Repository: ManimCommunity/manim
File: manim/camera/moving_camera.py (Python)

Code before:
            else:
                if m.get_critical_point(LEFT)[0] < scene_critical_x_left:
                    scene_critical_x_left = m.get_critical_point(LEFT)[0]

                if m.get_critical_point(RIGHT)[0] > scene_critical_x_right:
                    scene_critical_x_right = m.get_critical_point(RIGHT)[0]

                if m.get_critical_point(UP)[1] > scene_critical_y_up:
                    scene_critical_y_up = m.get_critical_point(UP)[1]

                if m.get_critical_point(DOWN)[1] < scene_critical_y_down:
                    scene_critical_y_down = m.get_critical_point(DOWN)[1]

        # calculate center x and y
        x = (scene_critical_x_left + scene_critical_x_right) / 2
        y = (scene_critical_y_up + scene_critical_y_down) / 2

        # calculate proposed width and height of zoomed scene
        new_Width = abs(scene_critical_x_left - scene_critical_x_right)
        new_Height = abs(scene_critical_y_up - scene_critical_y_down)

        # zoom to fit all mobjects along the side that has the largest size
        if new_Width / self.frame.width > new_Height / self.frame.height:
            return self.frame.animate.set_x(x).set_y(y).set(width=new_Width + margin)
        else:
            return self.frame.animate.set_x(x).set_y(y).set(height=new_Height + margin)


Review comment (suggestion):
Sorry, this is not quite what I meant -- this is now a weird mix between snake_casing and CamelCasing. Please use `new_width` and `new_height`, respectively.

Code after:
"""A camera able to move through a scene.

.. SEEALSO::

    :mod:`.moving_camera_scene`

"""

__all__ = ["CameraFrame", "MovingCamera"]

from .. import config
from ..camera.camera import Camera
from ..constants import DOWN, LEFT, ORIGIN, RIGHT, UP
from ..mobject.frame import ScreenRectangle
from ..mobject.types.vectorized_mobject import VGroup
from ..utils.color import WHITE


# TODO, think about how to incorporate perspective
class CameraFrame(VGroup):
    def __init__(self, center=ORIGIN, **kwargs):
        super().__init__(center=center, **kwargs)
        self.width = config["frame_width"]
        self.height = config["frame_height"]


class MovingCamera(Camera):
    """
    Stays in line with the height, width and position of it's 'frame', which is a Rectangle

    .. SEEALSO::

        :class:`.MovingCameraScene`

    """

    def __init__(
        self,
        frame=None,
        fixed_dimension=0,  # width
        default_frame_stroke_color=WHITE,
        default_frame_stroke_width=0,
        **kwargs
    ):
        """
        Frame is a Mobject, (should almost certainly be a rectangle)
        determining which region of space the camera displays
        """
        self.fixed_dimension = fixed_dimension
        self.default_frame_stroke_color = default_frame_stroke_color
        self.default_frame_stroke_width = default_frame_stroke_width
        if frame is None:
            frame = ScreenRectangle(height=config["frame_height"])
            frame.set_stroke(
                self.default_frame_stroke_color,
                self.default_frame_stroke_width,
            )
        self.frame = frame
        super().__init__(**kwargs)

    # TODO, make these work for a rotated frame
    @property
    def frame_height(self):
        """Returns the height of the frame.

        Returns
        -------
        float
            The height of the frame.
        """
        return self.frame.height

    @property
    def frame_width(self):
        """Returns the width of the frame

        Returns
        -------
        float
            The width of the frame.
        """
        return self.frame.width

    @property
    def frame_center(self):
        """Returns the centerpoint of the frame in cartesian coordinates.

        Returns
        -------
        np.array
            The cartesian coordinates of the center of the frame.
        """
        return self.frame.get_center()

    @frame_height.setter
    def frame_height(self, frame_height):
        """Sets the height of the frame in MUnits.

        Parameters
        ----------
        frame_height : int, float
            The new frame_height.
        """
        self.frame.stretch_to_fit_height(frame_height)

    @frame_width.setter
    def frame_width(self, frame_width):
        """Sets the width of the frame in MUnits.

        Parameters
        ----------
        frame_width : int, float
            The new frame_width.
        """
        self.frame.stretch_to_fit_width(frame_width)

    @frame_center.setter
    def frame_center(self, frame_center):
        """Sets the centerpoint of the frame.

