三.接上一节，分析windowManager中添加一个悬浮框的方式，首先看代码
WindowManager.LayoutParams params = new LayoutParams();
params.width = width;
params.height = height;
params.format = PixelFormat.TRANSLUCENT;
params.type = WindowManager.LayoutParams.TYPE_APPLICATION_ATTACHED_DIALOG;
params.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL;//后面窗口仍然可以处理点设备事件
params.setTitle("Toast");
params.gravity = gravity;
params.windowAnimations = styleAnimations;
WindowManager windowManager = (WindowManager)context.getSystemService(Context.WINDOW_SERVICE);
TextView float = new TextView(context);
float.settext("this is a float window ");
windowManager.addView(view, this.mLayoutParams);
params中一般参数都容易理解，这里有几个特别要注意的地方：type、flags、windowAnimation
1.对于type ：
type 的取值：
应用程序窗口。
public static final int FIRST_APPLICATION_WINDOW = 1; 所有程序窗口的“基地”窗口，其他应用程序窗口都显示在它上面。
public static final int TYPE_BASE_APPLICATION =1; 普通应用功能程序窗口。token必须设置为Activity的token，以指出该窗口属谁。
public static final int TYPE_APPLICATION = 2; 用于应用程序启动时所显示的窗口。应用本身不要使用这种类型。
它用于让系统显示些信息，直到应用程序可以开启自己的窗口。
public static final int TYPE_APPLICATION_STARTING = 3; 应用程序窗口结束。
public static final int LAST_APPLICATION_WINDOW = 99; 子窗口。子窗口的Z序和坐标空间都依赖于他们的宿主窗口。
public static final int FIRST_SUB_WINDOW = 1000; 面板窗口，显示于宿主窗口上层。
public static final int TYPE_APPLICATION_PANEL = FIRST_SUB_WINDOW; 媒体窗口，例如视频。显示于宿主窗口下层。
public static final int TYPE_APPLICATION_MEDIA = FIRST_SUB_WINDOW+1; 应用程序窗口的子面板。显示于所有面板窗口的上层。（GUI的一般规律，越“子”越靠上）
public static final int TYPE_APPLICATION_SUB_PANEL = FIRST_SUB_WINDOW +2; 对话框。类似于面板窗口，绘制类似于顶层窗口，而不是宿主的子窗口。
public static final int TYPE_APPLICATION_ATTACHED_DIALOG = FIRST_SUB_WINDOW +3; 媒体信息。显示在媒体层和程序窗口之间，需要实现透明（半透明）效果。（例如显示字幕）
public static final int TYPE_APPLICATION_MEDIA_OVERLAY = FIRST_SUB_WINDOW +4; 子窗口结束。（ End of types of sub-windows ）
public static final int LAST_SUB_WINDOW = 1999; 系统窗口。非应用程序创建。
public static final int FIRST_SYSTEM_WINDOW = 2000; 状态栏。只能有一个状态栏；它位于屏幕顶端，其他窗口都位于它下方。
public static final int TYPE_STATUS_BAR = FIRST_SYSTEM_WINDOW; 搜索栏。只能有一个搜索栏；它位于屏幕上方。
public static final int TYPE_SEARCH_BAR = FIRST_SYSTEM_WINDOW+1; 电话窗口。它用于电话交互（特别是呼入）。它置于所有应用程序之上，状态栏之下。
public static final int TYPE_PHONE = FIRST_SYSTEM_WINDOW+2; 系统提示。它总是出现在应用程序窗口之上。
public static final int TYPE_SYSTEM_ALERT = FIRST_SYSTEM_WINDOW +3; 锁屏窗口。
public static final int TYPE_KEYGUARD = FIRST_SYSTEM_WINDOW +4; 信息窗口。用于显示toast。
public static final int TYPE_TOAST = FIRST_SYSTEM_WINDOW +5; 系统顶层窗口。显示在其他一切内容之上。此窗口不能获得输入焦点，否则影响锁屏。
public static final int TYPE_SYSTEM_OVERLAY = FIRST_SYSTEM_WINDOW +6; 电话优先，当锁屏时显示。此窗口不能获得输入焦点，否则影响锁屏。
public static final int TYPE_PRIORITY_PHONE = FIRST_SYSTEM_WINDOW +7; 系统对话框。（例如音量调节框）。
public static final int TYPE_SYSTEM_DIALOG = FIRST_SYSTEM_WINDOW +8; 锁屏时显示的对话框。
public static final int TYPE_KEYGUARD_DIALOG = FIRST_SYSTEM_WINDOW +9; 系统内部错误提示，显示于所有内容之上。
public static final int TYPE_SYSTEM_ERROR = FIRST_SYSTEM_WINDOW +10; 内部输入法窗口，显示于普通UI之上。应用程序可重新布局以免被此窗口覆盖。
public static final int TYPE_INPUT_METHOD = FIRST_SYSTEM_WINDOW +11; 内部输入法对话框，显示于当前输入法窗口之上。
public static final int TYPE_INPUT_METHOD_DIALOG= FIRST_SYSTEM_WINDOW +12; 墙纸窗口。
public static final int TYPE_WALLPAPER = FIRST_SYSTEM_WINDOW +13; 状态栏的滑动面板。
public static final int TYPE_STATUS_BAR_PANEL = FIRST_SYSTEM_WINDOW +14; 系统窗口结束。
public static final int LAST_SYSTEM_WINDOW = 2999;
这里需要注意的地方是：
对于需要依附于activity的选择2000以下的，独立于activity，使用2002
2.对于flag，这里详细的说明
int FLAGS_CHANGED
int FLAG_ALLOW_LOCK_WHILE_SCREEN_ON Window flag: as long as this window is visible to the user, allow the lock screen to activate while the screen is on.
