Module `fpdf.syntax`

Classes & functions that represent core elements of the PDF syntax

Most of what happens in a PDF happens in objects, which are formatted like so:

3 0 obj
<</Type /Page
/Parent 1 0 R
/Resources 2 0 R
/Contents 4 0 R>>
endobj

The first line says that this is the third object in the structure of the document.

There are 8 kinds of objects (Adobe Reference, 51):

Boolean values
Integer and real numbers
Strings
Names
Arrays
Dictionaries
Streams
The null object

The << in the second line and the >> in the line preceding endobj denote that it is a dictionary object. Dictionaries map Names to other objects.

Names are the strings preceded by /, valid Names do not have to start with a capital letter, they can be any ascii characters, # and two characters can escape non-printable ascii characters, described on page 57.

3 0 obj means what follows here is the third object, but the name Type (represented here by /Type) is mapped to an indirect object reference: 0 obj vs 0 R.

The structure of this data, in python/dict form, is thus:

third_obj = {
  '/Type': '/Page'),
  '/Parent': iobj_ref(1),
  '/Resources': iobj_ref(2),
  '/Contents': iobj_ref(4),
}

Content streams are of the form:

4 0 obj
<</Filter /ASCIIHexDecode /Length 22>>
stream
68656c6c6f20776f726c64
endstream
endobj

The contents of this module are internal to fpdf2, and not part of the public API. They may change at any time without prior warning or any deprecation period, in non-backward-compatible ways.

Functions

def build_obj_dict(key_values: Dict[str, object]) ‑> Dict[str, object]

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def build_obj_dict(
    key_values: Dict[str, object],
    _security_handler: Optional["StandardSecurityHandler"] = None,
    _obj_id: Optional[int] = None,
) -> Dict[str, object]:
    """
    Build the PDF Object associative map to serialize, based on a key-values dict.
    The property names are converted from snake_case to CamelCase,
    and prefixed with a slash character "/".
    """

    obj_dict = {}
    for key, value in key_values.items():
        if (
            callable(value)
            or key.startswith("_")
            or key in ("id", "ref")
            or value is None
        ):
            continue
        # pylint: disable=redefined-loop-name
        if hasattr(value, "value"):  # e.g. Enum subclass
            value = value.value
        if isinstance(value, PDFObject):  # indirect object reference
            value = value.ref
        elif hasattr(value, "serialize"):  # pyright: ignore[reportUnknownArgumentType]
            # e.g. PDFArray, PDFString, Name, Destination, Action...
            value = value.serialize(
                _security_handler=_security_handler, _obj_id=_obj_id
            )
        elif isinstance(value, bool):
            value = str(value).lower()
        obj_dict[f"/{camel_case(key)}"] = value
    return obj_dict

Build the PDF Object associative map to serialize, based on a key-values dict. The property names are converted from snake_case to CamelCase, and prefixed with a slash character "/".

def camel_case(snake_case: str) ‑> str

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def camel_case(snake_case: str) -> str:
    return "".join(x for x in snake_case.title() if x != "_")

def clear_empty_fields(d: Mapping[str, object]) ‑> Mapping[str, object]

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def clear_empty_fields(d: Mapping[str, object]) -> Mapping[str, object]:
    return {k: v for k, v in d.items() if v}

def create_dictionary_string(dict_: Mapping[str, object], open_dict: str = '<<', close_dict: str = '>>', field_join: str = '\n', key_value_join: str = ' ', has_empty_fields: bool = False) ‑> str

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def create_dictionary_string(
    dict_: Mapping[str, object],
    open_dict: str = "<<",
    close_dict: str = ">>",
    field_join: str = "\n",
    key_value_join: str = " ",
    has_empty_fields: bool = False,
) -> str:
    """format dictionary as PDF dictionary

