android有关Home按键的TYPE_KEYGUARD作用的仿照及其流程说明

先看到PhoneWindowManager中public boolean interceptKeyTi(WindowState win, int code, int metaKeys, boolean down, 
            int repeatCount, int flags) 这个方法的实现，interceptKeyTi你可以暂时理解为WindowManagerService中处理驱动和上层按键实现的过滤器

        if (code == KeyEvent.KEYCODE_HOME) {            // If a system window has focus, then it doesn't make sense            // right now to interact with applications.            WindowManager.LayoutParams attrs = win != null ? win.getAttrs() : null;            if (attrs != null) {                final int type = attrs.type;                if (type == WindowManager.LayoutParams.TYPE_KEYGUARD                        || type == WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG) {                    // the "app" is keyguard, so give it the key                    return false;                }                final int typeCount = WINDOW_TYPES_WHERE_HOME_DOESNT_WORK.length;                for (int i=0; i<typeCount; i++) {                    if (type == WINDOW_TYPES_WHERE_HOME_DOESNT_WORK[i]) {                        // don't do anything, but also don't pass it to the app                        return true;                    }                }            }

从上面的注释可以看到注释：// the "app" is keyguard, so give it the key ，就是说当在应用界面下的时候，按了HOME键而且当前应用的WindowManager.LayoutParams.type的值是WindowManager.LayoutParams.TYPE_KEYGUARD就让直接返回；返回做什么呢，我先告诉大家，这个interceptKeyTi方法被调用的地方的流程后续步骤就是根据这个interceptKeyTi的返回值来判断，如果返回的是false就让当前应用自己去做HOME键的业务处理通过类似下面的代码

  /* 按键按下 */    public boolean onKeyDown(int keyCode, KeyEvent event)    {        switch (keyCode)        {            case KeyEvent.KEYCODE_HOME:                DisplayToast("HOME键按下");                break;                  }        return super.onKeyDown(keyCode, event);    }        /*按键弹起*/    public boolean onKeyUp(int keyCode, KeyEvent event)    {        switch (keyCode)        {            case KeyEvent.KEYCODE_HOME:                DisplayToast("HOME键弹起");                break;                   }                return super.onKeyUp(keyCode, event);    }

这里就产生了疑问：一、WindowManager.LayoutParams.type的值是在应用的哪里初始化的，二、interceptKeyTi方法被调用的地方的流程后续步骤是怎么调应用的HOME键的处理方式的，三、interceptKeyTi方法被调用的地方的流程后续步骤是怎么获取到WindowManager.LayoutParams.type初始化的值的；这三个疑问基本上就是按键的一个流程即怎么通过底层驱动到Activity相应按键事件相应的。

下面我们来看第一个问题的解答：Activity中有两个可覆盖的方法,都可以做如下的初始化：

    /**     * Called when the current {@link Window} of the activity gains or loses     * focus.  This is the best indicator of whether this activity is visible     * to the user.  The default implementation clears the key tracking     * state, so should always be called.     *      * <p>Note that this provides information about global focus state, which     * is managed independently of activity lifecycles.  As such, while focus     * changes will generally have some relation to lifecycle changes (an     * activity that is stopped will not generally get window focus), you     * should not rely on any particular order between the callbacks here and     * those in the other lifecycle methods such as {@link #onResume}.     *      * <p>As a general rule, however, a resumed activity will have window     * focus...  unless it has displayed other dialogs or popups that take     * input focus, in which case the activity itself will not have focus     * when the other windows have it.  Likewise, the system may display     * system-level windows (such as the status bar notification panel or     * a system alert) which will temporarily take window input focus without     * pausing the foreground activity.     *     * @param hasFocus Whether the window of this activity has focus.     *      * @see #hasWindowFocus()     * @see #onResume     * @see View#onWindowFocusChanged(boolean)     */    public void onWindowFocusChanged(boolean hasFocus) {        WindowManager.LayoutParams lp = new WindowManager.LayoutParams();        lp.type = WindowManager.LayoutParams.TYPE_KEYGUARD ;        this.getWindow().setAttributes(lp);    }    /** * Called when the main window associated with the activity has been         * attached     to the window manager.       * See {@link View#onAttachedToWindow() View.onAttachedToWindow()}       * for more information.      * @see View#onAttachedToWindow      */     public void onAttachedToWindow() {            this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);              super.onAttachedToWindow();     } onWindowFocusChanged(boolean) 当窗口包含的view获取或失去焦点时触发 onAttachedToWindow() 当view被附着到一个窗口时触发

LayoutParams的构造方式有很多种可以顺带学习下,同时最好学习下它的参数，项目中用到就知道它的重要性了：

        public LayoutParams() {            super(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);            type = TYPE_APPLICATION;            format = PixelFormat.OPAQUE;        }                public LayoutParams(int _type) {            super(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);            type = _type;            format = PixelFormat.OPAQUE;        }            public LayoutParams(int _type, int _flags) {            super(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);            type = _type;            flags = _flags;            format = PixelFormat.OPAQUE;        }            public LayoutParams(int _type, int _flags, int _format) {            super(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);            type = _type;            flags = _flags;            format = _format;        }                public LayoutParams(int w, int h, int _type, int _flags, int _format) {            super(w, h);            type = _type;            flags = _flags;            format = _format;        }                public LayoutParams(int w, int h, int xpos, int ypos, int _type,                int _flags, int _format) {            super(w, h);            x = xpos;            y = ypos;            type = _type;            flags = _flags;            format = _format;        }

