1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_FRAME_SUBSCRIBER_H_ 6 #define CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_FRAME_SUBSCRIBER_H_ 7 8 #include "base/callback.h" 9 #include "base/time/time.h" 10 11 namespace gfx { 12 class Rect; 13 class Size; 14 } // namespace gfx 15 16 namespace media { 17 class VideoFrame; 18 } // namespace media 19 20 namespace content { 21 22 // Defines an interface for listening to events of frame presentation and to 23 // instruct the platform layer (i.e. RenderWidgetHostView) to copy a frame. 24 // 25 // Further processing is possible (e.g. scale and color space conversion) 26 // through this interface. See ShouldCaptureFrame() for details. 27 // 28 // It is platform dependent which thread this object lives on, but it is 29 // guaranteed to be used on a single thread. 30 class RenderWidgetHostViewFrameSubscriber { 31 public: ~RenderWidgetHostViewFrameSubscriber()32 virtual ~RenderWidgetHostViewFrameSubscriber() {} 33 34 // Called when a captured frame is available or the frame is no longer 35 // needed by the platform layer. 36 // 37 // If |frame_captured| is true then frame provided contains valid content and 38 // |timestamp| is the time when the frame was painted. 39 // 40 // If |frame_captured| is false then the content in frame provided is 41 // invalid. There was an error during the process of frame capture or the 42 // platform layer is shutting down. |timestamp| is also invalid in this case. 43 typedef base::Callback<void(base::TimeTicks /* timestamp */, 44 bool /* frame_captured */)> DeliverFrameCallback; 45 46 // Called when a new frame is going to be presented at time 47 // |present_time| with |damage_rect| being the region of the frame that has 48 // changed since the last frame. The implementation decides whether the 49 // current frame should be captured or not. 50 // 51 // Return true if the current frame should be captured. If so, |storage| 52 // will be set to hold an appropriately sized and allocated buffer into which 53 // to copy the frame. The platform presenter will perform scaling and color 54 // space conversion to fit into the output frame. 55 // 56 // Destination format is determined by |storage|, currently only 57 // media::VideoFrame::YV12 is supported. Platform layer will perform color 58 // space conversion if needed. 59 // 60 // When the frame is available |callback| will be called. It is up to the 61 // platform layer to decide when to deliver a captured frame. 62 // 63 // Return false if the current frame should not be captured. 64 virtual bool ShouldCaptureFrame(const gfx::Rect& damage_rect, 65 base::TimeTicks present_time, 66 scoped_refptr<media::VideoFrame>* storage, 67 DeliverFrameCallback* callback) = 0; 68 }; 69 70 } // namespace content 71 72 #endif // CONTENT_PORT_BROWSER_RENDER_WIDGET_HOST_VIEW_FRAME_SUBSCRIBER_H_ 73