Qt WebEngine 支持下列特征：
Qt WebEngine 才支持 MPEG-4 Part 14 (MP4) 文件格式若所需专有音频 视频编解码器 (如 H.264 和 MPEG layer-3 (MP3)) 被启用。专有编解码器可以被启用通过将以下选项传递给
configure
工具当配置 Qt 时：
-webengine-proprietary-codecs
例如，传递以下选项当在顶层配置 Qt 以构建它时：
configure -webengine-proprietary-codecs
更多信息，见 Qt 配置选项 .
当使用 qmake 仅仅构建 Qt WebEngine 模块时，可以使用以下命令 (在此范例中，Qt WebEngine 源代码位于
C:\qt\qtwebengine
):
qmake C:\qt\qtwebengine -- -webengine-proprietary-codecs
警告： 当分发专有编解码器库时，它们必须获得许可。
FFmpeg 是录制、转换及流化音频 视频的跨平台解决方案。可以将其配置为与多个编解码器一起使用，但带编解码器库分发时会引发许可问题。对于某些编解码器，开源实现，譬如 OpenH264 ，是可用的。
Chromium DevTools 提供审查 调试任何 Web 内容的布局和性能问题的能力。
可以测试此特征通过启动 Qt WebEngine 应用程序采用命令行选项
--remote-debugging-port=[your-port]
或通过设置环境变量
QTWEBENGINE_REMOTE_DEBUGGING
，然后使用基于 Chromium 的浏览器 (譬如
简单浏览器
or
纳米浏览器
) 连接到
http://localhost:[your-port]
.
The Chromium DevTools page can also be shown within the application. To set this up, you can call either
QWebEnginePage::setInspectedPage
() to the page to be inspected, which implicitly loads the DevTools into the
this
page, or
QWebEnginePage::setDevToolsPage
() to let the
this
page be inspected.
The respective QML properties are WebEngineView.devToolsView and WebEngineView.inspectedView .
更多信息，见 Qt WebEngine 调试和剖分析 .
Some web servers, in particular many intranet sites, require the client to authenticate itself with a certificate, called a
client certificate
. Qt WebEngine will read the client certificates installed in the system settings in macOS and Windows, and on Linux those installed into the NSS database. Certificates can be installed into the NSS database using the
pk12util
工具。
By default, Qt WebEngine will not offer any client certificates to servers, as doing so uniquely identifies the user and might violate privacy expectations.
To activate support for client certificates, an application needs to listen to the QWebEnginePage::selectClientCertificate or WebEngineView.selectClientCertificate signals and select one of the offered certificates. For applications that can navigate to untrusted web sites, it is recommended to always give the user a choice before uniquely identifying them to a remote server.
Qt WebEngine makes it possible for the application to define its own custom URL schemes with specialized security policies and transport mechanisms.
Custom schemes can be used to implement alternative network protocols with all the usual web security policies, privileged internal schemes for displaying user interface compoments or debugging information, sandboxed schemes with extra restrictions, and so on.
更多信息，见 QWebEngineUrlScheme and QWebEngineUrlSchemeHandler .
Qt WebEngine 支持 HTML5 拖放。
可以通过打开 HTML5 拖放演示来测试此特征，譬如 HTML5 演示 - 拖放 , HTML5 演示 - 简单拖放 ，或 HTML5 演示 - 拖放，自动上传 , in 简单浏览器 or 纳米浏览器 .
把文件拖拽到浏览器中实际上不属于 HTML5，但它是受支持的。可以测试它通过打开 HTML5 演示 - 文件 API .
该特征支持在 Qt 5.7.0 添加。
Qt WebEngine supports viewing web content in fullscreen mode. For more information, see WebEngineSettings.fullscreenSupportEnabled , WebEngineView.fullScreenRequested , QWebEngineSettings::FullScreenSupportEnabled ，和 QWebEnginePage::fullScreenRequested .
This feature can be tested by playing a video from YouTube in Video Player or 纳米浏览器 , and clicking the full screen icon to go into fullscreen mode.
该特征支持在 Qt 5.6.0 添加。
Qt WebEngine 支持查看 DRM (数字版权管理) 保护视频若 Widevine CDM plugin has been installed. CDM plugin is a replacement of Flash based plugins for displaying DRM-protected content. It comes only in a binary format, so it can hide DRM decryption implementation details. It can be obtained from a third party or from a Google Chrome installation.
Qt WebEngine on startup looks for the
Widevine CDM
plugin in well know locations, like default Google Chrome installation directory or Linux distro specific paths. However, plugin location can be also passed with
QTWEBENGINE_CHROMIUM_FLAGS
使用
widevine-path
.
