Android6.0 WMS（三） WMS窗口次序
这篇博客我们主要分析下，窗口位置排序的一些原理。
一、添加窗口的时候 调整窗口位置
上篇博客我们分析了WMS的addWindow函数，这里我们就窗口的次序问题继续分析。
boolean imMayMove = true;
if (type == TYPE_INPUT_METHOD) {//如果窗口类是输入法窗口
win.mGivenInsetsPending = true;
mInputMethodWindow = win;
addInputMethodWindowToListLocked(win);//插入输入法窗口到应用窗口上层
imMayMove = false;
} else if (type == TYPE_INPUT_METHOD_DIALOG) {//如果窗口是输入法对话框
mInputMethodDialogs.add(win);
addWindowToListInOrderLocked(win, true);//插入到正常位置
moveInputMethodDialogsLocked(findDesiredInputMethodWindowIndexLocked(true));//调整对话框位置
imMayMove = false;
} else {
addWindowToListInOrderLocked(win, true);//插入正常位置
if (type == TYPE_WALLPAPER) {
mLastWallpaperTimeoutTime = 0;
displayContent.pendingLayoutChanges |= FINISH_LAYOUT_REDO_WALLPAPER;
} else if ((attrs.flags&FLAG_SHOW_WALLPAPER) != 0) {
displayContent.pendingLayoutChanges |= FINISH_LAYOUT_REDO_WALLPAPER;
} else if (mWallpaperTarget != null
&& mWallpaperTarget.mLayer >= win.mBaseLayer) {
// If there is currently a wallpaper being shown, and
// the base layer of the new window is below the current
// layer of the target window, then adjust the wallpaper.
// This is to avoid a new window being placed between the
// wallpaper and its target.
displayContent.pendingLayoutChanges |= FINISH_LAYOUT_REDO_WALLPAPER;
}
}DisplayContent类的mWindows列表按Z序保存了每个窗口，这段代码就是在根据窗口类型把窗口加入到DisplayContent合适位置。
addInputMethodWindowToListLocked方法作用就是一个输入法窗口放子啊需要显示输入法窗口的上面。
addWindowToListInOrderLocked将一个窗口插入到窗口堆栈的当前位置。
我们继续看addWindow函数，
final WindowStateAnimator winAnimator = win.mWinAnimator;
winAnimator.mEnterAnimationPending = true;
winAnimator.mEnteringAnimation = true;
if (displayContent.isDefaultDisplay) {
mPolicy.getInsetHintLw(win.mAttrs, mRotation, outContentInsets, outStableInsets,//计算窗口大小
outOutsets);
} else {
outContentInsets.setEmpty();
outStableInsets.setEmpty();
}
if (mInTouchMode) {
res |= WindowManagerGlobal.ADD_FLAG_IN_TOUCH_MODE;//加入支持触屏的标志
}
if (win.mAppToken == null || !win.mAppToken.clientHidden) {
res |= WindowManagerGlobal.ADD_FLAG_APP_VISIBLE;//加入应用可用的标志
}
mInputMonitor.setUpdateInputWindowsNeededLw();//设置更新输入法窗口的标志
boolean focusChanged = false;
if (win.canReceiveKeys()) {//如果窗口能接受输入计算是否引起焦点变化
focusChanged = updateFocusedWindowLocked(UPDATE_FOCUS_WILL_ASSIGN_LAYERS,
false /*updateInputWindows*/);
if (focusChanged) {
imMayMove = false;
}
}
if (imMayMove) {
moveInputMethodWindowsIfNeededLocked(false);//调整输入法的窗口位置
}
assignLayersLocked(displayContent.getWindowList());//重新计算z轴的位置
// Don't do layout here, the window must call
// relayout to be displayed, so we'll do it there.
