CardView 設置水波紋效果

設置CardView水波紋效果

<android.support.v7.widget.CardView
    android:id="@+id/news_list_card_view"
    style="@style/cardStyle"
    android:background="@drawable/item_selector"
    android:clickable="true"
    android:focusable="true"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    card_view:cardCornerRadius="4dp"
    card_view:cardElevation="4dp">


</android.support.v7.widget.CardView>

cardview設置了背景選擇器，代碼如下：

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@color/text_Grey" android:state_pressed="true"/>
    <item android:drawable="@color/text_Grey" android:state_focused="true"/>
    <item android:drawable="@color/colorWhite"/>
</selector>

發現並沒有效果，解決方案如下，給CardView添加個前景：

android:clickable="true"
android:focusable="true"
android:foreground="?android:attr/selectableItemBackground"

這樣就可以了，在5.0以上的設備上有點擊有波紋效果，5.0以下無波紋，只有前景色變化

自定義CardView前景

分爲5.0之前和之後兩種設置，因爲5.0之前沒有ripple，所以5.0之前採用inset 代替。
設置CardView自定義的前景：

android:foreground="@drawable/card_foreground"

5.0之後

drawable-v21/card_foreground.xml

<ripple xmlns:android="http://schemas.android.com/apk/res/android" 
android:color="#20000000"
android:drawable="@drawable/card_foreground_selector" />

drawable-v21/card_foreground_selector.xml

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <shape android:shape="rectangle">
            <solid android:color="#18ffc400"/>
        </shape>
    </item>
    <item android:state_focused="true" android:state_enabled="true">
        <shape android:shape="rectangle">
            <solid android:color="#0f000000"/>
        </shape>
    </item>
</selector>

效果：

5.0之前
drawable/card_foreground.xml

<inset xmlns:android="http://schemas.android.com/apk/res/android" 
    android:drawable="@drawable/card_foreground_selector"
    android:insetLeft="2dp"
    android:insetRight="2dp"
    android:insetTop="4dp"
    android:insetBottom="4dp"/>

drawable/card_foreground_selector.xml

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <shape android:shape="rectangle">
            <solid android:color="#1838f508"/>
            <corners android:radius="@dimen/card_radius" />
        </shape>
    </item>
    <item android:state_focused="true" android:state_enabled="true">
        <shape android:shape="rectangle">
            <solid android:color="#0f000000"/>
            <corners android:radius="@dimen/card_radius" />
        </shape>
    </item>
</selector>

效果：

直接設置selector也是可以的：

android:foreground="@drawable/card_foreground_selector"