Window源码解析(四)：Window的删除机制

    @Override
    public void removeView(View view) {
        mGlobal.removeView(view, false);
    }

    public void removeView(View view, boolean immediate) {
        if (view == null) {
            throw new IllegalArgumentException("view must not be null");
        }

        synchronized (mLock) {
            // 得到当前 view 的索引
            int index = findViewLocked(view, true);
            View curView = mRoots.get(index).getView();
            // 主要执行删除 view 的操作
            removeViewLocked(index, immediate);
            // 如果要删除的 view 不是 viewrootimpl 中的 view ，那么会抛出异常
            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();
        
        // 关闭输入法
        if (view != null) {
            InputMethodManager imm = InputMethodManager.getInstance();
            if (imm != null) {
                imm.windowDismissed(mViews.get(index).getWindowToken());
            }
        }
        // 调用 die 方法，将 immediate 传入，即是否为同步删除
        boolean deferred = root.die(immediate);
        if (view != null) {
            view.assignParent(null);
            if (deferred) {
                // 添加到马上移除的集合中
                mDyingViews.add(view);
            }
        }
    }

    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.

        // 如果是同步移除，则马上执行 doDie
        if (immediate && !mIsInTraversal) {
            doDie();
            return false;
        }

        if (!mIsDrawing) {
            destroyHardwareRenderer();
        } else {
            Log.e(mTag, "Attempting to destroy the window while drawing!\n" +
                    "  window=" + this + ", title=" + mWindowAttributes.getTitle());
        }
        // 异步的话就利用 handler 发一个 messaage , 接收到 message 后也是执行 doDie 方法
        mHandler.sendEmptyMessage(MSG_DIE);
        return true;
    }

    void doDie() {
        // 先检查线程，要在主线程中进行
        checkThread();
        if (LOCAL_LOGV) Log.v(mTag, "DIE in " + this + " of " + mSurface);
        synchronized (this) {
            if (mRemoved) {
                return;
            }
            mRemoved = true;
            if (mAdded) {
                // 如果是已经添加到 Window 上的，执行删除操作
                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();
                }
            }
            // 将 mAdded 设置为 false
            mAdded = false;
        }

        // 从对应的 mRoots mParams mDyingViews 中移除该 view 的引用
        WindowManagerGlobal.getInstance().doRemoveView(this);
    }

    void dispatchDetachedFromWindow() {
        // 在这里调用 view 的 dispatchDetachedFromWindow 方法
        if (mView != null && mView.mAttachInfo != null) {
            mAttachInfo.mTreeObserver.dispatchOnWindowAttachedChange(false);
            mView.dispatchDetachedFromWindow();
        }

        // 辅助功能相关的操作
        mAccessibilityInteractionConnectionManager.ensureNoConnection();
        mAccessibilityManager.removeAccessibilityStateChangeListener(
                mAccessibilityInteractionConnectionManager);
        mAccessibilityManager.removeHighTextContrastStateChangeListener(
                mHighContrastTextManager);
        removeSendWindowContentChangedCallback();
        // 垃圾回收的工作
        destroyHardwareRenderer();

        setAccessibilityFocus(null, null);

        mView.assignParent(null);
        mView = null;
        mAttachInfo.mRootView = null;

        mSurface.release();

        if (mInputQueueCallback != null && mInputQueue != null) {
            mInputQueueCallback.onInputQueueDestroyed(mInputQueue);
            mInputQueue.dispose();
            mInputQueueCallback = null;
            mInputQueue = null;
        }
        if (mInputEventReceiver != null) {
            mInputEventReceiver.dispose();
            mInputEventReceiver = null;
        }
        // 重点来了，调用 session 来做 window 移除操作
        try {
            mWindowSession.remove(mWindow);
        } catch (RemoteException e) {
        }

        // Dispose the input channel after removing the window so the Window Manager
        // doesn't interpret the input channel being closed as an abnormal termination.
        if (mInputChannel != null) {
            mInputChannel.dispose();
            mInputChannel = null;
        }

        mDisplayManager.unregisterDisplayListener(mDisplayListener);
        // 解除 view 绘制之类的操作
        unscheduleTraversals();
    }

    public void remove(IWindow window) {
        mService.removeWindow(this, window);
    }

    public void removeWindow(Session session, IWindow client) {
        synchronized(mWindowMap) {
            // 得到 windowstate 对象
            WindowState win = windowForClientLocked(session, client, false);
            if (win == null) {
                return;
            }
            // 进行移除 window 操作
            removeWindowLocked(win);
        }
    }