安卓高手之路之 WindowManager - 修补C++ - ITeye技术网站
安卓中的画面不是纯粹由window组成。而是改成了window+view的组织模式。window是一个顶层窗口的概念。view就相当于在window内的控件。而subwindow则是依附于window的一些对话框。安卓在对window进行管理的时候，将window分为很多层，不同的层又对应于不同的window类型。下面这个图阐释了这种概念：
安卓首先将窗口按照layer分层，然后每一层又有很多window，每一个window又包含了很多的view和sublayer。这些分层的概念对于用户端是透明的，用户端只知道windowType，这样，用户就能通过windowType的命名从直观概念上知道窗口大概表现出来是什么样子的。下面是windowTYpe转换为
layer的函数：
Java代码
- public int windowTypeToLayerLw(int type) {
- if (type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW) {
- return APPLICATION_LAYER;
- }
- switch (type) {
- case TYPE_STATUS_BAR:
- return STATUS_BAR_LAYER;//14
- case TYPE_STATUS_BAR_PANEL:
- return STATUS_BAR_PANEL_LAYER;//15
- case TYPE_STATUS_BAR_SUB_PANEL:
- return STATUS_BAR_SUB_PANEL_LAYER;//13
- case TYPE_SYSTEM_DIALOG:
- return SYSTEM_DIALOG_LAYER;//5
- case TYPE_SEARCH_BAR:
- return SEARCH_BAR_LAYER;//4 //4
- case TYPE_PHONE:
- return PHONE_LAYER;//3 //3
- case TYPE_KEYGUARD:
- return KEYGUARD_LAYER;//11
- case TYPE_KEYGUARD_DIALOG:
- return KEYGUARD_DIALOG_LAYER;//12
- case TYPE_SYSTEM_ALERT:
- return SYSTEM_ALERT_LAYER;//8
- case TYPE_SYSTEM_ERROR:
- return SYSTEM_ERROR_LAYER;//19
- case TYPE_INPUT_METHOD:
- return INPUT_METHOD_LAYER;//9
- case TYPE_INPUT_METHOD_DIALOG:
- return INPUT_METHOD_DIALOG_LAYER;//10
- case TYPE_VOLUME_OVERLAY:
- return VOLUME_OVERLAY_LAYER;//16
- case TYPE_SYSTEM_OVERLAY:
- return SYSTEM_OVERLAY_LAYER;//17
- case TYPE_SECURE_SYSTEM_OVERLAY:
- return SECURE_SYSTEM_OVERLAY_LAYER;//21
- case TYPE_PRIORITY_PHONE:
- return PRIORITY_PHONE_LAYER;//7
- case TYPE_TOAST:
- return TOAST_LAYER;//6
- case TYPE_WALLPAPER:
- return WALLPAPER_LAYER;// 2
- case TYPE_DRAG:
- return DRAG_LAYER;//20
- case TYPE_POINTER:
- return POINTER_LAYER; //23
- case TYPE_NAVIGATION_BAR:
- return NAVIGATION_BAR_LAYER;//18
- case TYPE_BOOT_PROGRESS:
- return BOOT_PROGRESS_LAYER; //22
- case TYPE_HIDDEN_NAV_CONSUMER:
- return HIDDEN_NAV_CONSUMER_LAYER; //24
- }
- Log.e(TAG, "Unknown window type: " + type);
- return APPLICATION_LAYER;
- }
public int windowTypeToLayerLw(int type) { if (type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW) { return APPLICATION_LAYER; } switch (type) { case TYPE_STATUS_BAR: return STATUS_BAR_LAYER;//14 case TYPE_STATUS_BAR_PANEL: return STATUS_BAR_PANEL_LAYER;//15 case TYPE_STATUS_BAR_SUB_PANEL: return STATUS_BAR_SUB_PANEL_LAYER;//13 case TYPE_SYSTEM_DIALOG: return SYSTEM_DIALOG_LAYER;//5 case TYPE_SEARCH_BAR: return SEARCH_BAR_LAYER;//4 //4 case TYPE_PHONE: return PHONE_LAYER;//3 //3 case TYPE_KEYGUARD: return KEYGUARD_LAYER;//11 case TYPE_KEYGUARD_DIALOG: return KEYGUARD_DIALOG_LAYER;//12 case TYPE_SYSTEM_ALERT: return SYSTEM_ALERT_LAYER;//8 case TYPE_SYSTEM_ERROR: return SYSTEM_ERROR_LAYER;//19 case