replicant-frameworks_native/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h
Jesse Hall 80e0a397a4 Add BufferQueueInterposer and use it for virtual displays
BufferQueueInterposer allows a client to tap into a
IGraphicBufferProducer-based buffer queue, and modify buffers as they
pass from producer to consumer. VirtualDisplaySurface uses this to
layer HWC composition on top of GLES composition before passing the
buffer to the virtual display consumer.

Bug: 8384764
Change-Id: I61ae54f3d90de6a35f4f02bb5e64e7cc88e1cb83
2013-03-18 14:21:45 -07:00

85 lines
3.2 KiB
C++

/*
* Copyright 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H
#define ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H
#include "BufferQueueInterposer.h"
#include "DisplaySurface.h"
// ---------------------------------------------------------------------------
namespace android {
// ---------------------------------------------------------------------------
class HWComposer;
/* This DisplaySurface implementation uses a BufferQueueInterposer to pass
* partially- or fully-composited buffers from the OpenGL ES driver to
* HWComposer to use as the output buffer for virtual displays. Allowing HWC
* to compose into the same buffer that contains GLES results saves bandwidth
* compared to having two separate BufferQueues for frames with at least some
* GLES composition.
*
* The alternative would be to have two complete BufferQueues, one from GLES
* to HWC and one from HWC to the virtual display sink (e.g. video encoder).
* For GLES-only frames, the same bandwidth saving could be achieved if buffers
* could be acquired from the GLES->HWC queue and inserted into the HWC->sink
* queue. That would be complicated and doesn't help the mixed GLES+HWC case.
*
* On frames with no GLES composition, the VirtualDisplaySurface dequeues a
* buffer directly from the sink IGraphicBufferProducer and passes it to HWC,
* bypassing the GLES driver. This is only guaranteed to work if
* eglSwapBuffers doesn't immediately dequeue a buffer for the next frame,
* since we can't rely on being able to dequeue more than one buffer at a time.
*
* TODO(jessehall): Add a libgui test that ensures that EGL/GLES do lazy
* dequeBuffers; we've wanted to require that for other reasons anyway.
*/
class VirtualDisplaySurface : public DisplaySurface {
public:
VirtualDisplaySurface(HWComposer& hwc, int disp,
const sp<IGraphicBufferProducer>& sink,
const String8& name);
virtual sp<IGraphicBufferProducer> getIGraphicBufferProducer() const;
virtual status_t compositionComplete();
virtual status_t advanceFrame();
virtual status_t setReleaseFenceFd(int fenceFd);
virtual void dump(String8& result) const;
private:
virtual ~VirtualDisplaySurface();
// immutable after construction
HWComposer& mHwc;
int mDisplayId;
sp<BufferQueueInterposer> mSource;
String8 mName;
// mutable, must be synchronized with mMutex
Mutex mMutex;
sp<GraphicBuffer> mAcquiredBuffer;
sp<Fence> mReleaseFence;
};
// ---------------------------------------------------------------------------
} // namespace android
// ---------------------------------------------------------------------------
#endif // ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H