    @param dict_: dictionary of values to render
    @param open_dict: string to open PDF dictionary
    @param close_dict: string to close PDF dictionary
    @param field_join: string to join fields with
    @param key_value_join: string to join key to value with
    @param has_empty_fields: whether or not to clear_empty_fields first.
    """
    if has_empty_fields:
        dict_ = clear_empty_fields(dict_)

    return "".join(
        [
            open_dict,
            field_join.join(key_value_join.join((k, str(v))) for k, v in dict_.items()),
            close_dict,
        ]
    )

format dictionary as PDF dictionary

@param dict_: dictionary of values to render @param open_dict: string to open PDF dictionary @param close_dict: string to close PDF dictionary @param field_join: string to join fields with @param key_value_join: string to join key to value with @param has_empty_fields: whether or not to clear_empty_fields first.

def create_list_string(list_: list[str]) ‑> str

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def create_list_string(list_: list[str]) -> str:
    """format list of strings as PDF array"""
    return f"[{' '.join(list_)}]"

format list of strings as PDF array

def create_stream(stream: bytearray | bytes | str, encryption_handler: StandardSecurityHandler | None = None, obj_id: int | None = None) ‑> str

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def create_stream(
    stream: bytearray | bytes | str,
    encryption_handler: Optional["StandardSecurityHandler"] = None,
    obj_id: Optional[int] = None,
) -> str:
    if isinstance(stream, (bytearray, bytes)):
        stream = str(stream, "latin-1")
    if encryption_handler:
        assert obj_id is not None
        encryption_handler.encrypt(stream, obj_id)
    return "\n".join(["stream", stream, "endstream"])

def iobj_ref(n: int) ‑> str

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def iobj_ref(n: int) -> str:
    """format an indirect PDF Object reference from its id number"""
    return f"{n} 0 R"

format an indirect PDF Object reference from its id number

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def render_pdf_primitive(primitive: PDFPrimitive) -> Raw:
    """
    Render a Python value as a PDF primitive type.

    Container types (tuples/lists and dicts) are rendered recursively. This supports
    values of the type Name, str, bytes, numbers, booleans, list/tuple, and dict.

    Any custom type can be passed in as long as it provides a `serialize` method that
    takes no arguments and returns a string. The primitive object is returned directly
    if it is an instance of the `Raw` class. Otherwise, The existence of the `serialize`
    method is checked before any other type checking is performed, so, for example, a
    `dict` subclass with a `serialize` method would be converted using its `pdf_repr`
    method rather than the built-in `dict` conversion process.

    Args:
        primitive: the primitive value to convert to its PDF representation.

    Returns:
        Raw-wrapped str of the PDF representation.

    Raises:
        ValueError: if a dictionary key is not a Name.
        TypeError: if `primitive` does not have a known conversion to a PDF
            representation.
    """

    if isinstance(primitive, Raw):
        return primitive

    if isinstance(primitive, PrimitiveSerializable):
        output = primitive.serialize()
    elif primitive is None:
        output = "null"
    elif isinstance(primitive, str):
        output = f"({escape_parens(primitive)})"
    elif isinstance(primitive, bytes):
        output = f"<{primitive.hex()}>"
    elif isinstance(primitive, bool):  # has to come before number check
        output = ["false", "true"][primitive]
    elif isinstance(primitive, NumberClass):
        output = number_to_str(primitive)
    elif isinstance(primitive, (list, tuple)):
        output = "[" + " ".join(render_pdf_primitive(val) for val in primitive) + "]"
    elif isinstance(primitive, dict):
        item_list: list[str] = []
        for key, val in primitive.items():
            if not isinstance(key, Name):
                raise ValueError("dict keys must be Names")

            item_list.append(
                render_pdf_primitive(key) + " " + render_pdf_primitive(val)
            )

        output = "<< " + "\n".join(item_list) + " >>"
    else:
        raise TypeError(f"cannot produce PDF representation for value {primitive!r}")

    return Raw(output)

Render a Python value as a PDF primitive type.

Container types (tuples/lists and dicts) are rendered recursively. This supports values of the type Name, str, bytes, numbers, booleans, list/tuple, and dict.