if (focusChanged) {
mInputMonitor.setInputFocusLw(mCurrentFocus, false /*updateInputWindows*/);
}
mInputMonitor.updateInputWindowsLw(false /*force*/);//更新输入法窗口的信息
if (localLOGV || DEBUG_ADD_REMOVE) Slog.v(TAG, "addWindow: New client "
+ client.asBinder() + ": window=" + win + " Callers=" + Debug.getCallers(5));
if (win.isVisibleOrAdding() && updateOrientationFromAppTokensLocked(false)) {
reportNewConfig = true;//配置发生变化
}
}
if (reportNewConfig) {
sendNewConfiguration();//发送新的配置
}
Binder.restoreCallingIdentity(origId);
return res;
}如果窗口显示在缺省的显示设备，调用mPolicy的getInsetHintLw函数来获得除了状态条、导航条所占区域后的窗口大小。
接下来如果窗口能接受输入，调用updateFocusedWindowLocked来重新确定系统的焦点位置。如果焦点发生变化，则将imMayMove置为false。
新加入的窗口的位置在前面调用addWindowToListInOrderLocked的时候位置已经确定了，所以这里调用assignLayersLocked只是重新计算Z轴的位置。如果调用updateOrientationFromAppTokensLocked函数计算窗口的配置发生变化，调用sendNewConfiguration函数发送配置。
二、确定窗口的mLayer值
显示设备的水平方向，垂直方向作为X轴Y轴，我们还可以想象有一个垂直于屏幕的Z轴，Z轴的值越来越靠近屏幕。系统中所有的窗口都按次序排列在Z轴上。窗口对象WindowState的成员变量mLayer表示窗口在Z轴的值，值越小越靠近底层。
WMS作用之一就是管理各个窗口Z轴位置，确保正确显示。在所有窗口中输入法和壁纸窗口比较特殊。输入法窗口出现时，需要显示在应用窗口的前面。壁纸窗口通常在底层，但是又不是位于所有窗口的底层，而是位于当前Activity窗口的下面。
因此，当系统调整某个应用窗口的位置时，如果需要也会调整输入法和壁纸窗口，使当前Activity的窗口位于输入法窗口和壁纸窗口之间。
WindowState的成员变量mLayer的值表示窗口在Z轴的位置，这个值越小，位置越靠下。mLayer是通过计算得到，会经常变化。WindowState的另一个成员变量mBaseLayer的值是固定不变的，只和窗口类型有关。mLayer的值是根据mBaseLayer的值计算而来。
下面我们先来看看mBaseLayer的值如何而来,在WindowState的构造函数中有如下代码：
if ((mAttrs.type >= FIRST_SUB_WINDOW &&
mAttrs.type <= LAST_SUB_WINDOW)) {//如果是子窗口
// The multiplier here is to reserve space for multiple
// windows in the same type layer.
mBaseLayer = mPolicy.windowTypeToLayerLw(//使用依附窗口的类型
attachedWindow.mAttrs.type) * WindowManagerService.TYPE_LAYER_MULTIPLIER
+ WindowManagerService.TYPE_LAYER_OFFSET;
mSubLayer = mPolicy.subWindowTypeToLayerLw(a.type);//计算mSubLayer
......
} else {//非子窗口
// The multiplier here is to reserve space for multiple
// windows in the same type layer.
mBaseLayer = mPolicy.windowTypeToLayerLw(a.type)
* WindowManagerService.TYPE_LAYER_MULTIPLIER
+ WindowManagerService.TYPE_LAYER_OFFSET;
mSubLayer = 0;
......
}如果窗口类型是子窗口，则使用它所依附的窗口类型来计算mBaseLayer，否则使用窗口类型来计算mBaseLayer。计算的方法是先调用mPolicy.windowTypeToLayerLw方法将窗口的类型转化成一个基数，然后再乘以TYPE_LAYER_MULTIPLIER（10000），最后加上TYPE_LAYER_OFFSET（1000），我们先来看看windowTypeToLayerLw函数是如果根据类型返回一个基数的。
public int windowTypeToLayerLw(int type) {
if (type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW) {//应用窗口
return 2;
}
switch (type) {
case TYPE_PRIVATE_PRESENTATION:
return 2;
case TYPE_WALLPAPER:
// wallpaper is at the bottom, though the window manager may move it.
return 2;
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_DREAM:
// used for Dreams (screensavers with TYPE_DREAM windows)
return 10;
case TYPE_SYSTEM_ALERT:
// like the ANR / app crashed dialogs
return 11;
case TYPE_INPUT_METHOD:
// on-screen keyboards and other such input method user interfaces go here.
return 12;
case TYPE_INPUT_METHOD_DIALOG:
// on-screen keyboards and other such input method user interfaces go here.
