Animation. Classes in Python. Importing Modules. Modules in Python. CS111 Computer Programming. o We studied classes last week o Convention:

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1 Animatin CS111 Cmputer Prgramming Department f Cmputer Science Wellesley Cllege Classes in Pythn We studied classes last week Cnventin: We will start names f classes with an upper case letter, and cntinue in lwer case (except t indicate wrd bundaries). class ThisIsALegitimateClassName: class AndThis: class Canvas: This is just a cnventin. Pythn desn t care if yu flut it. But yu will cnfuse readers f yur cde if yu write uncnventinal names like: class badname: class classwithaterriblename 18-2 Mdules in Pythn A mdule is a file cntaining pythn definitins. Cnventin: name yur mdules in lwercase. Our Intentin: Mdules will cntain definitins f classes Try t keep related classes tgether in ne mdule We re nt the nly nes cs1graphics.py had a lt f class definitins Many classes: Canvas, Circle, etc.. Imprting Mdules The ld, lazy way: frm cs1graphics imprt * Lets us refer t Canvas, Circle, Plygn, etc The better way: imprt cs1graphics Nw yu must use full names f classes: cs1graphics.canvas, cs1graphics.plygn, etc The preferred Pythnic way: imprt cs1graphics as cs1g # r sme ther shrt name Nw the full names f classes are shrtened: cs1g.canvas, cs1g.plygn, etc

2 Drawing with Tkinter Fairly similar t cs1graphics Tends t require fewer lines f cde Sme things that are easy in cs1graphics can be challenging in Tkinter: N built-in Layers. Layers will require a list f what s been drawn, and yu ll use fr lps t affect each layer item. N rtatins. Yu ll have t maintain a list f crdinates and perfrm trignmetry and linear algebra t achieve rtatins (r trickery, as we ll see in Windmills shrtly). N flips. Again, yu ll have t maintain lists f crdinates. First Example Lk at cde in TkinterDrawDem Things t nte: tk.tk # rt bject tk.frame # t hld the tk.canvas # in which we draw The App class Alternative way t make clrs RGB tri #rrggbb rr is tw hex digits frm 00 t FF (0-255) fr red cmpnent. Similarly gg green, bb blue Add sme bells and whistles Lk at TkinterDrawDem2.py Observe hw yu can mve items n a canvas self.canvas.mve(id, dx, dy) Observe hw yu can mdify sme attributes (like clr) f items n a canvas self.canvas.itemcnfig(id, ) Observe hw yu can time things t ccur after a specified number f millisecnds after(time, functin) Macs nly (bserve hw t bring drawing windw t frnt) A first animatin The Blb Canpy nly: Need t kill rt after animatin!

3 Animatins Our animatins will use the tkinter and animatin mdules: imprt Tkinter as tk imprt animatin The animatin mdule cntains tw classes: AnimatinCanvas and AnimatedObject T create animatins, we will perfrm the fllwing steps: Create an animatedcanvas bject canvas = animatin.animatincanvas(frame, width=500, height=300) Add an animated bject t the Animatin canvas.additem(blb.blb(canvas, (100, 150), 40, 20, "gld", 5)) Start the animatin canvas.start() 18-9 canvas.additem(blb.blb(canvas, (100, 150), 40, 20, "gld", 5)) A Blb The Blb class is defined in the mdule blb.py S yu will want t imprt blb class Blb(animatin.AnimatedObject): A Blb is an animatin.animatedobject What s an Animated Object? Animated Objects Like any bject, an animated bject has state and behavirs (instance variables and methds), and the state f the bject can change ver time. T enable creatin f animated bjects, we write a new class that inherits frm the AnimatedObject class and verrides the fllwing methd: mve(self) '''Changes the state f the bject frm ne frame t the next''' Example Animated Object: Blb imprt animatin class Blb(animatin.AnimatedObject): def mve(self):

4 Blb init methd class Blb(animatin.AnimatedObject): What prperties are the same fr all Blb bjects? What prperties differ? Hw will Blb bjects be drawn (d we want Rectangles, Arcs, etc.)? What instance variables d we want? Hw shuld the instance variables be initialized? class Blb(AnimatedObject): def init (self, canvas xy, w, h, ink, delta): self.canvas = canvas # my animatincanvas self.delta = delta # my speed self.id = self.canvas.create_val( xy[0], xy[1], xy[0]+w, xy[1]+h, # bunding bx fill=ink # clr ) class Blb(AnimatedObject): def mve(self): Many Blbs Animatin T create animatins, we will perfrm the fllwing steps: Create a Canvas bject Create an animated bject Add the animated bject t the Animatin Start the animatin But this time we ll add a bunch f Blbs canvas = animatincanvas.animatincanvas(frame, width=500, height=300) canvas.pack() canvas.additem(blb.blb(canvas, (100, 100), 40, 20, "red", 3)) canvas.additem(blb.blb(canvas, (100, 150), 40, 40, "blue", 5)) canvas.additem(blb.blb(canvas, (200, 200), 20, 40, "gld", -5)) canvas.additem(blb.blb(canvas, (20, 250), 5, 5, "black", -1))

5 Windmill Animatin Recall: fr animatins, we will perfrm the fllwing steps: Create an animatincanvas bject Create an animated bject Add the animated bject t the Animatin Start the animatin canvas = animatin.animatincanvas(frame, width=500, height=300) canvas.additem(windmill.windmill(canvas, (250, 100), 50, 10, "red", 2)) canvas.additem(windmill.windmill(canvas, (150, 100), 50, 10, "blue", -2)) canvas.additem(windmill.windmill(canvas, (350, 200), 50, 10, "green", 14)) Animatins -- Reminders Our animatins use the tkinter and animatin mdules: imprt Tkinter as tk imprt animatin T create animatins, we perfrm the fllwing steps: Create an animatedcanvas bject canvas = animatincanvas.animatincanvas(frame, width=500, height=300) Add an animated bject t the Animatin canvas.additem(windmill.windmill(canvas, (250, 100), 50, 10, "red", 2) Start the animatin canvas.start() Animated Objects Like any bject, an animated bject has state and behavirs (instance variables and methds), and the state f the bject can change ver time. T enable creatin f animated bjects, we write a new class that inherits frm the AnimatedObject class and verrides the fllwing methd: mve(self) '''Changes the state f the bject frm ne frame t the next''' Example Animated Object: Windmill imprt animatin class Windmill(animatin.AnimatedObject): def mve(self):

6 Windmill init methd class Windmill(animatin.AnimatedObject): class Windmill(AnimatedObject): What prperties are the same fr all Windmill bjects? What prperties differ? Hw will Windmill bjects be drawn (d we want Rectangles, Arcs, Lines etc.)? What instance variables d we want? Hw shuld the instance variables be initialized? class Windmill(AnimatedObject): Windmill Animatin T create animatins, we will perfrm the fllwing steps: Create a Canvas bject Create an animated bject Add the animated bject t the Animatin Start the animatin

7 Other Prperties t Animate In the windmill animatin, the Layer cntaining the blades was rtated each frame. What if we wanted an animated bject t change its size each frame? Or mve acrss the screen? Or change its clr? 18-25