Example 2: A Threshold Slider

Let’s try for a slightly more interactive example. Recall that in our sample database we have an edge feature called freq. If we want the user to be able to control the frequency easily we can easily create a toolbar with a slider that hides and shows edges depending on the user controlled threshold. The code and screenshot for this included below:

import java
import javax.swing
import com

class dockexample2(com.hp.hpl.guess.ui.DockableAdapter):

   testSlider = JSlider()  # keep the label and slider
   label = JLabel("Frequency threshold (0)   ")

   def __init__(self):
         # set up the slider limits
         self.testSlider.setMinimum(freq.min)
         self.testSlider.setMaximum(freq.max + 1)

         # set up the slider visual properties
         self.testSlider.setMajorTickSpacing(50)
         self.testSlider.setMinorTickSpacing(10)
         self.testSlider.setPaintTicks(true)
         self.testSlider.setPaintLabels(true)
         self.testSlider.setValue(freq.min)  # default value

         # every time the mouse is released call the "sc" method
         self.testSlider.mouseReleased = self.sc

         # add the label and slider to the UI
         self.add(self.label)
         self.add(self.testSlider)

         # dock the new panel into the UI
         ui.dock(self)

         # call the event function once so that the
         # display matches the slider value
         self.sc(None)

   def getTitle(self):
         return("dockexample2")

   def sc(self,evt):
         # get the value
         val = self.testSlider.getValue()

         # show all the nodes
         g.nodes.visible = 1

         # hide all edges under value and show all over
         (freq < val).visible = 0
         (freq >= val).visible = 1

         # hide nodes not connected to visible edges
         self.hideDisconnectedNodes()

         # set the label text
         self.label.setText("Frequency threshold ("+str(val)+")")

   def hideDisconnectedNodes(self):
         # keep a list of nodes to hide, java doesn’t
         # like us to modify objects as we iterate over them
         toHide = []

         for nod in g.nodes:  # for all nodes
               vis = 0      # default to invisble

               # for all edges connected to this node
               # if there is any visible edge
               # keep this node visible
               for ed in nod.getOutEdges():
                     if (ed.visible == 1):
                           vis = 1
                           break

               if (vis == 0):  # should we hide the node?
                     toHide += [nod]

         # hide all the nodes we put in our list
         toHide.visible = 0