Android有关Home按键的TYPE_KEYGUARD作用的仿照及其流程详解
发布时间：2021-11-24 18:31:27 所属栏目：教程 来源：互联网
导读：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
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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  （编辑：东莞站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