int FLAG_ALT_FOCUSABLE_IM Window flag: invert the state of FLAG_NOT_FOCUSABLE with respect to how this window interacts with the current method.
int FLAG_BLUR_BEHIND This constant was deprecated in API level 14. Blurring is no longer supported.
int FLAG_DIM_BEHIND Window flag: everything behind this window will be dimmed.
int FLAG_DISMISS_KEYGUARD Window flag: when set the window will cause the keyguard to be dismissed, only if it is not a secure lock keyguard.
int FLAG_DITHER This constant was deprecated in API level 17. This flag is no longer used.
int FLAG_FORCE_NOT_FULLSCREEN Window flag: override FLAG_FULLSCREEN and force the screen decorations (such as the status bar) to be shown.
int FLAG_FULLSCREEN Window flag: hide all screen decorations (such as the status bar) while this window is displayed.
int FLAG_HARDWARE_ACCELERATED
Indicates whether this window should be hardware accelerated.
int FLAG_IGNORE_CHEEK_PRESSES Window flag: intended for windows that will often be used when the user is holding the screen against their face, it will aggressively filter the event stream to prevent unintended presses in this situation that may not be desired for a particular window, when such an event stream is detected, the application will receive a CANCEL motion event to indicate this so applications can handle this accordingly by taking no action on the event until the finger is released.
int FLAG_KEEP_SCREEN_ON Window flag: as long as this window is visible to the user, keep the device's screen turned on and bright.
int FLAG_LAYOUT_INSET_DECOR Window flag: a special option only for use in combination with FLAG_LAYOUT_IN_SCREEN.
int FLAG_LAYOUT_IN_OVERSCAN Window flag: allow window contents to extend in to the screen's overscan area, if there is one.
int FLAG_LAYOUT_IN_SCREEN Window flag: place the window within the entire screen, ignoring decorations around the border (such as the status bar).
int FLAG_LAYOUT_NO_LIMITS Window flag: allow window to extend outside of the screen.
int FLAG_NOT_FOCUSABLE Window flag: this window won't ever get key input focus, so the user can not send key or other button events to it.
int FLAG_NOT_TOUCHABLE Window flag: this window can never receive touch events.
int FLAG_NOT_TOUCH_MODAL Window flag: even when this window is focusable (its FLAG_NOT_FOCUSABLE is not set), allow any pointer events outside of the window to be sent to the windows behind it.
int FLAG_SCALED Window flag: a special mode where the layout parameters are used to perform scaling of the surface when it is composited to the screen.
int FLAG_SECURE Window flag: treat the content of the window as secure, preventing it from appearing in screenshots or from being viewed on non-secure displays.
int FLAG_SHOW_WALLPAPER Window flag: ask that the system wallpaper be shown behind your window.
int FLAG_SHOW_WHEN_LOCKED Window flag: special flag to let windows be shown when the screen is locked.
int FLAG_SPLIT_TOUCH Window flag: when set the window will accept for touch events outside of its bounds to be sent to other windows that also support split touch.
int FLAG_TOUCHABLE_WHEN_WAKING Window flag: when set, if the device is asleep when the touch screen is pressed, you will receive this first touch event.
int FLAG_TURN_SCREEN_ON Window flag: when set as a window is being added or made visible, once the window has been shown then the system will poke the power manager's user activity (as if the user had woken up the device) to turn the screen on.
int FLAG_WATCH_OUTSIDE_TOUCH Window flag: if you have set FLAG_NOT_TOUCH_MODAL, you can set this flag to receive a single special MotionEvent with the action MotionEvent.ACTION_OUTSIDE for touches that occur outside of your window.
3.对于windowAnimation
很多人说为什么我设置了windowAnimation，但是没有动画效果呢？
这里一定要注意，这里需要使用style，在style中添加如下：
<style name="top">
<item name="@android:windowEnterAnimation">@anim/sanqiwan_toast_slide_top_enter</item>
<item name="@android:windowExitAnimation">@anim/sanqiwan_toast_slide_top_exit</item>
</style>
然后将style的resourceId赋给params.windowAnimation,如果是将动画的resourceId赋值给params.windowAnimation，死也看得不到动画效果滴。
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