Inky Frame Dither Test

dither.py

from picographics import PicoGraphics, DISPLAY_INKY_FRAME_7 as DISPLAY

graphics = PicoGraphics(DISPLAY)
WIDTH, HEIGHT = graphics.get_bounds()

BLACK = 0
WHITE = 1
GREEN = 2
BLUE = 3
RED = 4
YELLOW = 5
ORANGE = 6

colors = {
    'black': BLACK,
    'white': WHITE,
    'red': RED,
    'green': GREEN,
    'blue': BLUE,
    'yellow': YELLOW,
    'orange': ORANGE
}

color_pairs = [
    ('white', 'orange'), ('yellow', 'white'), ('white', 'red'), ('green', 'white'), ('white', 'blue'), ('blue', 'orange'), ('orange', 'red'),
    ('green', 'orange'), ('orange', 'yellow'), ('yellow', 'red'), ('red', 'green'), ('green', 'blue'),('blue', 'yellow'), ('yellow', 'green'),
    ('black', 'orange'), ('yellow', 'black'), ('black', 'red'), ('green', 'black'), ('black', 'blue'),  ('red', 'blue'), ('black', 'white')
]

# --- Bayer Dithering Matrix ---
# A 4x4 Bayer matrix for ordered dithering.
# The values are scaled by 16.
BAYER_MATRIX_4X4 = [
    [0, 8, 2, 10],
    [12, 4, 14, 6],
    [3, 11, 1, 9],
    [15, 7, 13, 5]
]

def apply_bayer_dither(x_start, y_start, width, height, color1, color2):
    """
    Applies Bayer dithering to a rectangular area of the display.

    Args:
        x_start (int): The starting x-coordinate of the pattern.
        y_start (int): The starting y-coordinate of the pattern.
        width (int): The width of the pattern.
        height (int): The height of the pattern.
        color1 (int): The first color (pen index).
        color2 (int): The second color (pen index).
    """
    for y in range(height):
        for x in range(width):
            # Calculate the gradient value from left (0) to right (1)
            gradient = x / (width - 1)

            # Get the threshold from the Bayer matrix
            threshold = BAYER_MATRIX_4X4[y % 4][x % 4] / 16.0

            # Determine which color to use based on the gradient and threshold
            if gradient > threshold:
                graphics.set_pen(color2)
            else:
                graphics.set_pen(color1)

            # Draw the pixel on the display buffer
            graphics.pixel(x_start + x, y_start + y)

def add_labels(color_pairs, cols, pattern_width, pattern_height):
    """
    Adds text labels to each dithering pattern on the display.

    Args:
        color_pairs (list): A list of tuples, where each tuple contains
                            the names of the two colors in a pair.
        cols (int): The number of columns in the grid.
        pattern_width (int): The width of each pattern.
        pattern_height (int): The height of each pattern.
    """
    graphics.set_font('bitmap8')

    for idx, (color1_name, color2_name) in enumerate(color_pairs):
        row = idx // cols
        col = idx % cols

        # Calculate the position for the label
        x = col * pattern_width
        y = row * pattern_height

        # Create the label text (e.g., "whi->ora")
        label = f"{color1_name[:3]}->{color2_name[:3]}"

        # Set the pen to black for the text shadow
        graphics.set_pen(BLACK)
        graphics.text(label, x + 2 + 20, y + 2 + 66, scale=2)
        # Set the pen to white for the main text
        graphics.set_pen(WHITE)
        graphics.text(label, x + 1 + 20, y + 1 + 66, scale=2)

def generate_test_pattern():
    """
    Generates the complete dithering test pattern on the Inky Frame display.
    """
    print("Generating dithering test pattern for Inky Frame 7.3\"...")

    # Clear the display to white
    graphics.set_pen(WHITE)
    graphics.clear()

    # Define the grid layout
    cols = 7
    rows = 3

    # Calculate the dimensions of each pattern
    pattern_width = WIDTH // cols
    pattern_height = HEIGHT // rows

    # Generate and draw each dithered pattern
    for idx, (color1_name, color2_name) in enumerate(color_pairs):
        row = idx // cols
        col = idx % cols

        x_start = col * pattern_width
        y_start = row * pattern_height

        print(f"Generating pattern {idx+1}/{len(color_pairs)}: {color1_name} to {color2_name}")

        apply_bayer_dither(x_start, y_start, pattern_width, pattern_height,
                           colors[color1_name], colors[color2_name])

    # Add the labels to the patterns
    add_labels(color_pairs, cols, pattern_width, pattern_height)

    # Update the display to show the generated pattern
    print("Updating the display...")
    graphics.update()
    print("Done.")

# --- Main Execution ---
if __name__ == "__main__":
    generate_test_pattern()