Use Qwebengineview To Display Something Larger Than 2mb?

February 26, 2024 Post a Comment

I'm trying to display some Plot.ly or Plot.ly Dash plots ( I haven't settled on using one or the other, so I'm experimenting with both right now) in a PyQt5 GUI using QWebEngineVie

Solution 1:

As this answer indicates a possible solution is to use a QWebEngineUrlSchemeHandler, in the next section I have created a class that allows you to register functions that are invoked through custom urls:

qtplotly.py

from PyQt5 import QtCore, QtWebEngineCore, QtWebEngineWidgets

import plotly.offline as po
import plotly.graph_objs as go


classPlotlySchemeHandler(QtWebEngineCore.QWebEngineUrlSchemeHandler):
    def__init__(self, app):
        super().__init__(app)
        self.m_app = app

    defrequestStarted(self, request):
        url = request.requestUrl()
        name = url.host()
        if self.m_app.verify_name(name):
            fig = self.m_app.fig_by_name(name)
            ifisinstance(fig, go.Figure):
                raw_html = '<html><head><meta charset="utf-8" />'
                raw_html += '<script src="https://cdn.plot.ly/plotly-latest.min.js"></script></head>'
                raw_html += "<body>"
                raw_html += po.plot(fig, include_plotlyjs=False, output_type="div")
                raw_html += "</body></html>"
                buf = QtCore.QBuffer(parent=self)
                request.destroyed.connect(buf.deleteLater)
                buf.open(QtCore.QIODevice.WriteOnly)
                buf.write(raw_html.encode())
                buf.seek(0)
                buf.close()
                request.reply(b"text/html", buf)
                return
        request.fail(QtWebEngineCore.QWebEngineUrlRequestJob.UrlNotFound)


classPlotlyApplication(QtCore.QObject):
    scheme = b"plotly"def__init__(self, parent=None):
        super().__init__(parent)
        scheme = QtWebEngineCore.QWebEngineUrlScheme(PlotlyApplication.scheme)
        QtWebEngineCore.QWebEngineUrlScheme.registerScheme(scheme)
        self.m_functions = dict()

    definit_handler(self, profile=None):
        if profile isNone:
            profile = QtWebEngineWidgets.QWebEngineProfile.defaultProfile()
        handler = profile.urlSchemeHandler(PlotlyApplication.scheme)
        if handler isnotNone:
            profile.removeUrlSchemeHandler(handler)

        self.m_handler = PlotlySchemeHandler(self)
        profile.installUrlSchemeHandler(PlotlyApplication.scheme, self.m_handler)

    defverify_name(self, name):
        return name in self.m_functions

    deffig_by_name(self, name):
        return self.m_functions.get(name, lambda: None)()

    defregister(self, name):
        defdecorator(f):
            self.m_functions[name] = f
            return f

        return decorator

    defcreate_url(self, name):
        url = QtCore.QUrl()
        url.setScheme(PlotlyApplication.scheme.decode())
        url.setHost(name)
        return url

main.py

import numpy as np
import plotly.graph_objs as go

from PyQt5 import QtCore, QtWidgets, QtWebEngineWidgets

from qtplotly import PlotlyApplication

# PlotlyApplication must be created before the creation# of QGuiApplication or QApplication
plotly_app = PlotlyApplication()


@plotly_app.register("scatter")defscatter():
    t = np.arange(0, 200000, 1)
    y = np.sin(t / 20000)
    fig = go.Figure(data=[{"type": "scattergl", "y": y}])
    return fig


@plotly_app.register("scatter2")defscatter2():
    N = 100000
    r = np.random.uniform(0, 1, N)
    theta = np.random.uniform(0, 2 * np.pi, N)

    fig = go.Figure(
        data=[
            {
                "type": "scattergl",
                "x": r * np.cos(theta),
                "y": r * np.sin(theta),
                "marker": dict(color=np.random.randn(N), colorscale="Viridis"),
            }
        ]
    )
    return fig


@plotly_app.register("scatter3")defscatter3():
    x0 = np.random.normal(2, 0.45, 30000)
    y0 = np.random.normal(2, 0.45, 30000)

    x1 = np.random.normal(6, 0.4, 20000)
    y1 = np.random.normal(6, 0.4, 20000)

    x2 = np.random.normal(4, 0.3, 20000)
    y2 = np.random.normal(4, 0.3, 20000)

    traces = []
    for x, y in ((x0, y0), (x1, y1), (x2, y2)):
        trace = go.Scatter(x=x, y=y, mode="markers")
        traces.append(trace)

    fig = go.Figure(data=traces)
    return fig


classWidget(QtWidgets.QWidget):
    def__init__(self, parent=None):
        super().__init__(parent)

        self.m_view = QtWebEngineWidgets.QWebEngineView()

        combobox = QtWidgets.QComboBox()
        combobox.currentIndexChanged[str].connect(self.onCurrentIndexChanged)
        combobox.addItems(["scatter", "scatter2", "scatter3"])

        vlay = QtWidgets.QVBoxLayout(self)
        hlay = QtWidgets.QHBoxLayout()
        hlay.addWidget(QtWidgets.QLabel("Select:"))
        hlay.addWidget(combobox)
        vlay.addLayout(hlay)
        vlay.addWidget(self.m_view)
        self.resize(640, 480)

    @QtCore.pyqtSlot(str)defonCurrentIndexChanged(self, name):
        self.m_view.load(plotly_app.create_url(name))


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    # Init_handler must be invoked before after the creation# of QGuiApplication or QApplication
    plotly_app.init_handler()
    w = Widget()
    w.show()
    sys.exit(app.exec_())