Android P WMS簡介

Android P WMS簡介

Android P WMS初始化過程

Android P WMS addwindow流程

Android P WMS removewindow流程

Android P WMS relayoutWindow流程

Android P WMS windowanimator

Android P WMS Surface

Android P WMS 問題種類和debug分析技巧

Android P WMS View System 簡介

Android P WMS簡介

WMS是系統的其他服務，無論對於應用開發還是Framework開發都是重點的知識，它的職責有很多，主要有以下幾點：

窗口管理
WMS是窗口的管理者，它負責窗口的啓動、添加和刪除，另外窗口的大小和層級也是由WMS進行管理的。窗口管理的核心成員有DisplayContent、WindowToken和WindowState。

窗口動畫
窗口間進行切換時，使用窗口動畫可以顯得更炫一些，窗口動畫由WMS的動畫子系統來負責，動畫子系統的管理者爲WindowAnimator。

輸入系統的中轉站
通過對窗口的觸摸從而產生觸摸事件，InputManagerService（IMS）會對觸摸事件進行處理，它會尋找一個最合適的窗口來處理觸摸反饋信息，WMS是窗口的管理者，因此，WMS“理所應當”的成爲了輸入系統的中轉站。

Surface管理
窗口並不具備有繪製的功能，因此每個窗口都需要有一塊Surface來供自己繪製。爲每個窗口分配Surface是由WMS來完成的。

WMS的職責可以簡單總結爲下圖。

2.windowState

windowState就是window，每個window都有一個surface來繪畫，window本身是沒法畫的。

Window的類型

Android系統的Window有很多個，大體上來說，Framework定義了三種窗口類型；

系統Window
常見的系統Window有哪些呢？比如在手機電量低的時候，會有一個提示電量低的Window,我們輸入文字的時候，會彈出輸入法Window,還有搜索條Window,來電顯示Window,Toast對應的Window,可以總結出來，系統Window是獨立與我們的應用程序的，對於應用程序而言，我們理論上是無法創建系統Window，因爲沒有權限，這個權限只有系統進程有。

應用程序Window
所謂應用窗口指的就是該窗口對應一個Activity，因此，要創建應用窗口就必須在Activity中完成了。本節後面會分析Activity對應的Window的創建過程。

子Window
所謂的子Window，是說這個Window必須要有一個父窗體，比如PopWindow，Dialog是屬於應用程序Window,這個比較特殊。

每一種窗口類型定義了一種對應的type
應用類型的窗口的type範圍是１~99

 

應用類型的窗口

子窗口的type範圍是1000~1999

 

子窗口

系統的窗口的type範圍是2000以上　

 

系統的窗口

系統窗口的type值>子窗口的type值>應用類型窗口的type值，一般來說，根據type值大小關係，可以推出系統窗口在子窗口的上面，子窗口在應用窗口的上面。

 

3.z-order

手機上採用的是層疊式佈局，層疊式佈局是一個三維的空間，將手機的水平方向作爲Ｘ軸，豎直方向作爲Ｙ軸，還有一根垂直與屏幕從裏朝外方向的虛擬的Z軸，所有窗口 (WindowState) 按照順序排列在Ｚ軸上，如下圖。z軸座標就是z-order，越大證明他的windowState越在前面。

3.1 、 mBaseLayer 主序 確認

@/frameworks/base/services/core/java/com/android/server/wm/WindowState.java
WindowState(WindowManagerService service, Session s, IWindow c, WindowToken token,
        WindowState parentWindow, int appOp, int seq, WindowManager.LayoutParams a,
        int viewVisibility, int ownerId, boolean ownerCanAddInternalSystemWindow,
        PowerManagerWrapper powerManagerWrapper) {
        ...
    if (mAttrs.type >= FIRST_SUB_WINDOW && mAttrs.type <= LAST_SUB_WINDOW) {
        // The multiplier here is to reserve space for multiple
        // windows in the same type layer.
        mBaseLayer = mPolicy.getWindowLayerLw(parentWindow    //mBaseLayer 主序
                * TYPE_LAYER_MULTIPLIER + TYPE_LAYER_OFFSET;  ////TYPE_LAYER_MULTIPLIER = 10000    TYPE_LAYER_OFFSET = 1000
        mSubLayer = mPolicy.getSubWindowLayerFromTypeLw(a.type);  //mSubLayer 次序
        mIsChildWindow = true;
 
        if (DEBUG_ADD_REMOVE) Slog.v(TAG, "Adding " + this + " to " + parentWindow);
        parentWindow.addChild(this, sWindowSubLayerComparator);
 
        mLayoutAttached = mAttrs.type !=
                WindowManager.LayoutParams.TYPE_APPLICATION_ATTACHED_DIALOG;
        mIsImWindow = parentWindow.mAttrs.type == TYPE_INPUT_METHOD
                || parentWindow.mAttrs.type == TYPE_INPUT_METHOD_DIALOG;
        mIsWallpaper = parentWindow.mAttrs.type == TYPE_WALLPAPER;
    } else {
        // The multiplier here is to reserve space for multiple
        // windows in the same type layer.
        mBaseLayer = mPolicy.getWindowLayerLw(this)
                * TYPE_LAYER_MULTIPLIER + TYPE_LAYER_OFFSET;
        mSubLayer = 0;
        mIsChildWindow = false;
        mLayoutAttached = false;
        mIsImWindow = mAttrs.type == TYPE_INPUT_METHOD
                || mAttrs.type == TYPE_INPUT_METHOD_DIALOG;
        mIsWallpaper = mAttrs.type == TYPE_WALLPAPER;
    }
...
}

mBaseLayer =窗口類型×10000+1000,窗口類型判斷如下

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;
    }
}

3.2 、mSubLayer 子序的確認

SubLayer(稱爲子序)，SubLayer值是用來描述一個窗口是否屬於另外一個窗口的子窗口，或者說SubLayer值是用來確定子窗口和父窗口之間的相對位置的。

