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

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] view plain copy 在CODE上查看代码片派生到我的代码片 void SurfaceFlinger::doComposition() { ATRACE_CALL(); const bool repaintEverything = android_atomic_and(0, mRepaintEverything); for (size_t dpy=0 ; dpymDisplays.size() ; dpy++) { const spDisplayDevice hw(mDisplays[dpy]); if (hw-isDisplayOn()) { // transform the dirty region into this screens coordinate space const Region dirtyRegion(hw-getDirtyRegion(repaintEverything)); // repaint the framebuffer (if needed) doDisplayComposition(hw, dirtyRegion); hw-dirtyRegion.clear(); hw-flip(hw-swapRegion); hw-swapRegion.clear(); } // inform the h/w that were done compositing hw-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] view plain copy 在CODE上查看代码片派生到我的代码片 void SurfaceFlinger::doDisplayComposition(const spconst DisplayDevice hw, const Region inDirtyRegion) { bool isHwcDisplay = hw-getHwcDisplayId() = 0; if (!isHwcDisplay inDirtyRegion.isEmpty()) { return; } Region dirtyRegion(inDirtyRegion); //swapRegion设置为需要更新的区域 hw-swapRegion.orSelf(dirtyRegion); uint32_t flags = hw-getFlags();//获得显示设备支持的更新方式标志 if (flags 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 !mHasColorMatrix)) { if (!doComposeSurfaces(hw, dirtyRegion)) return;