Raspberry Pi + Realsense: Flask server

I would start first with the easy part, Flask

Flask is a micro framework to set up at server, app

and without setup like the whole Django file structure framework.

The good part is the variable they use is quite similar, because template of jinja2 and django is very similar

the code: https://github.com/soarwing52/Remote-Realsense/blob/master/flask_server.py

The Hello World

from flask import Flask, render_template, Response
app = Flask(__name__)
@app.route('/')
def index():
    return "Hello World"

if __name__ == '__main__':

    try:

        app.run('0.0.0.0')

    except KeyboardInterrupt:

        pass

    finally:

        pass

just as easy as this, a basic server is up

I can connect my phone, tablet to it

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The MJPEG

I was looking for how to stream image from Pi to tablet.

the easiest way is html, and how to stream, with Flask is kind of the best example I can found

def gen():

    while True:

        yield (b'--frame\r\n'

               b'Content-Type: image/jpeg\r\n\r\n' + a.img + b'\r\n')

@app.route('/video_feed')

def video_feed():

    return Response(gen(),

                    mimetype='multipart/x-mixed-replace; boundary=frame')

this is the example, I found with key word first found in one gist as mjpeg
because I was looking for socket possibility, and found some with SimpleHTTP library,
then the framework hit me, thanks to all the communities!

so I changed to look for stream image with flask.

what I give to this need to be image in bytes.

So I used opencv

cv2.imencode('.jpg', image)[1].tobytes()

imencode will return True/False then the image

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Dynamic URL

so, to prevent writing a ton of @app.rout("/url") to set up all the GET method I want for my commands, this comes in handy

@app.route('/auto/<in_text>')
def auto(in_text):
    a.command = in_text
    return in_text

with <variable> this will be input to the text when the GET method is sent. So all my commands are sent through this method

I have /cmd/<command> for camera control
/auto/<> for turn on and off the auto camera shots
/dis/<distance> for changing the distance per photo when using auto mode

basically with Regular Expression, I can handle all other requests from buttons, switch and spinbox
because I also built html user interface for IOS possibility

This thanks to

actually I found this video when I was basically done with the whole framework, while I use a really basic function and he is doing some fun projects
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Templates

The structure is create a folder "templates" and put all the html files in it, and it can use render_templetes function

and to put in variables using

{{ variable}}

and

@app.route('/')
def index():
    return render_template(index.html, variable = "text or list")

and it can be used with if, else

{%  if  variable =  100 %}

{%  endif  %}

or dictionatry

         {% for key, value in result.iteritems() %}

            <tr>

               <th> {{ key }} </th>

               <td> {{ value }} </td>

            </tr>

         {% endfor %}

(https://www.tutorialspoint.com/flask/flask_templates.htm)

I was trying to also put the information  to the html showing the current status of the system

but it cant be done with a lot of JavaScript work

So I just write it in the image with Opencv putText function

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This is basically how a server is set up, the functions I used in this project.

The main hard side is how to design the structure behind, using threading and multiprocessing