WindowManager的分析
一、Window和WindowManager
Window：表示一个窗口，从下面Window的源码中可以看出它有且只有一个实现类PhoneWindow。
The only existing implementation of this abstract class is
* android.policy.PhoneWindow, which you should instantiate when needing a
* Window.
WindowManager：它是系统提供我们操作Window的一个接口，我们可以通过WindowManage提供的方法对window进行添加、修改、删除等操作。一般有View的地方都有window。
二、Window在事件分发中的应用
当一个点击事件产生时，它首先传递到Activity、在Activity的dispatchToucheEvent的方法中进行分发、然后传递到Window、最后才到顶级view。看源码：
public boolean dispatchTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_DOWN) {
onUserInteraction();
}
if (getWindow().superDispatchTouchEvent(ev)) {
return true;
}
return onTouchEvent(ev);
}
由于window只有一个实现类，所以查看PhoneWindow的源码。
@Override
public boolean superDispatchTouchEvent(MotionEvent event) {
return mDecor.superDispatchTouchEvent(event);
}
而这里的mDecor就是顶级View，就这样事件就从window传递到了顶级View了。
三、创建Window的快速入门
运行截图
由于Toast的源码也是通过添加window实现的，只不过使用了handler而已，因此这里我们参照Toast来简单实现
xml文件
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".MainActivity" >
<Button android:id="@+id/btn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="创建Window" />
</LinearLayout>
java代码
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn = (Button) findViewById(R.id.btn);
button = new Button(this);
button.setText("我是Window");
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Toast.makeText(getApplicationContext(), "我是被Window按钮点击的", 0).show();
}
}) ;
btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
mWM = (WindowManager)getSystemService(Context.WINDOW_SERVICE);
mParams = new WindowManager.LayoutParams();
// XXX This should be changed to use a Dialog, with a Theme.Toast
// defined that sets up the layout params appropriately.
final WindowManager.LayoutParams params = mParams;
params.height = WindowManager.LayoutParams.WRAP_CONTENT;
params.width = WindowManager.LayoutParams.WRAP_CONTENT;
params.flags =
WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
// | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
| WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE ;
params.format = PixelFormat.TRANSLUCENT;
//设置这个flag可以将被添加按钮有点击事件
params.type = WindowManager.LayoutParams.FLAG_TOUCHABLE_WHEN_WAKING;
params.setTitle("Toast");
mWM.addView(button, mParams) ;
}
});
简单说明下：上面的代码大部分是我从Toast的源码中赋值下来的，不过为了让显示的Toast有点击效果，做了小小的修改，上面已经做了注释。
四、Toast创建的源码分析
首先查看Toast的makeText()方法
public static Toast makeText(Context context, CharSequence text, int duration) {
Toast result = new Toast(context);
LayoutInflater inflate = (LayoutInflater)
context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View v = inflate.inflate(com.android.internal.R.layout.transient_notification, null);
TextView tv = (TextView)v.findViewById(com.android.internal.R.id.message);
tv.setText(text);
result.mNextView = v;
result.mDuration = duration;
return result;
}
从源码中看，并没有做什么特别的操作，只是创建了Toast变量、获取了TextView并将赋值给了Toast变量。
接着，我们看Toast显示的重要代码show()方法:
public void show() {
if (mNextView == null) {
throw new RuntimeException("setView must have been called");
}
INotificationManager service = getService();
String pkg = mContext.getPackageName();
TN tn = mTN;
tn.mNextView = mNextView;
try {
service.enqueueToast(pkg, tn, mDuration);
} catch (RemoteException e) {
// Empty
}
}
虽然看上去代码很少，但这却是实现了Toast的显示，首先，通过getService()获取一个INotificationManager的aidl对象，而实现它的Binder是NotificationManagerService，这一点我们可以从NotificationManagerService的源码中可以看出
/** {@hide} */
public class NotificationManagerService extends INotificationManager.Stub
接着，通过上下文获取应用的包名，然后就最重要的一个类TN了，看源码:
private static class TN extends ITransientNotification.Stub {
final Runnable mShow = new Runnable() {
@Override
public void run() {
handleShow();
}
};
final Runnable mHide = new Runnable() {
@Override
public void run() {
handleHide();
// Don't do this in handleHide() because it is also invoked by handleShow()
mNextView = null;
}
};
private final WindowManager.LayoutParams mParams = new WindowManager.LayoutParams();
final Handler mHandler = new Handler();
int mGravity = Gravity.CENTER_HORIZONTAL | Gravity.BOTTOM;
int mX, mY;
float mHorizontalMargin;
float mVerticalMargin;
View mView;
View mNextView;
WindowManager mWM;
TN() {
// XXX This should be changed to use a Dialog, with a Theme.Toast
// defined that sets up the layout params appropriately.
