先重新看看 DisplayContent 类的定义：

class DisplayContent extends RootDisplayArea implements WindowManagerPolicy.DisplayContentInfo {

直接父类为 RootDisplayArea， 而它的定义：

class RootDisplayArea extends DisplayArea.Dimmable {

因此要再看 DisplayArea.Dimmable

1.DisplayArea.Dimmable

作为 DisplayArea 的内部静态类, 表示可以置灰，而它实际上是继承了 DisplayArea

    /**
     * DisplayArea that can be dimmed.
     */
    static class Dimmable extends DisplayArea<DisplayArea> {
        private final Dimmer mDimmer = new Dimmer(this);
        private final Rect mTmpDimBoundsRect = new Rect();

        Dimmable(WindowManagerService wms, Type type, String name, int featureId) {
            super(wms, type, name, featureId);
        }

        @Override
        Dimmer getDimmer() {
            return mDimmer;
        }

        @Override
        void prepareSurfaces() {
            mDimmer.resetDimStates();
            super.prepareSurfaces();
            // Bounds need to be relative, as the dim layer is a child.
            getBounds(mTmpDimBoundsRect);
            mTmpDimBoundsRect.offsetTo(0 /* newLeft */, 0 /* newTop */);

            // If SystemUI is dragging for recents, we want to reset the dim state so any dim layer
            // on the display level fades out.
            if (forAllTasks(task -> !task.canAffectSystemUiFlags())) {
                mDimmer.resetDimStates();
            }

            if (mDimmer.updateDims(getSyncTransaction(), mTmpDimBoundsRect)) {
                scheduleAnimation();
            }
        }
    }

可以看出来，它的创建实际上依赖父类 DisplayArea 的构造函数.
并且类本身的也做为泛型对象..

2. DisplayArea 源码

用于将 WindowContainer 分组到 DisplayContent 下面的容器。
DisplayAreas 由 {@link DisplayAreaPolicy} 管理, 可以重写配置并且可以被束缚。
DisplayAreas 可以包含嵌套的 DisplayAreas.

frameworks/base/services/core/java/com/android/server/wm/DisplayArea.java

类的定义：

/**
 * Container for grouping WindowContainer below DisplayContent.
 *
 * DisplayAreas are managed by a {@link DisplayAreaPolicy}, and can override configurations and
 * can be leashed.
 *
 * DisplayAreas can contain nested DisplayAreas.
 *
 * DisplayAreas come in three flavors, to ensure that windows have the right Z-Order:
 * - BELOW_TASKS: Can only contain BELOW_TASK DisplayAreas and WindowTokens that go below tasks.
 * - ABOVE_TASKS: Can only contain ABOVE_TASK DisplayAreas and WindowTokens that go above tasks.
 * - ANY: Can contain any kind of DisplayArea, and any kind of WindowToken or the Task container.
 *
 * @param <T> type of the children of the DisplayArea.
 */
public class DisplayArea<T extends WindowContainer> extends WindowContainer<T> {

可以看到它的 父类其实也是 WindowContainer，代表也是一个窗口容器

构造方法

    DisplayArea(WindowManagerService wms, Type type, String name, int featureId) {
        super(wms);
        // TODO(display-area): move this up to ConfigurationContainer
        setOverrideOrientation(SCREEN_ORIENTATION_UNSET);
        mType = type;
        mName = name;
        mFeatureId = featureId;
        mRemoteToken = new RemoteToken(this);
        mOrganizerController =
                wms.mAtmService.mWindowOrganizerController.mDisplayAreaOrganizerController;
    }

999
基于 Android 14 源码. (20230913 codesearch main 分支)

-- END --