Any custom type can be passed in as long as it provides a serialize method that takes no arguments and returns a string. The primitive object is returned directly if it is an instance of the Raw class. Otherwise, The existence of the serialize method is checked before any other type checking is performed, so, for example, a dict subclass with a serialize method would be converted using its pdf_repr method rather than the built-in dict conversion process.

Args

primitive: the primitive value to convert to its PDF representation.

Returns

Raw-wrapped str of the PDF representation.

Raises

ValueError: if a dictionary key is not a Name.
TypeError: if primitive does not have a known conversion to a PDF representation.

def wrap_in_local_context(draw_commands: list[str]) ‑> list[str]

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def wrap_in_local_context(draw_commands: list[str]) -> list[str]:
    """
    Wrap a series of draw commands (list of strings) in a local context marker, so that changes to
    draw style only apply to these commands.
    """
    return ["q"] + draw_commands + ["Q"]

Wrap a series of draw commands (list of strings) in a local context marker, so that changes to draw style only apply to these commands.

Classes

class Destination

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class Destination(ABC):
    def serialize(
        self,
        _security_handler: Optional["StandardSecurityHandler"] = None,
        _obj_id: Optional[int] = None,
    ) -> str:
        raise NotImplementedError

Helper class that provides a standard way to create an ABC using inheritance.

Ancestors

abc.ABC

Subclasses

DestinationXYZ

Methods

def serialize(self) ‑> str

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def serialize(
    self,
    _security_handler: Optional["StandardSecurityHandler"] = None,
    _obj_id: Optional[int] = None,
) -> str:
    raise NotImplementedError

class DestinationXYZ (page: int, top: float | None, left: float = 0, zoom: str | float = 'null')

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class DestinationXYZ(Destination):
    def __init__(
        self,
        page: int,
        top: Optional[float],
        left: float = 0,
        zoom: str | float = "null",
    ) -> None:
        self.page_number = page
        self.top = top
        self.left = left
        self.zoom = zoom
        self.page_ref: Optional[str] = None

    def __eq__(self, dest: object) -> bool:
        if not isinstance(dest, DestinationXYZ):
            return False
        return (
            self.page_number == dest.page_number
            and self.top == dest.top
            and self.left == dest.left
            and self.zoom == dest.zoom
        )

    def __hash__(self) -> int:
        return hash((self.page_number, self.top, self.left, self.zoom))

    def __repr__(self) -> str:
        return f'DestinationXYZ(page_number={self.page_number}, top={self.top}, left={self.left}, zoom="{self.zoom}", page_ref={self.page_ref})'

    def serialize(
        self,
        _security_handler: Optional["StandardSecurityHandler"] = None,
        _obj_id: Optional[int] = None,
    ) -> str:
        left = round(self.left, 2) if isinstance(self.left, float) else self.left
        top = round(self.top, 2) if isinstance(self.top, float) else self.top
        assert self.page_ref
        return f"[{self.page_ref} /XYZ {left} {top} {self.zoom}]"

    def replace(
        self,
        page: Optional[int] = None,
        top: Optional[float] = None,
        left: Optional[float] = None,
        zoom: Optional[str | float] = None,
    ) -> "DestinationXYZ":
        assert (
            not self.page_ref
        ), "DestinationXYZ should not be copied after serialization"
        return DestinationXYZ(
            page=self.page_number if page is None else page,
            top=self.top if top is None else top,
            left=self.left if left is None else left,
            zoom=self.zoom if zoom is None else zoom,
        )

Helper class that provides a standard way to create an ABC using inheritance.

