CEF Python Documentation

The cefpython module provides the core functions for managing the CEF (Chromium Embedded Framework) lifecycle, browser instances, and global callbacks. Key functional areas include:

• Lifecycle Management: Initialize, Shutdown, MessageLoop, and QuitMessageLoop.
• Browser Management: CreateBrowser, CreateBrowserSync, GetBrowserByIdentifier, and GetBrowserByWindowHandle.
• Global Callbacks: SetGlobalClientCallback, GetGlobalClientCallback, and SetGlobalClientHandler.
• System & Environment: GetAppPath, GetAppSetting, GetCommandLineSwitch, and GetVersion.
• Task Scheduling: PostTask and PostDelayedTask.

By default, CEF 3 handles downloads automatically if ApplicationSettings.downloads_enabled is set to True (which is the default setting). When a download is triggered, the operating system's default SaveAs file dialog is displayed to the user.

If a user aborts the download via the dialog, LoadHandler.OnLoadError will be triggered with the error code ERR_ABORTED.

The CEF Python API is organized into several functional categories. You can explore the API surface through the following groups:

• Modules: Core functionality provided by the cefpython module.
• Settings: Configuration dictionaries including ApplicationSettings, BrowserSettings, and CommandLineSwitches.
• Classes and objects: Core entities such as Browser, CookieManager, JavascriptBindings, Request, and WindowInfo.
• Client handlers (interfaces): Interfaces used to intercept and handle browser events, such as LoadHandler, RequestHandler, DisplayHandler, and KeyboardHandler.
• Other interfaces: Specialized interfaces like CookieVisitor and WebRequestClient.

When distributing Mac apps, CEF expects the framework at Contents/Frameworks/Chromium Embedded Framework.framework in the top-level app bundle. If your structure differs, set ApplicationSettings.framework_dir_path before calling cef.Initialize().

If you change the directory structure, you may need to update embedded paths in the libraries using install_name_tool:

• install_name_tool -rpath old new
• install_name_tool -change old new
• install_name_tool -id name

Verify changes with otool -l file or otool -L file.

To use the jQuery selectBox plugin, include the JavaScript and CSS files in your project. You can initialize the plugin on any <select> element using the .selectBox() method.

Default initialization: $('select').selectBox();

Initialization with custom settings: $('select').selectBox({ mobile: true, menuSpeed: 'fast' });

When implementing RequestHandler.OnCertificateError(), you may encounter several certificate-related error constants. Common ones include:

• ERR_CERT_AUTHORITY_INVALID: The certificate is signed by an untrusted authority (e.g., self-signed).
• ERR_CERT_COMMON_NAME_INVALID: The certificate's common name does not match the hostname.
• ERR_CERT_DATE_INVALID: The certificate is expired or not yet valid.
• ERR_CERT_INVALID: The certificate is invalid (non-recoverable).
• ERR_CERT_REVOKED: The certificate has been revoked.
• ERR_CERT_UNABLE_TO_CHECK_REVOCATION: Revocation information is unavailable.
• ERR_SSL_PROTOCOL_ERROR: An SSL protocol error occurred.
• ERR_SSL_VERSION_OR_CIPHER_MISMATCH: Client and server do not share a common SSL version or cipher suite.

When contributing code, adhere to the following standards:

• PEP 8: Comply with the PEP 8 style guide.
• Docstrings: Follow PEP 257 conventions.
• Line Length: Limit all lines to a maximum of 79 characters. Comments should be shorter (max 60-65 characters).
• Indentation: Use 4 spaces.
• Newlines: Use Unix-style newlines (\n).
• Consistency: Ensure new code is consistent with the existing codebase.

CEF Python provides various resources to help you get started, including tutorials, full examples, code snippets, and guidance on using PyInstaller for packaging:

• Tutorial: Detailed step-by-step guide.
• All examples: A collection of comprehensive usage examples.
• Snippets: Small, focused code snippets.
• PyInstaller packager: Instructions for bundling your application.

CEF Python does not currently provide built-in download progress updates. To implement progress tracking, you must create a custom download implementation by investigating and utilizing callbacks from client handlers. Specifically, consider using:

• RequestHandler.OnBeforeBrowse
• RequestHandler.OnBeforeResourceLoad
• ResourceHandler

To verify your installation and run the basic hello_world.py example, install the cefpython3 package, clone the repository, and execute the script from the examples/ directory.

pip install cefpython3==66.0
git clone https://github.com/cztomczak/cefpython.git
cd cefpython/examples/
python hello_world.py