private synchronized void updateLayers() {
mLayers = new Layer[mLayerList.size()];
int numRenderLayers = 0;
for (int i = 0, n = mLayerList.size(); i < n; i++) {
Layer o = mLayerList.get(i);
if (o.getRenderer() != null) numRenderLayers++;
mLayers[i] = o;
}
mLayerRenderer = new LayerRenderer[numRenderLayers];
for (int i = 0, cnt = 0, n = mLayerList.size(); i < n; i++) {
Layer o = mLayerList.get(i);
LayerRenderer l = o.getRenderer();
if (l != null) mLayerRenderer[cnt++] = l;
}
mDirtyLayers = false;
}
void destroy() {
if (mDirtyLayers) updateLayers();
for (Layer o : mLayers) o.onDetach();
}