在 Windows：
set QTWEBENGINE_CHROMIUM_FLAGS=--widevine-path="C:/some path/widevinecdm.dll"
在 Linux：
export QTWEBENGINE_CHROMIUM_FLAGS=--widevine-path="/some path/libwidevinecdm.so"
在 macOS：
export QTWEBENGINE_CHROMIUM_FLAGS=--widevine-path="/some path/libwidevinecdm.dylib"
The video format most commonly used by DRM services, H.264, requires proprietary audio and video codecs. For more information about enabling the codecs, see 音频和视频编解码器 .
This feature can be tested by playing a video in 简单浏览器 or 纳米浏览器 from castLabs , Swank Motion Pictures, Inc. ，或 Bitmovin Player .
该特征支持在 Qt 5.7.0 添加。
Qt WebEngine supports JavaScript Geolocation API with Qt Location as a backend. The application has to explicitly allow the feature by using QWebEnginePage::Geolocation or WebEngineView.Feature .
If Qt Location has been built before Qt WebEngine then this feature can be tested by using 映射 and allowing it to find the current position of the user. Note that on Windows an external GPS receiver must be connected to the application. For more information, see Qt Positioning .
该特征支持在 Qt 5.5.0 添加。
Qt WebEngine supports the Chromium implementation of the HTTP/2 协议。
This feature can be tested by opening an HTTP/2 demo, such as the Akamai HTTP/2 Demo , in 简单浏览器 or 纳米浏览器 .
A web page might request dialogs for the following functions:
Qt WebEngine provides standard dialogs for these functions. In widget-based applications, the standard dialogs are based on
QDialog
, whereas in Qt Quick applications, they can be based either on Qt Quick Controls 1 or Qt Quick Controls 2 (since Qt 5.8). The latter are used only on
eglfs
平台。
To explicitly force either dialogs based on Qt Quick Controls 1 or Qt Quick Controls 2, set the
QTWEBENGINE_DIALOG_SET
environment variable to either
QtQuickControls1
or
QtQuickControls2
.
Qt WebEngine Widgets dialogs can be customized by reimplementing the QWebEnginePage::chooseFiles (), QWebEnginePage::javaScriptAlert (), QWebEnginePage::javaScriptConfirm ()，和 QWebEnginePage::javaScriptPrompt () 函数。
Since Qt 5.8, Qt Quick dialogs can be customized by connecting to the WebEngineView::authenticationDialogRequested (), WebEngineView::javaScriptDialogRequested (), WebEngineView::colorDialogRequested (), WebEngineView::fileDialogRequested (), and WebEngineView::formValidationMessageRequested() signals. For an example, see WebEngine Qt Quick 自定义对话框范例 .
Qt WebEngine supports loading Pepper Plugin API (PPAPI) plugins if WebEngineSettings::pluginsEnabled or QWebEngineSettings::PluginsEnabled 有设置。
The plugins must be loaded manually using the Chromium command line syntax with the
--register-pepper-plugins
argument. The argument value is a list of entries, separated by commas, that contain the file path and one or several MIME types, separated by semicolons:
<file-path-plugin1>;<mime-type-plugin1>,<file-path-plugin2>;<mime-type1-plugin2>;<mime-type2-plugin2>
例如：
--register-pepper-plugins="libppapi_example.so;application/x-ppapi-example"
The MIME type is important because it determines which embeds the plugin is used for.
该特征支持在 Qt 5.6.0 添加。
Qt WebEngine supports viewing PDF documents by navigating to them. This feature uses the Chromium extensions API and PDF viewer plugin to display the PDF documents. It can be tested in 简单浏览器 or 纳米浏览器 .
Loading plugins needs to be enabled using QWebEngineSettings::PluginsEnabled or WebEngineSettings::pluginsEnabled in order to use this feature.
This feature can be turned on (default) or off via the QWebEngineSettings::PdfViewerEnabled or WebEngineSettings::pdfViewerEnabled 设置。
该特征支持在 Qt 5.13.0 添加。
Qt WebEngine supports the 页面生命周期 API 规范 , a work-in-progress extension to the HTML standard for allowing user agents to reduce their resource consumption by freezing or discarding background pages. The feature is exposed both in the Widgets and QML APIs.
在使用中的 QML API 范例，见 WebEngine 生命周期范例 .