到这一步为至即为网上很多转的都一样的帖子即屏蔽Home键写一些自己的业务逻辑，明天我们解决另外三个问题，待续。。。。。。

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流程说明暂缓一下，针对仿照我先写一下：

一、在应用中运用

@Overridepublic void onWindowFocusChanged(boolean hasFocus) {final int stretch = ViewGroup.LayoutParams.FILL_PARENT;WindowManager.LayoutParams lp = new WindowManager.LayoutParams(stretch,stretch, WindowManager.LayoutParams.TYPE_KEYGUARD_VUI,WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN,PixelFormat.TRANSPARENT);lp.screenOrientation = ActivityInfo.SCREEN_ORIENTATION_NOSENSOR;PoiSearchActivity.this.getWindow().setAttributes(lp);super.onWindowFocusChanged(hasFocus);}

public boolean onKeyDown(int keyCode, KeyEvent event) {if ((keyCode == KeyEvent.KEYCODE_MOD) && (event.getRepeatCount() == 0)) {        ......}

二、fromwork层实现

1、PhoneWindowManager.java

import static android.view.WindowManager.LayoutParams.TYPE_KEYGUARD_VUI;      public int windowTypeToLayerLw(int type) {        if (type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW) {            return APPLICATION_LAYER;        }        switch (type) {case TYPE_KEYGUARD_VUI:            return KEYGUARD_LAYER;        }        Log.e(TAG, "Unknown window type: " + type);        return APPLICATION_LAYER;    }

    public int prepareAddWindowLw(WindowState win, WindowManager.LayoutParams attrs) {        switch (attrs.type) {            case TYPE_STATUS_BAR:                if (mStatusBar != null) {                    return WindowManagerImpl.ADD_MULTIPLE_SINGLETON;                }                mStatusBar = win;                break;            case TYPE_SEARCH_BAR:                if (mSearchBar != null) {                    return WindowManagerImpl.ADD_MULTIPLE_SINGLETON;                }                mSearchBar = win;                break;            case TYPE_KEYGUARD:                if (mKeyguard != null) {                    return WindowManagerImpl.ADD_MULTIPLE_SINGLETON;                }                mKeyguard = win;                break;            case TYPE_KEYGUARD_VUI:                if (mKeyguard != null) {                    return WindowManagerImpl.ADD_MULTIPLE_SINGLETON;                }                mKeyguard = win;                break;        }        return WindowManagerImpl.ADD_OKAY;    }

    public boolean interceptKeyTi(WindowState win, int code, int metaKeys, boolean down,             int repeatCount) {        boolean keyguardOn = keyguardOn();       ......        if (code == KeyEvent.KEYCODE_HOME) {       ......       else if (code == KeyEvent.KEYCODE_MODE/*KeyEvent.KEYCODE_SRC*/) {            //--added by ting.li@1009-2009: do with KEYCODE_SRC Down!            if(DEBUG)                Log.d(TAG,"PhoneWindowManager->KEYCODE_MODE!!");            // If a system window has focus, then it doesn't make sense            // right now to interact with applications.            WindowManager.LayoutParams attrs = win != null ? win.getAttrs() : null;            if (attrs != null) {                final int type = attrs.type;                if (type == WindowManager.LayoutParams.TYPE_KEYGUARD                        || type == WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG) {                    // the "app" is keyguard, so give it the key                    return false;                }else if(type == WindowManager.LayoutParams.TYPE_KEYGUARD_VUI)                {                  // the "app" is keyguard, so give it the key                   return false;                  }                final int typeCount = WINDOW_TYPES_WHERE_HOME_DOESNT_WORK.length;                for (int i=0; i<typeCount; i++) {                    if (type == WINDOW_TYPES_WHERE_HOME_DOESNT_WORK[i]) {                        // don't do anything, but also don't pass it to the app                        return true;                    }                }            }                        if (down && repeatCount == 0) {                mModePressed = true;            }            return true;           .......

WindowManager.java

public static final int TYPE_KEYGUARD_VUI           = FIRST_SYSTEM_WINDOW+15;

MidWindowManager.java

    /** {@inheritDoc} */    public int windowTypeToLayerLw(int type) {        if (type >= FIRST_APPLICATION_WINDOW && type <= LAST_APPLICATION_WINDOW) {            return APPLICATION_LAYER;        }        switch (type) {       ....... case TYPE_KEYGUARD_VUI:            return KEYGUARD_LAYER;        }        Log.e(TAG, "Unknown window type: " + type);        return APPLICATION_LAYER;    }

    public int prepareAddWindowLw(WindowState win, WindowManager.LayoutParams attrs) {        switch (attrs.type) {            case TYPE_STATUS_BAR:                if (mStatusBar != null) {                    return WindowManagerImpl.ADD_MULTIPLE_SINGLETON;                }                mStatusBar = win;                break;            case TYPE_SEARCH_BAR:                if (mSearchBar != null) {                    return WindowManagerImpl.ADD_MULTIPLE_SINGLETON;                }                mSearchBar = win;                break;            case TYPE_KEYGUARD:                if (mKeyguard != null) {                    return WindowManagerImpl.ADD_MULTIPLE_SINGLETON;                }                mKeyguard = win;                break;            case TYPE_KEYGUARD_VUI:                if (mKeyguard != null) {                    return WindowManagerImpl.ADD_MULTIPLE_SINGLETON;                }                mKeyguard = win;                break;        }        return WindowManagerImpl.ADD_OKAY;    }