ENH: Generalize add_widget function.

skimage/viewer/plugins/base.py

@@ -78,17 +78,16 @@ class Plugin(QtGui.QDialog):
         else:
             return param
 
-    def add_widget(self, name, low, high, **kwargs):
-        slider = Slider(name, low, high, **kwargs)
-        if slider.ptype == 'kwarg':
-            self.keyword_arguments[name] = slider
-            slider.callback = self.filter_image
-        elif slider.ptype == 'arg':
-            self.keyword_arguments[name] = slider
-            self.arguments.append(slider)
-        self.layout.addWidget(slider, self.row, 0)
+    def add_widget(self, widget):
+        if widget.ptype == 'kwarg':
+            name = widget.name.replace(' ', '_')
+            self.keyword_arguments[name] = widget
+            widget.callback = self.filter_image
+        elif widget.ptype == 'arg':
+            self.arguments.append(widget)
+            widget.callback = self.filter_image
+        self.layout.addWidget(widget, self.row, 0)
         self.row += 1
-        return name.replace(' ', '_'), slider
 
     def closeEvent(self, event):
         """Disconnect all artists and events from ImageViewer.

skimage/viewer/plugins/canny.py

@@ -1,6 +1,7 @@
 from skimage.filter import canny
 
 from .overlayplugin import OverlayPlugin
+from ..widgets import Slider
 
 
 class CannyPlugin(OverlayPlugin):
@@ -12,9 +13,9 @@ class CannyPlugin(OverlayPlugin):
         width = kwargs.get('width', 400)
         super(CannyPlugin, self).__init__(image_viewer,
                                           width=width, height=height)
-        self.add_widget('sigma', 0, 5, update_on='release')
-        self.add_widget('low_threshold', 0, 255, update_on='release')
-        self.add_widget('high_threshold', 0, 255, update_on='release')
+        self.add_widget(Slider('sigma', 0, 5, update_on='release'))
+        self.add_widget(Slider('low threshold', 0, 255, update_on='release'))
+        self.add_widget(Slider('high threshold', 0, 255, update_on='release'))
         # Update image overlay to default slider values.
         self.filter_image()
 

skimage/viewer/widgets/core.py

@@ -7,8 +7,9 @@ class Slider(IntelligentSlider):
     ----------
     name : str
         Name of slider parameter. If this parameter is passed as a keyword
-        argument, it must match the name of that keyword argument. In addition,
-        this name is displayed as the name of the slider.
+        argument, it must match the name of that keyword argument (spaces are
+        replaced with underscores). In addition, this name is displayed as the
+        name of the slider.
     low, high : float
         Range of slider values.
     ptype : {'arg' | 'kwarg' | ...}