Ancestors

Destination
abc.ABC

Methods

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def replace(
    self,
    page: Optional[int] = None,
    top: Optional[float] = None,
    left: Optional[float] = None,
    zoom: Optional[str | float] = None,
) -> "DestinationXYZ":
    assert (
        not self.page_ref
    ), "DestinationXYZ should not be copied after serialization"
    return DestinationXYZ(
        page=self.page_number if page is None else page,
        top=self.top if top is None else top,
        left=self.left if left is None else left,
        zoom=self.zoom if zoom is None else zoom,
    )

def serialize(self) ‑> str

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def serialize(
    self,
    _security_handler: Optional["StandardSecurityHandler"] = None,
    _obj_id: Optional[int] = None,
) -> str:
    left = round(self.left, 2) if isinstance(self.left, float) else self.left
    top = round(self.top, 2) if isinstance(self.top, float) else self.top
    assert self.page_ref
    return f"[{self.page_ref} /XYZ {left} {top} {self.zoom}]"

class Name (...)

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class Name(str):
    """str subclass signifying a PDF name, which are emitted differently than normal strings."""

    NAME_ESC = re.compile(
        b"[^" + bytes(v for v in range(33, 127) if v not in b"()<>[]{}/%#\\") + b"]"
    )

    def serialize(
        self,
        _security_handler: Optional["StandardSecurityHandler"] = None,
        _obj_id: Optional[int] = None,
    ) -> str:
        escaped = self.NAME_ESC.sub(
            lambda m: b"#%02X" % m[0][0], self.encode()
        ).decode()
        return f"/{escaped}"

str subclass signifying a PDF name, which are emitted differently than normal strings.

Ancestors

builtins.str

Class variables

var NAME_ESC: The type of the None singleton.

Methods

def serialize(self) ‑> str

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def serialize(
    self,
    _security_handler: Optional["StandardSecurityHandler"] = None,
    _obj_id: Optional[int] = None,
) -> str:
    escaped = self.NAME_ESC.sub(
        lambda m: b"#%02X" % m[0][0], self.encode()
    ).decode()
    return f"/{escaped}"

class PDFArray (*args, **kwargs)

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class PDFArray(list[Any]):
    def serialize(
        self,
        _security_handler: Optional["StandardSecurityHandler"] = None,
        _obj_id: Optional[int] = None,
    ) -> str:
        if all(isinstance(elem, str) for elem in self):
            serialized_elems = " ".join(self)
        elif all(isinstance(elem, (int, float)) for elem in self):
            serialized_elems = " ".join(str(elem) for elem in self)
        else:
            serialized_chunks: list[str] = []
            for elem in self:
                if isinstance(elem, PDFObject):
                    serialized_chunks.append(elem.ref)
                elif hasattr(elem, "serialize"):
                    serialized_chunks.append(
                        elem.serialize(
                            _security_handler=_security_handler, _obj_id=_obj_id
                        )
                    )
                elif isinstance(elem, bool):
                    serialized_chunks.append(str(elem).lower())
                elif isinstance(elem, (int, float)):
                    serialized_chunks.append(str(elem))
                else:
                    serialized_chunks.append(str(elem))
            serialized_elems = "\n".join(serialized_chunks)
        return f"[{serialized_elems}]"

Built-in mutable sequence.

If no argument is given, the constructor creates a new empty list. The argument must be an iterable if specified.

Ancestors

builtins.list

Methods

def serialize(self) ‑> str

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def serialize(
    self,
    _security_handler: Optional["StandardSecurityHandler"] = None,
    _obj_id: Optional[int] = None,
) -> str:
    if all(isinstance(elem, str) for elem in self):
        serialized_elems = " ".join(self)
    elif all(isinstance(elem, (int, float)) for elem in self):
        serialized_elems = " ".join(str(elem) for elem in self)
    else:
        serialized_chunks: list[str] = []
        for elem in self:
            if isinstance(elem, PDFObject):
                serialized_chunks.append(elem.ref)
            elif hasattr(elem, "serialize"):
                serialized_chunks.append(
                    elem.serialize(
                        _security_handler=_security_handler, _obj_id=_obj_id
                    )
                )
            elif isinstance(elem, bool):
                serialized_chunks.append(str(elem).lower())
            elif isinstance(elem, (int, float)):
                serialized_chunks.append(str(elem))
            else:
                serialized_chunks.append(str(elem))
        serialized_elems = "\n".join(serialized_chunks)
    return f"[{serialized_elems}]"

class PDFContentStream (contents: bytes | bytearray, compress: bool = False)

