一. Window 分类
- 应用 Window（ApplicationWindow： 对应一个 Acitivity）
- 子 Window （SubWindow：不能单独存在，需要依附在特定的父 Window 中，比如常见的一些 Dialog 就是一个子 Window）
- 系统 Window （SystemWindow：需要声明权限才能创建的 Window，比如 Toast 和系统状态栏都是系统 Window）
二. Window层级
Window 是分层的，每个 Window 都有对应的 z-ordered，层级大的会覆盖在层级小的 Window 上面，这和 HTML 中的 z-index 概念是完全一致的。
在三种 Window 中，每一种Window的层级范围也是不同的，如下：
应用Window 1~99
子Window 1000~1999
系统Window 2000~2999
这些层级范围对应着 WindowManager.LayoutParams 的 type 参数，如果想要 Window 位于所有 Window 的最顶层，那么采用较大的层级即可，很显然系统 Window 的层级是最大的，当我们采用系统层级时，需要声明权限。
（1）应用程序窗口：
package android.view;
public interface WindowManager
public static final int FIRST_APPLICATION_WINDOW = 1;
public static final int TYPE_BASE_APPLICATION = 1;
public static final int TYPE_APPLICATION = 2;
public static final int TYPE_APPLICATION_STARTING = 3;
public static final int TYPE_DRAWN_APPLICATION = 4;
public static final int LAST_APPLICATION_WINDOW = 99;（2）子窗口：
package android.view;
public interface WindowManager
public static final int FIRST_SUB_WINDOW = 1000;
public static final int TYPE_APPLICATION_PANEL = FIRST_SUB_WINDOW;
public static final int TYPE_APPLICATION_MEDIA = FIRST_SUB_WINDOW + 1;
public static final int TYPE_APPLICATION_SUB_PANEL = FIRST_SUB_WINDOW + 2;
public static final int TYPE_APPLICATION_ATTACHED_DIALOG = FIRST_SUB_WINDOW + 3;
@UnsupportedAppUsage
public static final int TYPE_APPLICATION_MEDIA_OVERLAY = FIRST_SUB_WINDOW + 4;
public static final int TYPE_APPLICATION_ABOVE_SUB_PANEL = FIRST_SUB_WINDOW + 5;
public static final int LAST_SUB_WINDOW = 1999;（3）系统窗口：
package android.view;
public interface WindowManager
public static final int FIRST_SYSTEM_WINDOW = 2000;
public static final int TYPE_STATUS_BAR = FIRST_SYSTEM_WINDOW;
public static final int TYPE_SEARCH_BAR = FIRST_SYSTEM_WINDOW+1;
@Deprecated
public static final int TYPE_PHONE = FIRST_SYSTEM_WINDOW+2;
@Deprecated
public static final int TYPE_SYSTEM_ALERT = FIRST_SYSTEM_WINDOW+3;
public static final int TYPE_KEYGUARD = FIRST_SYSTEM_WINDOW+4;
@Deprecated
public static final int TYPE_TOAST = FIRST_SYSTEM_WINDOW+5;
@Deprecated
public static final int TYPE_SYSTEM_OVERLAY = FIRST_SYSTEM_WINDOW+6;
@Deprecated
public static final int TYPE_PRIORITY_PHONE = FIRST_SYSTEM_WINDOW+7;
public static final int TYPE_SYSTEM_DIALOG = FIRST_SYSTEM_WINDOW+8;
public static final int TYPE_KEYGUARD_DIALOG = FIRST_SYSTEM_WINDOW+9;
@Deprecated
public static final int TYPE_SYSTEM_ERROR = FIRST_SYSTEM_WINDOW+10;
public static final int TYPE_INPUT_METHOD = FIRST_SYSTEM_WINDOW+11;
public static final int TYPE_INPUT_METHOD_DIALOG= FIRST_SYSTEM_WINDOW+12;
public static final int TYPE_WALLPAPER = FIRST_SYSTEM_WINDOW+13;
public static final int TYPE_STATUS_BAR_PANEL = FIRST_SYSTEM_WINDOW+14;
@UnsupportedAppUsage
public static final int TYPE_SECURE_SYSTEM_OVERLAY = FIRST_SYSTEM_WINDOW+15;
public static final int TYPE_DRAG = FIRST_SYSTEM_WINDOW+16;
public static final int TYPE_STATUS_BAR_SUB_PANEL = FIRST_SYSTEM_WINDOW+17;
public static final int TYPE_POINTER = FIRST_SYSTEM_WINDOW+18;
public static final int TYPE_NAVIGATION_BAR = FIRST_SYSTEM_WINDOW+19;
public static final int TYPE_VOLUME_OVERLAY = FIRST_SYSTEM_WINDOW+20;
public static final int TYPE_BOOT_PROGRESS = FIRST_SYSTEM_WINDOW+21;
public static final int TYPE_INPUT_CONSUMER = FIRST_SYSTEM_WINDOW+22;
public static final int TYPE_DREAM = FIRST_SYSTEM_WINDOW+23;
