Window 和 WindowManager

   <h2><strong>概述</strong></h2>    <h2><strong>window</strong></h2>    <ul>     <li> <p>window 是一个抽象类，具体实现是 PhoneWindow</p> </li>     <li> <p>window 也是一个抽象的概念，每个 window 内对应这一个 DecorView 和一个 ViewRootImpl ， window 和 DecorView 通过 ViewRootImpl</p> <p>联系。</p> <h2><strong>WindowManager</strong></h2> WindowManager 是 外界访问 Window <p>的入口</p> <p><!-- more --></p> <h2><strong>WindowManagerService</strong></h2> window 的具体实现位于 WindowManagerService 中， WindowManager 和 WindowManagerService <p>的交互是一个 IPC 的过程，</p> </li>    </ul>    <h2><strong>源码分析</strong></h2>    <p>window 的添加、删除、更新 view 均是通过 WindowManager 来完成的，而 WindowManager 继承了 ViewManager 的接口</p>    <pre>  <code class="language-java">/** Interface to let you add and remove child views to an Activity. To get an instance    * of this class, call {@link android.content.Context#getSystemService(java.lang.String) Context.getSystemService()}.    */  public interface ViewManager  {      /**       * Assign the passed LayoutParams to the passed View and add the view to the window.       * <p>Throws {@link android.view.WindowManager.BadTokenException} for certain programming       * errors, such as adding a second view to a window without removing the first view.       * <p>Throws {@link android.view.WindowManager.InvalidDisplayException} if the window is on a       * secondary {@link Display} and the specified display can't be found       * (see {@link android.app.Presentation}).       * @param view The view to be added to this window.       * @param params The LayoutParams to assign to view.       */      public void addView(View view, ViewGroup.LayoutParams params);      public void updateViewLayout(View view, ViewGroup.LayoutParams params);      public void removeView(View view);  }</code></pre>    <p>对应的三个方法，继续看 WindowManager 对应的具体实现类， WindowManagerImple</p>    <pre>  <code class="language-java">@Override      public void addView(@NonNull View view, @NonNull ViewGroup.LayoutParams params) {          applyDefaultToken(params);          mGlobal.addView(view, params, mDisplay, mParentWindow);      }            @Override      public void removeView(View view) {          mGlobal.removeView(view, false);      }            @Override      public void updateViewLayout(@NonNull View view, @NonNull ViewGroup.LayoutParams params) {          applyDefaultToken(params);          mGlobal.updateViewLayout(view, params);      }</code></pre>    <p>可以看到，具体的方法均交给 WindowManagerGlobal 来处理，而 WindowManagerGlobal 则以工程模式提供了自己的实例</p>    <pre>  <code class="language-java">private final WindowManagerGlobal mGlobal = WindowManagerGlobal.getInstance();</code></pre>    <p>看看``中比较重要的几个成员变量</p>    <pre>  <code class="language-java">private final ArrayList<View> mViews = new ArrayList<View>();//所有 window 对应的 DecorView      private final ArrayList<ViewRootImpl> mRoots = new ArrayList<ViewRootImpl>();////所有 window 对应的 ViewRootImpl      private final ArrayList<WindowManager.LayoutParams> mParams =              new ArrayList<WindowManager.LayoutParams>(); //所有 window 对应的 WindowManager.LayoutParams      private final ArraySet<View> mDyingViews = new ArraySet<View>();//所有 window 对应需要删除的 view</code></pre>    <h2><strong>添加过程</strong></h2>    <p>具体分析 WindowManagerGlobal 的 addview</p>    <pre>  <code class="language-java">public void addView(View view, ViewGroup.LayoutParams params,              Display display, Window parentWindow) {          //首先检查了参数，并抛出对应的异常          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) {              parentWindow.adjustLayoutParamsForSubWindow(wparams);          } else {              // If there's no parent, then hardware acceleration for this view is              // set from the application's hardware acceleration setting.              final Context context = view.getContext();              if (context != null                      && (context.getApplicationInfo().flags                              & ApplicationInfo.FLAG_HARDWARE_ACCELERATED) != 0) {                  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();                              }                          }                      }                  };                  SystemProperties.addChangeCallback(mSystemPropertyUpdater);              }    //通过findViewLocked找到 view 对应的 index              int index = findViewLocked(view, false);              if (index >= 0) {              //如果找到了，说明这个 view 已经被添加进来了                  if (mDyingViews.contains(view)) {                  //这个 view 是需要删除的话，那么不用管直接用doDie 删除                      // Don't wait for MSG_DIE to make it's way through root's queue.                      mRoots.get(index).doDie();                  } else {                  //说明这个 view 已经被添加进来了,抛出异常                      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.              