HeadlessExperimental

This domain provides experimental commands only supported in headless mode.

This CDP domain is experimental.

Types

Generally, you do not need to instantiate CDP types yourself. Instead, the API creates objects for you as return values from commands, and then you can use those objects as arguments to other commands.

class cdp.headless_experimental.ScreenshotParams(format_=None, quality=None)

Encoding options for a screenshot.

format_ = None

Image compression format (defaults to png).

quality = None

Compression quality from range [0..100] (jpeg only).

Commands

Each command is a generator function. The return type Generator[x, y, z] indicates that the generator yields arguments of type x, it must be resumed with an argument of type y, and it returns type z. In this library, types x and y are the same for all commands, and z is the return type you should pay attention to. For more information, see Getting Started: Commands.

cdp.headless_experimental.begin_frame(frame_time_ticks=None, interval=None, no_display_updates=None, screenshot=None)

Sends a BeginFrame to the target and returns when the frame was completed. Optionally captures a screenshot from the resulting frame. Requires that the target was created with enabled BeginFrameControl. Designed for use with –run-all-compositor-stages-before-draw, see also https://goo.gl/3zHXhB for more background.

Parameters:
  • frame_time_ticks (Optional[float]) – (Optional) Timestamp of this BeginFrame in Renderer TimeTicks (milliseconds of uptime). If not set, the current time will be used.
  • interval (Optional[float]) – (Optional) The interval between BeginFrames that is reported to the compositor, in milliseconds. Defaults to a 60 frames/second interval, i.e. about 16.666 milliseconds.
  • no_display_updates (Optional[bool]) – (Optional) Whether updates should not be committed and drawn onto the display. False by default. If true, only side effects of the BeginFrame will be run, such as layout and animations, but any visual updates may not be visible on the display or in screenshots.
  • screenshot (Optional[ScreenshotParams]) – (Optional) If set, a screenshot of the frame will be captured and returned in the response. Otherwise, no screenshot will be captured. Note that capturing a screenshot can fail, for example, during renderer initialization. In such a case, no screenshot data will be returned.
Return type:

Generator[Dict[str, Any], Dict[str, Any], Tuple[bool, Optional[str]]]
Returns:

A tuple with the following items:

  1. hasDamage - Whether the BeginFrame resulted in damage and, thus, a new frame was committed to the display. Reported for diagnostic uses, may be removed in the future.
  2. screenshotData - (Optional) Base64-encoded image data of the screenshot, if one was requested and successfully taken.
cdp.headless_experimental.disable()

Disables headless events for the target.

Return type:Generator[Dict[str, Any], Dict[str, Any], None]
cdp.headless_experimental.enable()

Enables headless events for the target.

Return type:Generator[Dict[str, Any], Dict[str, Any], None]

Events

Generally, you do not need to instantiate CDP events yourself. Instead, the API creates events for you and then you use the event’s attributes.

class cdp.headless_experimental.NeedsBeginFramesChanged(needs_begin_frames)

Issued when the target starts or stops needing BeginFrames.

needs_begin_frames = None

True if BeginFrames are needed, false otherwise.