layouts

Layouts for the WindowManager.

ROW_BREAK = Slot('Row Break', Static(0), Static(0)) module-attribute

When encountered in Layout.build_rows, a new row will be started at the next element.

Auto dataclass

Bases: Dimension

An automatically calculated dimension.

The value of this dimension is overwritten on Layout.apply.

Generally, the way calculations are done is by looking at the available size of the layout by subtracting the sum of all the non-auto dimensions from the terminal's width or height, and dividing it by the number of Auto-type dimensions in the current context.

An additional offset is applied to the first dimension (left-most or top-most) of the context when the division has a remainder.

Source code in pytermgui/window_manager/layouts.py

@dataclass
class Auto(Dimension):
    """An automatically calculated dimension.

    The value of this dimension is overwritten on `Layout.apply`.

    Generally, the way calculations are done is by looking at the available
    size of the layout by subtracting the sum of all the non-auto dimensions
    from the terminal's width or height, and dividing it by the number of
    Auto-type dimensions in the current context.

    An additional offset is applied to the first dimension (left-most or top-most)
    of the context when the division has a remainder.
    """

    _value = 0

    def __repr__(self) -> str:
        return f"{type(self).__name__}(value={self.value})"

Dimension

The base class for layout dimensions.

Each dimension has a value property. This returns an integer, and is essentially the meaning of the object.

Source code in pytermgui/window_manager/layouts.py

class Dimension:
    """The base class for layout dimensions.

    Each dimension has a `value` property. This returns an integer,
    and is essentially the *meaning* of the object.
    """

    _value: int

    @property
    def value(self) -> int:
        """Returns the value of the object.

        Override this for custom behaviour."""

        return self._value

    @value.setter
    def value(self, new: int) -> None:
        """Sets a new value."""

        self._value = new

    def __repr__(self) -> str:
        """Returns `{typename}(value={value})`.

        We use this over the dataclasses one as that used `_value`, and it's
        a bit ugly.
        """

        return f"{type(self).__name__}(value={self.value})"

value: int property writable

Returns the value of the object.

Override this for custom behaviour.

__repr__()

Returns {typename}(value={value}).

We use this over the dataclasses one as that used _value, and it's a bit ugly.

Source code in pytermgui/window_manager/layouts.py

def __repr__(self) -> str:
    """Returns `{typename}(value={value})`.

    We use this over the dataclasses one as that used `_value`, and it's
    a bit ugly.
    """

    return f"{type(self).__name__}(value={self.value})"

Layout

Defines a layout of Widgets, used by WindowManager.

Internally, it keeps track of a list of Slot. This list is then turned into a list of rows, all containing slots. This is done either when the current row has run out of the terminal's width, or ROW_BREAK is encountered.

Source code in pytermgui/window_manager/layouts.py

class Layout:
    """Defines a layout of Widgets, used by WindowManager.

    Internally, it keeps track of a list of `Slot`. This list is then turned into a list
    of rows, all containing slots. This is done either when the current row has run out
    of the terminal's width, or `ROW_BREAK` is encountered.
    """

    name: str

    def __init__(self, name: str = "Layout") -> None:
        self.name = name
        self.slots: list[Slot] = []

    @property
    def terminal(self) -> Terminal:
        """Returns the current global terminal instance."""

        return get_terminal()

    def __len__(self) -> int:
        """Gets the slot count of this layout."""

        return len(self.slots)

    def _to_rows(self) -> list[list[Slot]]:
        """Breaks `self.slots` into a list of list of slots.

        The terminal's remaining width is kept track of, and when a slot doesn't have enough
        space left it is pushed to a new row. Additionally, `ROW_BREAK` will force a new
        row to be created, starting with the next slot.
        """

        rows: list[list[Slot]] = []
        available = self.terminal.width

        row: list[Slot] = []
        for slot in self.slots:
            if available <= 0 or slot is ROW_BREAK:
                rows.append(row)

                row = []
                available = self.terminal.width - slot.width.value

            if slot is ROW_BREAK:
                continue

            available -= slot.width.value
            row.append(slot)

        if len(row) > 0:
            rows.append(row)

        return rows

    def build_rows(self) -> list[list[Slot]]:
        """Builds a list of slot rows, breaking them & applying automatic dimensions.