public static final int TYPE_NAVIGATION_BAR_PANEL = FIRST_SYSTEM_WINDOW+24;
@UnsupportedAppUsage
public static final int TYPE_DISPLAY_OVERLAY = FIRST_SYSTEM_WINDOW+26;
public static final int TYPE_MAGNIFICATION_OVERLAY = FIRST_SYSTEM_WINDOW+27;
public static final int TYPE_PRIVATE_PRESENTATION = FIRST_SYSTEM_WINDOW+30;
public static final int TYPE_VOICE_INTERACTION = FIRST_SYSTEM_WINDOW+31;
public static final int TYPE_ACCESSIBILITY_OVERLAY = FIRST_SYSTEM_WINDOW+32;
public static final int TYPE_VOICE_INTERACTION_STARTING = FIRST_SYSTEM_WINDOW+33;
public static final int TYPE_DOCK_DIVIDER = FIRST_SYSTEM_WINDOW+34;
public static final int TYPE_QS_DIALOG = FIRST_SYSTEM_WINDOW+35;
public static final int TYPE_SCREENSHOT = FIRST_SYSTEM_WINDOW + 36;
public static final int TYPE_PRESENTATION = FIRST_SYSTEM_WINDOW + 37;
public static final int TYPE_APPLICATION_OVERLAY = FIRST_SYSTEM_WINDOW + 38;
public static final int LAST_SYSTEM_WINDOW = 2999;窗口显示顺序：
Type 值越大层级越高，Type 值大的覆盖 Type 值小的，这只是一般规律。
（三）如何真正查看 Window 的优先级
/frameworks/base/services/core/java/com/android/server/policy/WindowManagerPolicy.java
default int getWindowLayerFromTypeLw(int type, boolean canAddInternalSystemWindow) {
if (type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW) {
return APPLICATION_LAYER;
}
switch (type) {
case TYPE_WALLPAPER:
// wallpaper is at the bottom, though the window manager may move it.
return 1;
case TYPE_PRESENTATION:
case TYPE_PRIVATE_PRESENTATION:
return APPLICATION_LAYER;
case TYPE_DOCK_DIVIDER:
return APPLICATION_LAYER;
case TYPE_QS_DIALOG:
return APPLICATION_LAYER;
case TYPE_PHONE:
return 3;
case TYPE_SEARCH_BAR:
case TYPE_VOICE_INTERACTION_STARTING:
return 4;
case TYPE_VOICE_INTERACTION:
// voice interaction layer is almost immediately above apps.
return 5;
case TYPE_INPUT_CONSUMER:
return 6;
case TYPE_SYSTEM_DIALOG:
return 7;
case TYPE_TOAST:
// toasts and the plugged-in battery thing
return 8;
case TYPE_PRIORITY_PHONE:
// SIM errors and unlock. Not sure if this really should be in a high layer.
return 9;
case TYPE_SYSTEM_ALERT:
// like the ANR / app crashed dialogs
return canAddInternalSystemWindow ? 11 : 10;
case TYPE_APPLICATION_OVERLAY:
return 12;
case TYPE_DREAM:
// used for Dreams (screensavers with TYPE_DREAM windows)
return 13;
case TYPE_INPUT_METHOD:
// on-screen keyboards and other such input method user interfaces go here.
return 14;
case TYPE_INPUT_METHOD_DIALOG:
// on-screen keyboards and other such input method user interfaces go here.
return 15;
case TYPE_STATUS_BAR:
return 17;
case TYPE_STATUS_BAR_PANEL:
return 18;
case TYPE_STATUS_BAR_SUB_PANEL:
return 19;
case TYPE_KEYGUARD_DIALOG:
return 20;
case TYPE_VOLUME_OVERLAY:
// the on-screen volume indicator and controller shown when the user
// changes the device volume
return 21;
case TYPE_SYSTEM_OVERLAY:
// the on-screen volume indicator and controller shown when the user
// changes the device volume
return canAddInternalSystemWindow ? 22 : 11;
case TYPE_NAVIGATION_BAR:
// the navigation bar, if available, shows atop most things
return 23;
case TYPE_NAVIGATION_BAR_PANEL:
// some panels (e.g. search) need to show on top of the navigation bar
return 24;
case TYPE_SCREENSHOT:
// screenshot selection layer shouldn't go above system error, but it should cover
// navigation bars at the very least.