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class PDFContentStream(PDFObject):
    # Passed to zlib.compress() - In range 0-9 - Default is currently equivalent to 6:
    _COMPRESSION_LEVEL = -1

    def __init__(self, contents: bytes | bytearray, compress: bool = False):
        super().__init__()
        self._contents = (
            zlib.compress(contents, level=self._COMPRESSION_LEVEL)
            if compress
            else bytes(contents)
        )
        self.filter = Name("FlateDecode") if compress else None
        self.length = len(self._contents)

    # method override
    def content_stream(self) -> bytes:
        return self._contents

    # method override
    def serialize(
        self,
        obj_dict: Optional[Dict[str, object]] = None,
        _security_handler: Optional["StandardSecurityHandler"] = None,
    ) -> str:
        if _security_handler:
            assert not obj_dict
            if not isinstance(self._contents, (bytearray, bytes)):
                self._contents = self._contents.encode("latin-1")
            self._contents = _security_handler.encrypt_stream(self._contents, self.id)
            self.length = len(self._contents)
        return super().serialize(obj_dict, _security_handler)

Ancestors

PDFObject

Subclasses

Methods

def content_stream(self) ‑> bytes

Inherited from: PDFObject.content_stream

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def content_stream(self) -> bytes:
    return self._contents

Subclasses can override this method to indicate the presence of a content stream

def serialize(self, obj_dict: Dict[str, object] | None = None) ‑> str

Inherited from: PDFObject.serialize

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def serialize(
    self,
    obj_dict: Optional[Dict[str, object]] = None,
    _security_handler: Optional["StandardSecurityHandler"] = None,
) -> str:
    if _security_handler:
        assert not obj_dict
        if not isinstance(self._contents, (bytearray, bytes)):
            self._contents = self._contents.encode("latin-1")
        self._contents = _security_handler.encrypt_stream(self._contents, self.id)
        self.length = len(self._contents)
    return super().serialize(obj_dict, _security_handler)

Serialize the PDF object as an obj<</>>endobj text block

class PDFDate (date: datetime.datetime, with_tz: bool = False, encrypt: bool = False)

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class PDFDate:
    def __init__(
        self, date: datetime, with_tz: bool = False, encrypt: bool = False
    ) -> None:
        """
        Args:
            date (datetime): self-explanatory
            with_tz (bool): should the timezone be encoded in included in the date?
            encrypt (bool): if document encryption is enabled, should this string be encrypted?
        """
        self.date = date
        self.with_tz = with_tz
        self.encrypt = encrypt

    def __repr__(self) -> str:
        return f"PDFDate({self.date}, with_tz={self.with_tz}, encrypt={self.encrypt})"

    def serialize(
        self,
        _security_handler: Optional["StandardSecurityHandler"] = None,
        _obj_id: Optional[int] = None,
    ) -> str:
        if self.with_tz:
            assert self.date.tzinfo
            if self.date.tzinfo == timezone.utc:
                out_str = f"D:{self.date:%Y%m%d%H%M%SZ}"
            else:
                out_str = f"D:{self.date:%Y%m%d%H%M%S%z}"
                out_str = out_str[:-2] + "'" + out_str[-2:] + "'"
        else:
            out_str = f"D:{self.date:%Y%m%d%H%M%S}"
        if _security_handler and self.encrypt:
            assert _obj_id
            return _security_handler.encrypt_string(out_str, _obj_id)
        return f"({out_str})"

Args

date : datetime: self-explanatory
with_tz : bool: should the timezone be encoded in included in the date?
encrypt : bool: if document encryption is enabled, should this string be encrypted?