        Returns:
            A list[list[Slot]], aka. a list of slot-rows.
        """

        def _get_height(row: list[Slot]) -> int:
            defined = list(filter(lambda slot: not isinstance(slot.height, Auto), row))

            if len(defined) > 0:
                return max(slot.height.value for slot in defined)

            return 0

        def _calculate_widths(row: list[Slot]) -> tuple[int, int]:
            defined: list[Slot] = list(
                filter(lambda slt: not isinstance(slt.width, Auto), row)
            )
            undefined = list(filter(lambda slt: slt not in defined, row))

            available = self.terminal.width - sum(slot.width.value for slot in defined)

            return divmod(available, len(undefined) or 1)

        rows = self._to_rows()
        heights = [_get_height(row) for row in rows]

        occupied = sum(heights)
        auto_height, extra_height = divmod(
            self.terminal.height - occupied, heights.count(0) or 1
        )

        for row, height in zip(rows, heights):
            height = height or auto_height

            auto_width, extra_width = _calculate_widths(row)
            for slot in row:
                width = auto_width if isinstance(slot.width, Auto) else slot.width.value

                if isinstance(slot.height, Auto):
                    slot.height.value = height + extra_height
                    extra_height = 0

                if isinstance(slot.width, Auto):
                    slot.width.value = width + extra_width
                    extra_width = 0

        return rows

    def add_slot(  # pylint: disable=too-many-arguments
        self,
        name: str = "Slot",
        *,
        slot: Slot | None = None,
        width: Dimension | int | float | None = None,
        height: Dimension | int | float | None = None,
        index: int = -1,
    ) -> Slot:
        """Adds a new slot to the layout.

        Args:
            name: The **snakeified** name of the slot. A non-snake case name
                will cause issues when trying to retrieve the slot (see GH#147).
            slot: An already instantiated `Slot` instance. If this is given,
                the additional width & height arguments will be ignored.
            width: The width for the new slot. See below for special types.
            height: The height for the new slot. See below for special types.
            index: The index to add the new slot to.

        Returns:
            The just-added slot.

        When defining dimensions, either width or height, some special value
        types can be given:
        - `Dimension`: Passed directly to the new slot.
        - `None`: An `Auto` dimension is created with no value.
        - `int`: A `Static` dimension is created with the given value.
        - `float`: A `Relative` dimension is created with the given value as its
            scale. Its `bound` attribute will default to the relevant part of the
            terminal's size.
        """

        if slot is None:
            if width is None:
                width = Auto()

            elif isinstance(width, int):
                width = Static(width)

            elif isinstance(width, float):
                width = Relative(width, bound=lambda: self.terminal.width)

            if height is None:
                height = Auto()

            elif isinstance(height, int):
                height = Static(height)

            elif isinstance(height, float):
                height = Relative(height, bound=lambda: self.terminal.height)

            slot = Slot(name, width=width, height=height)

        if index == -1:
            self.slots.append(slot)
            return slot

        self.slots.insert(index, slot)

        return slot

    def add_break(self, *, index: int = -1) -> None:
        """Adds `ROW_BREAK` to the given index.

        This special slot is ignored for all intents and purposes, other than when
        breaking the slots into rows. In that context, when encountered, the current
        row is deemed completed, and the next slot will go into a new row list.
        """

        self.add_slot(slot=ROW_BREAK, index=index)

    def assign(self, widget: Widget, *, index: int = -1, apply: bool = True) -> None:
        """Assigns a widget to the slot at the specified index.

