Android 12(S) SurfaceView/SurfaceFlinger/BLASTBufferQueue 零星点记录，好烦

Android S 相对于Android R 在SurfaceView/SurfaceFlinger部分，代码有诸多改动，

创建SurfaceView时，调用到updateSurface

http://aosp.opersys.com/xref/android-12.0.0_r2/xref/frameworks/base/core/java/android/view/SurfaceView.java#1065

第一次需要创建时调用到createBlastSurfaceControls

http://aosp.opersys.com/xref/android-12.0.0_r2/xref/frameworks/base/core/java/android/view/SurfaceView.java#1326

在createBlastSurfaceControls中可以看到会去创建3个SurfaceControl：mSurfaceControl, mBlastSurfaceControl, mBackgroundControl

摘抄主要代码：

mSurfaceControl = new SurfaceControl.Builder(mSurfaceSession)
                    .setName(name)
                    .setLocalOwnerView(this)
                    .setParent(viewRoot.getBoundsLayer())
                    .setCallsite("SurfaceView.updateSurface")
                    .setContainerLayer()
                    .build();


/////

            mBlastSurfaceControl = new SurfaceControl.Builder(mSurfaceSession)
                    .setName(name + "(BLAST)")
                    .setLocalOwnerView(this)
                    .setParent(mSurfaceControl)
                    .setFlags(mSurfaceFlags)
                    .setHidden(false)
                    .setBLASTLayer()
                    .setCallsite("SurfaceView.updateSurface")
                    .build();

/////


    private SurfaceControl createBackgroundControl(String name) {
        return new SurfaceControl.Builder(mSurfaceSession)
        .setName("Background for " + name)
        .setLocalOwnerView(this)
        .setOpaque(true)
        .setColorLayer()
        .setParent(mSurfaceControl)
        .setCallsite("SurfaceView.updateSurface")
        .build();
    }

分别对应的Surface的name:

• "SurfaceView[" + viewRoot.getTitle().toString() + "]"
• "SurfaceView[" + viewRoot.getTitle().toString() + "]" + "(BLAST)"
• "Background for " + "SurfaceView[" + viewRoot.getTitle().toString() + "]"

关系：

• mSurfaceControl.setParent(viewRoot.getBoundsLayer()) 
• mBlastSurfaceControl.setParent(mSurfaceControl) 
• mBackgroundControl.setParent(mSurfaceControl)

这里有个新东西，先随便瞧瞧吧

 mBlastBufferQueue = new BLASTBufferQueue(name, mBlastSurfaceControl, mSurfaceWidth, mSurfaceHeight, mFormat);

http://aosp.opersys.com/xref/android-12.0.0_r2/xref/frameworks/base/core/java/android/view/SurfaceView.java#1367

 再回到updateSurface函数里：

==>performSurfaceTransaction ==> setBufferSize    ==  SurfaceView发生变化时这里会更新一些信息

==>performSurfaceTransaction ==> onSetSurfacePositionAndScaleRT    ==   SurfaceView发生变化时这里会更新一些信息

记录下setBufferSize的过程（最近有用到）

SurfaceView::setBufferSize   ==> BLASTBufferQueue::update ==> JNI nativeUpdate  ==> BLASTBufferQueuw::update

如果在BLASTBufferQueuw::update中增加一个setSize流程，可以把信息传递到SurfaceFLinger ==>Layer，

            if (mSurfaceControl != nullptr && outTransaction != nullptr) {
                outTransaction->setSize(mSurfaceControl, newSize.getWidth(), newSize.getHeight());
            }

SurfaceFlinger出就会收到信息 

    if (what & layer_state_t::eSizeChanged) {
        if (layer->setSize(s.w, s.h)) {
            flags |= eTraversalNeeded;
        }
    }

注意BufferStateLayer有override setSize方法，导致不生效

http://aosp.opersys.com/xref/android-12.0.0_r2/xref/frameworks/native/services/surfaceflinger/BufferStateLayer.h#76