From ee117fd957c1f001a089c1dc6733ce35fb4dff69 Mon Sep 17 00:00:00 2001
From: Luke Campagnola <ausqualius@yahoo.com>
Date: Wed, 13 Sep 2017 21:02:58 -0700
Subject: [PATCH] Give CanvasItem alpha/setAlpha methods

---
 pyqtgraph/canvas/CanvasItem.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/pyqtgraph/canvas/CanvasItem.py b/pyqtgraph/canvas/CanvasItem.py
index bab89e89..eb6d0a61 100644
--- a/pyqtgraph/canvas/CanvasItem.py
+++ b/pyqtgraph/canvas/CanvasItem.py
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+import numpy as np
 from ..Qt import QtGui, QtCore, QtSvg, QT_LIB
 from ..graphicsItems.ROI import ROI
 from .. import SRTTransform, ItemGroup
@@ -239,6 +240,12 @@ class CanvasItem(QtCore.QObject):
         alpha = val / 1023.
         self._graphicsItem.setOpacity(alpha)
         
+    def setAlpha(self, alpha):
+        self.alphaSlider.setValue(int(np.clip(alpha * 1023, 0, 1023)))
+        
+    def alpha(self):
+        return self.alphaSlider.value() / 1023.
+        
     def isMovable(self):
         return self.opts['movable']