        Args:
            widget: The widget to assign.
            index: The target slot's index.
            apply: If set, `apply` will be called once the widget has been assigned.
        """

        slots = [slot for slot in self.slots if slot is not ROW_BREAK]
        if index > len(slots) - 1:
            return

        slot = slots[index]

        slot.content = widget

        if apply:
            self.apply()

    def apply(self) -> None:
        """Applies the layout to each slot."""

        position = list(self.terminal.origin)
        for row in self.build_rows():
            position[0] = 1

            for slot in row:
                slot.apply((position[0], position[1]))

                position[0] += slot.width.value

            position[1] += max(slot.height.value for slot in row)

    def __getattr__(self, attr: str) -> Slot:
        """Gets a slot by its (slugified) name."""

        def _snakeify(name: str) -> str:
            return name.lower().replace(" ", "_")

        for slot in self.slots:
            if _snakeify(slot.name) == attr:
                return slot

        raise AttributeError(f"Slot with name {attr!r} could not be found.")

terminal: Terminal property

Returns the current global terminal instance.

__getattr__(attr)

Gets a slot by its (slugified) name.

Source code in pytermgui/window_manager/layouts.py

def __getattr__(self, attr: str) -> Slot:
    """Gets a slot by its (slugified) name."""

    def _snakeify(name: str) -> str:
        return name.lower().replace(" ", "_")

    for slot in self.slots:
        if _snakeify(slot.name) == attr:
            return slot

    raise AttributeError(f"Slot with name {attr!r} could not be found.")

__len__()

Gets the slot count of this layout.

Source code in pytermgui/window_manager/layouts.py

def __len__(self) -> int:
    """Gets the slot count of this layout."""

    return len(self.slots)

add_break(*, index=-1)

Adds ROW_BREAK to the given index.

This special slot is ignored for all intents and purposes, other than when breaking the slots into rows. In that context, when encountered, the current row is deemed completed, and the next slot will go into a new row list.

Source code in pytermgui/window_manager/layouts.py

def add_break(self, *, index: int = -1) -> None:
    """Adds `ROW_BREAK` to the given index.

    This special slot is ignored for all intents and purposes, other than when
    breaking the slots into rows. In that context, when encountered, the current
    row is deemed completed, and the next slot will go into a new row list.
    """

    self.add_slot(slot=ROW_BREAK, index=index)

add_slot(name='Slot', *, slot=None, width=None, height=None, index=-1)

Adds a new slot to the layout.

Parameters:

Name	Type	Description	Default
name	str	The snakeified name of the slot. A non-snake case name will cause issues when trying to retrieve the slot (see GH#147).	'Slot'
slot	Slot | None	An already instantiated Slot instance. If this is given, the additional width & height arguments will be ignored.	None
width	Dimension | int | float | None	The width for the new slot. See below for special types.	None
height	Dimension | int | float | None	The height for the new slot. See below for special types.	None
index	int	The index to add the new slot to.	-1

Returns:

Type	Description
Slot	The just-added slot.

When defining dimensions, either width or height, some special value types can be given: - Dimension: Passed directly to the new slot. - None: An Auto dimension is created with no value. - int: A Static dimension is created with the given value. - float: A Relative dimension is created with the given value as its scale. Its bound attribute will default to the relevant part of the terminal's size.

Source code in pytermgui/window_manager/layouts.py

def add_slot(  # pylint: disable=too-many-arguments
    self,
    name: str = "Slot",
    *,
    slot: Slot | None = None,
    width: Dimension | int | float | None = None,
    height: Dimension | int | float | None = None,
    index: int = -1,
) -> Slot:
    """Adds a new slot to the layout.

    Args:
        name: The **snakeified** name of the slot. A non-snake case name
            will cause issues when trying to retrieve the slot (see GH#147).
        slot: An already instantiated `Slot` instance. If this is given,
            the additional width & height arguments will be ignored.
        width: The width for the new slot. See below for special types.
        height: The height for the new slot. See below for special types.
        index: The index to add the new slot to.

    Returns:
        The just-added slot.

