264 lines
7 KiB
Python
Executable file
264 lines
7 KiB
Python
Executable file
#!/usr/bin/env python3
|
|
|
|
# SPDX-License-Identifier: LGPL-3.0-or-later
|
|
# Copyright (C) 2020 Daniel Thompson
|
|
|
|
import argparse
|
|
import sys
|
|
import os.path
|
|
from PIL import Image
|
|
|
|
def varname(p):
|
|
return os.path.basename(os.path.splitext(p)[0])
|
|
|
|
def encode(im):
|
|
pixels = im.load()
|
|
|
|
rle = []
|
|
rl = 0
|
|
px = pixels[0, 0]
|
|
|
|
def encode_pixel(px, rl):
|
|
while rl > 255:
|
|
rle.append(255)
|
|
rle.append(0)
|
|
rl -= 255
|
|
rle.append(rl)
|
|
|
|
for y in range(im.height):
|
|
for x in range(im.width):
|
|
newpx = pixels[x, y]
|
|
if newpx == px:
|
|
rl += 1
|
|
assert(rl < (1 << 21))
|
|
continue
|
|
|
|
# Code the previous run
|
|
encode_pixel(px, rl)
|
|
|
|
# Start a new run
|
|
rl = 1
|
|
px = newpx
|
|
|
|
# Handle the final run
|
|
encode_pixel(px, rl)
|
|
|
|
return (im.width, im.height, bytes(rle))
|
|
|
|
def encode_2bit(im):
|
|
"""2-bit palette based RLE encoder.
|
|
|
|
This encoder has a reprogrammable 2-bit palette. This allows it to encode
|
|
arbitrary images with a full 8-bit depth but the 2-byte overhead each time
|
|
a new colour is introduced means it is not efficient unless the image is
|
|
carefully constructed to keep a good locality of reference for the three
|
|
non-background colours.
|
|
|
|
The encoding competes well with the 1-bit encoder for small monochrome
|
|
images but once run-lengths longer than 62 start to become frequent then
|
|
this encoding is about 30% larger than a 1-bit encoding.
|
|
"""
|
|
pixels = im.load()
|
|
assert(im.width <= 255)
|
|
assert(im.height <= 255)
|
|
|
|
rle = []
|
|
rl = 0
|
|
px = pixels[0, 0]
|
|
palette = [0, 0xfc, 0x2d, 0xff]
|
|
next_color = 1
|
|
|
|
def encode_pixel(px, rl):
|
|
nonlocal next_color
|
|
px = (px[0] & 0xe0) | ((px[1] & 0xe0) >> 3) | ((px[2] & 0xc0) >> 6)
|
|
if px not in palette:
|
|
rle.append(next_color << 6)
|
|
rle.append(px)
|
|
palette[next_color] = px
|
|
next_color += 1
|
|
if next_color >= len(palette):
|
|
next_color = 1
|
|
px = palette.index(px)
|
|
if rl >= 63:
|
|
rle.append((px << 6) + 63)
|
|
rl -= 63
|
|
while rl >= 255:
|
|
rle.append(255)
|
|
rl -= 255
|
|
rle.append(rl)
|
|
else:
|
|
rle.append((px << 6) + rl)
|
|
|
|
# Issue the descriptor
|
|
rle.append(2)
|
|
rle.append(im.width)
|
|
rle.append(im.height)
|
|
|
|
for y in range(im.height):
|
|
for x in range(im.width):
|
|
newpx = pixels[x, y]
|
|
if newpx == px:
|
|
rl += 1
|
|
assert(rl < (1 << 21))
|
|
continue
|
|
|
|
# Code the previous run
|
|
encode_pixel(px, rl)
|
|
|
|
# Start a new run
|
|
rl = 1
|
|
px = newpx
|
|
|
|
# Handle the final run
|
|
encode_pixel(px, rl)
|
|
|
|
return bytes(rle)
|
|
|
|
def encode_8bit(im):
|
|
"""Experimental 8-bit RLE encoder.
|
|
|
|
For monochrome images this is about 3x less efficient than the 1-bit
|
|
encoder. This encoder is not currently used anywhere in wasp-os and
|
|
currently there is no decoder either (so don't assume this code
|
|
actually works).
