Merge pull request #183 from ericdill/zero-div-is-bad

MNT: Don't allow divide by zero

pyqtgraph/graphicsItems/ImageItem.py

@@ -291,8 +291,8 @@ class ImageItem(GraphicsObject):
             y = self.mapToDevice(QtCore.QPointF(0,1))
             w = Point(x-o).length()
             h = Point(y-o).length()
-            xds = max(1, int(1/w))
-            yds = max(1, int(1/h))
+            xds = int(1/max(1, w))
+            yds = int(1/max(1, h))
             image = fn.downsample(self.image, xds, axis=0)
             image = fn.downsample(image, yds, axis=1)
         else:

pyqtgraph/graphicsItems/tests/test_ImageItem.py

@@ -0,0 +1,24 @@
+import gc
+import weakref
+# try:
+#     import faulthandler
+#     faulthandler.enable()
+# except ImportError:
+#     pass
+
+from pyqtgraph.Qt import QtCore, QtGui, QtTest
+import numpy as np
+import pyqtgraph as pg
+app = pg.mkQApp()
+
+
+def test_dividebyzero():
+    import pyqtgraph as pg
+    im = pg.image(pg.np.random.normal(size=(100,100)))
+    im.imageItem.setAutoDownsample(True)
+    im.view.setRange(xRange=[-5+25, 5e+25],yRange=[-5e+25, 5e+25])
+    app.processEvents()
+    QtTest.QTest.qWait(1000)
+    # must manually call im.imageItem.render here or the exception
+    # will only exist on the Qt event loop
+    im.imageItem.render()