final WindowManager.LayoutParams params = mParams;
params.height = WindowManager.LayoutParams.WRAP_CONTENT;
params.width = WindowManager.LayoutParams.WRAP_CONTENT;
params.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
| WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
| WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
params.format = PixelFormat.TRANSLUCENT;
params.windowAnimations = com.android.internal.R.style.Animation_Toast;
params.type = WindowManager.LayoutParams.TYPE_TOAST;
params.setTitle("Toast");
}
/** * schedule handleShow into the right thread */
@Override
public void show() {
if (localLOGV) Log.v(TAG, "SHOW: " + this);
mHandler.post(mShow);
}
/** * schedule handleHide into the right thread */
@Override
public void hide() {
if (localLOGV) Log.v(TAG, "HIDE: " + this);
mHandler.post(mHide);
}
public void handleShow() {
if (localLOGV) Log.v(TAG, "HANDLE SHOW: " + this + " mView=" + mView
+ " mNextView=" + mNextView);
if (mView != mNextView) {
// remove the old view if necessary
handleHide();
mView = mNextView;
Context context = mView.getContext().getApplicationContext();
if (context == null) {
context = mView.getContext();
}
mWM = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
// We can resolve the Gravity here by using the Locale for getting
// the layout direction
final Configuration config = mView.getContext().getResources().getConfiguration();
final int gravity = Gravity.getAbsoluteGravity(mGravity, config.getLayoutDirection());
mParams.gravity = gravity;
if ((gravity & Gravity.HORIZONTAL_GRAVITY_MASK) == Gravity.FILL_HORIZONTAL) {
mParams.horizontalWeight = 1.0f;
}
if ((gravity & Gravity.VERTICAL_GRAVITY_MASK) == Gravity.FILL_VERTICAL) {
mParams.verticalWeight = 1.0f;
}
mParams.x = mX;
mParams.y = mY;
mParams.verticalMargin = mVerticalMargin;
mParams.horizontalMargin = mHorizontalMargin;
if (mView.getParent() != null) {
if (localLOGV) Log.v(TAG, "REMOVE! " + mView + " in " + this);
mWM.removeView(mView);
}
if (localLOGV) Log.v(TAG, "ADD! " + mView + " in " + this);
mWM.addView(mView, mParams);
trySendAccessibilityEvent();
}
}
private void trySendAccessibilityEvent() {
AccessibilityManager accessibilityManager =
AccessibilityManager.getInstance(mView.getContext());
if (!accessibilityManager.isEnabled()) {
return;
}
// treat toasts as notifications since they are used to
// announce a transient piece of information to the user
AccessibilityEvent event = AccessibilityEvent.obtain(
AccessibilityEvent.TYPE_NOTIFICATION_STATE_CHANGED);
event.setClassName(getClass().getName());
event.setPackageName(mView.getContext().getPackageName());
mView.dispatchPopulateAccessibilityEvent(event);
accessibilityManager.sendAccessibilityEvent(event);
}
public void handleHide() {
if (localLOGV) Log.v(TAG, "HANDLE HIDE: " + this + " mView=" + mView);
if (mView != null) {
// note: checking parent() just to make sure the view has
// been added... i have seen cases where we get here when
// the view isn't yet added, so let's try not to crash.
