Array-Backed Grid#

Screenshot of a program that shows an array backed grid.

If you work with grids much, you’ll find this to be slow. You may want to look at:

array_backed_grid.py#
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"""
Array Backed Grid

Show how to use a two-dimensional list/array to back the display of a
grid on-screen.

Note: Regular drawing commands are slow. Particularly when drawing a lot of
items, like the rectangles in this example.

For faster drawing, create the shapes and then draw them as a batch.
See array_backed_grid_buffered.py

If Python and Arcade are installed, this example can be run from the command line with:
python -m arcade.examples.array_backed_grid
"""
import arcade

# Set how many rows and columns we will have
ROW_COUNT = 15
COLUMN_COUNT = 15

# This sets the WIDTH and HEIGHT of each grid location
WIDTH = 30
HEIGHT = 30

# This sets the margin between each cell
# and on the edges of the screen.
MARGIN = 5

# Do the math to figure out our screen dimensions
SCREEN_WIDTH = (WIDTH + MARGIN) * COLUMN_COUNT + MARGIN
SCREEN_HEIGHT = (HEIGHT + MARGIN) * ROW_COUNT + MARGIN
SCREEN_TITLE = "Array Backed Grid Example"


class MyGame(arcade.Window):
    """
    Main application class.
    """

    def __init__(self, width, height, title):
        """
        Set up the application.
        """

        super().__init__(width, height, title)

        # Create a 2 dimensional array. A two-dimensional
        # array is simply a list of lists.
        self.grid = []
        for row in range(ROW_COUNT):
            # Add an empty array that will hold each cell
            # in this row
            self.grid.append([])
            for column in range(COLUMN_COUNT):
                self.grid[row].append(0)  # Append a cell

        arcade.set_background_color(arcade.color.BLACK)

    def on_draw(self):
        """
        Render the screen.
        """

        # This command has to happen before we start drawing
        self.clear()

        # Draw the grid
        for row in range(ROW_COUNT):
            for column in range(COLUMN_COUNT):
                # Figure out what color to draw the box
                if self.grid[row][column] == 1:
                    color = arcade.color.GREEN
                else:
                    color = arcade.color.WHITE

                # Do the math to figure out where the box is
                x = (MARGIN + WIDTH) * column + MARGIN + WIDTH // 2
                y = (MARGIN + HEIGHT) * row + MARGIN + HEIGHT // 2

                # Draw the box
                arcade.draw_rectangle_filled(x, y, WIDTH, HEIGHT, color)

    def on_mouse_press(self, x, y, button, modifiers):
        """
        Called when the user presses a mouse button.
        """

        # Change the x/y screen coordinates to grid coordinates
        column = int(x // (WIDTH + MARGIN))
        row = int(y // (HEIGHT + MARGIN))

        print(f"Click coordinates: ({x}, {y}). Grid coordinates: ({row}, {column})")

        # Make sure we are on-grid. It is possible to click in the upper right
        # corner in the margin and go to a grid location that doesn't exist
        if row < ROW_COUNT and column < COLUMN_COUNT:

            # Flip the location between 1 and 0.
            if self.grid[row][column] == 0:
                self.grid[row][column] = 1
            else:
                self.grid[row][column] = 0


def main():

    MyGame(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
    arcade.run()


if __name__ == "__main__":
    main()