先上一张uml关系图,自己制作的哦
QQ拼音截图20170915211245.png
- WindowManager是Android中一个重要的服务（Service ）。WindowManager Service 是全局的，是唯一的。它将用户的操作，翻译成为指令，发送给呈现在界面上的各个Window。Activity会将顶级的控件注册到 Window Manager 中.
WindowManager 继承自ViewManager,ViewManager是一个接口,代码如下
public interface ViewManager{
public void addView(View view, ViewGroup.LayoutParams params);
public void updateViewLayout(View view, ViewGroup.LayoutParams params);
public void removeView(View view);
}
- windowManager 里一个重要的内部类就是 LayoutParams , LayoutParams 继承 ViewGroup.LayoutParams
实现了 Parcelable接口
layoutParams 里边定义了window的层级关系.代码如下
public static final int TYPE_BASE_APPLICATION = 1;
public static final int TYPE_APPLICATION = 2;
public static final int LAST_APPLICATION_WINDOW = 99;
public static final int LAST_SUB_WINDOW = 1999;
public static final int FIRST_SYSTEM_WINDOW = 2000;
其中.应用Window的层级范围是1-99,子Window的层级是1000-1999,系统Window的层级是2000-2999.想让window位于所有window的最顶层,采用较大的层级就可以.使用系统层级的window需要在权限中声名对应的window权限如
<user-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
3.window 是一个抽象概念.每个window都对应着一个View和ViewRootImpl,Window和View通过ViewRootImpl来建立联系.下边分别讲解
-
window的添加过程
window的add,remove,update过程都有WindowManager来实现,WindowManager是一个接口,具体实现类是WindowManagerImpl类.WindowManagerImpl 代码 private final WindowManagerGlobal mGlobal = WindowManagerGlobal.getInstance(); @Override public void addView(View view, ViewGroup.LayoutParams params) { mGlobal.addView(view, params, mDisplay, mParentWindow); } @Override public void updateViewLayout(View view, ViewGroup.LayoutParams params) { mGlobal.updateViewLayout(view, params); } @Override public void removeView(View view) { mGlobal.removeView(view, false); } @Override public void removeViewImmediate(View view) { mGlobal.removeView(view, true); }
1.WindowManagerImpl 通过 WindowManagerGlobal 来对View进行操作. WindowManagerGlobal通过单例模式提供他自己的对象.
//WindowManagerGlobal 代码
public static WindowManagerGlobal getInstance() {
synchronized (WindowManagerGlobal.class) {
if (sDefaultWindowManager == null) {
sDefaultWindowManager = new WindowManagerGlobal();
}
return sDefaultWindowManager;
}
}
2.接下来讲解 WindowManagerGlobal,他里边有几个重要参数先列出来
// WindowManagerGlobal 代码
private static IWindowManager sWindowManagerService;
private static IWindowSession sWindowSession; //前两个先不看
private final Object mLock = new Object(); //线程的锁
//所有Window对应的view的集合
private final ArrayList<View> mViews = new ArrayList<View>();
//所有window对应的ViewRootImpl 的集合
private final ArrayList<ViewRootImpl> mRoots = new ArrayList<ViewRootImpl>();
//所有Window对应的布局参数集合
private final ArrayList<WindowManager.LayoutParams> mParams =
new ArrayList<WindowManager.LayoutParams>();
//所有调用removeView方法但删除操作还没完成的View集合
private final ArraySet<View> mDyingViews = new ArraySet<View>();
3.看WindowManagerGolbal的addView方法
//WindowManagerGolbal 代码
public void addView(View view, ViewGroup.LayoutParams params,
Display display, Window parentWindow) {
// ------- 1.先检查参数是否合法,
if (view == null) {
throw new IllegalArgumentException("view must not be null");
}
if (display == null) {
throw new IllegalArgumentException("display must not be null");
}
if (!(params instanceof WindowManager.LayoutParams)) {
throw new IllegalArgumentException("Params must be WindowManager.LayoutParams");
}
final WindowManager.LayoutParams wparams = (WindowManager.LayoutParams)params;
if (parentWindow != null) { //调整parentWindow的param参数
parentWindow.adjustLayoutParamsForSubWindow(wparams);
} else {
// If there's no parent and we're running on L or above (or in the
// system context), assume we want hardware acceleration.