一個Activity中有三個子窗口WindowState1、WindowState２、WindowState３，WindowState1WindowState２在窗口Ａ的前面，WindowState３在Ａ的後面，這幾個兄弟窗口爲什麼可以這樣排序呢，這就是mSubLayer的作用，子序越大，則相對其他兄弟窗口越靠前，反之，越靠後，如果爲負數，就處在父窗口的後面，如窗口Ａ中的WindowState3，子序是根據窗口類型調用subWindowTypeToLayerLw確定的，subWindowTypeToLayerLw同樣是在Window的構造方法中調用的。

public int subWindowTypeToLayerLw(int type) {
       switch (type) {
       case TYPE_APPLICATION_PANEL:
       case TYPE_APPLICATION_ATTACHED_DIALOG:
           return APPLICATION_PANEL_SUBLAYER;//返回值是1
       case TYPE_APPLICATION_MEDIA:
           return APPLICATION_MEDIA_SUBLAYER;//返回值是-2  
       case TYPE_APPLICATION_MEDIA_OVERLAY:
           return APPLICATION_MEDIA_OVERLAY_SUBLAYER;//返回值是-1  
       case TYPE_APPLICATION_SUB_PANEL:
           return APPLICATION_SUB_PANEL_SUBLAYER;//返回值是2 
       case TYPE_APPLICATION_ABOVE_SUB_PANEL:
           return APPLICATION_ABOVE_SUB_PANEL_SUBLAYER;//返回值是3  
       }
       Log.e(TAG, "Unknown sub-window type: " + type);
       return 0;
   }

 3.3 、窗口Z序的調整

當WindowState創建完成，並且被添加到WMS維持的數組裏面後，就需要調用WindowLayersController的assignLayersLocked(windows)，進行Z序的調整。

//參數windows是窗口列表
final void assignLayersLocked(WindowList windows) {
       if (DEBUG_LAYERS) Slog.v(TAG_WM, "Assigning layers based on windows=" + windows,
               new RuntimeException("here").fillInStackTrace());
 
       clear();
       int curBaseLayer = 0;
       int curLayer = 0;
       boolean anyLayerChanged = false;
      //遍歷窗口列表，上面通過Z序的計算公式計算出來的Z序值保存在WindowState的變量mBaseLayer
       中，這個循環的意思是，遇到同類型的窗口，後一個窗口在前一個窗口的基礎上偏移５。
       for (int i = 0, windowCount = windows.size(); i < windowCount; i++) {
           final WindowState w = windows.get(i);
           boolean layerChanged = false;
 
           int oldLayer = w.mLayer;
           if (w.mBaseLayer == curBaseLayer || w.mIsImWindow || (i > 0 && w.mIsWallpaper)) {
               curLayer += WINDOW_LAYER_MULTIPLIER;
           } else {
               curBaseLayer = curLayer = w.mBaseLayer;
           }
          // 更新該窗口的mAnimLayer，也就是動畫顯示時，該窗口的層級
           assignAnimLayer(w, curLayer);
 
           // TODO: Preserved old behavior of code here but not sure comparing
           // oldLayer to mAnimLayer and mLayer makes sense...though the
           // worst case would be unintentionalp layer reassignment.
           if (w.mLayer != oldLayer || w.mWinAnimator.mAnimLayer != oldLayer) {
               layerChanged = true;
               anyLayerChanged = true;
           }
 
　　　　　// 將當前應用窗口的最高顯示層級記錄在mHighestApplicationLayer中
           if (w.mAppToken != null) {
               mHighestApplicationLayer = Math.max(mHighestApplicationLayer,
                       w.mWinAnimator.mAnimLayer);
           }
        　 //  對於分屏等相關的窗口，它們的顯示層級需要再次處理
           collectSpecialWindows(w);
 
           if (layerChanged) {
               w.scheduleAnimationIfDimming();
           }
       }
 
　　　　// 調整特殊窗口的層級
       adjustSpecialWindows();
 
       //TODO (multidisplay): Magnification is supported only for the default display.
       if (mService.mAccessibilityController != null && anyLayerChanged
               && windows.get(windows.size() - 1).getDisplayId() == Display.DEFAULT_DISPLAY) {
           mService.mAccessibilityController.onWindowLayersChangedLocked();
       }
 
       if (DEBUG_LAYERS) logDebugLayers(windows);
   }

4.token

Android AMS(六) Activity與WMS的連接過程之AppWindowToken

WmS詳解(一)之token到底是什麼？基於Android7.0源碼

 

參考：

Android解析WindowManagerService（一）WMS的誕生

Android窗口系統第一篇---Window的類型與Z-Order確定

Android AMS(六) Activity與WMS的連接過程之AppWindowToken

WmS詳解(一)之token到底是什麼？基於Android7.0源碼