Android6.0 图像合成过程详解(二) doComposition函数

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1、Android6.0图像合成过程详解（二）doComposition函数一、doComposition合成图层doComposition这个函数就是合成所有层的图像[cpp]viewplaincopy在CODE上查看代码片派生到我的代码片voidSurfaceFlinger::doComposition(){ATRACE_CALL();constboolrepaintEverything=android_atomic_and(0,&mRepaintEverything);for(size_tdpy=0;dpy

2、stsp&hw(mDisplays[dpy]);if(hw->isDisplayOn()){//transformthedirtyregionintothisscreen'scoordinatespaceconstRegiondirtyRegion(hw->getDirtyRegion(repaintEverything));//repainttheframebuffer(ifneeded)doDisplayComposition(hw,dirtyRegion);hw->dirtyRegion.clear();hw->flip(hw-

3、>swapRegion);hw->swapRegion.clear();}//informtheh/wthatwe'redonecompositinghw->compositionComplete();}postFramebuffer();}上面函数遍历所有的DisplayDevice然后调用doDisplayComposition函数。然后我们再看看doDisplayComposition函数[cpp]viewplaincopy在CODE上查看代码片派生到我的代码片voidSurfaceFlinger::doDisplayComposition(constsp<

4、constDisplayDevice>&hw,constRegion&inDirtyRegion){boolisHwcDisplay=hw->getHwcDisplayId()>=0;if(!isHwcDisplay&&inDirtyRegion.isEmpty()){return;}RegiondirtyRegion(inDirtyRegion);//swapRegion设置为需要更新的区域hw->swapRegion.orSelf(dirtyRegion);uint32_tflags=hw->getFlags();//获得显示设备支持的更新方式标志if(fla

5、gs&DisplayDevice::SWAP_RECTANGLE){//支持矩阵更新dirtyRegion.set(hw->swapRegion.bounds());}else{if(flags&DisplayDevice::PARTIAL_UPDATES){//支持部分更新dirtyRegion.set(hw->swapRegion.bounds());}else{//将更新区域调整为整个窗口大小dirtyRegion.set(hw->bounds());hw->swapRegion=dirtyRegion;}}if(CC_LIKELY(!mDaltonize&

6、&!mHasColorMatrix)){if(!doComposeSurfaces(hw,dirtyRegion))return;//合成}else{RenderEngine&engine(getRenderEngine());mat4colorMatrix=mColorMatrix;if(mDaltonize){colorMatrix=colorMatrix*mDaltonizer();}mat4oldMatrix=engine.setupColorTransform(colorMatrix);doComposeSurfaces(hw,dirtyRegion);

7、//合成engine.setupColorTransform(oldMatrix);}//updatetheswapregionandclearthedirtyregionhw->swapRegion.orSelf(dirtyRegion);//swapbuffers(presentation)hw->swapBuffers(getHwComposer());//使用egl将egl中的合成好的图像，输出到DisplayDevice的mSurface中}这个函数设置下需要更新的区域，后面调用doComposeSurfaces函数来合成图层，调用完doComposeS

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