Bug Fixes/Enhancements:

- Added the chart.spinner method, which when set to `True` shows a loading spinner on the chart (a nice visual for API calls, large datasets etc).
- If an empty data frame is passed to set (eg.`chart.set(pd.DataFrame())`) the volume series and candle series will be cleared.
- added the `cumulative_volume` parameter to `update_from_tick`, which adds the given volume tick onto the latest bar.
- Added `vert_visible` and `horz_visible` parameters to `crosshair`.
- Small style improvements to the searchbox and topbar.
- Fixed a bug preventing callbacks within `WxChart` and `QtChart`

Thanks to @emma-uw for the following fixes and enhancements!
- Methods `hide_data`, `show_data`  and `price_line` can be used within Charts, Subcharts and Lines to change the visibility of data, price lines, and the price line labels.
- Added the `delete` method to Line, which irreversably deletes the Line on the chart as well as its objects in JavaScript and Python.
- Added the `lines` common method, which returns a list of all Line objects for the chart.
- Added the `fit` method to the common methods, which uses the `fitContent()` method from Lightweight Charts.
- Fixed a big which caused synced SubCharts to be out of sync upon loading.

BETA: Polygon.io integration
- Added the `PolygonChart` and `polygon` method, allowing for direct integration of polygon.io’s API.
- This feature is still in beta, and there will be a full announcement and update once the feature is complete!

lightweight_charts/chart.py

@@ -1,6 +1,7 @@
 import asyncio
-import webview
+import time
 import multiprocessing as mp
+import webview
 
 from lightweight_charts.js import LWC, CALLBACK_SCRIPT, TopBar
 
@@ -63,6 +64,7 @@ class Chart(LWC):
         if not topbar and not searchbox:
             return
         self.run_script(CALLBACK_SCRIPT)
+        self.run_script(f'makeSpinner({self.id})')
         self.topbar = TopBar(self) if topbar else None
         self._make_search_box() if searchbox else None
 
@@ -79,10 +81,18 @@ class Chart(LWC):
             self._q.put('show')
         if block:
             try:
-                self._exit.wait()
+                while 1:
+                    while not self._exit.is_set() and self.polygon._q.empty():
+                        time.sleep(0.05)
+                        continue
+                    if self._exit.is_set():
+                        self._exit.clear()
+                        return
+                    value = self.polygon._q.get_nowait()
+                    func, args = value[0], value[1:]
+                    func(*args)
             except KeyboardInterrupt:
                 return
-            self._exit.clear()
 
     async def show_async(self, block=False):
         if not self.loaded:
@@ -94,17 +104,23 @@ class Chart(LWC):
         if block:
             try:
                 while 1:
-                    while self._emit.empty() and not self._exit.is_set():
-                        await asyncio.sleep(0.1)
+                    while self._emit.empty() and not self._exit.is_set() and self.polygon._q.empty():
+                        await asyncio.sleep(0.05)
                     if self._exit.is_set():
+                        self._exit.clear()
                         return
-                    key, chart_id, arg = self._emit.get()
-                    self.api.chart = self._charts[chart_id]
-                    if widget := self.api.chart.topbar._widget_with_method(key):
-                        widget.value = arg
-                        await getattr(self.api, key)()
-                    else:
-                        await getattr(self.api, key)(arg)
+                    elif not self._emit.empty():
+                        key, chart_id, arg = self._emit.get()
+                        self.api.chart = self._charts[chart_id]
+                        if widget := self.api.chart.topbar._widget_with_method(key):
+                            widget.value = arg
+                            await getattr(self.api, key)()
+                        else:
+                            await getattr(self.api, key)(arg)
+                        continue
+                    value = self.polygon._q.get()
+                    func, args = value[0], value[1:]
+                    func(*args)
             except KeyboardInterrupt:
                 return
         asyncio.create_task(self.show_async(block=True))
@@ -123,4 +139,3 @@ class Chart(LWC):
         self._exit.wait()
         self._process.terminate()
         del self
-