standalone-flask-qgis.py

import uuid
from io import BytesIO
import os

from flask import Flask, request, Response, send_file
app = Flask(__name__)

from qgis.PyQt.Qt import Qt
from qgis.PyQt.QtCore import QSize

from qgis.core import (QgsApplication, QgsFeature, QgsProject,
    QgsGeometry, QgsVectorLayer, QgsMapSettings,
    QgsMapRendererSequentialJob)
from qgis.gui import QgsMapCanvas, QgsLayerTreeMapCanvasBridge
from qgis.server import *



QgsApplication.setPrefixPath("/usr", False)
qgisapp = QgsApplication([], False)
qgisapp.initQgis()
qgisserver = QgsServer()

@app.route('/qgis-server')
def qgisServer():
    qgisrequest = QgsBufferServerRequest(request.url)
    qgisresponse = QgsBufferServerResponse()
    qgisserver.handleRequest(qgisrequest, qgisresponse)
    response = Response(qgisresponse.body().data(), status=str(qgisresponse.statusCode()), headers=qgisresponse.headers()) #
    return(response)

@app.route('/qgis-desktop')
def qgisdesktop():
    canvas = QgsMapCanvas()
    bridge = QgsLayerTreeMapCanvasBridge(
             QgsProject.instance().layerTreeRoot(), canvas)

    title = "PyQGIS Standalone Application Example"
    canvas.setWindowTitle(title)
    canvas.setCanvasColor(Qt.white)
    layer_info = 'LineString?crs=epsg:4326'
    layer =  QgsVectorLayer(layer_info, 'MyLine' , "memory")
    pr = layer.dataProvider()
    linstr = QgsFeature()
    wkt = "LINESTRING (1 1, 10 15, 40 35)"
    geom = QgsGeometry.fromWkt(wkt)
    linstr.setGeometry(geom)
    pr.addFeatures([linstr])
    layer.updateExtents()
    QgsProject.instance().addMapLayer(layer)
    canvas.setExtent(layer.extent())
    canvas.setLayers([layer])
    # canvas.zoomToFullExtent()
    filename = str(uuid.uuid4())
    filepath = '/tmp/{}.png'.format(filename)
    QgsProject.instance().write('/tmp/out.qgs')
    # canvas.saveAsImage(filepath)
    settings = QgsMapSettings()
    settings.setOutputSize(QSize(800, 600))
    settings.setExtent(layer.extent())
    settings.setLayers([layer])

    job = QgsMapRendererSequentialJob(settings)
    job.start()
    job.waitForFinished()
    img = job.renderedImage()
    img.save(filepath)

    with open(filepath, 'rb') as fh:
        buf = BytesIO(fh.read())

    os.remove(filepath)
    # QgsProject.instance().write('/tmp/out.qgs')

    return send_file(buf, mimetype='image/png')

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