TYPE_INPUT_METHOD: return INPUT_METHOD_LAYER;//9 case TYPE_INPUT_METHOD_DIALOG: return INPUT_METHOD_DIALOG_LAYER;//10 case TYPE_VOLUME_OVERLAY: return VOLUME_OVERLAY_LAYER;//16 case TYPE_SYSTEM_OVERLAY: return SYSTEM_OVERLAY_LAYER;//17 case TYPE_SECURE_SYSTEM_OVERLAY: return SECURE_SYSTEM_OVERLAY_LAYER;//21 case TYPE_PRIORITY_PHONE: return PRIORITY_PHONE_LAYER;//7 case TYPE_TOAST: return TOAST_LAYER;//6 case TYPE_WALLPAPER: return WALLPAPER_LAYER;// 2 case TYPE_DRAG: return DRAG_LAYER;//20 case TYPE_POINTER: return POINTER_LAYER; //23 case TYPE_NAVIGATION_BAR: return NAVIGATION_BAR_LAYER;//18 case TYPE_BOOT_PROGRESS: return BOOT_PROGRESS_LAYER; //22 case TYPE_HIDDEN_NAV_CONSUMER: return HIDDEN_NAV_CONSUMER_LAYER; //24 } Log.e(TAG, "Unknown window type: " + type); return APPLICATION_LAYER; }很多人看到这个后不知道怎么分析，一下子被从2到24层的结构吓坏了。那么我就分析一下，这些层次关系。我们只要找到一个突破点，那就是锁屏所在的层，而在锁屏之上的层暂时不要关心：
case TYPE_KEYGUARD:
return KEYGUARD_LAYER;//11锁屏之下的层依次为：
//输入法对话框
case TYPE_INPUT_METHOD_DIALOG:
return INPUT_METHOD_DIALOG_LAYER;//10//输入法
case TYPE_INPUT_METHOD:
return INPUT_METHOD_LAYER;//9//系统警告[低电等]
case TYPE_SYSTEM_ALERT:
return SYSTEM_ALERT_LAYER;//8// case TYPE_PRIORITY_PHONE:
return PRIORITY_PHONE_LAYER;//7case TYPE_TOAST:
return TOAST_LAYER;//6case TYPE_SYSTEM_DIALOG:
return SYSTEM_DIALOG_LAYER;//5case TYPE_SEARCH_BAR:
return SEARCH_BAR_LAYER;//4 //4case TYPE_PHONE:
return PHONE_LAYER;//3 //3if (type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW) {
return APPLICATION_LAYER;
}case TYPE_WALLPAPER:
return WALLPAPER_LAYER;// 2从上可以看出，大部分是可以理解的。只有如下两种不好理解：
TYPE_PHONE 3 和 TYPE_PRIORITY_PHONE 7， 很明显与电话有关。
TYPE_PHONE 3 这个基本上没有使用只有在CompatModeDialog用了一下，而TYPE_PRIORITY_PHONE 则是锁网用的。这样可以给运营商带来更多福利。
2.KEYGUARD_LAYER之上又是什么呢？依次如下：
case TYPE_KEYGUARD_DIALOG:
return KEYGUARD_DIALOG_LAYER;//12 关机时候使用case TYPE_STATUS_BAR_SUB_PANEL:
return STATUS_BAR_SUB_PANEL_LAYER;//13case TYPE_STATUS_BAR:
return STATUS_BAR_LAYER;//14case TYPE_STATUS_BAR_PANEL:
return STATUS_BAR_PANEL_LAYER;//15case TYPE_VOLUME_OVERLAY:
return VOLUME_OVERLAY_LAYER;//16case TYPE_SYSTEM_OVERLAY:
return SYSTEM_OVERLAY_LAYER;//17这些为一类，都好理解。从 SYSTEM_OVERLAY_LAYER往下，基本上就是不常见的了
case TYPE_NAVIGATION_BAR:
return NAVIGATION_BAR_LAYER;//18case TYPE_SYSTEM_ERROR:
return SYSTEM_ERROR_LAYER;//19case TYPE_DRAG:
return DRAG_LAYER;//20case TYPE_SECURE_SYSTEM_OVERLAY:
return SECURE_SYSTEM_OVERLAY_LAYER;//21
case TYPE_BOOT_PROGRESS:
return BOOT_PROGRESS_LAYER; //22case TYPE_POINTER:
return POINTER_LAYER; //23
case TYPE_HIDDEN_NAV_CONSUMER:
return HIDDEN_NAV_CONSUMER_LAYER; //24可以看出大部分的对话框无法加在锁屏之上。那么有些对话框希望在锁屏的时候能显示，同时，在不锁屏的时候又能保持按照一般对话框来处理。该如何办呢？例如电话，闹钟等。第一种方法，动态改变window的type。根据当前是否正在锁屏，来设置不同的layer来处理。第二种，在锁屏的时候，如果启动了这种window，就隐藏掉锁屏。等这种window被remove走之后，再显示锁屏。