if (mView.getParent() != null) {
if (localLOGV) Log.v(TAG, "REMOVE! " + mView + " in " + this);
mWM.removeView(mView);
}
mView = null;
}
}
}
这个类的结构还是比较清晰的，首先是两个runnable对象，分别用来做显示和隐藏，接着就是TN的构造函数创建mPamas，接着是show、和hide两个方法通过handler来post上面的两个runanable，接着又是两个方法具体实现显示和隐藏。这里需要主要的是TN它是继承ITransientNotification.Stub的，所以它也是一个Binder。
再回到上面的show()方法，通过调用NotificationManagerService的enqueueToast()方法，将包名，TN，duration传递过去。
record = new ToastRecord(callingPid, pkg, callback, duration);
mToastQueue.add(record);
在enqueueToast()方法中，将我们传递过来的参数分装成一个ToastRecord，然后将其添加到mToastQueue中。mToastQueue是一个ArrayList。注意：这里的callback就是我们之前传递过来的TN。
接着:
if (index == 0) {
showNextToastLocked();
}
private void showNextToastLocked() {
ToastRecord record = mToastQueue.get(0);
while (record != null) {
if (DBG) Slog.d(TAG, "Show pkg=" + record.pkg + " callback=" + record.callback);
try {
record.callback.show();
scheduleTimeoutLocked(record, false);
return;
} catch (RemoteException e) {
Slog.w(TAG, "Object died trying to show notification " + record.callback
+ " in package " + record.pkg);
// remove it from the list and let the process die
int index = mToastQueue.indexOf(record);
if (index >= 0) {
mToastQueue.remove(index);
}
keepProcessAliveLocked(record.pid);
if (mToastQueue.size() > 0) {
record = mToastQueue.get(0);
} else {
record = null;
}
}
}
}
这个方法首先取出ArrayList中的record，然后调用record中的callback的show()方法，我们知道这里的callback就是TN，也就是说这里调用的是TN的show()方法。即如下:
/** * schedule handleShow into the right thread */
@Override
public void show() {
if (localLOGV) Log.v(TAG, "SHOW: " + this);
mHandler.post(mShow);
}
final Runnable mShow = new Runnable() {
@Override
public void run() {
handleShow();
}
};
public void handleShow() {
if (localLOGV) Log.v(TAG, "HANDLE SHOW: " + this + " mView=" + mView
+ " mNextView=" + mNextView);
if (mView != mNextView) {
// remove the old view if necessary
handleHide();
mView = mNextView;
Context context = mView.getContext().getApplicationContext();
if (context == null) {
context = mView.getContext();
}
mWM = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
// We can resolve the Gravity here by using the Locale for getting
// the layout direction
final Configuration config = mView.getContext().getResources().getConfiguration();
final int gravity = Gravity.getAbsoluteGravity(mGravity, config.getLayoutDirection());
mParams.gravity = gravity;
if ((gravity & Gravity.HORIZONTAL_GRAVITY_MASK) == Gravity.FILL_HORIZONTAL) {
mParams.horizontalWeight = 1.0f;
}
if ((gravity & Gravity.VERTICAL_GRAVITY_MASK) == Gravity.FILL_VERTICAL) {
mParams.verticalWeight = 1.0f;
}
mParams.x = mX;
mParams.y = mY;
mParams.verticalMargin = mVerticalMargin;
mParams.horizontalMargin = mHorizontalMargin;
if (mView.getParent() != null) {
if (localLOGV) Log.v(TAG, "REMOVE! " + mView + " in " + this);
mWM.removeView(mView);
}
if (localLOGV) Log.v(TAG, "ADD! " + mView + " in " + this);
mWM.addView(mView, mParams);
trySendAccessibilityEvent();
}
}
上面显示的核心代码其实就是获取WindowManager，然就是通过wm调用addView()方法进行添加，这里就完成了添加工作，关于WindowManager的addView()实现原理将会在下面分析。再回到 record.callback.show();下面就是调用scheduleTimeoutLocked()方法：
private void scheduleTimeoutLocked(ToastRecord r, boolean immediate)
{
Message m = Message.obtain(mHandler, MESSAGE_TIMEOUT, r);
long delay = immediate ? 0 : (r.duration == Toast.LENGTH_LONG ? LONG_DELAY : SHORT_DELAY);
mHandler.removeCallbacksAndMessages(r);
mHandler.sendMessageDelayed(m, delay);
}
这里比较简单，无非就是timeout了，移除record。这样，关于Toast的show方法就分析完了。
五、addView()的底层实现原理
再谈之前，我们再看看windowmanager的结构,它继承ViewManager
public interface WindowManager extends ViewManager {
再看看ViewPager：
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);
}
可以看出，ViewPager只提供了三个方法，增加、修改、删除。而这也是windowManager主要功能。
从上面WindowManager的结构可以看出它是一个接口，主要是通过它的实现类完成的：
public final class WindowManagerImpl implements WindowManager {
查看addView()方法
@Override public void addView(View view, ViewGroup.LayoutParams params) { mGlobal.addView(view, params, mDisplay, mParentWindow); }
private final WindowManagerGlobal mGlobal = WindowManagerGlobal.getInstance();
在WindowManagerGlobal中比较几个重要的代码如下
...
root = new ViewRootImpl(view.getContext(), display);
...
mViews[index] = view;
mRoots[index] = root;
mParams[index] = wparams;
...
// do this last because it fires off messages to start doing things
try {
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;
}
从源码可以看出，最后调用ViewRootImp的setView()方法来实现view的添加。
res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
getHostVisibility(), mDisplay.getDisplayId(),
mAttachInfo.mContentInsets, mInputChannel);
private final IWindowSession mWindowSession;
final class Session extends IWindowSession.Stub
session的addToDisplay方法如下：
@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);
}
这个mService又是WindowManagerservice，就这样window的添加就交给了WindowManagerservice，由于篇幅，关于windowmanagerservice如何添加的就不详细分析了。到这里，而且已经知道了添加大致流程了
OK，这篇就到这了。。。