Workaround for plotting data containing NaNs

Data containing NaNs doesn't render properly with the current versions
of PyQtGraph (0.11.0rc0) and PyQt (5.14.x). This commit adds a function
to work around this which is used in the distance detector.

Related issues:
SainsburyWellcomeCentre/lasagna#247
pyqtgraph/pyqtgraph#1057

Fix taken from here:
pyqtgraph/pyqtgraph#1057 (comment)

Change-Id: Ia57dadc66551c171bd52da6379d4e8524e8a82bd

examples/processing/distance_detector.py

@@ -661,7 +661,8 @@ def setup(self, win):
     def update(self, data):
         self.sweep_curve.setData(100.0 * self.r, data["sweep"])
         self.mean_sweep_curve.setData(100.0 * self.r, data["last_mean_sweep"])
-        self.threshold_curve.setData(100.0 * self.r, data["threshold"])
+        utils.pg_curve_set_data_with_nan(  # Workaround for bug in PyQt5/PyQtGraph
+            self.threshold_curve, 100.0 * self.r, data["threshold"])
 
         m = max(2 * np.nanmax(data["threshold"]),
                 np.max(data["sweep"]),

src/acconeer/exptool/__init__.py

@@ -1,3 +1,3 @@
-__version__ = "3.2.19"
+__version__ = "3.2.20"
 
 SDK_VERSION = "2.1.0"

src/acconeer/exptool/utils.py

@@ -391,3 +391,16 @@ def hex_to_rgb_tuple(hex_color):
 
 def is_power_of_2(n):
     return (n & (n - 1) == 0) and n != 0
+
+
+def pg_curve_set_data_with_nan(curve, x, y):
+    # Workaround for PyQt5 related bug in PyQtGraph where curves don't render if they contain NaNs
+    # https://github.com/SainsburyWellcomeCentre/lasagna/issues/247
+    # https://github.com/pyqtgraph/pyqtgraph/issues/1057
+    # https://github.com/pyqtgraph/pyqtgraph/issues/1057#issuecomment-543190337
+
+    z = np.array(y)
+    finite = np.isfinite(z)
+    z[~finite] = 0
+    connect = np.logical_and(finite, np.roll(finite, -1))
+    return curve.setData(x, z, connect=connect)