return 13;
case TYPE_KEYGUARD_SCRIM:
// the safety window that shows behind keyguard while keyguard is starting
return 14;
case TYPE_STATUS_BAR_SUB_PANEL:
return 15;
case TYPE_STATUS_BAR:
return 16;
case TYPE_STATUS_BAR_PANEL:
return 17;
case TYPE_KEYGUARD_DIALOG:
return 18;
case TYPE_VOLUME_OVERLAY:
// the on-screen volume indicator and controller shown when the user
// changes the device volume
return 19;
case TYPE_SYSTEM_OVERLAY:
// the on-screen volume indicator and controller shown when the user
// changes the device volume
return 20;
case TYPE_NAVIGATION_BAR:
// the navigation bar, if available, shows atop most things
return 21;
case TYPE_NAVIGATION_BAR_PANEL:
// some panels (e.g. search) need to show on top of the navigation bar
return 22;
case TYPE_SYSTEM_ERROR:
// system-level error dialogs
return 23;
case TYPE_MAGNIFICATION_OVERLAY:
// used to highlight the magnified portion of a display
return 24;
case TYPE_DISPLAY_OVERLAY:
// used to simulate secondary display devices
return 25;
case TYPE_DRAG:
// the drag layer: input for drag-and-drop is associated with this window,
// which sits above all other focusable windows
return 26;
case TYPE_ACCESSIBILITY_OVERLAY:
// overlay put by accessibility services to intercept user interaction
return 27;
case TYPE_SECURE_SYSTEM_OVERLAY:
return 28;
case TYPE_BOOT_PROGRESS:
return 29;
case TYPE_POINTER:
// the (mouse) pointer layer
return 30;
}
Log.e(TAG, "Unknown window type: " + type);
return 2;
}这个方法很简单就是根据类型返回一个基数。
WindowState中的成员变量mSubLayer只有在窗口是子窗口的时候才有作用，它表示在窗口和父窗口之间的相对位置。代码如下
public int subWindowTypeToLayerLw(int type) {
switch (type) {
case TYPE_APPLICATION_PANEL:
case TYPE_APPLICATION_ATTACHED_DIALOG:
return APPLICATION_PANEL_SUBLAYER;//等于1
case TYPE_APPLICATION_MEDIA:
return APPLICATION_MEDIA_SUBLAYER;//等于-2
case TYPE_APPLICATION_MEDIA_OVERLAY:
return APPLICATION_MEDIA_OVERLAY_SUBLAYER;//等于-1
case TYPE_APPLICATION_SUB_PANEL:
return APPLICATION_SUB_PANEL_SUBLAYER;//等于2
case TYPE_APPLICATION_ABOVE_SUB_PANEL:
return APPLICATION_ABOVE_SUB_PANEL_SUBLAYER;//等于3
}
Log.e(TAG, "Unknown sub-window type: " + type);
return 0;
}理解了mBaseLayer和mSubLayer后，我们再来看看mLayer是如何计算出来的，是通过assignLayersLocked方法：
private final void assignLayersLocked(WindowList windows) {
int N = windows.size();
int curBaseLayer = 0;
int curLayer = 0;
int i;
boolean anyLayerChanged = false;
for (i=0; i 0 && w.mIsWallpaper)) {//如果窗口的mBaseLayer和前一个相同、或者是输入法和壁纸窗口
curLayer += WINDOW_LAYER_MULTIPLIER;
w.mLayer = curLayer;
} else {
curBaseLayer = curLayer = w.mBaseLayer;
w.mLayer = curLayer;
}
if (w.mLayer != oldLayer) {//层级发生改变
layerChanged = true;
anyLayerChanged = true;
}
final AppWindowToken wtoken = w.mAppToken;
oldLayer = winAnimator.mAnimLayer;//后面都是调整mAnimLayerd的值
if (w.mTargetAppToken != null) {
winAnimator.mAnimLayer =
w.mLayer + w.mTargetAppToken.mAppAnimator.animLayerAdjustment;
} else if (wtoken != null) {
winAnimator.mAnimLayer =
w.mLayer + wtoken.mAppAnimator.animLayerAdjustment;
} else {
winAnimator.mAnimLayer = w.mLayer;
}
if (w.mIsImWindow) {
winAnimator.mAnimLayer += mInputMethodAnimLayerAdjustment;
} else if (w.mIsWallpaper) {
winAnimator.mAnimLayer += mWallpaperAnimLayerAdjustment;
}
if (winAnimator.mAnimLayer != oldLayer) {
layerChanged = true;
anyLayerChanged = true;
}
final TaskStack stack = w.getStack();
if (layerChanged && stack != null && stack.isDimming(winAnimator)) {
// Force an animation pass just to update the mDimLayer layer.
