How to Display Image in Flask after a button is pressed

I am new to flask and web development. I want to display an image on a local web server after I press a button on the webpage. I am using Flask.Ive been trying to figure this out for a while and havent been able too so any help would be incredible. FLASK CODE:

@app.route('/graph_select')
def graph_select():
    return render_template('live_stream.html')


@app.route('/read_ph', methods=["GET"])
def ph_plot():
    if request.method == "GET":
        all_plots.ph_plot()
        return render_template('live_stream.html')


@app.route("/read_temp", methods=["GET"])
def temp_plot():
    if request.method == "GET":
        all_plots.temperature_plot()
        return render_template('live_stream.html')


@app.route('/read_distance', methods=["GET"])
def distance_plot():
    if request.method == "GET":
        all_plots.distance_plot()
        return render_template('live_stream.html')

HTML CODE:

    <h1>Data Monitoring Station</h1>

      <form method="GET" 
        <a href="read_temp"><button type="button">Temperature Graph</button></a>
        <a href="read_ph"><button type="button">PH Graph</button></a>
        <a href="read_distance"><button type="button">Distance Graph</button></a>
      </form>

    <h3><img src="{{ url_for('static', filename='ph_plot.png') }}" width="30%">$
    <h3><img src="{{ url_for('static', filename='temperature_plot.png') }}" width="30%">$
    <h3><img src="{{ url_for('static', filename='distance_plot.png') }}" width="30%">$




  </body>
</html>

Solution

TLDR;

I wrote a minimal example on displaying images on button click using Flask and Ajax.

In essence, I just returned the URL of the image to the HTML page and set the src attribute of <img> tag with the returned URL.

app.py:

from flask import Flask, render_template

app = Flask(__name__)


@app.route("/")
def hello():
    return render_template('a.html')

@app.route("/getimage")
def get_img():
    return "a.jpg"


if __name__ == '__main__':
    app.run()

a.html:

<html>
  <head>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
  </head>
   <body>
     <button type='button' id ='retrieve'>Submit</button>
     <img src="" id="myimg" />
   </body>
  <script>
    $(document).ready(function() {
       $('#retrieve').click(function(){
           $.ajax({
           url: "{{ url_for ('get_img') }}",
           type: "GET",
           success: function(response) {
               $("#myimg").attr('src', '/static/' + response);
          },
          error: function(xhr) {
            //Do Something to handle error
         }
         });
       });
    });
  </script>
</html>

You can modify this code as you wish.

Note: The a.html file should be in templates folder and the a.jpg file should be in the static folder.

Hope this helps. Good luck.