from dataclasses import dataclass, field
from typing import Dict
class ImageInfo(dict):
"""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):
"Intrinsic image width"
return self["w"]
@property
def height(self):
"Intrinsic image height"
return self["h"]
@property
def rendered_width(self):
"Only available if the image has been placed on the document"
return self["rendered_width"]
@property
def rendered_height(self):
"Only available if the image has been placed on the document"
return self["rendered_height"]
def __str__(self):
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, y, w, h):
"""
Make an image fit within a bounding box, maintaining its proportions.
In the reduced dimension it will be centered within the available space.
"""
ratio = self.width / self.height
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, h, scale=1):
if w == 0 and h == 0: # Put image at 72 dpi
w = self["w"] / scale
h = self["h"] / scale
elif w == 0:
w = h * self["w"] / self["h"]
elif h == 0:
h = w * self["h"] / self["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 the raster images
images: Dict[str, dict] = 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: str = "AUTO"
def reset_usages(self):
for img in self.images.values():
img["usages"] = 0