mirror of https://github.com/home-assistant/core
104 lines
3.2 KiB
Python
104 lines
3.2 KiB
Python
"""Image processing for cameras."""
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from __future__ import annotations
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import logging
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from typing import TYPE_CHECKING, Literal, cast
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SUPPORTED_SCALING_FACTORS = [(7, 8), (3, 4), (5, 8), (1, 2), (3, 8), (1, 4), (1, 8)]
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_LOGGER = logging.getLogger(__name__)
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JPEG_QUALITY = 75
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if TYPE_CHECKING:
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from turbojpeg import TurboJPEG
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from . import Image
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def find_supported_scaling_factor(
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current_width: int, current_height: int, target_width: int, target_height: int
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) -> tuple[int, int] | None:
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"""Find a supported scaling factor to scale the image.
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If there is no exact match, we use one size up to ensure
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the image remains crisp.
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"""
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for idx, supported_sf in enumerate(SUPPORTED_SCALING_FACTORS):
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ratio = supported_sf[0] / supported_sf[1]
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width_after_scale = current_width * ratio
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height_after_scale = current_height * ratio
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if width_after_scale == target_width and height_after_scale == target_height:
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return supported_sf
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if width_after_scale < target_width or height_after_scale < target_height:
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return None if idx == 0 else SUPPORTED_SCALING_FACTORS[idx - 1]
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# Giant image, the most we can reduce by is 1/8
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return SUPPORTED_SCALING_FACTORS[-1]
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def scale_jpeg_camera_image(cam_image: Image, width: int, height: int) -> bytes:
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"""Scale a camera image.
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Scale as close as possible to one of the supported scaling factors.
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"""
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turbo_jpeg = TurboJPEGSingleton.instance()
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if not turbo_jpeg:
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return cam_image.content
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try:
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(current_width, current_height, _, _) = turbo_jpeg.decode_header(
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cam_image.content
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)
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except OSError:
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return cam_image.content
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scaling_factor = find_supported_scaling_factor(
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current_width, current_height, width, height
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)
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if scaling_factor is None:
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return cam_image.content
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return cast(
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bytes,
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turbo_jpeg.scale_with_quality(
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cam_image.content,
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scaling_factor=scaling_factor,
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quality=JPEG_QUALITY,
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),
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)
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class TurboJPEGSingleton:
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"""Load TurboJPEG only once.
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Ensures we do not log load failures each snapshot
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since camera image fetches happen every few
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seconds.
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"""
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__instance: TurboJPEG | Literal[False] | None = None
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@staticmethod
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def instance() -> TurboJPEG | Literal[False] | None:
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"""Singleton for TurboJPEG."""
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if TurboJPEGSingleton.__instance is None:
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TurboJPEGSingleton()
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return TurboJPEGSingleton.__instance
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def __init__(self) -> None:
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"""Try to create TurboJPEG only once."""
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try:
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# TurboJPEG checks for libturbojpeg
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# when its created, but it imports
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# numpy which may or may not work so
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# we have to guard the import here.
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from turbojpeg import TurboJPEG # pylint: disable=import-outside-toplevel
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TurboJPEGSingleton.__instance = TurboJPEG()
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except Exception: # pylint: disable=broad-except
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_LOGGER.exception(
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"Error loading libturbojpeg; Cameras may impact HomeKit performance"
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)
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TurboJPEGSingleton.__instance = False
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