Methods

def serialize(self) ‑> str

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def serialize(
    self,
    _security_handler: Optional["StandardSecurityHandler"] = None,
    _obj_id: Optional[int] = None,
) -> str:
    if self.with_tz:
        assert self.date.tzinfo
        if self.date.tzinfo == timezone.utc:
            out_str = f"D:{self.date:%Y%m%d%H%M%SZ}"
        else:
            out_str = f"D:{self.date:%Y%m%d%H%M%S%z}"
            out_str = out_str[:-2] + "'" + out_str[-2:] + "'"
    else:
        out_str = f"D:{self.date:%Y%m%d%H%M%S}"
    if _security_handler and self.encrypt:
        assert _obj_id
        return _security_handler.encrypt_string(out_str, _obj_id)
    return f"({out_str})"

class PDFObject

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class PDFObject:
    # Main features of this class:
    # * delay ID assignment
    # * implement serializing
    # Note: several child classes use __slots__ to save up some memory

    def __init__(self) -> None:
        self._id: Optional[int] = None

    @property
    def id(self) -> int:
        if self._id is None:
            raise AttributeError(
                f"{self.__class__.__name__} has not been assigned an ID yet"
            )
        return self._id

    @id.setter
    def id(self, n: int) -> None:
        self._id = n

    @property
    def ref(self) -> str:
        return iobj_ref(self.id)

    def serialize(
        self,
        obj_dict: Optional[Dict[str, object]] = None,
        _security_handler: Optional["StandardSecurityHandler"] = None,
    ) -> str:
        "Serialize the PDF object as an obj<</>>endobj text block"
        output: list[str] = []
        output.append(f"{self.id} 0 obj")
        output.append("<<")
        if not obj_dict:
            obj_dict = self._build_obj_dict(_security_handler)
        output.append(create_dictionary_string(obj_dict, open_dict="", close_dict=""))
        output.append(">>")
        content_stream = self.content_stream()
        if content_stream:
            output.append(create_stream(content_stream))
        output.append("endobj")
        return "\n".join(output)

    # pylint: disable=no-self-use
    def content_stream(self) -> bytes:
        "Subclasses can override this method to indicate the presence of a content stream"
        return b""

    def _build_obj_dict(
        self, security_handler: Optional["StandardSecurityHandler"] = None
    ) -> Dict[str, object]:
        """
        Build the PDF Object associative map to serialize,
        based on this class instance properties.
        The property names are converted from snake_case to CamelCase,
        and prefixed with a slash character "/".
        """
        return build_obj_dict(
            {key: getattr(self, key) for key in dir(self)},
            _security_handler=security_handler,
            _obj_id=self.id,
        )

Subclasses

Instance variables

prop id : int

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@property
def id(self) -> int:
    if self._id is None:
        raise AttributeError(
            f"{self.__class__.__name__} has not been assigned an ID yet"
        )
    return self._id

prop ref : str

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@property
def ref(self) -> str:
    return iobj_ref(self.id)

Methods

def content_stream(self) ‑> bytes

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def content_stream(self) -> bytes:
    "Subclasses can override this method to indicate the presence of a content stream"
    return b""

Subclasses can override this method to indicate the presence of a content stream

def serialize(self, obj_dict: Dict[str, object] | None = None) ‑> str

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def serialize(
    self,
    obj_dict: Optional[Dict[str, object]] = None,
    _security_handler: Optional["StandardSecurityHandler"] = None,
) -> str:
    "Serialize the PDF object as an obj<</>>endobj text block"
    output: list[str] = []
    output.append(f"{self.id} 0 obj")
    output.append("<<")
    if not obj_dict:
        obj_dict = self._build_obj_dict(_security_handler)
    output.append(create_dictionary_string(obj_dict, open_dict="", close_dict=""))
    output.append(">>")
    content_stream = self.content_stream()
    if content_stream:
        output.append(create_stream(content_stream))
    output.append("endobj")
    return "\n".join(output)

Serialize the PDF object as an obj<</>>endobj text block

class PDFString (content: str, encrypt: bool = False)

