manim/manimlib/scene/zoomed_scene.py

from manimlib.animation.transform import ApplyMethod
from manimlib.camera.moving_camera import MovingCamera
from manimlib.camera.multi_camera import MultiCamera
from manimlib.constants import *
from manimlib.mobject.types.image_mobject import ImageMobjectFromCamera
from manimlib.scene.moving_camera_scene import MovingCameraScene
from manimlib.utils.simple_functions import fdiv

# Note, any scenes from old videos using ZoomedScene will almost certainly
# break, as it was restructured.


class ZoomedScene(MovingCameraScene):
    """
    This is a Scene with special configurations made for when
    a particular part of the scene must be zoomed in on and displayed
    separately.
    """
    CONFIG = {
        "camera_class": MultiCamera,
        "zoomed_display_height": 3,
        "zoomed_display_width": 3,
        "zoomed_display_center": None,
        "zoomed_display_corner": UP + RIGHT,
        "zoomed_display_corner_buff": DEFAULT_MOBJECT_TO_EDGE_BUFFER,
        "zoomed_camera_config": {
            "default_frame_stroke_width": 2,
            "background_opacity": 1,
        },
        "zoomed_camera_image_mobject_config": {},
        "zoomed_camera_frame_starting_position": ORIGIN,
        "zoom_factor": 0.15,
        "image_frame_stroke_width": 3,
        "zoom_activated": False,
    }

    def setup(self):
        """
        This method is used internally by Manim to
        setup the scene for proper use.
        """
        MovingCameraScene.setup(self)
        # Initialize camera and display
        zoomed_camera = MovingCamera(**self.zoomed_camera_config)
        zoomed_display = ImageMobjectFromCamera(
            zoomed_camera, **self.zoomed_camera_image_mobject_config
        )
        zoomed_display.add_display_frame()
        for mob in zoomed_camera.frame, zoomed_display:
            mob.stretch_to_fit_height(self.zoomed_display_height)
            mob.stretch_to_fit_width(self.zoomed_display_width)
        zoomed_camera.frame.scale(self.zoom_factor)

        # Position camera and display
        zoomed_camera.frame.move_to(self.zoomed_camera_frame_starting_position)
        if self.zoomed_display_center is not None:
            zoomed_display.move_to(self.zoomed_display_center)
        else:
            zoomed_display.to_corner(
                self.zoomed_display_corner,
                buff=self.zoomed_display_corner_buff
            )

        self.zoomed_camera = zoomed_camera
        self.zoomed_display = zoomed_display

    def activate_zooming(self, animate=False):
        """
        This method is used to activate the zooming for
        the zoomed_camera.
        
        Parameters
        ----------
        animate (bool=False)
            Whether or not to animate the activation
            of the zoomed camera.
        """
        self.zoom_activated = True
        self.camera.add_image_mobject_from_camera(self.zoomed_display)
        if animate:
            self.play(self.get_zoom_in_animation())
            self.play(self.get_zoomed_display_pop_out_animation())
        self.add_foreground_mobjects(
            self.zoomed_camera.frame,
            self.zoomed_display,
        )

    def get_zoom_in_animation(self, run_time=2, **kwargs):
        """
        Returns the animation of camera zooming in.
        
        Parameters
        ----------
        run_time (Union[int,float=2])
            The run_time of the animation of the camera zooming in.
        **kwargs
            Any valid keyword arguments of ApplyMethod()
        
        Returns
        -------
        ApplyMethod
            The animation of the camera zooming in.
        """
        frame = self.zoomed_camera.frame
        full_frame_height = self.camera.get_frame_height()
        full_frame_width = self.camera.get_frame_width()
        frame.save_state()
        frame.stretch_to_fit_width(full_frame_width)
        frame.stretch_to_fit_height(full_frame_height)
        frame.center()
        frame.set_stroke(width=0)
        return ApplyMethod(frame.restore, run_time=run_time, **kwargs)

    def get_zoomed_display_pop_out_animation(self, **kwargs):
        """
        This is the animation of the popping out of the
        mini-display that shows the content of the zoomed
        camera. 

        Returns
        -------
        ApplyMethod
            The Animation of the Zoomed Display popping out.
        """
        display = self.zoomed_display
        display.save_state(use_deepcopy=True)
        display.replace(self.zoomed_camera.frame, stretch=True)
        return ApplyMethod(display.restore)

    def get_zoom_factor(self):
        """
        Returns the Zoom factor of the Zoomed camera.
        Defined as the ratio between the height of the
        zoomed camera and the height of the zoomed mini
        display.
        Returns
        -------
        float
            The zoom factor.
        """
        return fdiv(
            self.zoomed_camera.frame.get_height(),
            self.zoomed_display.get_height()
        )