        Parameters
        ----------
        frame_center : np.array, list, tuple, Mobject
            The point to which the frame must be moved.
            If is of type mobject, the frame will be moved to
            the center of that mobject.
        """
        self.frame.move_to(frame_center)

    def capture_mobjects(self, mobjects, **kwargs):
        # self.reset_frame_center()
        # self.realign_frame_shape()
        super().capture_mobjects(mobjects, **kwargs)

    # Since the frame can be moving around, the cairo
    # context used for updating should be regenerated
    # at each frame.  So no caching.
    def get_cached_cairo_context(self, pixel_array):
        """
        Since the frame can be moving around, the cairo
        context used for updating should be regenerated
        at each frame.  So no caching.
        """
        return None

    def cache_cairo_context(self, pixel_array, ctx):
        """
        Since the frame can be moving around, the cairo
        context used for updating should be regenerated
        at each frame.  So no caching.
        """
        pass

    # def reset_frame_center(self):
    #     self.frame_center = self.frame.get_center()

    # def realign_frame_shape(self):
    #     height, width = self.frame_shape
    #     if self.fixed_dimension == 0:
    #         self.frame_shape = (height, self.frame.width
    #     else:
    #         self.frame_shape = (self.frame.height, width)
    #     self.resize_frame_shape(fixed_dimension=self.fixed_dimension)

    def get_mobjects_indicating_movement(self):
        """
        Returns all mobjects whose movement implies that the camera
        should think of all other mobjects on the screen as moving

        Returns
        -------
        list
        """
        return [self.frame]

    def auto_zoom(self, mobjects, margin=0, only_mobjects_in_frame=False):
        """Zooms on to a given array of mobjects (or a singular mobject)
        and automatically resizes to frame all the mobjects.

        .. NOTE::

            This method only works when 2D-objects in the XY-plane are considered, it
            will not work correctly when the camera has been rotated.

        Parameters
        ----------
        mobjects
            The mobject or array of mobjects that the camera will focus on.

        margin
            The width of the margin that is added to the frame (optional, 0 by default).

        only_mobjects_in_frame
            If set to ``True``, only allows focusing on mobjects that are already in frame.

        Returns
        -------
        _AnimationBuilder
            Returns an animation that zooms the camera view to a given
            list of mobjects.

        """
        scene_critical_x_left = None
        scene_critical_x_right = None
        scene_critical_y_up = None
        scene_critical_y_down = None

        for m in mobjects:
            if (m == self.frame) or (
                only_mobjects_in_frame and not self.is_in_frame(m)
            ):
                # detected camera frame, should not be used to calculate final position of camera
                continue

            # initialize scene critical points with first mobjects critical points
            if scene_critical_x_left == None:
                scene_critical_x_left = m.get_critical_point(LEFT)[0]
                scene_critical_x_right = m.get_critical_point(RIGHT)[0]
                scene_critical_y_up = m.get_critical_point(UP)[1]
                scene_critical_y_down = m.get_critical_point(DOWN)[1]

            else:
                if m.get_critical_point(LEFT)[0] < scene_critical_x_left:
                    scene_critical_x_left = m.get_critical_point(LEFT)[0]

                if m.get_critical_point(RIGHT)[0] > scene_critical_x_right:
                    scene_critical_x_right = m.get_critical_point(RIGHT)[0]

                if m.get_critical_point(UP)[1] > scene_critical_y_up:
                    scene_critical_y_up = m.get_critical_point(UP)[1]

                if m.get_critical_point(DOWN)[1] < scene_critical_y_down:
                    scene_critical_y_down = m.get_critical_point(DOWN)[1]

        # calculate center x and y
        x = (scene_critical_x_left + scene_critical_x_right) / 2
        y = (scene_critical_y_up + scene_critical_y_down) / 2

        # calculate proposed width and height of zoomed scene
        new_width = abs(scene_critical_x_left - scene_critical_x_right)
        new_height = abs(scene_critical_y_up - scene_critical_y_down)

        # zoom to fit all mobjects along the side that has the largest size
        if new_width / self.frame.width > new_height / self.frame.height:
            return self.frame.animate.set_x(x).set_y(y).set(width=new_width + margin)
        else:
            return self.frame.animate.set_x(x).set_y(y).set(height=new_height + margin)