如何“渲染"带有 PyQt5 的 QWebEngineView 的 HTML [英] How to "render" HTML with PyQt5's QWebEngineView

问题描述

如何使用 PyQt5 v5.6 QWebEngineView渲染"HTML?

How can I "render" HTML with with PyQt5 v5.6 QWebEngineView?

我之前曾使用 PyQt5 v5.4.1 QWebPage 执行过该任务，但建议尝试使用较新的 QWebEngineView.

I have previously performed the task with PyQt5 v5.4.1 QWebPage, but it was suggested to try the newer QWebEngineView.

这是该实现(它通常按预期工作，但在某些站点和情况下可能会无限期挂起):

Here's that implementation (it generally works as expected, but has a tendency to hang indefinitely for some sites and situations):

def render(source_html):
    """Fully render HTML, JavaScript and all."""

    import sys
    from PyQt5.QtWidgets import QApplication
    from PyQt5.QtWebKitWidgets import QWebPage

    class Render(QWebPage):
        def __init__(self, html):
            self.html = None
            self.app = QApplication(sys.argv)
            QWebPage.__init__(self)
            self.loadFinished.connect(self._loadFinished)
            self.mainFrame().setHtml(html)
            self.app.exec_()

        def _loadFinished(self, result):
            self.html = self.mainFrame().toHtml()
            self.app.quit()

    return Render(source_html).html

import requests
sample_html = requests.get(dummy_url).text
print(render(sample_html))

接下来是我尝试使用 QWebEngineView.一、Ubuntu上PyQt5 v5.6的安装设置:

What follows is my attempt at using QWebEngineView. First, the installation and setup of PyQt5 v5.6 on Ubuntu:

# install PyQt5 v5.6 wheel from PyPI
pip3 install --user pyqt5

# link missing resources
ln -s ../resources/icudtl.dat ../resources/qtwebengine_resources.pak ../resources/qtwebengine_resources_100p.pak ../resources/qtwebengine_resources_200p.pak ../translations/qtwebengine_locales ~/.local/lib/python3.5/site-packages/PyQt5/Qt/libexec/

现在对于 Python... 以下导致分段错误:

Now for the Python... The following results in a segmentation fault:

def render(source_html):
    """Fully render HTML, JavaScript and all."""

    import sys
    from PyQt5.QtWidgets import QApplication
    from PyQt5.QtWebEngineWidgets import QWebEngineView

    class Render(QWebEngineView):
        def __init__(self, html):
            self.html = None
            self.app = QApplication(sys.argv)
            QWebEngineView.__init__(self)
            self.loadFinished.connect(self._loadFinished)
            self.setHtml(html)
            self.app.exec_()

        def _loadFinished(self, result):
            # what's going on here? how can I get the HTML from toHtml?
            self.page().toHtml(self.callable)
            self.app.quit()

        def callable(self, data):
            self.html = data

    return Render(source_html).html

import requests
sample_html = requests.get(dummy_url).text
print(render(sample_html))

问题似乎在于对异步toHtml() 的调用.看起来它应该相当简单，但我不知道该怎么做.我看到它已经在 C++ 的上下文中讨论，但我不确定如何将其转换为 Python.如何获取 HTML?

The trouble appears to lie in the call to asynchronous toHtml(). It seems like it should be fairly simple, but I'm at a loss with what to do with it. I see it's been discussed in the context of C++, but I'm not sure how to translate this to Python. How can I get the HTML out?

推荐答案

在以下线程中对该主题进行了大量讨论:https://riverbankcomputing.com/pipermail/pyqt/20​​15-January/035324.html

Quite a bit of discussion on the topic was made in the following thread: https://riverbankcomputing.com/pipermail/pyqt/2015-January/035324.html

新的 QWebEngine 接口考虑了以下事实:底层的 Chromium 引擎是异步的.因此，我们必须将异步 API 转换为同步 API.

The new QWebEngine interface takes account of the fact that the underlying Chromium engine is asynchronous. As such we have to turn an asynchronous API into a synchronous one.

外观如下:

def render(source_html):
    """Fully render HTML, JavaScript and all."""

    import sys
    from PyQt5.QtCore import QEventLoop
    from PyQt5.QtWidgets import QApplication
    from PyQt5.QtWebEngineWidgets import QWebEngineView

    class Render(QWebEngineView):
        def __init__(self, html):
            self.html = None
            self.app = QApplication(sys.argv)
            QWebEngineView.__init__(self)
            self.loadFinished.connect(self._loadFinished)
            self.setHtml(html)
            while self.html is None:
                self.app.processEvents(QEventLoop.ExcludeUserInputEvents | QEventLoop.ExcludeSocketNotifiers | QEventLoop.WaitForMoreEvents)
            self.app.quit()

        def _callable(self, data):
            self.html = data

        def _loadFinished(self, result):
            self.page().toHtml(self._callable)

    return Render(source_html).html

import requests
sample_html = requests.get(dummy_url).text
print(render(sample_html))

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