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++) {                  //找到对应的 window                      if (mRoots.get(i).mWindow.asBinder() == wparams.token) {                          panelParentView = mViews.get(i);                      }                  }              }                root = new ViewRootImpl(view.getContext(), display);                view.setLayoutParams(wparams);  //将得DecorView viewimpl params 都加入到 list 中              mViews.add(view);              mRoots.add(root);              mParams.add(wparams);          }            // do this last because it fires off messages to start doing things          try {          //这个重要，通过 viewrootImpl 的 setview 方法来刷新 view              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;          }      }</code></pre>    <p>setview 的方法比较长，看其中比较重要的几个方法</p>    <p>requestLayout();</p>    <pre>  <code class="language-java">@Override      public void requestLayout() {          if (!mHandlingLayoutInLayoutRequest) {              checkThread();              mLayoutRequested = true;              scheduleTraversals();          }      }</code></pre>    <p>scheduleTraversals 是 view 开始绘制的入口</p>    <p>继续往下看 window 的添加过程</p>    <pre>  <code class="language-java">mOrigWindowType = mWindowAttributes.type;                      mAttachInfo.mRecomputeGlobalAttributes = true;                      collectViewAttributes();                      res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,                              getHostVisibility(), mDisplay.getDisplayId(),                              mAttachInfo.mContentInsets, mAttachInfo.mStableInsets,                              mAttachInfo.mOutsets, mInputChannel);</code></pre>    <p>IWindowSession 是一个 binder 对象。最终会调用到 windowManagerService 中的方法</p>    <h2><strong>删除过程</strong></h2>    <p>具体分析 WindowManagerGlobal 的 removeview</p>    <pre>  <code class="language-java">public void removeView(View view, boolean immediate) {          if (view == null) {              throw new IllegalArgumentException("view must not be null");          }            synchronized (mLock) {         //找到对应的 index ，再removeViewLocked              int index = findViewLocked(view, true);              View curView = mRoots.get(index).getView();              removeViewLocked(index, immediate);              if (curView == view) {                  return;              }                throw new IllegalStateException("Calling with view " + view                      + " but the ViewAncestor is attached to " + curView);          }      }             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());              }          }  //        ViewRootImpl 的 die 方法          boolean deferred = root.die(immediate);          if (view != null) {              view.assignParent(null);              if (deferred) {                  mDyingViews.add(view);              }          }      }        //die 方法比较简单，就是发送了一个 message，最后在处理 message 的时候调用了doDie          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();              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);          return true;      }           void doDie() {          checkThread();          if (LOCAL_LOGV) Log.v(TAG, "DIE in " + this + " of " + mSurface);          synchronized (this) {              if (mRemoved) {                  return;              }              mRemoved = true;              if (mAdded) {              //这里做了一些资源的回抽，停动画等                  dispatchDetachedFromWindow();              }                if (mAdded && !mFirst) {                  destroyHardwareRenderer();                    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);                              }                          } catch (RemoteException e) {                          }                      }                        mSurface.release();                  }              }                mAdded = false;          }          //在其中清理 那些成员 list 变量          WindowManagerGlobal.getInstance().doRemoveView(this);      }</code></pre>    <h2><strong>更新过程</strong></h2>    <pre>  <code class="language-java">public void updateViewLayout(View view, ViewGroup.LayoutParams params) {          if (view == null) {              throw new IllegalArgumentException("view must not be null");          }          if (!(params instanceof WindowManager.LayoutParams)) {              throw new IllegalArgumentException("Params must be WindowManager.LayoutParams");          }            final WindowManager.LayoutParams wparams = (WindowManager.LayoutParams)params;            view.setLayoutParams(wparams);            synchronized (mLock) {          //删除旧的 param 更新成新的 param              int index = findViewLocked(view, true);              ViewRootImpl root = mRoots.get(index);              mParams.remove(index);              mParams.add(index, wparams);              //通过 viewrootImpl 来刷新 view              root.setLayoutParams(wparams, false);          }      }</code></pre>    <p> </p>    <h2><strong>参考</strong></h2>    <p><a href="/misc/goto?guid=4959715864996358274" rel="nofollow,noindex">http://gold.xitu.io/entry/571338c7c4c9710054cea455</a></p>    <p><a href="/misc/goto?guid=4959715865101757630" rel="nofollow,noindex">http://www.jianshu.com/p/687010ccad66</a></p>    <p> </p>    <p>来自：http://www.jianshu.com/p/e75312330efc</p>    <p> </p>