该特征支持在 Qt 5.14.0 添加。
每个 WebEngineView item (or QWebEnginePage object) can be in one of three lifecycle states : active, frozen, or discarded. These states, like the sleep states of a CPU, control the resource usage of web views.
active state is the normal, unrestricted state of a web view. All visible web views are always in the active state, as are all web views that have not yet finished loading. Only invisible, idle web views can be transitioned to other lifecycle states.
frozen state is a low CPU usage state. In this state, most HTML task sources are suspended (frozen) and, as a result, most DOM event processing and JavaScript execution will also be suspended. The web view must be invisible in order to be frozen as rendering is not possible in this state.
discarded state is an extreme resource-saving state. In this state, the browsing context of the web view will be discarded and the corresponding renderer subprocess shut down. CPU and memory usage in this state is reduced virtually to zero. On exiting this state the web page will be automatically reloaded. The process of entering and exiting the discarded state is similar to serializing the browsing history of the web view and destroying the view, then creating a new view and restoring its history.
另请参阅 WebEngineView::LifecycleState . The equivalent in the Widgets API is QWebEnginePage::LifecycleState .
lifecycleState
and
recommendedState
特性
lifecycleState 特性为 WebEngineView type is a read-write property that controls the current lifecycle state of the web view. This property is designed to place as few restrictions as possible on what states can be transitioned to. For example, it is allowed to freeze a web view that is currently playing music in the background, stopping the music. In order to implement a less aggressive resource-saving strategy that avoids interrupting user-visible background activity, the recommendedState property must be used.
recommendedState
特性为
WebEngineView
type is a read-only property that calculates a safe limit on the
lifecycleState
property, taking into account the current activity of the web view. So, in the example of a web view playing music in the background, the recommended state will be
Active
since a more aggressive state would stop the music. If the application wants to avoid interrupting background activity, then it should avoid putting the web view into a more aggressively resource-saving lifecycle state than what's given by
recommendedState
.
另请参阅 WebEngineView::lifecycleState and WebEngineView::recommendedState . The equivalents in the Widgets API are QWebEnginePage::lifecycleState and QWebEnginePage::recommendedState .
lifecycleState
特性被连接到
页面生命周期 API 规范
，它指定 2 个新 DOM 事件
freeze
and
resume
，和添加新的
Document.wasDiscarded
布尔特性。
freeze
and
resume
events are fired when transitioning from the
Active
到
Frozen state
, and vice-versa. The
Document.wasDiscarded
property is set to
true
when transitioning from the
Discarded
state to the
Active
状态。
Qt WebEngine 支持把网页打印成 PDF 文件。更多信息，见 QWebEnginePage::printToPdf () 和 WebEngineView.printToPdf .
可以测试此特征使用 Html2Pdf .
该特征支持在 Qt 5.7.0 添加。
Qt WebEngine uses multiple OS processes to isolate web sites from each other and from the client application, improving security and robustness. The following process models, or ways to divide web sites between OS processes, are supported:
This is the default model. Pages from separate sites are put into separate processes and separate visits to the same site are also isolated.
Two web pages are considered as belonging to the same site if they originate from the same registered domain name (for example,
wikipedia.org
) and scheme (for example,
https
). This is similar to the same-origin policy but subdomains are ignored. For example, both
https://en.wikipedia.org/
and
https://de.wikipedia.org/
would belong to the same site.
A site instance is a collection of web pages belonging to the same site. When the application explicitly loads a URL into Qt WebEngine (via QWebEnginePage::setUrl , for example), a new site instance is created for the page. However, when the user clicks same-site links on the page, the existing site instance is merely extended with more pages.
For instance, in the
简单浏览器
example, when a user opens two tabs and explicitly enters
https://en.wikipedia.org/
into the URL bars, both tabs will have their own separate OS processes (because explicitly entering a URL creates a new site instance). However, when the user then middle-clicks some same-site links to open more tabs, these new tabs will share the same OS process (because user interaction extends the existing site instance).
Pages from separate sites are put into separate processes. Unlike Process per Site Instance, all visits to the same site will share an OS process.
The benefit of this model is reduced memory consumption, because more web pages will share processes. The drawbacks include reduced security, robustness, and responsiveness.
To enable this model, use the command-line argument
--process-per-site
。见
使用命令行参数
.
For debugging purposes only, a single process mode can be enabled using the command-line argument
--single-process
。见
使用命令行参数
and
Qt WebEngine 调试和剖分析
.
Qt WebEngine supports integrating spellchecking support into HTML forms to enable users to submit spellchecked messages. When the user clicks on an underlined misspelled word, the default context menu displays up to four suggestions. Selecting one will replace the misspelled word.
