67 lines
2 KiB
Python
67 lines
2 KiB
Python
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from __future__ import annotations
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import struct
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import zlib
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from pathlib import Path
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from .formats import ShapeFrame
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DEFAULT_BACKGROUND = (10, 12, 18, 255)
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def rgba_buffer(width: int, height: int, color: tuple[int, int, int, int]) -> bytearray:
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r, g, b, a = color
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row = bytes((r, g, b, a)) * width
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return bytearray(row * height)
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def blit_frame(
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buffer: bytearray,
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canvas_width: int,
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canvas_height: int,
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left: int,
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top: int,
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frame: ShapeFrame,
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pixels: list[int],
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palette: list[tuple[int, int, int]],
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flipped: bool,
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) -> None:
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for src_y in range(frame.height):
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dst_y = top + src_y
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if dst_y < 0 or dst_y >= canvas_height:
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continue
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row_base = src_y * frame.width
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for src_x in range(frame.width):
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color_index = pixels[row_base + (frame.width - 1 - src_x if flipped else src_x)]
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if color_index < 0:
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continue
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dst_x = left + src_x
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if dst_x < 0 or dst_x >= canvas_width:
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continue
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pixel_base = (dst_y * canvas_width + dst_x) * 4
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r, g, b = palette[color_index]
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buffer[pixel_base : pixel_base + 4] = bytes((r, g, b, 255))
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def write_png_rgba(path: Path, width: int, height: int, pixels: bytearray) -> None:
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def chunk(chunk_type: bytes, payload: bytes) -> bytes:
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return (
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struct.pack(">I", len(payload))
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+ chunk_type
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+ payload
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+ struct.pack(">I", zlib.crc32(chunk_type + payload) & 0xFFFFFFFF)
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)
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rows = bytearray()
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stride = width * 4
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for row in range(height):
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rows.append(0)
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start = row * stride
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rows.extend(pixels[start : start + stride])
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payload = bytearray(b"\x89PNG\r\n\x1a\n")
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payload.extend(chunk(b"IHDR", struct.pack(">IIBBBBB", width, height, 8, 6, 0, 0, 0)))
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payload.extend(chunk(b"IDAT", zlib.compress(bytes(rows), level=9)))
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payload.extend(chunk(b"IEND", b""))
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path.write_bytes(payload)
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