QWebEngineView 无法使用 setHtml 加载大型 SVG/HTML-解网

问：

我尝试了两种不同的方法来在 PyQt 中加载和显示 SVG 文件：

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

app = QApplication(sys.argv)
webView = QWebEngineView()

# Variant 1: Reasonably fast
webView.load(QUrl('file:///Test.svg'))

# Variant 2: Slow for small files, not working for big ones
webView.setHtml('<svg>........')

webView.show()
sys.exit(app.exec_())

第一种方法工作正常，但需要文件作为输入。不过，我想动态生成 SVG，所以这不是一个真正的选择。有谁知道为什么第二种方法对于更复杂的矢量图像如此缓慢或完全失败？

python qt svg pyqt5 qtwebengine

from PyQt5.QtCore import (
    QUrl, QByteArray, QBuffer, QIODevice,
)
from PyQt5.QtWidgets import (
    QApplication, QWidget, QPushButton, QCheckBox, QGridLayout,
)
from PyQt5.QtWebEngineCore import (
    QWebEngineUrlScheme, QWebEngineUrlSchemeHandler, QWebEngineUrlRequestJob,
    )
from PyQt5.QtWebEngineWidgets import QWebEngineView


HTML_DATA = {}
URL_SCHEME = 'local'
TEST_FILE = 'test.data'


class UrlSchemeHandler(QWebEngineUrlSchemeHandler):
    def requestStarted(self, job):
        href = job.requestUrl().path()
        if (data := HTML_DATA.get(href)) is not None:
            if not isinstance(data, bytes):
                data = str(data).encode()
            mime = QByteArray(b'text/html')
            buffer = QBuffer(job)
            buffer.setData(data)
            buffer.open(QIODevice.OpenModeFlag.ReadOnly)
            job.reply(mime, buffer)
        else:
            print(f'ERROR: request job failed: {href!r}')
            job.fail(QWebEngineUrlRequestJob.Error.UrlNotFound)


class Window(QWidget):
    def __init__(self):
        super().__init__()
        self.button = QPushButton('Load Source')
        self.button.clicked.connect(self.handleButtton)
        self.option = QCheckBox('Use url scheme handler')
        self.view = QWebEngineView()
        self.view.page().profile().installUrlSchemeHandler(
            bytes(URL_SCHEME, 'ascii'), UrlSchemeHandler(self))
        self.view.loadFinished.connect(self.handleLoaded)
        layout = QGridLayout(self)
        layout.addWidget(self.view, 0, 0, 1, 2)
        layout.addWidget(self.button, 1, 0)
        layout.addWidget(self.option, 1, 1)

    def handleButtton(self):
        if self.option.isChecked():
            url = QUrl(TEST_FILE)
            url.setScheme(URL_SCHEME)
            self.view.setUrl(url)
        else:
            self.view.setHtml(HTML_DATA[TEST_FILE])

    def handleLoaded(self, ok):
        if not ok:
            self.view.setHtml('<h3>414: URI Too Long</h3>')


if __name__ == '__main__':

    try:
        HTML_DATA[TEST_FILE] = open('large.svg').read()
    except OSError:
        HTML_DATA[TEST_FILE] = (html := f"""
            <html><head></head><body>
            <h3>Test Page ({{}} MB)</h3>{'''<p>
            Lorem ipsum dolor sit amet, consectetur adipiscing
            elit, sed do eiusmod tempor incididunt ut labore et
            dolore magna aliqua. Ut enim ad minim veniam, quis
            nostrud exercitation ullamco laboris nisi ut aliquip
            ex ea commodo consequat. Duis aute irure dolor in
            reprehenderit in voluptate velit esse cillum dolore
            eu fugiat nulla pariatur. Excepteur sint occaecat
            cupidatat non proident, sunt in culpa qui officia
            deserunt mollit anim id est laborum.
            </p>''' * 4000}</body></html>"""
            ).format(round(len(html) / 1e6, 1))

    scheme = QWebEngineUrlScheme(bytes(URL_SCHEME, 'ascii'))
    scheme.setFlags(QWebEngineUrlScheme.Flag.SecureScheme |
                    QWebEngineUrlScheme.Flag.LocalScheme |
                    QWebEngineUrlScheme.Flag.LocalAccessAllowed)
    QWebEngineUrlScheme.registerScheme(scheme)

    app = QApplication(['Test'])
    window = Window()
    window.setGeometry(600, 50, 800, 600)
    window.show()
    app.exec()

上一个答案：

该函数无法加载任何大小大于 2MB 的内容（不仅仅是 svg）。这是因为 Chromium 使用方案 url 来加载内容（这会将 url 的大小限制为最大长度）。因此，似乎唯一的选择是从本地文件加载svg。setHtmldata:

请参见：QTBUG-53414

QWebEngineView 无法使用 setHtml 加载大型 SVG/HTML

QWebEngineView cannot load large SVG/HTML using setHtml

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