Pygame Cheatsheet
=================

Here is a reference of popular commands needed for Pygame. Be advised that some of the more difficult concepts
will be spread out in the various sections of the game code. See :ref:`pygame/pygame-template:The parts of a game` for more info. In the examples
below, I do my best to indicate what parts of the example code go into what section of the overall game code
(initialization, event handling, game updates, and drawing) indicated my all caps comments, E.g., ``# DRAWING``.

.. note:: It is highly recommended that you create your own cheatsheet for concepts you personally want to remember
    and written in a way that you will easily understand it.

.. contents::
    :local:

Drawing Shapes
--------------

.. code-block:: python

    # DRAWING
    # Circle
    # pygame.draw.circle(screen, color: Tuple[int, int, int], position: Tuple[int, int], radius: int)
    pygame.draw.circle(screen, (0, 0, 255), (100, 100), 30)


Drawing Text
------------

.. code-block:: python

    # way up after pygame.init()
    pygame.font.init()

    ## INITIALIZATION
    some_font = pygame.font.SysFont('Arial', 50)

    # DRAWING (in loop)
    some_text = some_font.render('Hello', False, (0, 0, 0))
    screen.blit(some_text, (0, 0))

.. note:: Is is possible to "render" the text in the ``INITALIZATION`` section if the text will never change. If you need the
    text to change, like when displaying a score, then rendering must be done in the loop.


Mouse button down
-----------------
This code should print out for you the x and y location of the mouse in the terminal.

.. code-block:: python
    :emphasize-lines: 2, 12, 13, 14

    # add MOUSEBUTTONDOWN to your pygame.locals imports
    from pygame.locals import MOUSEBUTTONDOWN

    # EVENT HANDLING
    # In the game loop's event loop, add to existing event if structure
    for event in pygame.event.get():
        if event.type == KEYDOWN:
            if event.key == K_ESCAPE:
                running = False
        elif event.type == QUIT:
            running = False
        elif event.type == MOUSEBUTTONDOWN:  
            mouse_x, mouse_y = event.pos
            print(mouse_x, mouse_y)



Scene switch
------------

.. code-block:: python

    # INITIALIZATION
    current_screen = "menu"

    # inside loop
    if current_screen == "menu":
        # do menu screen stuff
    elif current_screen == "instructions":
        # do instructions screen stuff
    ...

.. note:: Each ``if`` section may have its own event handling, game updates and drawing sections.


``pygame.Rect`` objects
-----------------------
There is a lot of built in functionality for `pygame.Rect <https://www.pygame.org/docs/ref/rect.html>`_ s.
Here are a couple useful properties you can use.

.. code-block:: python

    #                  x   y   width height
    box1 = pygame.Rect(50, 50, 100, 100)
    box1.center  # (75, 75)
    box1.center = (0, 0)  # move the rect to (0, 0)
    box1.left = 100  # moves the rect to (100, 0)
    box1.width  # 100
    box1.width = 300  # can modify the width

Here are some methods for collision detection.

.. code-block:: python

    box1 = pygame.Rect(50, 50, 100, 100)
    box2 = pygame.Rect(100, 50, 100, 100)

    # collision between rects
    box1.colliderect(box2)  # True (they overlap)

    # collision with mouse
    # assume mouse at (75, 75)
    mouse_pos = pygame.mouse.get_pos()
    box1.collidepoint(mouse_pos)  # True
    box2.collidepoint(mouse_pos)  # False


Dragging
--------

.. code-block:: python

    box = pygame.Rect(50, 50, 100, 100)
    box_dragging = False

    ...
    # in game loop
        for event in pygame.event.get():
            ...
            elif event.type == MOUSEBUTTONDOWN:  # don't forget to import this
                if box.collidepoint(event.pos):
                    box_dragging = True
            elif event.type == MOUSEBUTTONUP:
                box_dragging = False
        ...
        
        # game updates
        if box_dragging is True:
            mouse_pos = pygame.mouse.get_pos()
            box.center = mouse_pos
        
        # drawing
        pygame.draw.rect(screen, (0, 0, 0), box)

Importing Images
----------------
.. code-block:: python

    # load the image OUTSIDE THE GAME LOOP
    fish_img = pygame.image.load("fishGreen.png")

    # Blit the image to the screen
    # Game loop: Drawing section
    screen.blit(fish_img, (0, 0))

Transforming Images
-------------------

.. code-block:: python

    # you need an original image
    fish_img = pygame.image.load("fishGreen.png")

    # applying transforms DOES NOT modify the original image,
    # but, returns a new copy of the image.
    flipped_img = pygame.transform.flip(fish_img, True, True)  # (image, flip_x?, flip_y?)
    scaled_img = pygame.transform.scale(fish_img, (50, 50))  # make it 50x50 pixels
    rotated_img = pygame.transform.rotate(fish_img, 45)  # 45 degrees