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‎docs/Knowledge-Base.md‎

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# Knowledge Base
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Table of contents:
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* [Notifications on new releases](#notifications-on-new-releases)
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* [Changes in API after CEF updates](#changes-in-api-after-cef-updates)
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* [Differences between Python 2 and Python 3](#differences-between-python-2-and-python-3)
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* [Flash support](#flash-support)
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* [Feature X works in Google Chrome, but doesn't work in CEF Python](#feature-x-works-in-google-chrome-but-doesnt-work-in-cef-python)
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* [How to capture Audio and Video in HTML5?](#how-to-capture-audio-and-video-in-html5)
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* [Touch and multi-touch support](#touch-and-multi-touch-support)
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* [Black or white browser screen](#black-or-white-browser-screen)
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* [Windows XP support](#windows-xp-support)
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* [Mac 32-bit support](#mac-32-bit-support)
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* [Security](#security)
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## Notifications on new releases
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To be notified of new releases subscribe to this [RSS/Atom feed]
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(../../../releases.atom).
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Announcements are also made on the [Forum]
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(https://groups.google.com/d/forum/cefpython).
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To be notified of these via email set your Membership and Email settings
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and change delivery preference to Daily summaries.
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## Changes in API after CEF updates
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CEF Python depends on CEF and API breaks are inevitable when updating
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to latest CEF. The [Migration Guide](Migration-guide.md) document which
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is still under works, will list most notable breaking changes since
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v31 release. Until it's done go to go to the [GitHub Releases]
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(../../../releases) page and check release notes for all the releases
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that appeared between your old version and the new version. Look for
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lists named "Changes in API that break backward compatibility" or
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similar.
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Due to unavoidable changes in API it is recommended for your setup
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scripts that use for example PIP to install the cefpython3 package,
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to hardcode the cefpython version string. If for example using PIP's
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requirements.txt file then list the cefpython3 package in the
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following format: `cefpython3 == 31.2`.
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## Differences between Python 2 and Python 3
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In Python 2 all cefpython strings are byte strings, but in Python 3
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they are all unicode strings. Be aware of this when porting cefpython
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based apps to Python 3, as it may cause issues.
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## Flash support
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See [Issue #235](../../../issues/235) ("Flash support in CEF 51+").
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## Feature X works in Google Chrome, but doesn't work in CEF Python
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CEF Python embeds Chromium Embedded Framework (CEF) which is based
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on Chromium browser. Functionality may differ a bit from Google Chrome.
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The browser from Google is a proprietary software that for example
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includes MPEG-4/H.264 codecs that aren't included in the open source
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Chromium. CEF currently doesn't support Chrome Extensions, but basic
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support for Chrome Extensions is being implemented in upstream CEF
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as of now.
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To see if some feature is working or a bug is fixed in newer CEF
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release perform the following steps:
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1. Download and install [CMake](https://cmake.org/download/) and
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[Ninja](https://github.com/ninja-build/ninja/releases)
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2. Go to [Spotify Automated Builds]
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(http://opensource.spotify.com/cefbuilds/index.html)
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and download latest CEF for your platform. Choose "Standard
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Distribution" binaries.
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3. Follow the instructions in `CMakeLists.txt` file
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4. Run either cefclient or cefsimple to test features
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## How to capture Audio and Video in HTML5?
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To be able to use the getUserMedia() function you need to set the
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"enable-media-stream" switch.
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See [api/Command line switches](../api/CommandLineSwitches.md) document.
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## Touch and multi-touch support
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In CEF v47 or later touch device is auto-detected and everything should
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work out of the box. If that's not the case try setting the following
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switches:
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* --touch-events=enabled
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* --enable-pinch
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See [api/Command line switches](../api/CommandLineSwitches.md) document.
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## Black or white browser screen
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If you get a black or white screen in the browser view then this may
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be caused by incompatible GPU (video card) drivers. There are following
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solutions to this:
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1. When CEF Python is updated to a newer CEF/Chromium version then the
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problem may be disappear. Check with latest Google Chrome if that is
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the case.
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2. Try updating your video card drivers to the latest version available
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3. You can disable GPU hardware acceleration by adding the "disable-gpu"
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and "disable-gpu-compositing" command line switches. See the
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[api/Command Line Switches](../api/CommandLineSwitches.md). Note that
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this will degrade performance if you're using any advanced 3D features.
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It will affect 2D accelerated content as well.
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Note that when web page uses WebGL then the black screen may still
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appear even after disabling GPU hardware acceleration. This is normal
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because GPU was disabled so WebGL cannot work.
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## Windows XP support
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CEF Python v31.2 was the last version to support Windows XP. This is
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due to Chromium/CEF dropping XP support, last CEF version that
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supported XP was v49.
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On XP you should disable GPU acceleration by using the --disable-gpu
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and --disable-gpu-compositing switches. These switches must be passed
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programmatically to cef.Initialize(), see [api/Command Line Switches]
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(../api/CommandLineSwitches.md).
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## Mac 32-bit support
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CEF Python v31.2 was the last version to support Mac 32-bit.
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This is due to CEF/Chromium dropping 32-bit support, last CEF version
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that supported 32-bit was v38.
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## Security
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A quote by Marshall Greenblatt:
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> CEF offers significant integration capabilities beyond what
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> is offered by a standard Google Chrome browser installation.
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> The trade off for these additional capabilities is that
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> organizations using CEF must take responsibility for their own
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> application security. CEF and the underlying open source projects
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> (Chromium, WebKit, etc) involve a significant amount of code and
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> offer no warranties. Organizations should document and follow best
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> practices to minimize potential security risks. Here are some
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> recommended best practices that organizations can consider:
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> - Only load known/trusted content. This is by far the best way
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> to avoid potential security issues.
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> - Disable plugins. This will avoid a large category of security
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> issues caused by buggy versions of Flash, Java, etc.
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> - Do not explicitly disable or bypass security features in your
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> application. For example, do not enable CefBrowserSettings that
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> bypass security features or add fake headers to bypass HTTP
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> access control.
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> - Keep your application up to date with the newest CEF release
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> branch. You may want to update the underlying Chromium release
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> version and perform your own builds to take immediate advantage
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> of any bug fixes.
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> - Enforce good programming practices. Every organization should
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> have best practices for design, testing and verification.
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> - Audit your application for potential security issues. Every
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> decision that may have security consequences should be evaluated
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> by people who are knowledgeable about security considerations.
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Reference: [Question on browser security]
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(http://magpcss.org/ceforum/viewtopic.php?f=10&t=10222)
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on the CEF Forum.
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