scheduleAnimationLocked();
}
}
if (mAccessibilityController != null && anyLayerChanged
&& windows.get(windows.size() - 1).getDisplayId() == Display.DEFAULT_DISPLAY) {
mAccessibilityController.onWindowLayersChangedLocked();
}
} 在调用assignLayersLocked函数之前，WindowList中的窗口其实已经排好序了，前面调用的函数addWindowToListInOrderLocked就是插入窗口到合适的位置，assignLayersLocked函数并不会改变窗口的位置，只是根据窗口的位置计算mLayer的值。
调整方法是从最底层的窗口开始，具有相同的mBaseLayer的值作为一组，每组窗口的mLayer的值从mBaseLayer的值开始，依次加上WINDOW_LAYER_MULTIPLIER（等于5），这样做的目的是在同层的窗口中每隔一个窗口就留下4个空位，方便下次插入新窗口。
这个方法还对输入法和壁纸窗口做了特殊处理。这两类窗口和它插入位置前面的窗口处于一个层级，而不是根据他们的mBaseLayer值计算。（就是前面说的当输入法和壁纸出现是在当前Activity的窗口之间的）。
三、插入窗口的位置
在addWindow函数中我们会调用addAppWindowToListLocked来确定窗口的位置，现在我们来看下这个函数。
private void addWindowToListInOrderLocked(final WindowState win, boolean addToToken) {
if (win.mAttachedWindow == null) {//非子窗口
final WindowToken token = win.mToken;
int tokenWindowsPos = 0;
if (token.appWindowToken != null) {//应用窗口的顶层窗口
tokenWindowsPos = addAppWindowToListLocked(win);
} else {
addFreeWindowToListLocked(win);//系统窗口
}
if (addToToken) {
if (DEBUG_ADD_REMOVE) Slog.v(TAG, "Adding " + win + " to " + token);
token.windows.add(tokenWindowsPos, win);
}
} else {
addAttachedWindowToListLocked(win, addToToken);//添加子窗口
}
if (win.mAppToken != null && addToToken) {
win.mAppToken.allAppWindows.add(win);
}
}上面这个函数根据窗口的类型，应用顶层窗口，系统窗口，子窗口。
我们现在分别对这三类窗口的处理方法进行解析，先来看插入Activity顶层窗口的addAppWindowToListLocked
1.插入Activity顶层方法的addAppWindowToListLocked方法
addAppWindowToListLocked方法先判断系统中是否存在和待插入的窗口是否有相同的Token,如果有代表它不是Activity的第一个窗口，因此再判断这个窗口的类型是不是TYPE_BASE_APPLICATION，如果是这类窗口需要放在所有和它相同Token的窗口下面，否则在判断这个应用的启动窗口是否位于最前面（说明正在启动），如果是放在启动窗口的下面。如果不是下面两种情况，则寻找同一应用中位置最高的窗口，然后插在它上面，这表示加入的窗口将覆盖在前面的窗口之上。
下面是部分代码，
private int addAppWindowToListLocked(final WindowState win) {
final IWindow client = win.mClient;
final WindowToken token = win.mToken;
final DisplayContent displayContent = win.getDisplayContent();
if (displayContent == null) {
// It doesn't matter this display is going away.
return 0;
}
final WindowList windows = win.getWindowList();
final int N = windows.size();
WindowList tokenWindowList = getTokenWindowsOnDisplay(token, displayContent);
int tokenWindowsPos = 0;
int windowListPos = tokenWindowList.size();
if (!tokenWindowList.isEmpty()) {//如果有，说明它不是第一个窗口
// If this application has existing windows, we
// simply place the new window on top of them... but
// keep the starting window on top.
if (win.mAttrs.type == TYPE_BASE_APPLICATION) {//放在和它相同Token的窗口下面
// Base windows go behind everything else.
WindowState lowestWindow = tokenWindowList.get(0);//第一个0，代表最底层的window
placeWindowBefore(lowestWindow, win);//放在这个window前面
tokenWindowsPos = indexOfWinInWindowList(lowestWindow, token.windows);
} else {
AppWindowToken atoken = win.mAppToken;
WindowState lastWindow = tokenWindowList.get(windowListPos - 1);
if (atoken != null && lastWindow == atoken.startingWindow) {
placeWindowBefore(lastWindow, win);
tokenWindowsPos = indexOfWinInWindowList(lastWindow, token.windows);
} else {
int newIdx = findIdxBasedOnAppTokens(win);//寻找同一token位置最前面的window
//there is a window above this one associated with the same
//apptoken note that the window could be a floating window
//that was created later or a window at the top of the list of
//windows associated with this token.