return 25;
case TYPE_SYSTEM_ERROR:
// system-level error dialogs
return canAddInternalSystemWindow ? 26 : 10;
case TYPE_MAGNIFICATION_OVERLAY:
// used to highlight the magnified portion of a display
return 27;
case TYPE_DISPLAY_OVERLAY:
// used to simulate secondary display devices
return 28;
case TYPE_DRAG:
// the drag layer: input for drag-and-drop is associated with this window,
// which sits above all other focusable windows
return 29;
case TYPE_ACCESSIBILITY_OVERLAY:
// overlay put by accessibility services to intercept user interaction
return 30;
case TYPE_SECURE_SYSTEM_OVERLAY:
return 31;
case TYPE_BOOT_PROGRESS:
return 32;
case TYPE_POINTER:
// the (mouse) pointer layer
return 33;
default:
Slog.e("WindowManager", "Unknown window type: " + type);
return APPLICATION_LAYER;
}
}以上返回的是除 Application 外的 Window 的层级，在开发系统应用时可以选择一种开发自己的 Window.
（四） 层级高低具体分析（对比Toast以及软键盘）
低于toast--->盖不住toast
低于软键盘--->盖不住软键盘
依附Activity使用--->is your activity running?
public static int getWindowType(int num) {
switch (num) {
case 1:
return WindowManager.LayoutParams.TYPE_PHONE;//低于toast 低于软键盘
case 2:
return WindowManager.LayoutParams.TYPE_SEARCH_BAR;//低于toast 低于软键盘
case 3:
return WindowManager.LayoutParams.TYPE_SYSTEM_DIALOG;//低于toast 低于软键盘
case 4:
return WindowManager.LayoutParams.TYPE_PRIORITY_PHONE;//高于toast 低于软键盘
case 5:
return WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;//高于toast 低于软键盘
case 6:
return WindowManager.LayoutParams.TYPE_INPUT_METHOD_DIALOG;//高于toast 盖住键盘
case 7:
return WindowManager.LayoutParams.TYPE_SYSTEM_ERROR;//高于toast 低于软键盘
case 8:
return WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG;//高于toast 低于软键盘
case 9:
return WindowManager.LayoutParams.TYPE_SYSTEM_ALERT;//高于toast 高于软键盘
case 10:
return WindowManager.LayoutParams.TYPE_STATUS_BAR;//高于toast 高于软键盘（键盘会把透明view顶起）
case 11:
return WindowManager.LayoutParams.TYPE_STATUS_BAR_PANEL;//高于toast 高于软键盘（键盘会把透明view顶起）
case 12:
return WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY;//低于下级页面
case 13:
return WindowManager.LayoutParams.TYPE_ACCESSIBILITY_OVERLAY;//is your activity running?
case 14:
return WindowManager.LayoutParams.TYPE_BASE_APPLICATION;// is your activity running?
case 15:
return WindowManager.LayoutParams.TYPE_APPLICATION;// is your activity running?
case 16:
return WindowManager.LayoutParams.TYPE_APPLICATION_STARTING;// is your activity running?
case 17:
return WindowManager.LayoutParams.TYPE_DRAWN_APPLICATION;// is your activity running?
case 18:
return WindowManager.LayoutParams.TYPE_APPLICATION_PANEL;// is your activity running?
case 19:
return WindowManager.LayoutParams.TYPE_APPLICATION_MEDIA;// is your activity running?
case 20:
return WindowManager.LayoutParams.TYPE_APPLICATION_SUB_PANEL;// is your activity running?
case 21:
return WindowManager.LayoutParams.TYPE_APPLICATION_ATTACHED_DIALOG;// is your activity running?
case 22:
return WindowManager.LayoutParams.TYPE_WALLPAPER;// is your activity running?
case 23:
return WindowManager.LayoutParams.TYPE_TOAST;// is your activity running?
case 24:
return WindowManager.LayoutParams.TYPE_INPUT_METHOD;//is your activity running?
case 25:
return WindowManager.LayoutParams.TYPE_PRIVATE_PRESENTATION;//permission denied for window type 2030
default:
return 0;
}
}（五）如何定制系统层级
改变层级关系需要改写 getWindowLayerFromTypeLw 的 switch 顺序结构和返回值
如果需要更改一些 Window 的行为，需要修改
/frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java
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