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# pyright: reportUnknownVariableType=false
from dataclasses import dataclass, field
from typing import Literal, TypeAlias, cast
ImageFilter: TypeAlias = Literal[
"AUTO",
"FlateDecode",
"DCTDecode",
"JPXDecode",
"LZWDecode",
"CCITTFaxDecode",
]
class ImageInfo(dict[str, object]):
"""Information about an image used in the PDF document (base class).
We subclass this to distinguish between raster and vector images."""
@property
def width(self) -> float:
"Intrinsic image width"
return cast(float, self["w"])
@property
def height(self) -> float:
"Intrinsic image height"
return cast(float, self["h"])
@property
def rendered_width(self) -> float:
"Only available if the image has been placed on the document"
return cast(float, self["rendered_width"])
@property
def rendered_height(self) -> float:
"Only available if the image has been placed on the document"
return cast(float, self["rendered_height"])
def __str__(self) -> str:
d = {
k: ("..." if k in ("data", "iccp", "smask") else v) for k, v in self.items()
}
return f"self.__class__.__name__({d})"
def scale_inside_box(
self, x: float, y: float, w: float, h: float
) -> tuple[float, float, float, float]:
"""
Make an image fit within a bounding box, maintaining its proportions.
In the reduced dimension it will be centered within the available space.
"""
img_w: float = self["w"] # type: ignore
img_h: float = self["h"] # type: ignore
ratio = img_w / img_h
if h * ratio < w:
new_w = h * ratio
new_h = h
x += (w - new_w) / 2
else: # => too wide, limiting width:
new_h = w / ratio
new_w = w
y += (h - new_h) / 2
return x, y, new_w, new_h
class RasterImageInfo(ImageInfo):
"Information about a raster image used in the PDF document"
def size_in_document_units(
self, w: float, h: float, scale: float = 1
) -> tuple[float, float]:
img_w: float = self["w"] # type: ignore
img_h: float = self["h"] # type: ignore
if w == 0 and h == 0: # Put image at 72 dpi
w = img_w / scale
h = img_h / scale
elif w == 0:
w = h * img_w / img_h
elif h == 0:
h = w * img_h / img_w
return w, h
class VectorImageInfo(ImageInfo):
"Information about a vector image used in the PDF document"
# pass
@dataclass
class ImageCache:
# Map image identifiers to dicts describing raster or vector images
images: dict[str, RasterImageInfo | VectorImageInfo] = field(default_factory=dict)
# Map icc profiles (bytes) to their index (number)
icc_profiles: dict[bytes, int] = field(default_factory=dict)
# Must be one of SUPPORTED_IMAGE_FILTERS values
image_filter: ImageFilter = "AUTO"
def reset_usages(self) -> None:
for img in self.images.values():
img["usages"] = 0
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