windows.add(newIdx + 1, win);//插在它前面
if (newIdx < 0) {
// No window from token found on win's display.
tokenWindowsPos = 0;
} else {
tokenWindowsPos = indexOfWinInWindowList(
windows.get(newIdx), token.windows) + 1;
}
mWindowsChanged = true;
}
}
return tokenWindowsPos;
}我们再来看几个函数
placeWindowBefore函数就是插入到windows这个位置前
private void placeWindowBefore(WindowState pos, WindowState window) {
final WindowList windows = pos.getWindowList();
int i = windows.indexOf(pos);
if (i < 0) {
Slog.w(TAG, "placeWindowBefore: Unable to find " + pos + " in " + windows);
i = 0;
}
windows.add(i, window);
mWindowsChanged = true;
}findIdxBasedOnAppTokens函数就是寻找相同token的最前面的window，所以要注意遍历循环的时候是从window的size最大的时候反过来遍历的。
private int findIdxBasedOnAppTokens(WindowState win) {
WindowList windows = win.getWindowList();
for(int j = windows.size() - 1; j >= 0; j--) {
WindowState wentry = windows.get(j);
if(wentry.mAppToken == win.mAppToken) {
return j;
}
}
return -1;
}
继续看这个函数，如果系统中不存在和窗口具有相同token的窗口（说明Activity刚启动，第一个窗口还没有创建完成），这时就会遍历系统所有的task以及task中包含的AppWindowToken，找到窗口的位置，再在task中排在本窗口前面的窗口中，找出离自己最近的，并且APPWindowToken的窗口列表不为NULL的窗口，插入到它的最后一个子窗口后面。如果前面的窗口的列表也都为NULL，则寻找排在本窗口后面的第一个包含有窗口对象的APPWindowToken，把本窗口插在前面。
WindowState pos = null;
final ArrayList tasks = displayContent.getTasks();
int taskNdx;
int tokenNdx = -1;
for (taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
AppTokenList tokens = tasks.get(taskNdx).mAppTokens;
for (tokenNdx = tokens.size() - 1; tokenNdx >= 0; --tokenNdx) {
final AppWindowToken t = tokens.get(tokenNdx);
if (t == token) {
--tokenNdx;
if (tokenNdx < 0) {
--taskNdx;
if (taskNdx >= 0) {
tokenNdx = tasks.get(taskNdx).mAppTokens.size() - 1;
}
}
break;
}
// We haven't reached the token yet; if this token
// is not going to the bottom and has windows on this display, we can
// use it as an anchor for when we do reach the token.
tokenWindowList = getTokenWindowsOnDisplay(t, displayContent);
if (!t.sendingToBottom && tokenWindowList.size() > 0) {
pos = tokenWindowList.get(0);
}
}
if (tokenNdx >= 0) {
// early exit
break;
}
}
// We now know the index into the apps. If we found
// an app window above, that gives us the position; else
// we need to look some more.
if (pos != null) {
// Move behind any windows attached to this one.
WindowToken atoken = mTokenMap.get(pos.mClient.asBinder());
if (atoken != null) {
tokenWindowList =
getTokenWindowsOnDisplay(atoken, displayContent);
final int NC = tokenWindowList.size();
if (NC > 0) {
WindowState bottom = tokenWindowList.get(0);
if (bottom.mSubLayer < 0) {
pos = bottom;
}
}
}
placeWindowBefore(pos, win);
return tokenWindowsPos;
}
// Continue looking down until we find the first
// token that has windows on this display.
for ( ; taskNdx >= 0; --taskNdx) {
AppTokenList tokens = tasks.get(taskNdx).mAppTokens;
for ( ; tokenNdx >= 0; --tokenNdx) {
final AppWindowToken t = tokens.get(tokenNdx);
tokenWindowList = getTokenWindowsOnDisplay(t, displayContent);
final int NW = tokenWindowList.size();
if (NW > 0) {
pos = tokenWindowList.get(NW-1);
break;
}
}
if (tokenNdx >= 0) {
// found
break;
}
}
if (pos != null) {
// Move in front of any windows attached to this
// one.
