fixed mouse scaling issue introduced in inp a few commits ago

added panning plot example

examples/PanningPlot.py

@@ -0,0 +1,37 @@
+# -*- coding: utf-8 -*-
+"""
+Shows use of PlotWidget to display panning data
+
+"""
+import initExample ## Add path to library (just for examples; you do not need this)
+
+import pyqtgraph as pg
+from pyqtgraph.Qt import QtCore, QtGui
+import numpy as np
+
+win = pg.GraphicsWindow()
+win.setWindowTitle('pyqtgraph example: PanningPlot')
+
+plt = win.addPlot()
+#plt.setAutoVisibleOnly(y=True)
+curve = plt.plot()
+
+data = []
+count = 0
+def update():
+    global data, curve, count
+    data.append(np.random.normal(size=10) + np.sin(count * 0.1) * 5)
+    if len(data) > 100:
+        data.pop(0)
+    curve.setData(np.hstack(data))
+    count += 1
+
+timer = QtCore.QTimer()
+timer.timeout.connect(update)
+timer.start(50)
+
+## Start Qt event loop unless running in interactive mode or using pyside.
+if __name__ == '__main__':
+    import sys
+    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
+        QtGui.QApplication.instance().exec_()

pyqtgraph/graphicsItems/ViewBox/ViewBox.py

@@ -950,7 +950,8 @@ class ViewBox(GraphicsWidget):
         dif = dif * -1
 
         ## Ignore axes if mouse is disabled
-        mask = np.array(self.state['mouseEnabled'], dtype=np.float)
+        mouseEnabled = np.array(self.state['mouseEnabled'], dtype=np.float)
+        mask = mouseEnabled.copy()
         if axis is not None:
             mask[1-axis] = 0.0
 
@@ -990,8 +991,8 @@ class ViewBox(GraphicsWidget):
             tr = self.childGroup.transform()
             tr = fn.invertQTransform(tr)
             
-            x = s[0] if mask[0] == 1 else None
-            y = s[1] if mask[1] == 1 else None
+            x = s[0] if mouseEnabled[0] == 1 else None
+            y = s[1] if mouseEnabled[1] == 1 else None
             
             center = Point(tr.map(ev.buttonDownPos(QtCore.Qt.RightButton)))
             self.scaleBy(x=x, y=y, center=center)