selector 使用自定义属性 图片引用

power_switch.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_checked="true">
        <bitmap android:src="?power_switch_on" />
    </item>
    <item>
        <bitmap android:src="?power_switch_off" />
    </item>
</selector>

attr.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="CustomView">
        <attr name="power_switch_on" format="reference" />
        <attr name="power_switch_off" format="reference" />
    </declare-styleable>
</resources>

styles.xml

<resources>
    <style name="AppThemeGreen" parent="Theme.AppCompat.DayNight.NoActionBar">
        <item name="power_switch_on">@mipmap/power_switch_on</item>
        <item name="power_switch_off">@mipmap/power_switch_off</item>
    </style>
</resources>