To be able to check the spelling, the spellchecker needs dictionaries. It supports dictionaries from the Hunspell project , but they have to be compiled into a special binary format. A Hunspell dictionary consists of two files:
.dic
file that is a dictionary containing words for the language
.aff
file that defines the meaning of special flags in the dictionary
These two files can be converted into the
bdic
format by using the
qwebengine_convert_dict
tool that is shipped together with Qt. When the Qt WebEngine spellchecker initializes, it will try to load the
bdict
dictionaries and to check them for consistency.
若
QTWEBENGINE_DICTIONARIES_PATH
is set, the spellchecker uses the dictionaries in the specified directory without looking anywere else. Otherwise, it uses the
qtwebengine_dictionaries
directory relative to the executable if it exists. If it does not exist, it will look in
QT_INSTALL_PREFIX/qtwebengine_dictionaries
.
On macOS, depending on how Qt WebEngine is configured at build time, there are two possibilities how spellchecking data is found:
Thus, in the macOS Hunspell case, Qt WebEngine will look in the
qtwebengine_dictionaries
subdirectory located inside the application bundle
资源
directory, and also in the
资源
directory located inside the Qt framework bundle.
To summarize, in case of Hunspell usage, the following paths are considered:
QTWEBENGINE_DICTIONARIES_PATH
, if set
Spellchecking is disabled by default and can be enabled per profile by using the QWebEngineProfile::setSpellCheckEnabled () method in widget-based applications and the WebEngineProfile.spellCheckEnabled property in Qt Quick applications.
The current language used for spellchecking is defined per profile, and can be set using the QWebEngineProfile::setSpellCheckLanguages () method or the WebEngineProfile.spellCheckLanguages 特性。
可以测试此特征通过构建和运行 拼写检查器范例 .
该特征支持在 Qt 5.8.0 添加。
Qt WebEngine 支持导航和交互网页的触摸设备。
Applications can prohibit the use of touch events in the following ways:
--touch-events=disabled
on the command line will disable touch event support in JavaScript API (meaning
ontouchstart
and related handlers will not be present in the
document.window
object). Touch events will still be delivered to web pages.
Qt WebEngine 支持查看网页的 HTML 源。
This feature can be used from custom menus or assigned to custom events. For more information, see WebEngineView::WebAction ，和 QWebEnginePage::WebAction .
This feature can be tested by opening a web page in
简单浏览器
or
纳米浏览器
, and then selecting
Page Source
in the context menu. The
Page Source
context menu entry opens the source view in a new tab.
For opening the source view in the current tab, URLs with view-source URI scheme are also supported. For example, you can type the following URL to the URL bar to view the HTML source of the qt.io web page:
view-source:https://www.qt.io/
Auto-completion of incomplete URLs with view-source URI scheme makes the usage of this feature more comfortable. For example, the following incomplete URL also loads the source view of the qt.io web page:
view-source:qt.io
该特征支持在 Qt 5.8.0 添加。
WebRTC provides browsers with Real-Time Communications (RTC) capabilities via simple APIs. For more information, see WebEngineView.Feature and QWebEnginePage::Feature .
This feature can be tested by setting up a webcam or microphone and then opening
https://test.webrtc.org/
in
简单浏览器
or
纳米浏览器
.
Qt WebEngine 支持 JavaScript Web 通知 API 。应用程序必须明确允许特征通过使用 QWebEnginePage::Notifications or WebEngineView.Notifications .
该特征支持在 Qt 5.13.0 添加。
For accessing icons a
QQuickImageProvider
is registered. This provider can be accessed by a special URL where the scheme is "image:" and the host is "favicon". For example,
Image { source: "image://favicon/url" }
url
can be the URL of the favicon. For example,
Image { source: "image://favicon/https://www.qt.io/hubfs/2016_Qt_Logo/qt_logo_green_rgb_16x16.png" }
url
also can be a page URL to access its icon. For example,
Image { source: "image://favicon/https://www.qt.io/" }
If more than one icon is available, the Image::sourceSize property can be specified to choose the icon with the desired size. If Image::sourceSize is not specified or 0, the largest available icon will be chosen.
The image provider looks up the requested icon in the existing WebEngineView instances. First, it tries to match the currently displayed icons. If no match has been found it requests the icon from the database. Each profile has its own icon database and it is stored in the persistent storage thus the stored icons can be accessed without network connection too. The icon must be previously loaded to be stored in the database.
注意： The icon database is not available for off-the-record profiles.