Merge pull request #21 from jemshit/master

Almost fixed ripple effect issue on android 6 when pressing preferences items. See this: #19
Also, for some reason, now it sometimes show the ripple in the middle.

Author: AndroidDeveloperLB

material_preferences_library/src/main/res/drawable-v21/mpl__custom_ripple_effect_background.xml

@@ -0,0 +1,10 @@
+<ripple
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:color="#a5a5a5">
+    <item>
+        <shape
+            android:shape="rectangle">
+            <solid android:color="@android:color/transparent" />
+        </shape>
+    </item>
+</ripple>

material_preferences_library/src/main/res/drawable/mpl__custom_ripple_effect_background.xml

@@ -0,0 +1,21 @@
+<selector
+    xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <shape
+            android:shape="rectangle">
+            <solid android:color="@android:color/transparent" />
+        </shape>
+    </item>
+    <item android:state_pressed="true">
+        <shape
+            android:shape="rectangle">
+            <solid android:color="@android:color/transparent" />
+        </shape>
+    </item>
+    <item android:state_focused="true">
+        <shape
+            android:shape="rectangle">
+            <solid android:color="@android:color/transparent" />
+        </shape>
+    </item>
+</selector>

material_preferences_library/src/main/res/layout/mpl__preference_activity.xml

@@ -25,7 +25,8 @@
     <ListView
       android:id="@android:id/list"
       android:layout_width="match_parent"
-      android:layout_height="match_parent"/>
+      android:layout_height="match_parent"
+      android:listSelector="@drawable/mpl__custom_ripple_effect_background"/>
 
     <ImageView
       android:id="@+id/abp__shadowView"