final Context context = view.getContext();
if (context != null //开启硬件加速
&& context.getApplicationInfo().targetSdkVersion >= Build.VERSION_CODES.LOLLIPOP) {
wparams.flags |= WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED;
}
}
ViewRootImpl root;
View panelParentView = null;
synchronized (mLock) {
// Start watching for system property changes.
if (mSystemPropertyUpdater == null) {
mSystemPropertyUpdater = new Runnable() {
@Override public void run() {
synchronized (mLock) {
for (int i = mRoots.size() - 1; i >= 0; --i) {
mRoots.get(i).loadSystemProperties();//ViewRootImpl 加载系统属性
}
}
}
};
SystemProperties.addChangeCallback(mSystemPropertyUpdater);//监听系统属性变化
}
int index = findViewLocked(view, false);//看这个view是否存在于mViews里
if (index >= 0) {
if (mDyingViews.contains(view)) { //如果已经添加到mViews里,看看是否是在待删的mDyingViews里,是的话直接删除
,不是的话,就抛出异常.
// Don't wait for MSG_DIE to make it's way through root's queue.
mRoots.get(index).doDie();
} else {
throw new IllegalStateException("View " + view
+ " has already been added to the window manager.");
}
// The previous removeView() had not completed executing. Now it has.
}
// If this is a panel window, then find the window it is being
// attached to for future reference.
//如果是面板view,就找到他第一次attach的window,以备以后查询.
if (wparams.type >= WindowManager.LayoutParams.FIRST_SUB_WINDOW &&
wparams.type <= WindowManager.LayoutParams.LAST_SUB_WINDOW) {
final int count = mViews.size();
for (int i = 0; i < count; i++) {
if (mRoots.get(i).mWindow.asBinder() == wparams.token) {
panelParentView = mViews.get(i);
}
}
}
//------- 2.生成一个新的viewRootImpl,并且把 view. viewrootImpl, param 都保存起来.
root = new ViewRootImpl(view.getContext(), display);
view.setLayoutParams(wparams);
mViews.add(view);
mRoots.add(root);
mParams.add(wparams);
}
// do this last because it fires off messages to start doing things
try {
//------- 3.调用ViewRoomImpl来更新界面并完成Window的添加过程
root.setView(view, wparams, panelParentView);
} catch (RuntimeException e) {
// BadTokenException or InvalidDisplayException, clean up.
synchronized (mLock) {
final int index = findViewLocked(view, false);
if (index >= 0) {
removeViewLocked(index, true);
}
}
throw e;
}
}
-------4.在 ViewRootImpl的setview方法里主要是一些对LayoutParams的处理,也看不太懂.不过其中重要是调用了requestLayout();
进行重新绘制.然后调用 mWindowSession完成view的添加过程.
//ViewRoomImpl内部成员
final IWindowSession mWindowSession;
//VewRoomImpl 的 setView 方法
try {
mOrigWindowType = mWindowAttributes.type;
mAttachInfo.mRecomputeGlobalAttributes = true;
collectViewAttributes();
res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
getHostVisibility(), mDisplay.getDisplayId(),
mAttachInfo.mContentInsets, mInputChannel);
}
其实,mWindowSession的类型是IWindowSession,他是一个Binder对象,真正的实现类是Session.也就是Window的一次添加过程是一次IPC调用
//Session代码
final WindowManagerService mService;
@Override
public int addToDisplay(IWindow window, int seq, WindowManager.LayoutParams attrs,
int viewVisibility, int displayId, Rect outContentInsets,
InputChannel outInputChannel) {
return mService.addWindow(this, window, seq, attrs, viewVisibility, displayId,
outContentInsets, outInputChannel);
}
这样,Window的一次添加过程就由WindowManagerService去处理了,而WindowManagerService内部会为每一个应用并保留一个单独的session
-
Window的删除过程
从 WindowManager的实现类WindowManagerImpl 看起//windowManagerImpl代码 private final WindowManagerGlobal mGlobal = WindowManagerGlobal.getInstance(); @Override public void removeView(View view) { mGlobal.removeView(view, false); }
接着看 WindowManagerGlobal
//WindowManagerGlobal 代码 为了方便.把之前列出的WindowManagerGlobal 几个成员写下
private static IWindowManager sWindowManagerService;
private static IWindowSession sWindowSession; //前两个先不看
private final Object mLock = new Object(); //线程的锁
//所有Window对应的view的集合
private final ArrayList<View> mViews = new ArrayList<View>();
//所有window对应的ViewRootImpl 的集合
private final ArrayList<ViewRootImpl> mRoots = new ArrayList<ViewRootImpl>();
//所有Window对应的布局参数集合
private final ArrayList<WindowManager.LayoutParams> mParams =
new ArrayList<WindowManager.LayoutParams>();
//所有调用removeView方法但删除操作还没完成的View集合
private final ArraySet<View> mDyingViews = new ArraySet<View>();
// WindowManagerGlobal 主要代码
public void removeView(View view, boolean immediate) {
if (view == null) {
throw new IllegalArgumentException("view must not be null");
}
synchronized (mLock) {
int index = findViewLocked(view, true);//在 mViews集合里查找这个view的index.
