====== Kreslení grafů v Flasku ======

===== 1. =====

<code python>
import base64
from io import BytesIO

from flask import Flask
from matplotlib.figure import Figure

app = Flask(__name__)

@app.route('/')
def image():
    # Generate the figure **without using pyplot**.
    fig = Figure()
    ax = fig.subplots()
    ax.plot([1, 2])
    # Save it to a temporary buffer.
    buf = BytesIO()
    fig.savefig(buf, format="png")
    # Embed the result in the html output.
    data = base64.b64encode(buf.getbuffer()).decode("ascii")
    return f"<img src='data:image/png;base64,{data}'/>"

if __name__ == '__main__':
    app.run(debug=True)
</code>

===== 2. =====

<code python>
import base64
from io import BytesIO

from flask import Flask, Response, render_template, request
import matplotlib as mpl
from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas
from matplotlib.figure import Figure
import numpy as np

@app.route('/')
def image():
    fig = Figure(figsize=(4,3))
    ax = fig.subplots()
    x = np.arange(0, 4*np.pi, 0.1)
    y = np.sin(x)
    ax.plot(x, y)
    # Save it to a temporary buffer.
    buf = BytesIO()
    FigureCanvas(fig).print_png(buf)
    return Response(buf.getvalue(), mimetype='image/png')

if __name__ == '__main__':
    app.run(debug=True)
</code>