394 lines
14 KiB
Python
394 lines
14 KiB
Python
# -*- coding: utf-8 -*-
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"""A small Python module for BMP image processing.
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- Author: Quan Lin
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- Adapted by: Dejvino
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- Adapted from: https://github.com/jacklinquan/micropython-microbmp
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- License: MIT
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"""
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from struct import pack, unpack
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# Project Version
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__version__ = "0.1.0"
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__all__ = ["MicroBMP"]
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class MicroBMP(object):
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def __init__(self, width=None, height=None, depth=None, palette=None, header_callback=None, data_callback=None):
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# BMP Header
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self.BMP_id = b"BM"
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self.BMP_size = None
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self.BMP_reserved1 = b"\x00\x00"
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self.BMP_reserved2 = b"\x00\x00"
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self.BMP_offset = None
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# DIB Header
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self.DIB_len = 40
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self.DIB_w = width
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self.DIB_h = height
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self.DIB_planes_num = 1
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self.DIB_depth = depth
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self.DIB_comp = 0
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self.DIB_raw_size = None
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self.DIB_hres = 2835 # 72 DPI * 39.3701 inches/metre.
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self.DIB_vres = 2835
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self.DIB_num_in_plt = None
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self.DIB_extra = None
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self.palette = palette
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self.parray = None # Pixel array
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self.ppb = None # Number of pixels per byte for depth <= 8.
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self.pmask = None # Pixel Mask
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self.row_size = None
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self.padded_row_size = None
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self.header_callback = header_callback
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self.data_callback = data_callback
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self.initialised = False
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self._init()
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def __getitem__(self, key):
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assert self.initialised, "Image not initialised!"
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assert key[0] < self.DIB_w and key[1] < self.DIB_h, "Out of image boundary!"
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# Pixels are arranged in HLSB format with high bits being the leftmost
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pindex = key[1] * self.DIB_w + key[0] # Pixel index
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if self.DIB_depth <= 8:
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return self._extract_from_bytes(self.parray, pindex)
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else:
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pindex *= 3
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if (len(key) > 2) and (key[2] in (0, 1, 2)):
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return self.parray[pindex + key[2]]
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else:
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return (
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self.parray[pindex],
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self.parray[pindex + 1],
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self.parray[pindex + 2],
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)
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def __setitem__(self, key, value):
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assert self.initialised, "Image not initialised!"
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assert key[0] < self.DIB_w and key[1] < self.DIB_h, "Out of image boundary!"
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# Pixels are arranged in HLSB format with high bits being the leftmost
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pindex = key[1] * self.DIB_w + key[0] # Pixel index
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if self.DIB_depth <= 8:
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self._fill_in_bytes(self.parray, pindex, value)
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else:
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pindex *= 3
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if (len(key) > 2) and (key[2] in (0, 1, 2)):
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self.parray[pindex + key[2]] = value
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else:
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self.parray[pindex] = value[0]
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self.parray[pindex + 1] = value[1]
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self.parray[pindex + 2] = value[2]
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def __str__(self):
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if not self.initialised:
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return repr(self)
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return "BMP image, {}, {}-bit, {}x{} pixels, {} bytes".format(
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"indexed" if self.DIB_depth <= 8 else "RGB",
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self.DIB_depth,
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self.DIB_w,
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self.DIB_h,
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self.BMP_size,
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)
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def _init(self):
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if None in (self.DIB_w, self.DIB_h, self.DIB_depth):
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self.initialised = False
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return self.initialised
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assert self.BMP_id == b"BM", "BMP id ({}) must be b'BM'!".format(self.BMP_id)
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assert (
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len(self.BMP_reserved1) == 2 and len(self.BMP_reserved2) == 2
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), "Length of BMP reserved fields ({}+{}) must be 2+2!".format(
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len(self.BMP_reserved1), len(self.BMP_reserved2)
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)
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assert self.DIB_planes_num == 1, "DIB planes number ({}) must be 1!".format(
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self.DIB_planes_num
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)
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assert self.DIB_depth in (
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1,
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2,
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4,
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8,
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24,
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), "Colour depth ({}) must be in (1, 2, 4, 8, 24)!".format(self.DIB_depth)
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assert (
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self.DIB_comp == 0
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or (self.DIB_depth == 8 and self.DIB_comp == 1)
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or (self.DIB_depth == 4 and self.DIB_comp == 2)
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), "Colour depth + compression ({}+{}) must be X+0/8+1/4+2!".format(
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self.DIB_depth, self.DIB_comp
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)
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if self.DIB_depth <= 8:
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self.ppb = 8 // self.DIB_depth
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self.pmask = 0xFF >> (8 - self.DIB_depth)
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if self.palette is None:
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# Default palette is black and white or full size grey scale.
