Draw Facebook logo by python and turtle

To draw the Facebook logo using Python and the Turtle graphics library, you can follow these steps. The Facebook logo consists of a square with rounded corners and the letter "f" inside it. Below is the Python code and an explanation of how it works.

### Python Code:

```python

import turtle

# Set up the screen

screen = turtle.Screen()

screen.bgcolor("white")

# Create a turtle object

pen = turtle.Turtle()

pen.speed(3)

pen.width(5)

# Function to draw a rounded square

def draw_rounded_square(size, radius):

for _ in range(4):

pen.forward(size)

pen.circle(radius, 90)

# Function to draw the letter "f"

def draw_f():

pen.penup()

pen.goto(-20, 60)

pen.pendown()

pen.right(90)

pen.forward(50)

pen.left(90)

pen.forward(30)

pen.backward(30)

pen.right(90)

pen.forward(20)

pen.left(90)

pen.forward(20)

# Draw the Facebook logo

def draw_facebook_logo():

pen.color("blue")

pen.begin_fill()

draw_rounded_square(100, 10)

pen.end_fill()

pen.color("white")

draw_f()

# Main function

def main():

draw_facebook_logo()

pen.hideturtle()

turtle.done()

# Run the program

if __name__ == "__main__":

main()

```

---

### Explanation:

1. **Import the Turtle Library**:

- The `turtle` library is imported to use its drawing functions.

2. **Set Up the Screen**:

- The screen is initialized with a white background using `screen.bgcolor("white")`.

3. **Create a Turtle Object**:

- A turtle object named `pen` is created to draw the logo. The speed is set to 3 (moderate speed), and the pen width is set to 5 for thicker lines.

4. **Draw a Rounded Square**:

- The `draw_rounded_square` function draws a square with rounded corners. It uses a loop to draw each side of the square and then draws a quarter circle (90 degrees) at each corner using `pen.circle(radius, 90)`.

5. **Draw the Letter "f"**:

- The `draw_f` function draws the letter "f" inside the square. The turtle moves to the correct position using `pen.goto()` and then draws the lines to form the letter.

6. **Draw the Facebook Logo**:

- The `draw_facebook_logo` function first draws the rounded square in blue and fills it with color using `pen.begin_fill()` and `pen.end_fill()`. Then, it draws the white letter "f" inside the square.

7. **Main Function**:

- The `main` function calls the `draw_facebook_logo` function, hides the turtle after drawing, and keeps the window open using `turtle.done()`.

8. **Run the Program**:

- The program is executed by calling the `main` function.

---

### Output:

When you run the code, a window will open displaying the Facebook logo: a blue rounded square with a white letter "f" inside it.

---

This code is a simple and fun way to use Python's Turtle graphics library to create recognizable shapes and logos!

### Introduction to Python's Turtle Graphics Library

The Turtle graphics library in Python is a powerful and beginner-friendly tool for creating drawings, animations, and visual designs. It is inspired by the concept of a "turtle" that moves around the screen, drawing lines as it moves. The library is part of Python's standard library, so no additional installation is required. It is widely used for teaching programming concepts, especially in visual and interactive ways.

---

### Key Features of the Turtle Library

1. **Turtle Object**:

- The core of the library is the `Turtle` object, which represents a cursor (or "turtle") that can move around the screen. You can control its movement, direction, and appearance.

2. **Screen Object**:

- The `Screen` object represents the drawing window. You can customize the background color, window size, and other properties.

3. **Simple Commands**:

- The library provides intuitive commands like `forward()`, `backward()`, `left()`, `right()`, and `circle()` to control the turtle's movement and drawing.

4. **Customization**:

- You can change the turtle's shape, color, and pen size. The pen can be lifted (`penup()`) or lowered (`pendown()`) to control whether it draws while moving.

5. **Event Handling**:

- The library supports keyboard and mouse events, allowing you to create interactive programs.

---

### How Turtle Graphics Works

1. **Import the Library**:

- To use the Turtle library, you first import it:

```python

import turtle

```

2. **Create a Turtle and Screen**:

- You create a `Turtle` object and a `Screen` object:

```python

pen = turtle.Turtle()

screen = turtle.Screen()

```

3. **Move the Turtle**:

- Use commands like `forward()`, `backward()`, `left()`, and `right()` to move the turtle:

```python

pen.forward(100) # Move the turtle forward by 100 units

pen.right(90) # Turn the turtle right by 90 degrees

```

4. **Draw Shapes**:

- By combining movement commands, you can draw shapes like squares, circles, and polygons:

```python

for _ in range(4):

pen.forward(100)

pen.right(90)

```

5. **Customize the Drawing**:

- Change the pen color, fill color, and pen size:

```python

pen.color("blue")

pen.pensize(5)

pen.begin_fill()

pen.circle(50)

pen.end_fill()

```

6. **Finish the Program**:

- Use `turtle.done()` to keep the window open after drawing.

---

### Example: Drawing a Square

Here’s a simple example to draw a square:

```python

import turtle

# Set up the screen

screen = turtle.Screen()

screen.bgcolor("white")

# Create a turtle

pen = turtle.Turtle()

pen.shape("turtle")

pen.color("blue")

# Draw a square

for _ in range(4):

pen.forward(100)

pen.right(90)

# Finish

turtle.done()

```

---

### Applications of Turtle Graphics

1. **Education**:

- Turtle graphics is widely used to teach programming concepts like loops, functions, and conditionals in a visual and engaging way.

2. **Art and Design**:

- You can create complex patterns, fractals, and artistic designs using the library.

3. **Prototyping**:

- It’s useful for quickly prototyping visual ideas or algorithms.

4. **Games**:

- Simple games like mazes or puzzles can be created using Turtle graphics.

---

### Advantages of Turtle Graphics

- **Easy to Learn**:

- The library’s commands are simple and intuitive, making it ideal for beginners.

- **Visual Feedback**:

- You can see the results of your code immediately, which helps in debugging and understanding.

- **Interactive**:

- The library supports user interaction through keyboard and mouse events.

---

### Limitations

- **Performance**:

- Turtle graphics is not suitable for high-performance or complex graphics.

- **Limited Features**:

- It lacks advanced features like 3D rendering or image manipulation.

---

### Conclusion

The Turtle graphics library is a fun and educational tool for learning programming and creating visual designs. Its simplicity and visual nature make it an excellent choice for beginners, educators, and anyone interested in exploring creative coding. Whether you’re drawing simple shapes or complex patterns, Turtle graphics provides a rewarding and interactive experience.