分析下Dialog源码，忽略一些细节，只扣重点。
Dialog构造方法
private final WindowManager mWindowManager;
final Window mWindow;
private final Handler mHandler = new Handler();
private final Runnable mDismissAction = this::dismissDialog;
public Dialog(@NonNull Context context) {
this(context, 0, true);
}
public Dialog(@NonNull Context context, @StyleRes int themeResId) {
this(context, themeResId, true);
}
Dialog(@NonNull Context context, @StyleRes int themeResId, boolean createContextThemeWrapper) {
if (createContextThemeWrapper) {
if (themeResId == 0) {
final TypedValue outValue = new TypedValue();
context.getTheme().resolveAttribute(R.attr.dialogTheme, outValue, true);
themeResId = outValue.resourceId;
}
mContext = new ContextThemeWrapper(context, themeResId);
} else {
mContext = context;
}
mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
//初始化Window实例PhoneWindow
final Window w = new PhoneWindow(mContext);
mWindow = w;
w.setCallback(this);
w.setOnWindowDismissedCallback(this);
//初始化WindowManager实例WindowManagerImpl
w.setWindowManager(mWindowManager, null, null);
w.setGravity(Gravity.CENTER);
mListenersHandler = new ListenersHandler(this);
}
Window.setWindowManager()
public void setWindowManager(WindowManager wm, IBinder appToken, String appName) {
setWindowManager(wm, appToken, appName, false);
}
public void setWindowManager(WindowManager wm, IBinder appToken, String appName,
boolean hardwareAccelerated) {
...
if (wm == null) {
wm = (WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE);
}
mWindowManager = ((WindowManagerImpl)wm).createLocalWindowManager(this);
}
Dialog.show()
public void show() {
//showing状态，显示DecorView
if (mShowing) {
if (mDecor != null) {
if (mWindow.hasFeature(Window.FEATURE_ACTION_BAR)) {
mWindow.invalidatePanelMenu(Window.FEATURE_ACTION_BAR);
}
mDecor.setVisibility(View.VISIBLE);
}
return;
}
...
//初始化DecorView
mDecor = mWindow.getDecorView();
...
WindowManager.LayoutParams l = mWindow.getAttributes();
if ((l.softInputMode
& WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION) == 0) {
WindowManager.LayoutParams nl = new WindowManager.LayoutParams();
nl.copyFrom(l);
nl.softInputMode |=
WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION;
l = nl;
}
//重点
mWindowManager.addView(mDecor, l);
mShowing = true;
sendShowMessage();
}
WindowManager.addView()流程前面讲过Android Activity、Window、View
简而言之，经过一系列调用，最终调用到ViewRootImpl.performTraversals()开启绘制流程。
Dialog.hide()
public void hide() {
if (mDecor != null) {
mDecor.setVisibility(View.GONE);
}
}
hide()和show()方法通过顶层View->DecorView的Visibility属性，显示隐藏。
Dialog.dismiss()
public void dismiss() {
//主线程直接关闭
if (Looper.myLooper() == mHandler.getLooper()) {
dismissDialog();
} else {//子线程调用handler.post()切换到主线程
mHandler.post(mDismissAction);
}
}
mDismissAction调用到dismissDialog()
private final Runnable mDismissAction = this::dismissDialog;
Dialog.dismissDialog()
void dismissDialog() {
if (mDecor == null || !mShowing) {
return;
}
if (mWindow.isDestroyed()) {
Log.e(TAG, "Tried to dismissDialog() but the Dialog's window was already destroyed!");
return;
}
try {
//重点
mWindowManager.removeViewImmediate(mDecor);
} finally {
if (mActionMode != null) {
mActionMode.finish();
}
mDecor = null;
mWindow.closeAllPanels();
onStop();
mShowing = false;
sendDismissMessage();
}
}
前面分析过WindowManager.addView()，这里继续分析WindowManager.removeView()
WindowManagerImpl.removeViewImmediate()
@Override
public void removeView(View view) {
mGlobal.removeView(view, false);
}
public void removeViewImmediate(View view) {
mGlobal.removeView(view, true);
}
WindowManagerGlobal.removeView()
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);
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);
}
}
WindowManagerGlobal.removeViewLocked
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());
}
}
boolean deferred = root.die(immediate);
if (view != null) {
view.assignParent(null);
if (deferred) {
mDyingViews.add(view);
}
}
}
ViewRootImpl.die()
immediate：
WindowManagerImpl.removeView(false)
WindowManagerImpl.removeViewImmediate(true)
true--->ViewRootImpl.die()直接调用ViewRootImpl.doDie()
false--->ViewRootImpl.die()通过handler发送消息，在主线程事件循环中调用ViewRootImpl.doDie()有一定的延迟。
boolean die(boolean immediate) {
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());
}
//mHandler是ViewRootHandler
mHandler.sendEmptyMessage(MSG_DIE);
return true;
}
ViewRootHandler.handleMessage()
switch (msg.what) {
...
case MSG_DIE:
doDie();
break;
}
ViewRootImpl.doDie()
void doDie() {
//主线程判断
checkThread();
if (LOCAL_LOGV) Log.v(mTag, "DIE in " + this + " of " + mSurface);
synchronized (this) {
if (mRemoved) {
return;
}
mRemoved = true;
if (mAdded) {
//解除Window关联
dispatchDetachedFromWindow();
}
if (mAdded && !mFirst) {
destroyHardwareRenderer();
if (mView != null) {
int viewVisibility = mView.getVisibility();
boolean viewVisibilityChanged = mViewVisibility != viewVisibility;
if (mWindowAttributesChanged || viewVisibilityChanged) {
try {
if ((relayoutWindow(mWindowAttributes, viewVisibility, false)
& WindowManagerGlobal.RELAYOUT_RES_FIRST_TIME) != 0) {
mWindowSession.finishDrawing(mWindow);
}
} catch (RemoteException e) {
}
}
mSurface.release();
}
}
mAdded = false;
}
WindowManagerGlobal.getInstance().doRemoveView(this);
}
WindowManagerGlobal.doRemoveView()
private final ArrayList<View> mViews = new ArrayList<View>();
private final ArrayList<ViewRootImpl> mRoots = new ArrayList<ViewRootImpl>();
private final ArrayList<WindowManager.LayoutParams> mParams =
new ArrayList<WindowManager.LayoutParams>();
private final ArraySet<View> mDyingViews = new ArraySet<View>();
void doRemoveView(ViewRootImpl root) {
synchronized (mLock) {
final int index = mRoots.indexOf(root);
if (index >= 0) {
mRoots.remove(index);
mParams.remove(index);
final View view = mViews.remove(index);
mDyingViews.remove(view);
}
}
if (ThreadedRenderer.sTrimForeground && ThreadedRenderer.isAvailable()) {
doTrimForeground();
}
}
将保存的View相关数据从对应数组中移除。