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self.DIB_num_in_plt = 2 ** self.DIB_depth
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self.palette = [None for i in range(self.DIB_num_in_plt)]
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for i in range(self.DIB_num_in_plt):
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# Assignment that suits all: 1/2/4/8-bit colour depth.
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s = 255 * i // (self.DIB_num_in_plt - 1)
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self.palette[i] = bytearray([s, s, s])
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else:
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self.DIB_num_in_plt = len(self.palette)
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else:
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self.ppb = None
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self.pmask = None
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self.DIB_num_in_plt = 0
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self.palette = None
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#if self.parray is None:
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# if self.DIB_depth <= 8:
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# div, mod = divmod(self.DIB_w * self.DIB_h, self.ppb)
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# self.parray = bytearray(div + (1 if mod else 0))
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# else:
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# self.parray = bytearray(self.DIB_w * self.DIB_h * 3)
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plt_size = self.DIB_num_in_plt * 4
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self.BMP_offset = 14 + self.DIB_len + plt_size
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self.row_size = self._size_from_width(self.DIB_w)
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self.padded_row_size = self._padded_size_from_size(self.row_size)
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if self.DIB_comp == 0:
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self.DIB_raw_size = self.padded_row_size * self.DIB_h
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self.BMP_size = self.BMP_offset + self.DIB_raw_size
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self.initialised = True
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return self.initialised
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def _size_from_width(self, width):
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return (width * self.DIB_depth + 7) // 8
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def _padded_size_from_size(self, size):
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return (size + 3) // 4 * 4
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def _extract_from_bytes(self, data, index):
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# One formula that suits all: 1/2/4/8-bit colour depth.
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byte_index, pos_in_byte = divmod(index, self.ppb)
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shift = 8 - self.DIB_depth * (pos_in_byte + 1)
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return (data[byte_index] >> shift) & self.pmask
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def _fill_in_bytes(self, data, index, value):
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# One formula that suits all: 1/2/4/8-bit colour depth.
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byte_index, pos_in_byte = divmod(index, self.ppb)
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shift = 8 - self.DIB_depth * (pos_in_byte + 1)
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value &= self.pmask
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data[byte_index] = (data[byte_index] & ~(self.pmask << shift)) + (
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value << shift
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)
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def _decode_rle(self, bf_io):
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# Only bottom-up bitmap can be compressed.
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x, y = 0, self.DIB_h - 1
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while True:
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data = bf_io.read(2)
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if data[0] == 0:
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if data[1] == 0:
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x, y = 0, y - 1
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elif data[1] == 1:
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return
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elif data[1] == 2:
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data = bf_io.read(2)
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x, y = x + data[0], y - data[1]
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else:
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num_of_pixels = data[1]
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num_to_read = (self._size_from_width(num_of_pixels) + 1) // 2 * 2
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data = bf_io.read(num_to_read)
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for i in range(num_of_pixels):
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self[x, y] = self._extract_from_bytes(data, i)
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x += 1
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else:
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b = bytes([data[1]])
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for i in range(data[0]):
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self[x, y] = self._extract_from_bytes(b, i % self.ppb)
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x += 1
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def read_io(self, bf_io):
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#print("BMP reading file")
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# BMP Header
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data = bf_io.read(14)
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self.BMP_id = data[0:2]
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self.BMP_size = unpack("<I", data[2:6])[0]
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self.BMP_reserved1 = data[6:8]
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self.BMP_reserved2 = data[8:10]
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self.BMP_offset = unpack("<I", data[10:14])[0]
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# DIB Header
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data = bf_io.read(4)
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self.DIB_len = unpack("<I", data[0:4])[0]
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data = bf_io.read(self.DIB_len - 4)
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(
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self.DIB_w,
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self.DIB_h,
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self.DIB_planes_num,
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self.DIB_depth,
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self.DIB_comp,
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self.DIB_raw_size,
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self.DIB_hres,
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self.DIB_vres,
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) = unpack("<iiHHIIii", data[0:28])
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DIB_plt_num_info = unpack("<I", data[28:32])[0]
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DIB_plt_important_num_info = unpack("<I", data[32:36])[0]
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if self.DIB_len > 40:
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self.DIB_extra = data[36:]
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# Palette
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if self.DIB_depth <= 8:
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if DIB_plt_num_info == 0:
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self.DIB_num_in_plt = 2 ** self.DIB_depth
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else:
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self.DIB_num_in_plt = DIB_plt_num_info
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self.palette = [None for i in range(self.DIB_num_in_plt)]
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for i in range(self.DIB_num_in_plt):
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data = bf_io.read(4)
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colour = bytearray([data[2], data[1], data[0]])
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self.palette[i] = colour
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# In case self.DIB_h < 0 for top-down format.
