218 CHAPTER12. OBJECT-ORIENTEDDESIGN
if b.clicked(p):
returnb.getLabel() # function exit here.TheotherwidgetsinourinterfacewillbeourDieViewthatwedevelopedinthelasttwo chapters.
Basically, wewillusethesameclassasbefore,butweneedtoaddjusta bitofnewfunctionality. As
discussedabove, wewanttochangethecolorofa dietoindicatewhetherit is selectedforrerolling.
YoumightwanttogobackandreviewtheDieViewclass. Remember, theclasscontructordraws
a squareandsevencirclestorepresentthepositionswherethepipsofvariousvalueswillappear. The
setValuemethodturnsontheappropriatepipstodisplaya givenvalue.To refreshyourmemorya bit,
hereis thesetValuemethodasweleftit:
def setValue(self,value):
# Turn all thepips off
for pip in self.pips:
pip.setFill(self.background)# Turn the appropriatepips back on
for i in self.onTable[value]:
self.pips[i].setFill(self.foreground)We needtomodifytheDieViewclassbyaddingasetColormethod. Thismethodwillbeusedto
changethecolorthatis usedfordrawingthepips.AsyoucanseeinthecodeforsetValue, thecolorof
thepipsis determinedbythevalueoftheinstancevariableforeground. Ofcourse,changingthevalueof
foregroudwillnotactuallychangetheappearanceofthedieuntilit is redrawnusingthenew color.
ThealgorithmforsetColorseemsstraightforward.We needtwo steps:
change foreground to the newcolor
redraw the currentvalue of the die
Unfortunately, thesecondsteppresentsa slightsnag. We alreadyhave codethatdrawsa value,namely
setValue. ButsetValuerequiresustosendthevalueasa parameter, andthecurrentversionof
DieViewdoesnotstorethisvalueanywhere.Oncetheproperpipshave beenturnedon,theactualvalueis
discarded.
InordertoimplementsetColor, weneedtotweaksetValuesothatit remembersthecurrentvalue.
ThensetColorcanredraw thedieusingitscurrentvalue.ThechangetosetValueis easy;wejustneed
toadda singleline.
self.value = value
Thislinestoresthevalueparameterinaninstancevariablecalledvalue.
WiththemodifiedversionofsetValue, implementingsetColoris a breeze.
def setColor(self,color):
self.foreground= color
self.setValue(self.value)Noticehow thelastlinesimplycallssetValueto(re)draw thedie,passingalongthevaluethatwassaved
fromthelasttimesetValuewascalled.
CreatingtheInterface
Nowthatwehave ourwidgetsundercontrol,wearereadytoactuallyimplementourGUIpokerinterface.
Theconstructorwillcreateallofourwidgets,settinguptheinterfaceforlaterinteractions.
class GraphicsInterface:
def init(self):
self.win = GraphWin("DicePoker", 600, 400)
self.win.setBackground("green3")