    When defining dimensions, either width or height, some special value
    types can be given:
    - `Dimension`: Passed directly to the new slot.
    - `None`: An `Auto` dimension is created with no value.
    - `int`: A `Static` dimension is created with the given value.
    - `float`: A `Relative` dimension is created with the given value as its
        scale. Its `bound` attribute will default to the relevant part of the
        terminal's size.
    """

    if slot is None:
        if width is None:
            width = Auto()

        elif isinstance(width, int):
            width = Static(width)

        elif isinstance(width, float):
            width = Relative(width, bound=lambda: self.terminal.width)

        if height is None:
            height = Auto()

        elif isinstance(height, int):
            height = Static(height)

        elif isinstance(height, float):
            height = Relative(height, bound=lambda: self.terminal.height)

        slot = Slot(name, width=width, height=height)

    if index == -1:
        self.slots.append(slot)
        return slot

    self.slots.insert(index, slot)

    return slot

apply()

Applies the layout to each slot.

Source code in pytermgui/window_manager/layouts.py

def apply(self) -> None:
    """Applies the layout to each slot."""

    position = list(self.terminal.origin)
    for row in self.build_rows():
        position[0] = 1

        for slot in row:
            slot.apply((position[0], position[1]))

            position[0] += slot.width.value

        position[1] += max(slot.height.value for slot in row)

assign(widget, *, index=-1, apply=True)

Assigns a widget to the slot at the specified index.

Parameters:

Name	Type	Description	Default
widget	Widget	The widget to assign.	required
index	int	The target slot's index.	-1
apply	bool	If set, apply will be called once the widget has been assigned.	True

Source code in pytermgui/window_manager/layouts.py

def assign(self, widget: Widget, *, index: int = -1, apply: bool = True) -> None:
    """Assigns a widget to the slot at the specified index.

    Args:
        widget: The widget to assign.
        index: The target slot's index.
        apply: If set, `apply` will be called once the widget has been assigned.
    """

    slots = [slot for slot in self.slots if slot is not ROW_BREAK]
    if index > len(slots) - 1:
        return

    slot = slots[index]

    slot.content = widget

    if apply:
        self.apply()

build_rows()

Builds a list of slot rows, breaking them & applying automatic dimensions.

Returns:

Type	Description
list[list[Slot]]	A list[list[Slot]], aka. a list of slot-rows.

Source code in pytermgui/window_manager/layouts.py

def build_rows(self) -> list[list[Slot]]:
    """Builds a list of slot rows, breaking them & applying automatic dimensions.

    Returns:
        A list[list[Slot]], aka. a list of slot-rows.
    """

    def _get_height(row: list[Slot]) -> int:
        defined = list(filter(lambda slot: not isinstance(slot.height, Auto), row))

        if len(defined) > 0:
            return max(slot.height.value for slot in defined)

        return 0

    def _calculate_widths(row: list[Slot]) -> tuple[int, int]:
        defined: list[Slot] = list(
            filter(lambda slt: not isinstance(slt.width, Auto), row)
        )
        undefined = list(filter(lambda slt: slt not in defined, row))

        available = self.terminal.width - sum(slot.width.value for slot in defined)

        return divmod(available, len(undefined) or 1)

    rows = self._to_rows()
    heights = [_get_height(row) for row in rows]

    occupied = sum(heights)
    auto_height, extra_height = divmod(
        self.terminal.height - occupied, heights.count(0) or 1
    )

    for row, height in zip(rows, heights):
        height = height or auto_height

        auto_width, extra_width = _calculate_widths(row)
        for slot in row:
            width = auto_width if isinstance(slot.width, Auto) else slot.width.value

            if isinstance(slot.height, Auto):
                slot.height.value = height + extra_height
                extra_height = 0

            if isinstance(slot.width, Auto):
                slot.width.value = width + extra_width
                extra_width = 0

    return rows

Relative dataclass

Bases: Dimension

A relative dimension.

This dimension has a scale attribute and bound method. Every time the value is queried, int(self.bound() * self.scale) is returned.

