klemek
120 lines
4.8 KiB
Python
120 lines
4.8 KiB
Python
from typing import Tuple
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class BitmapError(Exception):
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pass
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class Bitmap:
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HEADER_SIZE = 54
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FILE_TYPES = [("Bitmap Image", "*.bmp"), ("All Files", "*.*")]
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@classmethod
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def write_bmp(cls, path: str, width: int, color_depth: int, data: bytes) -> None:
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with open(path, mode="wb") as f:
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f.write(cls.__get_bmp_data(width, color_depth, data))
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@classmethod
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def __get_bmp_data(cls, width: int, color_depth: int, data: bytes) -> bytes:
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height = len(data) // (width * 3)
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return cls.__get_header(
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width, height, color_depth, len(data)
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) + cls.__format_data(width, height, color_depth, data)
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@classmethod
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def __get_header(
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cls, width: int, height: int, color_depth: int, data_len: int
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) -> bytes:
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header = bytes()
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# BMP header
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header += "BM".encode() # (0, 2) BM
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header += (cls.HEADER_SIZE + data_len).to_bytes(
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4, byteorder="little"
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) # (2, 4) file size
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header += bytes([0]) * 4 # (6, 4) application reserved
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header += (cls.HEADER_SIZE).to_bytes(
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4, byteorder="little"
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) # (10, 4) data offset
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# DIB header
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header += (40).to_bytes(4, byteorder="little") # (14, 4) DIB header size
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header += width.to_bytes(4, byteorder="little") # (18, 4) width
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header += height.to_bytes(4, byteorder="little") # (22, 4) height
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header += (1).to_bytes(2, byteorder="little") # (26, 2) color panes
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header += (color_depth * 8).to_bytes(
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2, byteorder="little"
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) # (28, 2) bits per pixel
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header += bytes([0]) * 4 # (30, 4) BI_RGB, no compression
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header += (data_len).to_bytes(
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4, byteorder="little"
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) # (34, 4) size of raw bitmap data
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header += (2835).to_bytes(
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4, byteorder="little"
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) # (38, 4) horizontal print resolution
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header += (2835).to_bytes(
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4, byteorder="little"
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) # (42, 4) vertical print resolution
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header += bytes([0]) * 4 # (46, 4) color in palette
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header += bytes([0]) * 4 # (50, 4) 0 important colors
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return header
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@classmethod
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def __format_data(
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cls, width: int, height: int, color_depth: int, data: bytes
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) -> bytes:
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size = width * height * color_depth
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if len(data) < size:
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data += bytes([0]) * (size - len(data))
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elif len(data) > size:
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data = data[:size]
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line_padding = (width * color_depth) % 4
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output_data = bytes()
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for y in range(height):
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start = (height - y - 1) * color_depth * width
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output_data += data[start : start + width * color_depth]
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if line_padding > 0:
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output_data += bytes([0]) * (4 - line_padding)
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return output_data
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@classmethod
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def read_bmp(cls, path: str) -> Tuple[int, int, int, bytes]:
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with open(path, mode="rb") as f:
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bmp_data = f.read()
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width, height, color_depth, data_start, data_size = cls.__read_header(bmp_data)
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content_data = bmp_data[data_start:]
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if data_size > 0:
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content_data = content_data[:data_size]
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output_data = cls.__read_formated_data(width, height, color_depth, content_data)
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return width, height, color_depth, output_data
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@classmethod
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def __read_header(cls, bmp_data: bytes) -> Tuple[int, int, int, int, int]:
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if bmp_data[0:2].decode() != "BM":
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raise BitmapError("Not a Bitmap Image")
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if int.from_bytes(bmp_data[30:34], byteorder="little") != 0:
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raise BitmapError("Cannot read Bitmap: need no compression")
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if int.from_bytes(bmp_data[26:28], byteorder="little") != 1:
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raise BitmapError("Cannot read Bitmap: need 1 color panes")
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width = int.from_bytes(bmp_data[18:22], byteorder="little")
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height = int.from_bytes(bmp_data[22:26], byteorder="little")
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color_depth = int.from_bytes(bmp_data[28:30], byteorder="little") // 8
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if color_depth < 1:
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raise BitmapError("Cannot read Bitmap: bits per pixels is < 8")
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data_start = int.from_bytes(bmp_data[10:14], byteorder="little")
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data_size = int.from_bytes(bmp_data[34:38], byteorder="little")
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return width, height, color_depth, data_start, data_size
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@classmethod
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def __read_formated_data(
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cls, width: int, height: int, color_depth: int, bmp_data: bytes
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) -> bytes:
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line_padding = (width * color_depth) % 4
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if line_padding > 0:
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real_width = width * color_depth + (4 - line_padding)
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else:
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real_width = width * color_depth
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output_data = bytes()
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for y in range(height):
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start = (height - y - 1) * real_width
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output_data += bmp_data[start : start + width * color_depth]
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return output_data
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