+from .utils.exceptions import WidgetCommunicationError, WidgetReducedError
 from .utils._coordinate_parser import parse_coordinate_string
 
 try:
@@ -212,6 +212,13 @@ class Aladin(anywidget.AnyWidget):
         "to convert the view to an astropy.HDUList",
     ).tag(sync=True)
 
+    # Temporary traitlets for widget size problem
+    _is_reduced = Bool(
+        False,
+        help="A private trait that stores if the widget "
+        "is reduced in size when hidden.",
+    ).tag(sync=True)
+
     init_options = traitlets.List(trait=Any()).tag(sync=True)
 
     @default("init_options")
@@ -289,6 +296,10 @@ def wcs(self) -> WCS:
             An astropy WCS object representing the world coordinate system.
 
         """
+        if self._is_reduced:
+            raise WidgetReducedError(
+                "WCS might be wrong if the Aladin Lite widget is not visible"
+            )
         if self._wcs == {}:
             raise WidgetCommunicationError(
                 "The world coordinate system is not available. "