WindowManager- InvalidDisplayException
最近在了解Window及WindowManger,
Window表示一个窗口，是一个抽象类，具体由PhoneWindow实现。
而创建一个Window需要用到WindowManager, WindowManagerImpl,WindowManagerGlobal, ViewRootImpl等等，
最终以View的形式展现给用户。具体概念不做介绍，分享一个简单的例子及遇到的问题以及解决的办法。
解决遇到问题的过程比较重要。
最初是想在一个Activity 里通过WindowManager添加一个View， 例子也是书上的
但是结果FC了， 原因如下
09-14 11:11:37.755 9367 9367 E AndroidRuntime: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.XX.viewmotiontest02/com.XX.viewmotiontest02.ViewMotionTest02}: android.view.WindowManager$InvalidDisplayException: Unable to add window android.view.ViewRootImpl$W@259f2ae -- the specified window type is not valid
......
09-14 11:11:37.755 9367 9367 E AndroidRuntime: Caused by: android.view.WindowManager$InvalidDisplayException: Unable to add window android.view.ViewRootImpl$W@259f2ae -- the specified window type is not valid
09-14 11:11:37.755 9367 9367 E AndroidRuntime: at android.view.ViewRootImpl.setView(ViewRootImpl.java:817)
对这种错误毫无头绪，并且是书上的例子。。
百度及谷歌了都没有类似的问题， 尝试新启动一个Service, 然后在Service 里面再添加一个View， 依然保持同样的错误。
准备放弃的时候，去官方API 瞄了一眼 WindowManager$InvalidDisplayException ，介绍说这个Exception是因为无法作为第二个View显示之类的。。
又看看错误 是 window type not valid, 想到了每添加一个View , 都会为其设置WindowManager.LayoutParms, 其中WindowManager.LayoutParms 就有type属性。。
而看了创建LayoutParms的代码：
mLayoutParams = new WindowManager.LayoutParams(WindowManager.LayoutParams.WRAP_CONTENT, WindowManager.LayoutParams.WRAP_CONTENT,
0 , 0, PixelFormat.TRANSPARENT); // w, h, type, flags, format;
从API上看，LayoutParms对应上面的构造函数中， type 并没有0这个值的！！！
type: 1~99 应用Window层
type: 1000 ~1999 子Window
type: 2000~2999 系统层 （最顶层）
因此type 为0 必须报错！！！！
改成 WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY， 并且添加 uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"
所以，关键时候，官方API 还是很有帮助的！！！
部分代码：
package com.XX.viewmotiontest02;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
public class ViewMotionTest02 extends Activity {
private static final String LOG_TAG = "ViewMotionTest02";
private boolean mIsUseService;
Button mStartBtn;
Button mFloatingButton;
WindowManager.LayoutParams mLayoutParams;
WindowManager mWindowManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(LOG_TAG,"onCreate ");
setContentView(R.layout.activity_view_motion_test02);
mIsUseService = false; // true: Service, false: Activity
Log.d(LOG_TAG,"mIsUseService: " + mIsUseService);
if(mIsUseService) {
mStartBtn = (Button) findViewById(R.id.startServiceBtn);
mStartBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.d(LOG_TAG, "onClick");
Intent intent = new Intent(getApplicationContext(), ViewMotionService.class);
startService(intent);
}
});
} else {
//mStartBtn.setVisibility(View.INVISIBLE);
mFloatingButton = new Button(this);
mFloatingButton.setText("Button In Activity");
mLayoutParams = new WindowManager.LayoutParams(WindowManager.LayoutParams.WRAP_CONTENT, WindowManager.LayoutParams.WRAP_CONTENT,
WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY , 0, PixelFormat.TRANSPARENT); // w, h, type, flags, format;
mLayoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
| WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
| WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED;
mLayoutParams.gravity = Gravity.LEFT | Gravity.TOP;
mLayoutParams.x = 100;
mLayoutParams.y = 300;
mWindowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
mWindowManager.addView(mFloatingButton,mLayoutParams);
}
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(LOG_TAG,"onDestroy ");
if(mIsUseService) {
Intent intent = new Intent(getApplicationContext(), ViewMotionService.class);
stopService(intent);
} else{
mWindowManager.removeView(mFloatingButton);
}
}
}
package com.XX.viewmotiontest02;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.util.Log;
import android.view.Gravity;
import android.view.WindowManager;
import android.widget.Button;
public class ViewMotionService extends Service {
private static final String LOG_TAG = "ViewMotionService";
Button mFloatingButton;
WindowManager.LayoutParams mLayoutParams;
WindowManager mWindowManager;
@Override
public void onCreate() {
super.onCreate();
Log.d(LOG_TAG, "onCreate" );
mFloatingButton = new Button(this);
mFloatingButton.setText("Button");
mLayoutParams = new WindowManager.LayoutParams(WindowManager.LayoutParams.WRAP_CONTENT, WindowManager.LayoutParams.WRAP_CONTENT,
WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY , 0, PixelFormat.TRANSPARENT); // w, h, type, flags, format;
//mLayoutParams = new WindowManager.LayoutParams();
//mLayoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
//mLayoutParams.width = WindowManager.LayoutParams.WRAP_CONTENT;
//mLayoutParams.type = WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY;
mLayoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
| WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
| WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED;
//mLayoutParams.format = PixelFormat.TRANSPARENT;
mLayoutParams.gravity = Gravity.LEFT | Gravity.TOP;
mLayoutParams.x = 100;
mLayoutParams.y = 300;
mWindowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
//Log.d(LOG_TAG,"onCreate - 2 change -3 ");
mWindowManager.addView(mFloatingButton,mLayoutParams);
//Log.d(LOG_TAG,"onCreate - 3 ");
}
@Nullable
@Override
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onDestroy() {
super.onDestroy();
Log.d(LOG_TAG, "onDestroy" );
mWindowManager.removeView(mFloatingButton);
}
}
AndroidManifest.xml
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