When instantiated through Layout.add_slot, bound will default to either the terminal's width or height, depending on which attribute it is applied to.

Source code in pytermgui/window_manager/layouts.py

@dataclass(repr=False)
class Relative(Dimension):
    """A relative dimension.

    This dimension has a scale attribute and bound method. Every time  the `value`
    is queried, `int(self.bound() * self.scale)` is returned.

    When instantiated through `Layout.add_slot`, `bound` will default to either
    the terminal's width or height, depending on which attribute it is applied to.
    """

    _value = 0
    scale: float
    bound: Callable[[], int]

    @property
    def value(self) -> int:
        """Calculates the new value for the dimension."""

        return int(self.bound() * self.scale)

    @value.setter
    def value(self, new: int) -> None:
        """Disallows setting the value.

        We can't inherit and then override a set-get property with a get one, so this
        kind of patches that issue up.
        """

        raise TypeError

    def __repr__(self) -> str:
        scale = self.scale
        bound = self.bound

        original = super().__repr__()
        return original[:-1] + f", {scale=}, {bound=}" + original[-1]

value: int property writable

Calculates the new value for the dimension.

Slot dataclass

A slot within a layout.

A slot has a name, width & height, as well as some content. It's apply method can be called to apply the slot's position & dimensions to its content.

Source code in pytermgui/window_manager/layouts.py

@dataclass
class Slot:
    """A slot within a layout.

    A slot has a name, width & height, as well as some content. It's `apply` method
    can be called to apply the slot's position & dimensions to its content.
    """

    name: str
    width: Dimension
    height: Dimension

    content: Widget | None = None

    _restore_data: tuple[int, int, tuple[int, int]] | None = None

    def apply(self, position: tuple[int, int]) -> None:
        """Applies the given position & dimension to the content.

        Args:
            position: The position that this object resides in. Set as its content's `pos`.
        """

        if self.content is None or self.width is None or self.height is None:
            return

        if self._restore_data is None:
            self._restore_data = (
                self.content.width,
                self.content.height,
                self.content.pos,
            )

        self.content.height = self.height.value
        self.content.width = self.width.value
        self.content.pos = position

    def detach_content(self) -> None:
        """Detaches content & restores its original state."""

        content = self.content
        if content is None:
            raise AttributeError(f"No content to detach in {self!r}.")

        assert self._restore_data is not None

        content.width, content.height, content.pos = self._restore_data

        self.content = None
        self._restore_data = None

apply(position)

Applies the given position & dimension to the content.

Parameters:

Name	Type	Description	Default
position	tuple[int, int]	The position that this object resides in. Set as its content's pos.	required

Source code in pytermgui/window_manager/layouts.py

def apply(self, position: tuple[int, int]) -> None:
    """Applies the given position & dimension to the content.

    Args:
        position: The position that this object resides in. Set as its content's `pos`.
    """

    if self.content is None or self.width is None or self.height is None:
        return

    if self._restore_data is None:
        self._restore_data = (
            self.content.width,
            self.content.height,
            self.content.pos,
        )

    self.content.height = self.height.value
    self.content.width = self.width.value
    self.content.pos = position

detach_content()

Detaches content & restores its original state.

Source code in pytermgui/window_manager/layouts.py

def detach_content(self) -> None:
    """Detaches content & restores its original state."""

    content = self.content
    if content is None:
        raise AttributeError(f"No content to detach in {self!r}.")

    assert self._restore_data is not None

    content.width, content.height, content.pos = self._restore_data

    self.content = None
    self._restore_data = None

Static dataclass

Bases: Dimension

A static dimension.

This dimension is immutable, and the Layout will always leave it unchanged.

Source code in pytermgui/window_manager/layouts.py

@dataclass(repr=False, frozen=True)
class Static(Dimension):
    """A static dimension.

    This dimension is immutable, and the Layout will always leave it unchanged.
    """

    _value: int = 0