ChunkyPNG is a pure-Ruby library to read, write, and manipulate PNG images without requiring external C extensions or ImageMagick.
Loading Images
require 'chunky_png'
# Load directly from filesystem
image = ChunkyPNG::Image.from_file('input.png')
# Load from binary in-memory blob or IO stream
image = ChunkyPNG::Image.from_blob(File.binread('input.png'))
image = ChunkyPNG::Image.from_io(io_stream)
Saving Images
# Save to file
image.save('output.png')
# Export to binary string blob
binary_blob = image.to_blob
# Write to stream
File.open('stream.png', 'wb') { |io| image.write(io) }
Pixel Drawing & Colors
# Set individual pixel RGBA values
image[0, 0] = ChunkyPNG::Color.rgba(255, 0, 0, 128)
# Color constructors
red = ChunkyPNG::Color.from_hex('#ff0000')
cyan = ChunkyPNG::Color.rgba(0, 255, 255, 255)
# Draw geometric primitives
image.line(10, 10, 100, 10, red)
image.rect(20, 20, 80, 80, red, cyan) # border, fill
image.circle(50, 50, 25, red)
Canvas Operations & Transforms
# Crop sub-rectangle: crop(x, y, width, height)
cropped = image.crop(10, 10, 200, 200)
# Flipping and rotation
transformed = image.flip_horizontally.rotate_right
flipped_v = image.flip_vertically