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LoadHandler.md

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API categories | API index

LoadHandler (interface)

Implement this interface to handle events related to browser load status. The methods of this class will be called on the UI thread.

For an example of how to implement handler see cefpython.CreateBrowser(). For a list of all handler interfaces see API > Client handlers.

Table of contents:

Callbacks

OnLoadingStateChange

Parameter Type
browser Browser
is_loading bool
can_go_back bool
can_go_forward bool
Return void

Called when the loading state has changed. This callback will be executed twice. Once when loading is initiated either programmatically or by user action, and once when loading is terminated due to completion, cancellation of failure. It will be called before any calls to OnLoadStart and after all calls to OnLoadError and/or OnLoadEnd.

OnLoadStart

Parameter Type
browser Browser
frame Frame
Return void

This callback is called for a number of different reasons, including when history.pushState or history.replaceState changes the reference fragment for the currently loaded page. In most cases you want to use OnLoadingStateChange. In newer CEF there is |transition_type| arg that provides information about the source of the navigation.

Description from upstream CEF:

Called when the browser begins loading a frame. The |frame| value will never be empty -- call the IsMain() method to check if this frame is the main frame. |transition_type| provides information about the source of the navigation and an accurate value is only available in the browser process. Multiple frames may be loading at the same time. Sub-frames may start or continue loading after the main frame load has ended. This method will always be called for all frames irrespective of whether the request completes successfully. For notification of overall browser load status use DisplayHandler.OnLoadingStateChange instead.

OnDomReady
Return void

Not yet implemented. See Issue #32.

OnLoadEnd

Parameter Type
browser Browser
frame Frame
http_code int
Return void

Called when the browser is done loading a frame. The |frame| value will never be empty -- call the IsMain() method to check if this frame is the main frame. Multiple frames may be loading at the same time. Sub-frames may start or continue loading after the main frame load has ended. This method will always be called for all frames irrespective of whether the request completes successfully. For notification of overall browser load status use OnLoadingStateChange instead.

This event behaves like window.onload, it waits for all the content to load (e.g. images), there is currently no callback for a DOMContentLoaded event, see Issue #32.

There are some cases when this callback won't get called, see this topic: http://www.magpcss.org/ceforum/viewtopic.php?f=6&t=10906

OnLoadError

Parameter Type
browser Browser
frame Frame
error_code NetworkError
error_text_out list[string]
failed_url string
Return void

Called when the resource load for a navigation fails or is canceled. |errorCode| is the error code number, |error_text_out[0]| is the error text and |failed_url| is the URL that failed to load. See net\base\net_error_list.h for complete descriptions of the error codes.

This callback may get called when Browser.StopLoad is called, or when file download is aborted (see DownloadHandler).