This migration guide will get you through to make your code work with latest CEF Python. This document includes notable changes that were introduced to cefpython and each topic is prefixed with version number in which a change was introduced. This migration guide doesn't cover all changes required for your software to run smoothly. Some changes depend on the GUI framework you are using and this guide doesn't cover these. You will have to go to the examples/ root directory and see the example for your GUI framework. The new examples are very straightforward and include many useful comments explaining whys. You will have to get through its code and see if anything changed that also requires changes in your application.
Table of contents:
- v49+ Distribution packages
- v49+ cefbuilds.com is deprected, use Spotify Automated CEF Builds
- v49+ Build instructions and build tools
- v49: GPU acceleration should be disabled on Windows XP
- v49+ Handlers' callbacks and other interfaces
- v49+ High DPI support on Windows
- v49+ Do not call the 'WindowUtils.OnSize' function
- v49+ Notify CEF on move or resize events
- v49+ Flash support
- v49+ Off-screen-rendering: new option "windowless_rendering_enabled"
- v49+ BrowserSettings options removed
- v49+ cef.Request.Flags changed
- v49+ Request.GetHeaderMap and SetHeaderMap change
- v49+ HTTPS cache problems on pages with certificate errors
In latest CEF Python there is only one distribution package available: a wheel package. Wheel packages are distributed on PyPI and you can install it using the pip tool (8.1+ required on Linux). You can also download wheel packages from GitHub Releases.
Windows
On Windows many of the distribution packages such as MSI, EXE, ZIP and InnoSetup files, are no more available. It is too much hassle to support these.
Linux debian package
On Linux the debian package is not supported anymore. Since pip 8.1+ added support for manylinux1 wheel packages, you can now easily install cefpython on Linux using the pip tool. Installing cefpython on Ubuntu using pip should work out of the box, all OS dependencies on Ubuntu should be satisfied by default. However since upstream CEF has OS dependencies that might not be installed by default on other OSes like e.g. Fedora, and since debian packages allow to list these and install in an automated manner, it might be reconsidered in the future to provide debian packages again.
The cefbuilds.com site with CEF prebuilt binaries is now deprecated. From now on download prebuilt CEF binaries from the Spotify Automated CEF Builds:
http://opensource.spotify.com/cefbuilds/index.html
There were many changes in regards to building CEF and CEF Python. There are now new tools in the tools/ root directory that fully automate building CEF and CEF Python. CEF Python now provides upstream CEF prebuilt binaries and libraries on GitHub Releases tagged eg. "v49-upstream". With these binaries you can build CEF Python from sources in less than 10 minutes. See the new Build instructions document.
On XP you should disable GPU acceleration by setting the --disable-gpu
and --disable-gpu-compositing
switches. These switches can
be passed programmatically to cef.Initialize
, see
api/Command Line Switches.
Since v55.3 all handlers' callbacks and other interfaces such as CookieVisitor, StringVisitor and WebRequestClient, are now called using keyword arguments (Issue #291). This will cause many of existing code to break. This is how you should declare callbacks using the new style:
def OnLoadStart(self, browser, **_):
pass
def OnLoadStart(self, **kwargs):
browser = kwargs["browser"]
In the first declaration you see that only one argument is declared, the browser, the others unused will be in the "_" variable (the name of the variable is so that PyCharm doesn't warn about unused variable).
Even if you specify and use all arguments, always add the
unused kwargs (**_
) at the end:
def OnLoadStart(self, browser, frame, **_):
pass
This will be handy in the future, in a case when upstream CEF adds a new argument to the API, your code won't break. When an argument is removed in upstream CEF API, if it's possible CEF Python will try to keep backward compatibility by emulating behavior of the old argument.
In case of OnLoadStart, when you've used "browser" and "frame"
names for the arguments, your code won't break. However in
many other callbacks, where you've used argument names that
differed from how they were named in API docs, your code will
break. Also argument names were changed from camelCase
to underscores. For example the OnLoadEnd callback has renamed
the httpStatusCode
argument to http_code
. So in this case
your code will definitely break, unless you've also used
"http_code" for argument name.
It is recommended to embed a DPI awareness manifest in both the main
process and the subprocesses (the subprocess.exe executable) instead
of calling DpiAware
.SetProcessDpiAware
which sets DPI awareness only for the main process.
The ApplicationSettings
.auto_zooming
option has a default value of an empty string now. Previously the
default was "system_dpi". When enabling High DPI support you should
set it to "system_dpi" explicitilly.
Note that DpiAware
.CalculateWindowSize
does not handle all DPI settings (e.g. 132% on Windows 10).
In newer CEF Python there is available DpiAware.Scale
which is more
reliable and can handle all DPI resolutions. You can copy see its
implementation in src/dpi_aware_win.pyx
.
This function can sometimes cause app hanging during window resize.
Call instead the new WindowUtils
.UpdateBrowserSize
function. Except when you use the pywin32.py
example, in such case
WindowUtils.OnSize
must be called. See Issue #464
for details.
It is required to notify the browser on move or resize events so that popup widgets (e.g. <select>) are displayed in the correct location and dismissed when the window moves. Also so that drag & drop areas are updated accordingly. Call Browser.NotifyMoveOrResizeStarted() during a move or resize event in your app window.
See Issue #235 ("Flash support in CEF v49+") for instructions on how to enable Flash.
When using off-screen-rendering you must set the ApplicationSettings "windowless_rendering_enabled" option to True. This applies to examples such as: Kivy, Panda3D, PySDL2 and screenshot example.
API ref: ApplicationSettings.windowless_rendering_enabled
The following options were removed from BrowserSettings:
- user_style_sheet_location
- java_disabled
- accelerated_compositing
- author_and_user_styles_disabled
The following flags were removed from cef.Request.Flags:
- AllowCookies
- ReportLoadTiming
- ReportRawHeaders
API ref: Request.GetFlags
GetHeaderMap() will not include the Referer value if any and SetHeaderMap() will ignore the Referer value.
API ref: Request.GetHeaderMap
The fix for HTTPS cache problems on pages with certificate errors (and that includes self-signed certificates) is no more applied on Windows.
Soon this will fix also won't be applied on Linux anymore when cefpython starts using CEF prebuilt binaries from Spotify.
See Issue #125 for more details.