Added 'stepMode' argument to PlotDataItem()

Merge branch 'plotdataitem_stepmode' into develop

CHANGELOG

@@ -47,6 +47,7 @@ pyqtgraph-0.9.9  [unreleased]
         - PeriodicTrace used to report deadlocks
     - Added AxisItem.setStyle()
     - Added configurable formatting for TableWidget
+    - Added 'stepMode' argument to PlotDataItem()
 
   Bugfixes:
     - PlotCurveItem now has correct clicking behavior--clicks within a few px

examples/histogram.py

@@ -2,8 +2,6 @@
 """
 In this example we draw two different kinds of histogram.
 """
-
-
 import initExample ## Add path to library (just for examples; you do not need this)
 
 import pyqtgraph as pg
@@ -22,11 +20,9 @@ vals = np.hstack([np.random.normal(size=500), np.random.normal(size=260, loc=4)]
 ## compute standard histogram
 y,x = np.histogram(vals, bins=np.linspace(-3, 8, 40))
 
+## Using stepMode=True causes the plot to draw two lines for each sample.
 ## notice that len(x) == len(y)+1
-## We are required to use stepMode=True so that PlotCurveItem will interpret this data correctly.
-curve = pg.PlotCurveItem(x, y, stepMode=True, fillLevel=0, brush=(0, 0, 255, 80))
-plt1.addItem(curve)
-
+plt1.plot(x, y, stepMode=True, fillLevel=0, brush=(0,0,255,150))
 
 ## Now draw all points as a nicely-spaced scatter plot
 y = pg.pseudoScatter(vals, spacing=0.15)

pyqtgraph/graphicsItems/PlotDataItem.py

@@ -68,6 +68,10 @@ class PlotDataItem(GraphicsObject):
             fillLevel    Fill the area between the curve and fillLevel
             fillBrush    Fill to use when fillLevel is specified. 
                          May be any single argument accepted by :func:`mkBrush() <pyqtgraph.mkBrush>`
+            stepMode     If True, two orthogonal lines are drawn for each sample
+                         as steps. This is commonly used when drawing histograms.
+                         Note that in this case, `len(x) == len(y) + 1`
+                         (added in version 0.9.9)
             ==========   ==============================================================================
         
         **Point style keyword arguments:**  (see :func:`ScatterPlotItem.setData() <pyqtgraph.ScatterPlotItem.setData>` for more information)
@@ -150,6 +154,7 @@ class PlotDataItem(GraphicsObject):
             'shadowPen': None,
             'fillLevel': None,
             'fillBrush': None,
+            'stepMode': None, 
             
             'symbol': None,
             'symbolSize': 10,
@@ -456,7 +461,7 @@ class PlotDataItem(GraphicsObject):
     def updateItems(self):
         
         curveArgs = {}
-        for k,v in [('pen','pen'), ('shadowPen','shadowPen'), ('fillLevel','fillLevel'), ('fillBrush', 'brush'), ('antialias', 'antialias'), ('connect', 'connect')]:
+        for k,v in [('pen','pen'), ('shadowPen','shadowPen'), ('fillLevel','fillLevel'), ('fillBrush', 'brush'), ('antialias', 'antialias'), ('connect', 'connect'), ('stepMode', 'stepMode')]:
             curveArgs[v] = self.opts[k]
         
         scatterArgs = {}