结构关系
ViewRootImpl单独是一个普通类，不是视图类。没有继承View。
DecorView是PhoneWindow的一个内部类，是一个视图类继承FrageLayout(ViewGroup).
ViewRootImpl.java
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, HardwareRenderer.HardwareDrawCallbacks {
//...
...
}
PhoneWindow.java
public class PhoneWindow extends Window implements MenuBuilder.Callback {
private final class DecorView extends FrameLayout implements RootViewSurfaceTaker {
//...
...
}
}
Window.java
public abstract class Window {
//
...
}
// This is the view in which the window contents are placed. It is either
// mDecor itself, or a child of mDecor where the contents go.
private ViewGroup mContentParent;
private void installDecor() {
if (mDecor == null) {
mDecor = generateDecor();
mDecor.setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
mDecor.setIsRootNamespace(true);
if (!mInvalidatePanelMenuPosted && mInvalidatePanelMenuFeatures != 0) {
mDecor.postOnAnimation(mInvalidatePanelMenuRunnable);
}
}
if (mContentParent == null) {
mContentParent = generateLayout(mDecor);
...
}
}