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if self.DIB_h < 0:
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self.DIB_h = -self.DIB_h
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is_top_down = True
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else:
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is_top_down = False
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header = [
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self.DIB_w,
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self.DIB_h,
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self.DIB_planes_num,
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self.DIB_depth,
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self.DIB_comp,
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self.DIB_raw_size,
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self.DIB_hres,
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self.DIB_vres,
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self.palette,
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]
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#print("BMP metadata: ", str(header))
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if self.header_callback is not None:
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self.header_callback(header)
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self.parray = None
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assert self._init(), "Failed to initialize the image!"
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# Pixels
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#print("BMP reading data")
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if self.DIB_comp == 0:
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# BI_RGB
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for h in range(self.DIB_h):
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y = h if is_top_down else self.DIB_h - h - 1
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data = bf_io.read(self.padded_row_size)
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#pixels_row = []
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for x in range(self.DIB_w):
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if self.DIB_depth <= 8:
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##self[x, y] = self._extract_from_bytes(data, x)
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byte_index, pos_in_byte = divmod(x, self.ppb)
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shift = 8 - self.DIB_depth * (pos_in_byte + 1)
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pixel_data = (data[byte_index] >> shift) & self.pmask
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#pixel_data = self._extract_from_bytes(data, x)
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pixel = pixel_data if self.palette is None else self.palette[pixel_data]
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##pixels_row.append(pixel)
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self.data_callback(x, y, pixel)
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else:
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v = x * 3
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# BMP colour is in BGR order.
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self[x, y] = (data[v + 2], data[v + 1], data[v])
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#self.data_callback(0, y, pixels_row)
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else:
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# BI_RLE8 or BI_RLE4
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self._decode_rle(bf_io)
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#print("BMP done")
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return self
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def write_io(self, bf_io, force_40B_DIB=False):
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if force_40B_DIB:
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self.DIB_len = 40
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self.DIB_extra = None
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# Only uncompressed image is supported to write.
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self.DIB_comp = 0
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assert self._init(), "Failed to initialize the image!"
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# BMP Header
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bf_io.write(self.BMP_id)
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bf_io.write(pack("<I", self.BMP_size))
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bf_io.write(self.BMP_reserved1)
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bf_io.write(self.BMP_reserved2)
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bf_io.write(pack("<I", self.BMP_offset))
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# DIB Header
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bf_io.write(
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pack(
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"<IiiHHIIiiII",
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self.DIB_len,
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self.DIB_w,
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self.DIB_h,
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self.DIB_planes_num,
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self.DIB_depth,
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self.DIB_comp,
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self.DIB_raw_size,
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self.DIB_hres,
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self.DIB_vres,
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self.DIB_num_in_plt,
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self.DIB_num_in_plt,
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)
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)
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if self.DIB_len > 40:
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bf_io.write(self.DIB_extra)
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# Palette
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if self.DIB_depth <= 8:
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for colour in self.palette:
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bf_io.write(bytes([colour[2], colour[1], colour[0], 0]))
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# Pixels
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for h in range(self.DIB_h):
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# BMP last row comes first.
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y = self.DIB_h - h - 1
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if self.DIB_depth <= 8:
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d = 0
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for x in range(self.DIB_w):
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self[x, y] %= self.DIB_num_in_plt
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# One formula that suits all: 1/2/4/8-bit colour depth.
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d = (d << (self.DIB_depth % 8)) + self[x, y]
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if x % self.ppb == self.ppb - 1:
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# Got a whole byte.
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bf_io.write(bytes([d]))
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d = 0
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if x % self.ppb != self.ppb - 1:
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# Last byte if width does not fit in whole bytes.
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d <<= (
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8
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- self.DIB_depth
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- (x % self.ppb) * (2 ** (self.DIB_depth - 1))
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)
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bf_io.write(bytes([d]))
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d = 0
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else:
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for x in range(self.DIB_w):
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r, g, b = self[x, y]
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bf_io.write(bytes([b, g, r]))
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# Pad row to multiple of 4 bytes with 0x00.
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bf_io.write(b"\x00" * (self.padded_row_size - self.row_size))
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num_of_bytes = bf_io.tell()
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return num_of_bytes
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def load(self, file_path):
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with open(file_path, "rb") as file:
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self.read_io(file)
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return self
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def save(self, file_path, force_40B_DIB=False):
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with open(file_path, "wb") as file:
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num_of_bytes = self.write_io(file, force_40B_DIB)
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return num_of_bytes
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