Moving Shapes with Functions and Mouse events Creative Task -Sep 2021

This week we are learning how to define functions, use shape properties and use mouse events . As we learn more, the results started to get more dynamic. Once again we will code using CMU Academy IDE (Integrated Development Environment). CMU CS Academy is an online, graphics-based computer science curriculum taught in Python provided by Carnegie Mellon University. They create novel, world-class Computer Science education forthe classroom —and it’s entirely free. You can sign up for it here: CMU CS Academy

Alternatively, To get started in Python, I also recommend getting PyCharm: https://www.jetbrains.com/pycharm/

In each blog post, I will go over some examples, creative tasks that I created, related code and summarize the key concepts and syntax we learned .

Now here’s how I created this animated Python code :

Now let’s go over some key concepts we learned in this topic.

Indent the body of a function by 4 spaces

Function parameters can be different types, including numbers, strings (like 'hello'), and booleans (True or False)
You can call the same function multiple times
Python has rules for legal function names
- Upper and lower case are different, so sayHi is not the same as sayhi
- Names must start with letters
- Names can contain digits, but they cannot start with a digit
- Names cannot contain spaces, newlines, or punctuation
- Python reserves some special words that you cannot use for function names
Legal names aren’t necessarily good names.
- Good names are short and clear
- Good names are camelCased
We can use pass to tell Python to do nothing for that function

Multiple Parameters

Parameters and arguments must match -- the same number, in the same order
When calling a function with no parameters, still use parentheses like: beHappy()

Mouse Events

Mouse Press Events

The onMousePress(mouseX, mouseY) function is called every time the canvas is clicked.
- The name of the function must match
- We can name the parameters whatever we want, but they will represent the x and y coordinate of where the mouse was pressed on the canvas

Using and Debugging Events

Using print properly:
- Use print to help you understand and debug your code
- The console is for programmers, not users
- Delete your print calls when you no longer need them
Use the control or ctrlkey to access the inspector
Top-level code is any code not inside a function
- Runs exactly once before any event is called
A little Math
- Use + to add, - to subtract, * to multiply, / to divide

Globals

To modify a shape after creating it, store the shape in a global variable
- You can get and set the properties of that shape in any function

Mouse Release Events

onMouseRelease(mouseX, mouseY) is called every time the mouse is released
- It is most common to use mouse release events to modify existing shapes

Properties

General Shape Properties

There are many shape properties that you can get and set. Default values are in parentheses next to the property name:
- Position Properties
  - left , right , top , bottom , centerX , centerY
- Size Properties
  - width , height
- Alignment Properties
  - align
    - Can not be changed after the shape is initialized
- Fill and Border Properties
  - fill ('black'), border (None), borderWidth (2), opacity (100), dashes (False)
- Other Properties
  - rotateAngle (0), visible (True)
- Changing Properties
  - Use += to add, -= to subtract, *= to multiply, /= to divide

Shape-Specific Properties

Some shapes have additional properties just for them
- Circle Properties
  - radius
- RegularPolygon Properties
  - radius , points
- Star Properties
  - radius , points , roundness
- Line Properties
  - x1 , y1 , x2 , y2 , dashes (False), lineWidth (2)
- Label Properties
  - value , font ('arial'), size (12), bold (False), italic (False)
App Background Property: app.background

I hope this helps.

Till next time.

Alara

Python Functions, Mouse Events, and Properties