Let’s add some code to make it hatch. You need to make sure that your various frames are all saved in the same folder together as individual .gif files.
We’ll start off by modifying the code we already have to make it easier to manage the different ‘frames’ of our creature. Add the following lines to the __init__() function.
self.frames = ['egg.gif',
'creature.gif']
self.frame = 0
Next we’ll update the draw() function so that it displays the frame pointed to by the self.frame variable:
class Creature(object):
def __init__(self, window, canvas, x=0, y=0):
...
def update(self):
...
def wobble(self):
...
def draw(self):
self.canvas.coords(self.id, (self.x, self.y))
self.img = PhotoImage(file=self.frames[self.frame])
self.canvas.itemconfigure(self.id, image=self.img)
self.canvas.update_idletasks()
self.window.after(5, self.draw)
We’ve only actually changed the second line, where we set self.img, so that instead of always setting the image to the egg, we set it to whatever self.frame is pointing at. We only currently have 2 frames, so now we need to add some code to actually switch frames!
First we’ll need another timer and some way of telling if we’ve hatched or not, so add these lines to __init__():
self.hatched = False
self.timer = 300
At this stage, __init__() should look like this:
class Creature(object):
def __init__(self, window, canvas, x=0, y=0):
self.x = x
self.y = y
self.canvas = canvas
self.window = window
self.img = PhotoImage(file='egg.gif')
self.id = canvas.create_image((self.x, self.y), image=self.img)
self.current_animation = self.wobble
self.animation_timer = 0
self.frames = ['egg.gif',
'creature.gif']
self.frame = 0
self.hatched = False
self.timer = 300
self.window.after(5, self.update)
self.window.after(5, self.draw)
Notice that the new code goes above the 2 self.window.after() lines, these should stay the last lines of the function - we don’t want to start updating and drawing until everything is properly initialised
Next we’ll modify update() to use the timer we created to hatch after a little while:
def update(self):
if self.animation_timer == 0:
self.current_animation()
else:
self.animation_timer -= 1
if self.timer == 0:
if not self.hatched:
self.hatch()
else:
self.timer -= 1
self.window.after(5, self.update)
The new code looks at self.timer to see if it is zero, if it isn’t, it just decrements it by 1. If it is zero, it checks to see if we’ve already hatched, if not, we call the hatch() function (that we need to create next!)
Create a new function as part of the Creature class:
class Creature(object):
def __init__(self, window, canvas, x=0, y=0):
...
def update(self):
...
def wobble(self):
..
def hatch(self):
self.frame = 1
self.hatched = True
def draw(self):
...
If you’ve entered the code correctly, your program should run now. After a short wait of wobbling egg, your creature should appear! Notice that it is still wobbling though! We’ll fix that next.