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// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_VIDEO_CAPTURE_VIDEO_CAPTURER_SOURCE_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_VIDEO_CAPTURE_VIDEO_CAPTURER_SOURCE_H_
#include <string>
#include <vector>
#include "base/functional/callback.h"
#include "base/time/time.h"
#include "base/token.h"
#include "media/capture/video/video_capture_feedback.h"
#include "media/capture/video_capture_types.h"
#include "third_party/blink/public/platform/media/video_capture.h"
#include "third_party/blink/renderer/platform/platform_export.h"
namespace blink {
// The state of the video capture device.
// The client can use this information to determine if the video capture
// device is currently running or not.
enum class VideoCaptureRunState {
kRunning = 0,
kStopped,
kSystemPermissionsError,
kCameraBusyError,
kStartTimeoutError,
};
// VideoCapturerSource is an interface representing the source for captured
// video. An implementation will periodically call the frame callback with new
// video frames.
class PLATFORM_EXPORT VideoCapturerSource {
public:
virtual ~VideoCapturerSource();
using VideoCaptureRunningCallbackCB =
base::RepeatingCallback<void(VideoCaptureRunState)>;
// Returns formats that are preferred and can currently be used. May be empty
// if no formats are available or known.
virtual media::VideoCaptureFormats GetPreferredFormats() = 0;
// Starts capturing frames using the capture |params|.
// |video_capture_callbacks.deliver_frame_cb| is triggered when a new video
// frame is available.
//
// If capturing is started successfully then |running_callback| will be
// called with a parameter of true. Note that some implementations may
// simply reject StartCapture (by calling running_callback with a false
// argument) if called with the wrong task runner.
//
// If capturing fails to start or stopped due to an external event then
// |running_callback| will be called with a parameter of false.
// |running_callback| will always be called on the same thread as the
// StartCapture.
//
// |video_capture_callbacks.sub_capture_target_version_cb| will be called when
// it is guaranteed that all subsequent frames
// |video_capture_callbacks.deliver_frame_cb| is called for, have a
// sub-capture-target version that is equal-to-or-greater-than the given
// sub-capture-target version.
//
// |video_capture_callbacks.frame_dropped_cb| will be called when a frame was
// dropped prior to delivery (i.e. |video_capture_callbacks.deliver_frame_cb|
// was not called for this frame).
virtual void StartCapture(const media::VideoCaptureParams& params,
VideoCaptureCallbacks video_capture_callbacks,
VideoCaptureRunningCallbackCB running_callback) = 0;
// Returns a callback for providing the feedback from the consumer.
// The callback can be called on any thread.
virtual media::VideoCaptureFeedbackCB GetFeedbackCallback() const;
// Asks source to send a refresh frame. In cases where source does not provide
// a continuous rate of new frames (e.g. canvas capture, screen capture where
// the screen's content has not changed in a while), consumers may request a
// "refresh frame" to be delivered. For instance, this would be needed when
// a new sink is added to a MediaStreamTrack.
//
// The default implementation is a no-op and implementations are not required
// to honor this request. If they decide to and capturing is started
// successfully, then |video_capture_callbacks.deliver_frame_cb| should be
// called with a frame.
//
// Note: This should only be called after StartCapture() and before
// StopCapture(). Otherwise, its behavior is undefined.
virtual void RequestRefreshFrame() {}
// Optionally suspends frame delivery. The source may or may not honor this
// request. Thus, the caller cannot assume frame delivery will actually
// stop. Even if frame delivery is suspended, this might not take effect
// immediately.
//
// The purpose of this is to allow minimizing resource usage while
// there are no frame consumers present.
//
// Note: This should only be called after StartCapture() and before
// StopCapture(). Otherwise, its behavior is undefined.
virtual void MaybeSuspend() {}
// Resumes frame delivery, if it was suspended. If frame delivery was not
// suspended, this is a no-op, and frame delivery will continue.
//
// Note: This should only be called after StartCapture() and before
// StopCapture(). Otherwise, its behavior is undefined.
virtual void Resume() {}
// Stops capturing frames and clears all callbacks including the
// SupportedFormatsCallback callback. Note that queued frame callbacks
// may still occur after this call, so the caller must take care to
// use refcounted or weak references in
// |video_capture_callbacks.deliver_frame_cb|.
virtual void StopCapture() = 0;
// Hints to the source that if it has an alpha channel, that alpha channel
// will be ignored and can be discarded.
virtual void SetCanDiscardAlpha(bool can_discard_alpha) {}
// Sends a log message to the source.
virtual void OnLog(const std::string& message) {}
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_VIDEO_CAPTURE_VIDEO_CAPTURER_SOURCE_H_
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