WindowToken atoken = mTokenMap.get(pos.mClient.asBinder());
if (atoken != null) {
final int NC = atoken.windows.size();
if (NC > 0) {
WindowState top = atoken.windows.get(NC-1);
if (top.mSubLayer >= 0) {
pos = top;
}
}
}
placeWindowAfter(pos, win);
return tokenWindowsPos;
}
...... 如果前面窗口的APPWindowToken的窗口列表也为空，则重新遍历整个窗口，然后根据mBaseLayer的值来确定窗口的位置。
final int myLayer = win.mBaseLayer;
int i;
for (i = N - 1; i >= 0; --i) {
WindowState w = windows.get(i);
if (w.mBaseLayer <= myLayer) {
break;
}
}
if (DEBUG_FOCUS_LIGHT || DEBUG_WINDOW_MOVEMENT || DEBUG_ADD_REMOVE) Slog.v(TAG,
"Based on layer: Adding window " + win + " at " + (i + 1) + " of " + N);
windows.add(i + 1, win);
mWindowsChanged = true;
return tokenWindowsPos;
2. 插入子窗口的addAttachedWindowToListLocked函数
addAttachedWindowToListLocked方法，如果mSubLayer大于0的子窗口，按mSubLayer的值大小插入到有相同WindowToken的子窗口的合适位置中，如果mSubLayer相同，插入已插入窗口的下层位置，如果mSubLayer小于0，如果还存在mSubLayer小于0，并且大于等于该窗口的mSubLayer的值的子窗口，则插入到该子窗口之下，否则插入到子窗口所依附的窗口下面。
private void addAttachedWindowToListLocked(final WindowState win, boolean addToToken) {
final WindowToken token = win.mToken;
final DisplayContent displayContent = win.getDisplayContent();
if (displayContent == null) {
return;
}
final WindowState attached = win.mAttachedWindow;
WindowList tokenWindowList = getTokenWindowsOnDisplay(token, displayContent);
// Figure out this window's ordering relative to the window
// it is attached to.
final int NA = tokenWindowList.size();
final int sublayer = win.mSubLayer;
int largestSublayer = Integer.MIN_VALUE;
WindowState windowWithLargestSublayer = null;
int i;
for (i = 0; i < NA; i++) {
WindowState w = tokenWindowList.get(i);
final int wSublayer = w.mSubLayer;
if (wSublayer >= largestSublayer) {
largestSublayer = wSublayer;
windowWithLargestSublayer = w;
}
if (sublayer < 0) {
// For negative sublayers, we go below all windows
// in the same sublayer.
if (wSublayer >= sublayer) {
if (addToToken) {
if (DEBUG_ADD_REMOVE) Slog.v(TAG, "Adding " + win + " to " + token);
token.windows.add(i, win);
}
placeWindowBefore(wSublayer >= 0 ? attached : w, win);
break;
}
} else {
// For positive sublayers, we go above all windows
// in the same sublayer.
if (wSublayer > sublayer) {
if (addToToken) {
if (DEBUG_ADD_REMOVE) Slog.v(TAG, "Adding " + win + " to " + token);
token.windows.add(i, win);
}
placeWindowBefore(w, win);
break;
}
}
}
if (i >= NA) {
if (addToToken) {
if (DEBUG_ADD_REMOVE) Slog.v(TAG, "Adding " + win + " to " + token);
token.windows.add(win);
}
if (sublayer < 0) {
placeWindowBefore(attached, win);
} else {
placeWindowAfter(largestSublayer >= 0
? windowWithLargestSublayer
: attached,
win);
}
}
}
3.插入系统窗口的addFreeWindowToListLocked
addFreeWindowToListLocked方法简单，只是遍历同一显示设备上的Windows，比较mBaseLayer值的大小，插入合适位置。
private void addFreeWindowToListLocked(final WindowState win) {
final WindowList windows = win.getWindowList();
// Figure out where window should go, based on layer.
final int myLayer = win.mBaseLayer;
int i;
for (i = windows.size() - 1; i >= 0; i--) {
if (windows.get(i).mBaseLayer <= myLayer) {
break;
}
}
i++;
if (DEBUG_FOCUS_LIGHT || DEBUG_WINDOW_MOVEMENT || DEBUG_ADD_REMOVE) Slog.v(TAG,
"Free window: Adding window " + win + " at " + i + " of " + windows.size());
windows.add(i, win);
mWindowsChanged = true;
}这篇博客我们分析了window插入到什么位置，以及mLayer的计算。但是具体里面有很多变量，stack task windows等，不是很熟悉，下篇博客我们主要分析这。