View curView = mRoots.get(index).getView();//找到这个所以的ViewRootImpl对应的view
removeViewLocked(index, immediate); //这是主要的删除办法
if (curView == view) { //两个view相同,代表数据是正确的.结束方法.否则就抛出异常
return;
}
throw new IllegalStateException("Calling with view " + view
+ " but the ViewAncestor is attached to " + curView);
}
}
// 接着看 removeViewLocked
//WindowManagerGlobal 方法 ,immediate 标识是否立即删除.
private void removeViewLocked(int index, boolean immediate) {
ViewRootImpl root = mRoots.get(index);
View view = root.getView();
if (view != null) {
InputMethodManager imm = InputMethodManager.getInstance();
if (imm != null) {
imm.windowDismissed(mViews.get(index).getWindowToken()); //这是一个调用InputManagerService的ipc的过程
}
}
boolean deferred = root.die(immediate); //通过ViewRootImpl 完成view的删除
if (view != null) {
view.assignParent(null);
if (deferred) { //如果是延时的remove view,则把view 添加到mDyingViews里
mDyingViews.add(view);
}
}
}
接下来追中到ViewRootImpl里的die方法
//ViewRootImpl代码 immediate
boolean die(boolean immediate) {
// Make sure we do execute immediately if we are in the middle of a traversal or the damage
// done by dispatchDetachedFromWindow will cause havoc on return.
if (immediate && !mIsInTraversal) {
doDie(); //直接执行
return false;
}
if (!mIsDrawing) {
destroyHardwareRenderer();
} else {
Log.e(TAG, "Attempting to destroy the window while drawing!\n" +
" window=" + this + ", title=" + mWindowAttributes.getTitle());
}
mHandler.sendEmptyMessage(MSG_DIE); //其实就是在handler在处理消息时会调用 dodie方法
return true;
}
//继续看dodie方法 ViewRootImpl代码
void doDie() {
checkThread(); //确保mThread=Thread.currentThread() //其实mThread初始化就是他
if (LOCAL_LOGV) Log.v(TAG, "DIE in " + this + " of " + mSurface);
synchronized (this) {
if (mRemoved) { //标记变量.标识view是否被删除
return;
}
mRemoved = true;
if (mAdded) {
dispatchDetachedFromWindow();//这是主要的删除方法
}
if (mAdded && !mFirst) {
destroyHardwareRenderer(); //销毁硬件渲染器
if (mView != null) {
int viewVisibility = mView.getVisibility();
boolean viewVisibilityChanged = mViewVisibility != viewVisibility;
if (mWindowAttributesChanged || viewVisibilityChanged) {
// If layout params have been changed, first give them
// to the window manager to make sure it has the correct
// animation info.
try {
if ((relayoutWindow(mWindowAttributes, viewVisibility, false)
& WindowManagerGlobal.RELAYOUT_RES_FIRST_TIME) != 0) {
mWindowSession.finishDrawing(mWindow); //用来更新window的layoutparams
}
} catch (RemoteException e) {
}
}
mSurface.release();
}
}
mAdded = false;
}
//这句代码主要是通过本ViewRoomImpl在WindowManagerGlobal mRoots中的index.
//分别在mRoots,mParams,mDyingViews 把这个index对应的不同数据都删除
WindowManagerGlobal.getInstance().doRemoveView(this);
}
最后 ViewRootImpl中注意做了以下的事
1.垃圾回收相关,清楚数据,和消息,移除回调
2.通过Session的remove方法删除Window,其实是通过IPC调用WindowManagerService的removeWindow方 法.
3.调用View的diapatchDetachedfromWindow 方法,内部会回调View的onDetachedFromWindow及onDetachedFromWindowInternal(),
到此.remove过程完毕
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