From 6b8bf824c652a659131dfbe594bd042c383fc85f Mon Sep 17 00:00:00 2001
From: "vn.py" <xiaoyou.chen@foxmail.com>
Date: Fri, 19 Jul 2019 16:04:24 +0800
Subject: [PATCH] [Mod] use partial update to improve plotting speed

---
 vnpy/chart/item.py   | 3 +++
 vnpy/chart/widget.py | 9 ++-------
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/vnpy/chart/item.py b/vnpy/chart/item.py
index c63adee3..467b9c3e 100644
--- a/vnpy/chart/item.py
+++ b/vnpy/chart/item.py
@@ -34,6 +34,9 @@ class ChartItem(pg.GraphicsObject):
 
         self._rect_area: Tuple[float, float] = None
 
+        # Very important! Only redraw the visible part and improve speed a lot.
+        self.setFlag(self.ItemUsesExtendedStyleOption)
+
     @abstractmethod
     def _draw_bar_picture(self, ix: int, bar: BarData) -> QtGui.QPicture:
         """
diff --git a/vnpy/chart/widget.py b/vnpy/chart/widget.py
index bf6455fe..53b5da1a 100644
--- a/vnpy/chart/widget.py
+++ b/vnpy/chart/widget.py
@@ -397,12 +397,7 @@ class ChartCursor(QtCore.QObject):
         """
         Connect mouse move signal to update function.
         """
-        self._proxy = pg.SignalProxy(
-            self._widget.scene().sigMouseMoved,
-            delay=0.1,
-            rateLimit=60,
-            slot=self._mouse_moved
-        )
+        self._widget.scene().sigMouseMoved.connect(self._mouse_moved)
 
     def _mouse_moved(self, evt: tuple) -> None:
         """
@@ -412,7 +407,7 @@ class ChartCursor(QtCore.QObject):
             return
 
         # First get current mouse point
-        pos = evt[0]
+        pos = evt
 
         for plot_name, view in self._views.items():
             rect = view.sceneBoundingRect()