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wmf

wmf

Image header parser for WMF (Windows Metafile) images.

A bare WMF records only drawing commands in metafile units and says nothing about how large the result should be. The physical size comes from the Aldus Placeable Metafile header, a 22-byte prefix carrying a bounding box and the number of metafile units per inch. Only a placeable WMF is recognized here, because a bare one gives us nothing to size the picture with.

Wmf 

Wmf(
    px_width: int,
    px_height: int,
    horz_dpi: int,
    vert_dpi: int,
    orientation: int = 1,
)

Bases: BaseImageHeader

Image header parser for WMF images having an Aldus Placeable Metafile header.

Source code in src/docx/image/image.py 
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def __init__(
    self,
    px_width: int,
    px_height: int,
    horz_dpi: int,
    vert_dpi: int,
    orientation: int = 1,
):
    self._px_width = px_width
    self._px_height = px_height
    self._horz_dpi = horz_dpi
    self._vert_dpi = vert_dpi
    self._orientation = orientation

content_type property 

content_type

MIME content type for this image, unconditionally image/x-wmf for WMF images.

default_ext property 

default_ext

Default filename extension, always 'wmf' for WMF images.

from_stream classmethod 

from_stream(stream)

Return a Wmf instance with header properties parsed from stream.

Source code in src/docx/image/wmf.py 
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@classmethod
def from_stream(cls, stream):
    """Return a |Wmf| instance with header properties parsed from `stream`."""
    stream.seek(0)
    header = stream.read(_APM_HEADER_LENGTH)
    if len(header) < _APM_HEADER_LENGTH:
        raise InvalidImageStreamError("unexpected end of WMF image stream")

    key, _hwmf, left, top, right, bottom, inch, _reserved, _checksum = _APM_HEADER.unpack(
        header
    )
    if key != _APM_KEY:
        raise InvalidImageStreamError(
            "WMF image has no Aldus Placeable Metafile header, so its display size is unknown"
        )
    if inch == 0:
        raise InvalidImageStreamError("WMF image declares zero metafile units per inch")

    # -- the bounding box is in metafile units, `inch` of them to the inch --
    inch_width = abs(right - left) / inch
    inch_height = abs(bottom - top) / inch
    if inch_width == 0 or inch_height == 0:
        raise InvalidImageStreamError("WMF image has a zero-size bounding box")

    px_width = int(round(inch_width * _WMF_DPI))
    px_height = int(round(inch_height * _WMF_DPI))
    return cls(px_width, px_height, _WMF_DPI, _WMF_DPI)