Python Turtle – Graphics Keyboard Commands
Python Turtle module is a graphical tool that can be used to draw simple graphics on the screen using a cursor. Python Turtle was a part of Logo programming language which had similar purpose of letting the users draw graphics on the screen with the help of simple commands. Turtle is a pre-installed module and has inbuilt commands and features that can be used to draw pictures on the screen. This article will be primarily focused on creating a graphic using keyboard commands along with how the same methodology can be used to add or change color to the graphic.
- Screen() – used to create a canvas for drawing
- Turtle Motion:
- forward(distance) | fd(distance) : move the turtle forward
- backward(distance) | back(distance) | bk(distance) : move the turtle backwards
- right(distance) | rt(distance) : move the turtle right
- left(distance) | lt(distance) : move the turtle left
- circle(radius) : draws a circle with a given radius
- color() : set the colors
- begin_fill() : this method is called before drawing a shape that is to be filled
- end_fill() : Fills the shape drawn after the call to begin_fill().
Given below are two approaches that deal and discuss how to create a graphics keyboard
- Import module and submodules
- Create setup- The setup() method sets up a window of size 500×500.
- Create window- The Screen() method creates a canvas for drawing.
- Instantiate turtle object
- Set turtle speed to 0 which is maximum
- Set visibility- The showturtle() method sets the visibility of the turtle.
- In order to capture the keystrokes we need to define few functions namely up, down, left, right. By default, the turtle points to the right.
- The setheading() method changes the orientation of the turtle to the given angle.
- The forward() method moves the turtle to the specified distance.
- The listen() method sets focus on the turtle screen to capture events.
- The onkey() method invokes the method specific to the captured keystroke. The first argument of onkey() is the function to be called and the second argument is the key.
- The Up,Down,Left and Right are the corresponding arrow keys on the keyboard.
- Add mainloop() command, it prevents the application from terminating before the user actually clicks the exit option.
Method 2: changing color
This is similar to the previous example with the addition of few more keys. Now we have added keys to change the color of the line.
- If the user presses r it turns red,
- If g it turns green and if b it turns blue.
- For resetting the line color to black the user must press z.
Also, the thickness of the line is increased by setting the width o the turtle to 5px using the width() method.