js: Uncaught SecurityError: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported

Question

我正在使用 plotly 和 pyqt5（GUI 开发），当我尝试 download/export 生成图像时，出现此消息：

js: Uncaught SecurityError: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported.

我用的是QtWebengine，下一个例子：

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

from PyQt5.QtWebEngineWidgets import QWebEngineView
from PyQt5 import QtCore, QtWidgets
import sys


def show_qt(fig):
    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>'

    fig_view = QWebEngineView()
    # setHtml has a 2MB size limit, need to switch to setUrl on tmp file
    # for large figures.
    fig_view.setHtml(raw_html)
    fig_view.show()
    fig_view.raise_()
    return fig_view


if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)

    fig = go.Figure(data=[{'type': 'scattergl', 'y': [2, 1, 3, 1]}])
    fig_view = show_qt(fig)
    sys.exit(app.exec_())

Answer 1

这是一个警告，警告下载图像的方式（将其转换为字节）可能导致安全错误，但在这种情况下您可以忽略它。如果你想下载一个文件，那么你必须使用 QWebEnginePage 的 downloadRequested 信号：

<b>def handle_downloadRequested(item):
    path, _ = QtWidgets.QFileDialog.getSaveFileName(
        None, "Save File", item.suggestedFileName()
    )
    if path:
        item.setPath(path)
        item.accept()</b>


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)

    fig = go.Figure(data=[{"type": "scattergl", "y": [2, 1, 3, 1]}])
    fig_view = show_qt(fig)
    <b>fig_view.page().profile().downloadRequested.connect(
        handle_downloadRequested
    )</b>
    sys.exit(app.exec_())

js: Uncaught SecurityError: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported

js: Uncaught SecurityError: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported

python

pyqt

pyqt5

plotly

qtwebengine