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class PDFString(str):
    USE_HEX_ENCODING = True
    encrypt: bool = False
    """
    Setting this to False can reduce the encoded strings size,
    but then there can be a risk of badly encoding some unicode strings - cf. issue #458
    """

    def __new__(cls, content: str, encrypt: bool = False) -> "PDFString":
        """
        Args:
            content (str): text
            encrypt (bool): if document encryption is enabled, should this string be encrypted?
        """
        self = super().__new__(cls, content)
        self.encrypt = encrypt
        return self

    def serialize(
        self,
        _security_handler: Optional["StandardSecurityHandler"] = None,
        _obj_id: Optional[int] = None,
    ) -> str:
        if _security_handler and self.encrypt:
            assert _obj_id is not None
            return _security_handler.encrypt_string(self, _obj_id)
        try:
            self.encode("ascii")
            # => this string only contains ASCII characters
            return f"({escape_parens(self)})"
        except UnicodeEncodeError:
            pass
        if self.USE_HEX_ENCODING:
            # Using the "Hexadecimal String" format defined in the PDF spec:
            hex_str = hexlify(BOM_UTF16_BE + self.encode("utf-16-be")).decode("latin-1")
            return f"<{hex_str}>"
        return f'({self.encode("UTF-16").decode("latin-1")})'

str(object='') -> str str(bytes_or_buffer[, encoding[, errors]]) -> str

Create a new string object from the given object. If encoding or errors is specified, then the object must expose a data buffer that will be decoded using the given encoding and error handler. Otherwise, returns the result of object.str() (if defined) or repr(object). encoding defaults to 'utf-8'. errors defaults to 'strict'.

Ancestors

builtins.str

Class variables

var USE_HEX_ENCODING: The type of the None singleton.
var encrypt : bool: Setting this to False can reduce the encoded strings size, but then there can be a risk of badly encoding some unicode strings - cf. issue #458

Methods

def serialize(self) ‑> str

Expand source code Browse git

def serialize(
    self,
    _security_handler: Optional["StandardSecurityHandler"] = None,
    _obj_id: Optional[int] = None,
) -> str:
    if _security_handler and self.encrypt:
        assert _obj_id is not None
        return _security_handler.encrypt_string(self, _obj_id)
    try:
        self.encode("ascii")
        # => this string only contains ASCII characters
        return f"({escape_parens(self)})"
    except UnicodeEncodeError:
        pass
    if self.USE_HEX_ENCODING:
        # Using the "Hexadecimal String" format defined in the PDF spec:
        hex_str = hexlify(BOM_UTF16_BE + self.encode("utf-16-be")).decode("latin-1")
        return f"<{hex_str}>"
    return f'({self.encode("UTF-16").decode("latin-1")})'

class PrimitiveSerializable (*args, **kwargs)

Expand source code Browse git

@runtime_checkable
class PrimitiveSerializable(Protocol):
    def serialize(self) -> str: ...

Base class for protocol classes.

Protocol classes are defined as::

class Proto(Protocol):
    def meth(self) -> int:
        ...

Such classes are primarily used with static type checkers that recognize structural subtyping (static duck-typing).

For example::

class C:
    def meth(self) -> int:
        return 0

def func(x: Proto) -> int:
    return x.meth()

func(C())  # Passes static type check

See PEP 544 for details. Protocol classes decorated with @typing.runtime_checkable act as simple-minded runtime protocols that check only the presence of given attributes, ignoring their type signatures. Protocol classes can be generic, they are defined as::

class GenProto[T](Protocol):
    def meth(self) -> T:
        ...

Ancestors

typing.Protocol
typing.Generic

Methods

def serialize(self) ‑> str

Expand source code Browse git

def serialize(self) -> str: ...

class Raw (...)

Expand source code Browse git

class Raw(str):
    """str subclass signifying raw data to be directly emitted to PDF without transformation."""

str subclass signifying raw data to be directly emitted to PDF without transformation.

Ancestors

builtins.str