"""

Moving TextGraphic label

========================

A TextGraphic that labels a point on a line and another TextGraphic that moves along the line on every draw.

"""

# test_example = false

# sphinx_gallery_pygfx_docs = 'animate 10s'

import numpy as np

import fastplotlib as fpl

# create a sinc wave

xs = np.linspace(-2 * np.pi, 2 * np.pi, 200)

ys = np.sinc(xs)

data = np.column_stack([xs, ys])

# create a figure

figure = fpl.Figure(size=(700, 450))

# sinc wave

line = figure[0, 0].add_line(data, thickness=2)

# position for the text label on the peak

pos = (0, max(ys), 0)

# create label for the peak

text_peak = figure[0, 0].add_text(

f"peak ",

font_size=20,

anchor="bottom-right",

offset=pos

)

# add a point on the peak

point_peak = figure[0, 0].add_scatter(np.asarray([pos]), sizes=10, colors="r")

# create a text that will move along the line

text_moving = figure[0, 0].add_text(

f"({xs[0]:.2f}, {ys[0]:.2f}) ",

font_size=16,

outline_color="k",

outline_thickness=1,

anchor="top-center",

offset=(*data[0], 0)

)

# a point that will move on the line

point_moving = figure[0, 0].add_scatter(np.asarray([data[0]]), sizes=10, colors="magenta")

index = 0

def update():

# moves the text and point before every draw

global index

# get the new position

new_pos = (*data[index], 0)

# move the text and point to the new position

text_moving.offset = new_pos

point_moving.data[0] = new_pos

# set the text to the new position

text_moving.text = f"({new_pos[0]:.2f}, {new_pos[1]:.2f})"

# increment index

index += 1

if index == data.shape[0]:

index = 0

# add update as an animation functions

figure.add_animations(update)

figure[0, 0].axes.visible = False

figure.show(maintain_aspect=False)

# NOTE: fpl.loop.run() should not be used for interactive sessions

# See the "JupyterLab and IPython" section in the user guide

if __name__ == "__main__":

print(__doc__)

fpl.loop.run()