SystemUI 显示通知布局文件详解

1.View层级图：

 2.View属性：

Type(Id)	width	height	margn		layout_gravity	visibility	special
			top	bottom
StatusBarWindowView	match_parent	match_parent					fitsSystemWindows="true"
NotificationPanelView(notification_panel)	match_parent	match_parent				gone	background="@android:color/transparent"
NotificationsQuickSettingsContainer(notification_container_parent)	match_parent	match_parent			fill_horizontal|top
NotificationStackScrollLayout(notification_stack_scroller)	match_parent	match_parent	0dp	32dp	fill_horizontal|top		importantForAccessibility="no"

 属性简单介绍:

• StatusBarWindowView                                                                            SystemUI的根布局
• NotificationPanelView(notification_panel)                                                SystemUI下来界面的根布局，默认隐藏，接收到下拉操作后显示
• NotificationsQuickSettingsContainer(notification_container_parent)        快捷设置布局，包含通知，跨界设置按钮 亮度进度条等
• NotificationStackScrollLayout(notification_stack_scroller)                        通知的根布局

3.特殊设置介绍：

在NotificationStackScrollLayout和NotificationsQuickSettingsContainer有一个特殊设置的写法

32    

在上面android:layout_gravity="@integer/notification_panel_layout_gravity"这种写法很少见但是属于正常设置，在dimen.xml中设置标签，使用integer值来具体设置layout位置，这个是根据常量定义的具体值来使用的。若熟悉APK反编译。可以看到xml文件反编译后所有的等号后的值都会使用常量的具体值来替换，例如：

32    

在dimen.xml中@integer/notification_panel_layout_gravity具体定义如下：

    0x31
    0x37

在源码中截取一些常用的常量值：

/**
 * This view will adjust its padding to fit sytem windows (e.g. status bar)
 */
private static final int FITS_SYSTEM_WINDOWS = 0x00000002;

/**
 * This view is visible.
 * Use with {@link #setVisibility} and {@code
 * android:visibility}.
 */
public static final int VISIBLE = 0x00000000;

/**
 * This view is invisible, but it still takes up space for layout purposes.
 * Use with {@link #setVisibility} and {@code
 * android:visibility}.
 */
public static final int INVISIBLE = 0x00000004;

/**
 * This view is invisible, and it doesn't take any space for layout
 * purposes. Use with {@link #setVisibility} and {@code
 * android:visibility}.
 */
public static final int GONE = 0x00000008;


/**
 * This view does not want keystrokes.
 * 

 * Use with {@link #setFocusable(int)} and {@code
 * android:focusable}.
 */
public static final int NOT_FOCUSABLE = 0x00000000;

/**
 * This view wants keystrokes.
 * 

 * Use with {@link #setFocusable(int)} and {@code
 * android:focusable}.
 */
public static final int FOCUSABLE = 0x00000001;

/**
 * This view determines focusability automatically. This is the default.
 * 

 * Use with {@link #setFocusable(int)} and {@code
 * android:focusable}.
 */
public static final int FOCUSABLE_AUTO = 0x00000010;

/**
 * 
Indicates this view can be clicked. When clickable, a View reacts
 * to clicks by notifying the OnClickListener.

 * {@hide}
 */
static final int CLICKABLE = 0x00004000;

/**
 * 
Indicates this view can take / keep focus when int touch mode.

 * {@hide}
 */
static final int FOCUSABLE_IN_TOUCH_MODE = 0x00040000;

/**
 * 

 * Indicates this view can be long clicked. When long clickable, a View
 * reacts to long clicks by notifying the OnLongClickListener or showing a
 * context menu.
 * 
 * {@hide}
 */
static final int LONG_CLICKABLE = 0x00200000;

/**
 * View flag indicating that the screen should remain on while the
 * window containing this view is visible to the user.  This effectively
 * takes care of automatically setting the WindowManager's
 * {@link WindowManager.LayoutParams#FLAG_KEEP_SCREEN_ON}.
 */
public static final int KEEP_SCREEN_ON = 0x04000000;

/**
 * View flag indicating whether {@link #addFocusables(ArrayList, int, int)}
 * should add only Views focusable in touch mode.
 */
public static final int FOCUSABLES_TOUCH_MODE = 0x00000001;

简单列了一些，详细可参考源码：

http://androidxref.com/8.1.0_r33/xref/frameworks/base/core/java/android/view/View.java

欢迎斧正！