PNG Writing Operations

class Writer:
    def __init__(self, width=None, height=None, size=None, greyscale=Default, 
                 alpha=False, bitdepth=8, palette=None, transparent=None, 
                 background=None, gamma=None, compression=None, interlace=False, 
                 planes=None, colormap=None, maxval=None, chunk_limit=2**20, 
                 x_pixels_per_unit=None, y_pixels_per_unit=None, unit_is_meter=False):
        """
        Initialize PNG writer with format and metadata options.
        
        Parameters:
        - width, height: int, image dimensions in pixels
        - size: tuple, alternative way to specify (width, height)
        - greyscale: bool or Default, whether to create greyscale image
        - alpha: bool, whether to include alpha channel
        - bitdepth: int, bits per sample (1, 2, 4, 8, 16)
        - palette: list, RGB or RGBA tuples for palette images
        - transparent: color value or index for transparency
        - background: color value for default background
        - gamma: float, gamma correction value
        - compression: int, zlib compression level (0-9)
        - interlace: bool, whether to use Adam7 interlacing
        - planes: int, deprecated, use greyscale and alpha instead
        - colormap: dict, deprecated, use palette instead
        - maxval: int, maximum pixel value for scaling
        - chunk_limit: int, maximum chunk size in bytes
        - x_pixels_per_unit, y_pixels_per_unit: int, resolution information
        - unit_is_meter: bool, whether resolution units are meters (vs. unknown)
        """

def write(self, outfile, rows):
    """
    Write PNG from row iterator.
    
    Parameters:
    - outfile: file-like object opened in binary write mode
    - rows: iterable of pixel rows, each row is sequence of pixel values
    """
    
def write_array(self, outfile, pixels):
    """
    Write PNG from 2D array or nested sequences.
    
    Parameters:
    - outfile: file-like object opened in binary write mode  
    - pixels: 2D array-like structure of pixel data
    """
    
def write_packed(self, outfile, rows):
    """
    Write PNG from pre-packed byte rows.
    
    Parameters:
    - outfile: file-like object opened in binary write mode
    - rows: iterable of byte strings representing packed pixel rows
    """
    
def write_passes(self, outfile, rows):
    """
    Write PNG with interlacing support.
    
    Parameters:
    - outfile: file-like object opened in binary write mode
    - rows: iterable of pixel rows for interlaced writing
    """

import png

# Create a simple RGB image
width, height = 256, 256
pixels = []

# Generate gradient pattern
for y in range(height):
    row = []
    for x in range(width):
        # RGB gradient
        r = (x * 255) // width
        g = (y * 255) // height  
        b = 128
        row.extend([r, g, b])
    pixels.append(row)

# Write PNG
writer = png.Writer(width=width, height=height, greyscale=False)
with open('gradient.png', 'wb') as f:
    writer.write_array(f, pixels)

import png

# Create greyscale image
width, height = 100, 100
pixels = []

for y in range(height):
    row = []
    for x in range(width):
        # Simple checkerboard pattern
        if (x // 10 + y // 10) % 2:
            grey = 255  # White
        else:
            grey = 0    # Black
        row.append(grey)
    pixels.append(row)

# Write greyscale PNG
writer = png.Writer(width=width, height=height, greyscale=True, bitdepth=8)
with open('checkerboard.png', 'wb') as f:
    writer.write_array(f, pixels)

import png

# Create RGBA image with transparency
width, height = 64, 64
pixels = []

for y in range(height):
    row = []
    for x in range(width):
        # Create a circle with alpha blending
        center_x, center_y = width // 2, height // 2
        distance = ((x - center_x) ** 2 + (y - center_y) ** 2) ** 0.5
        
        if distance < width // 3:
            # Inside circle - solid color
            r, g, b, a = 255, 100, 50, 255
        elif distance < width // 2:
            # Edge of circle - fade out
            alpha = int(255 * (1 - (distance - width//3) / (width//2 - width//3)))
            r, g, b, a = 255, 100, 50, alpha
        else:
            # Outside circle - transparent
            r, g, b, a = 0, 0, 0, 0
            
        row.extend([r, g, b, a])
    pixels.append(row)

# Write RGBA PNG
writer = png.Writer(width=width, height=height, greyscale=False, alpha=True)
with open('circle_alpha.png', 'wb') as f:
    writer.write_array(f, pixels)

import png

# Define color palette
palette = [
    (255, 0, 0),    # Red
    (0, 255, 0),    # Green  
    (0, 0, 255),    # Blue
    (255, 255, 0),  # Yellow
    (255, 0, 255),  # Magenta
    (0, 255, 255),  # Cyan
    (255, 255, 255), # White
    (0, 0, 0)       # Black
]

# Create image using palette indices
width, height = 32, 32
pixels = []

for y in range(height):
    row = []
    for x in range(width):
        # Use palette index based on position
        palette_index = (x // 4 + y // 4) % len(palette)
        row.append(palette_index)
    pixels.append(row)

# Write palette PNG
writer = png.Writer(width=width, height=height, palette=palette, bitdepth=8)
with open('palette_image.png', 'wb') as f:
    writer.write_array(f, pixels)

import png

# Create 16-bit per channel image
width, height = 64, 64
pixels = []

for y in range(height):
    row = []
    for x in range(width):
        # Use full 16-bit range (0-65535)
        r = (x * 65535) // width
        g = (y * 65535) // height
        b = 32768  # Mid-range value
        row.extend([r, g, b])
    pixels.append(row)

# Write 16-bit RGB PNG
writer = png.Writer(width=width, height=height, greyscale=False, bitdepth=16)
with open('high_bit_depth.png', 'wb') as f:
    writer.write_array(f, pixels)

import png

# Create simple image
width, height = 32, 32
pixels = [[y * 8 for x in range(width)] for y in range(height)]

# Write PNG with gamma correction and resolution metadata
writer = png.Writer(
    width=width, 
    height=height, 
    greyscale=True,
    gamma=2.2,                    # Gamma correction
    x_pixels_per_unit=2835,       # 72 DPI in pixels per meter
    y_pixels_per_unit=2835,
    unit_is_meter=True
)

with open('metadata_image.png', 'wb') as f:
    writer.write_array(f, pixels)

import png

def generate_rows(width, height):
    """Generator function that yields rows on demand"""
    for y in range(height):
        row = []
        for x in range(width):
            # Generate pixel data on-the-fly
            value = (x + y) % 256
            row.append(value)
        yield row

# Write PNG using row generator (memory efficient for large images)
width, height = 1000, 1000
writer = png.Writer(width=width, height=height, greyscale=True)

with open('large_generated.png', 'wb') as f:
    writer.write(f, generate_rows(width, height))