View SMT Kingdom .GRD data (WIP)

view_grid.py

# Copyright (c) 2023 Derrick W. Turk / terminus, LLC

# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.


import sys
import struct

import numpy as np
import numpy.typing as npt
import matplotlib.pyplot as plt # type: ignore

from typing import NamedTuple


_EPS = 1e-3

_KINGDOM_MISSING = struct.unpack('<f', b'\x0C\x13\x9A\xF9')


class KingdomGrid(NamedTuple):
    title: str
    colorbar_path: str
    rows: int
    cols: int
    color_index: int
    zmin: float
    zmax: float
    xmin: float
    ymin: float
    xmax: float
    ymax: float
    xinc: float
    yinc: float
    data: npt.NDArray[np.float32]

    def plot(self) -> None:
        plt.imshow(self.data,
          extent=(self.xmin, self.xmax, self.ymin, self.ymax),
          origin='upper')
        plt.title(f'{self.title}')
        plt.colorbar()
        plt.show()


def read_grid(buf: bytes) -> KingdomGrid:
    title, = struct.unpack_from('<256s', buf, 0x10)
    cols, rows, color_index, zmin, zmax, colorbar_path = struct.unpack_from(
      '<3I2f256s', buf, 0x230)
    xmin, ymin, xmax, ymax, xinc, yinc = struct.unpack_from(
      '<6d', buf, 0x354)
    arr = np.frombuffer(buf, dtype=np.dtype('<f'), offset=0x7a4)

    if np.abs(xmin + xinc * (cols - 1) - xmax) > _EPS:
        raise ValueError(f'have x = {xmin} to {xmax} but increment {xinc}')

    if np.abs(ymin + yinc * (rows - 1) - ymax) > _EPS:
        raise ValueError(f'have y = {ymin} to {ymax} but increment {yinc}')

    sz = arr.shape[0]
    if sz != rows * cols:
        raise ValueError(f'expected {rows} x {cols} grid, found {sz} elements')

    data = arr.reshape((cols, rows)).transpose().copy()
    data[data == _KINGDOM_MISSING] = np.nan

    return KingdomGrid(
        _asciz_string(title),
        _asciz_string(colorbar_path),
        rows,
        cols,
        color_index,
        zmin,
        zmax,
        xmin,
        ymin,
        xmax,
        ymax,
        xinc,
        yinc,
        data,
    )


def _asciz_string(buf: bytes) -> str:
    return buf[:buf.index(b'\x00')].decode('ascii')


def main(argv: list[str]) -> int:
    if len(argv) <= 1:
        print(f'Usage: {argv[0] if argv else "view_grid.py"} .grd-files...',
          file=sys.stderr)
        return 2

    had_err = False
    for grid in argv[1:]:
        try:
            with open(grid, 'rb') as f:
                g = read_grid(f.read())
                print(f'{g.title} ({g.rows} x {g.cols})')
                g.plot()
        except Exception as e:
            print(f'Error reading {grid}: {e}', file=sys.stderr)
            had_err = True

    return 1 if had_err else 0


if __name__ == '__main__':
    sys.exit(main(sys.argv))