|
|
"""
|
|
pixels = im.load()
|
|
|
|
rle = []
|
|
rl = 0
|
|
px = pixels[0, 0]
|
|
|
|
def encode_pixel(px, rl):
|
|
px = (px[0] & 0xe0) | ((px[1] & 0xe0) >> 3) | ((px[2] & 0xc0) >> 6)
|
|
|
|
rle.append(px)
|
|
if rl > 0:
|
|
rle.append(px)
|
|
rl -= 2
|
|
if rl > (1 << 14):
|
|
rle.append(0x80 | ((rl >> 14) & 0x7f))
|
|
if rl > (1 << 7):
|
|
rle.append(0x80 | ((rl >> 7) & 0x7f))
|
|
if rl >= 0:
|
|
rle.append( rl & 0x7f )
|
|
|
|
for y in range(im.height):
|
|
for x in range(im.width):
|
|
newpx = pixels[x, y]
|
|
if newpx == px:
|
|
rl += 1
|
|
assert(rl < (1 << 21))
|
|
continue
|
|
|
|
# Code the previous run
|
|
encode_pixel(px, rl)
|
|
|
|
# Start a new run
|
|
rl = 1
|
|
px = newpx
|
|
|
|
# Handle the final run
|
|
encode_pixel(px, rl)
|
|
|
|
return (im.width, im.height, bytes(rle))
|
|
|
|
def render_c(image, fname):
|
|
print(f'// 1-bit RLE, generated from {fname}, {len(image[2])} bytes')
|
|
print(f'static const uint8_t {varname(fname)}[] = {{')
|
|
print(' ', end='')
|
|
i = 0
|
|
for rl in image[2]:
|
|
print(f' {hex(rl)},', end='')
|
|
|
|
i += 1
|
|
if i == 12:
|
|
print('\n ', end='')
|
|
i = 0
|
|
|
|
print('\n};')
|
|
|
|
def decode_to_ascii(image):
|
|
(sx, sy, rle) = image
|
|
data = bytearray(2*sx)
|
|
dp = 0
|
|
black = ord('#')
|
|
white = ord(' ')
|
|
color = black
|
|
|
|
for rl in rle:
|
|
while rl:
|
|
data[dp] = color
|
|
data[dp+1] = color
|
|
dp += 2
|
|
rl -= 1
|
|
|
|
if dp >= (2*sx):
|
|
print(data.decode('utf-8'))
|
|
dp = 0
|
|
|
|
if color == black:
|
|
color = white
|
|
else:
|
|
color = black
|
|
|
|
# Check the image is the correct length
|
|
assert(dp == 0)
|
|
|
|
|
|
|
|
parser = argparse.ArgumentParser(description='RLE encoder tool.')
|
|
parser.add_argument('files', nargs='+',
|
|
help='files to be encoded')
|
|
parser.add_argument('--ascii', action='store_true',
|
|
help='Run the resulting image(s) through an ascii art decoder')
|
|
parser.add_argument('--c', action='store_true',
|
|
help='Render the output as C instead of python')
|
|
parser.add_argument('--indent', default=0, type=int,
|
|
help='Add extra indentation in the generated code')
|
|
parser.add_argument('--2bit', action='store_true', dest='twobit',
|
|
help='Generate 2-bit image')
|
|
parser.add_argument('--8bit', action='store_true', dest='eightbit',
|
|
help='Generate 8-bit image')
|
|
|
|
args = parser.parse_args()
|
|
extra_indent = ' ' * args.indent
|
|
if args.eightbit:
|
|
encoder = encode_8bit
|
|
depth = 8
|
|
elif args.twobit:
|
|
encoder = encode_2bit
|
|
depth = 2
|
|
else:
|
|
encoder = encode
|
|
depth =1
|
|
|
|
for fname in args.files:
|
|
image = encoder(Image.open(fname))
|
|
|
|
if args.c:
|
|
render_c(image, fname)
|
|
else:
|
|
if len(image) == 3:
|
|
print(f'{extra_indent}# {depth}-bit RLE, generated from {fname}, '
|
|
f'{len(image[2])} bytes')
|
|
(x, y, pixels) = image
|
|
print(f'{extra_indent}{varname(fname)} = (')
|
|
print(f'{extra_indent} {x}, {y},')
|
|
else:
|
|
print(f'{extra_indent}# {depth}-bit RLE, generated from {fname}, '
|
|
f'{len(image)} bytes')
|
|
pixels = image[3:]
|
|
print(f'{extra_indent}{varname(fname)} = (')
|
|
print(f'{extra_indent} {image[0:1]}')
|
|
print(f'{extra_indent} {image[1:3]}')
|
|
|
|
# Split the bytestring to ensure each line is short enough to
|
|
# be absorbed on the target if needed.
|
|
for i in range(0, len(pixels), 16):
|
|
print(f'{extra_indent} {pixels[i:i+16]}')
|
|
print(f'{extra_indent})')
|
|
|
|
if args.ascii:
|
|
print()
|
|
decode_to_ascii(image)
|