Android10 手势导航

种类

Android10 默认的系统导航有三种：

1.两个按钮的

2.三个按钮的

3.手势

它们分别对应三个包名

frameworks/base/packages/overlays/NavigationBarMode2ButtonOverlay
frameworks/base/packages/overlays/NavigationBarMode3ButtonOverlay

frameworks/base/packages/overlays/NavigationBarModeGesturalOverlay

在设置里切换导航模式的时候会执行SystemNavigationGestureSettings.java的如下方法：

    static void setCurrentSystemNavigationMode(Context context, IOverlayManager overlayManager,
            String key) {
        switch (key) {
            case KEY_SYSTEM_NAV_GESTURAL:
                int sensitivity = getBackSensitivity(context, overlayManager);
                setNavBarInteractionMode(overlayManager, BACK_GESTURE_INSET_OVERLAYS[sensitivity]);
                break;
            case KEY_SYSTEM_NAV_2BUTTONS:
                setNavBarInteractionMode(overlayManager, NAV_BAR_MODE_2BUTTON_OVERLAY);
                break;
            case KEY_SYSTEM_NAV_3BUTTONS:
                setNavBarInteractionMode(overlayManager, NAV_BAR_MODE_3BUTTON_OVERLAY);
                break;
        }
    }

    private static void setNavBarInteractionMode(IOverlayManager overlayManager,
            String overlayPackage) {
        try {
            overlayManager.setEnabledExclusiveInCategory(overlayPackage, USER_CURRENT);
        } catch (RemoteException e) {
            throw e.rethrowFromSystemServer();
        }
    }
-----------------------------------------------------------------------------------

    String NAV_BAR_MODE_3BUTTON_OVERLAY = "com.android.internal.systemui.navbar.threebutton";
    String NAV_BAR_MODE_2BUTTON_OVERLAY = "com.android.internal.systemui.navbar.twobutton";
    String NAV_BAR_MODE_GESTURAL_OVERLAY = "com.android.internal.systemui.navbar.gestural";

-----------------------------------------------------------------------------------

根据手势加载不同的overlayPackage，也就是上面的三个包名

配置文件

这三个包都有对应的配置文件

config

这个文件配置了config_navBarInteractionMode，即该模式编号。

如下是3按钮导航的config.xml文件

<resources>
    <!-- Controls the navigation bar interaction mode:
         0: 3 button mode (back, home, overview buttons)
         1: 2 button mode (back, home buttons + swipe up for overview)
         2: gestures only for back, home and overview -->
    <integer name="config_navBarInteractionMode">0</integer>
</resources>

strings

就是配置字符串，这个没什么好说的

dimens

这里配置了导航栏的宽高之类的，如下是手势导航的dimens.xml

<resources>
    <!-- Height of the bottom navigation / system bar. -->
    <dimen name="navigation_bar_height">16dp</dimen>
    <!-- Height of the bottom navigation bar in portrait; often the same as @dimen/navigation_bar_height -->
    <dimen name="navigation_bar_height_landscape">16dp</dimen>
    <!-- Width of the navigation bar when it is placed vertically on the screen -->
    <dimen name="navigation_bar_width">16dp</dimen>
    <!-- Height of the bottom navigation / system bar. -->
    <dimen name="navigation_bar_frame_height">48dp</dimen>
    <!-- The height of the bottom navigation gesture area. -->
    <dimen name="navigation_bar_gesture_height">32dp</dimen>
</resources>

当你选择了手势导航时，系统就会从这里获取资源。

如果你想配置三导航的宽高也可以在三导航的 overlayPackage 下添加dimens文件。

没有在对应的overlayPackage下添加dimens文件的话，系统默认会从frameworks/base/core/res/res/values/dimens.xml中获取，如下：

    <!-- Height of the bottom navigation / system bar. -->
    <dimen name="navigation_bar_height">48dp</dimen>
    <!-- Height of the bottom navigation bar in portrait; often the same as @dimen/navigation_bar_height -->
    <dimen name="navigation_bar_height_landscape">48dp</dimen>
    <!-- Width of the navigation bar when it is placed vertically on the screen -->
    <dimen name="navigation_bar_width">48dp</dimen>

    <!-- Height of the bottom navigation bar frame; this is different than navigation_bar_height
         where that is the height reported to all the other windows to resize themselves around the
         navigation bar window but navigation_bar_frame_height is reported to SystemUI navigation
         bar view's window -->
    <dimen name="navigation_bar_frame_height">@dimen/navigation_bar_height</dimen>
    <!-- Height of the bottom navigation bar frame in landscape -->
    <dimen name="navigation_bar_frame_height_landscape">@dimen/navigation_bar_frame_height</dimen>

    <!-- The height of the navigation gesture area if the gesture is starting from the bottom. -->
    <dimen name="navigation_bar_gesture_height">@dimen/navigation_bar_frame_height</dimen>

BUG

前提：源码设置的默认导航模式其实是三按钮导航，我的代码设置的默认导航模式是手势导航

顺带一提，默认系统导航模式在frameworks/base/core/res/res/values/config.xml中设置，如下：

    <!-- Controls the navigation bar interaction mode:
         0: 3 button mode (back, home, overview buttons)
         1: 2 button mode (back, home buttons + swipe up for overview)
         2: gestures only for back, home and overview -->
    <integer name="config_navBarInteractionMode">0</integer>

遇到过两个bug，一开始是设置大号字体且设置系统导航为三按钮导航后重启。

这个bug一开始我是将frameworks/base/core/res/res/values/dimens.xml的navigation_bar_height改回48dp（之前改为了16dp），设置大号字体且设置系统导航为三按钮导航后重启，问题完美解决，至少我是这么以为的。

然后恢复出厂设置第一次开机，默认是手势导航，然后高为48dp（应该为16dp的），导航栏空了一大块，整个人都不好了，然后又把frameworks/base/core/res/res/values/dimens.xml的值改回了16dp，检查了frameworks/base/packages/overlays/NavigationBarModeGesturalOverlay的配置，确实16dp，也没什么问题，但就是不起效，至今原因不明。

改动了很多值测试都没成功，没办法，又将代码恢复了最初的设置，将48dp改回了16dp，然后百度一下，大神还是很多的。

终于试了很多种方法后找出了一种有用的