pages/0_📹_Animation_Demo.py

# Copyright 2018-2022 Streamlit Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import streamlit as st
import inspect
import textwrap
import numpy as np
from typing import Any
from streamlit.hello.utils import show_code


def animation_demo():

    # Interactive Streamlit elements, like these sliders, return their value.
    # This gives you an extremely simple interaction model.
    iterations = st.sidebar.slider("Level of detail", 2, 20, 10, 1)
    separation = st.sidebar.slider("Separation", 0.7, 2.0, 0.7885)

    # Non-interactive elements return a placeholder to their location
    # in the app. Here we're storing progress_bar to update it later.
    progress_bar = st.sidebar.progress(0)

    # These two elements will be filled in later, so we create a placeholder
    # for them using st.empty()
    frame_text = st.sidebar.empty()
    image = st.empty()

    m, n, s = 960, 640, 400
    x = np.linspace(-m / s, m / s, num=m).reshape((1, m))
    y = np.linspace(-n / s, n / s, num=n).reshape((n, 1))

    for frame_num, a in enumerate(np.linspace(0.0, 4 * np.pi, 100)):
        # Here were setting value for these two elements.
        progress_bar.progress(frame_num)
        frame_text.text("Frame %i/100" % (frame_num + 1))

        # Performing some fractal wizardry.
        c = separation * np.exp(1j * a)
        Z = np.tile(x, (n, 1)) + 1j * np.tile(y, (1, m))
        C = np.full((n, m), c)
        M: Any = np.full((n, m), True, dtype=bool)
        N = np.zeros((n, m))

        for i in range(iterations):
            Z[M] = Z[M] * Z[M] + C[M]
            M[np.abs(Z) > 2] = False
            N[M] = i

        # Update the image placeholder by calling the image() function on it.
        image.image(1.0 - (N / N.max()), use_column_width=True)

    # We clear elements by calling empty on them.
    progress_bar.empty()
    frame_text.empty()

    # Streamlit widgets automatically run the script from top to bottom. Since
    # this button is not connected to any other logic, it just causes a plain
    # rerun.
    st.button("Re-run")


st.set_page_config(page_title="Animation Demo", page_icon="📹")
st.markdown("# Animation Demo")
st.sidebar.header("Animation Demo")
st.write(
    """This app shows how you can use Streamlit to build cool animations.
It displays an animated fractal based on the the Julia Set. Use the slider
to tune different parameters."""
)

animation_demo()

show_code(animation_demo)