addStatesFromChildren 和跑马灯

在Android中要显示跑马灯是比较容易的,只要设置2个属性就可以了:
android:singleLine="true"
android:ellipsize="marquee"

但是要显示跑马灯该View必需是可以取得焦点的,只有在取得焦点的情况下跑马灯才会出现.
如果是组合View的情况下就有问题了,如下一个组合View:

<!-- <br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--><?xml?version="1.0"?encoding="utf-8"?>
<LinearLayout
??xmlns:android="http://schemas.android.com/apk/res/android"
??android:orientation="vertical"
??android:gravity="center_vertical"
??android:background="@drawable/f_background"
??android:layout_width="fill_parent"
??android:focusable="true"
??android:layout_height="50px">
??<TextView?
??????android:id="@+id/info_text"
??????android:focusable="true"
??????android:layout_width="fill_parent"
??????android:layout_height="wrap_content"
??????android:text="test?marquee?..?"
??????android:textColor="@color/black"
??????android:singleLine="true"
??????android:ellipsize="marquee"
??????android:marqueeRepeatLimit="3"
??????android:textSize="18sp"
??/>
??<TextView?
??????android:id="@+id/date_text"
??????android:layout_width="fill_parent"
??????android:layout_height="wrap_content"
??????android:layout_gravity="bottom"
??????android:textColor="@color/gray"
??????android:text="2010/05/28"
??????android:textSize="12sp"
??/>
</LinearLayout>

上面示例中2个TextView组合为一个View,由于设置了LinearLayout为focusable而TextView就没法取得焦点了,这样这个TextView的跑马灯效果就显示不出来,就算你也设置TextView的 android:focusable="true" 也是没用的. 这个时候就要使用addStatesFromChildren 这个属性了,在LinearLayout中设置这个属性,然后设置TextView的focusable="true" 就可以了.关于addStatesFromChildren的说明:

Sets whether this ViewGroup's drawablestates also include its children's drawablestates.

可以正常显示的代码:


<!-- <br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--><?xml?version="1.0"?encoding="utf-8"?>
<LinearLayout
??xmlns:android="http://schemas.android.com/apk/res/android"
??android:orientation="vertical"
??android:gravity="center_vertical"
??android:background="@drawable/zixun_background"
??android:layout_width="fill_parent"
??android:addStatesFromChildren="true"
??android:layout_height="50px">
??<TextView?
??????android:id="@+id/info_text"
??????android:focusable="true"
??????android:layout_width="fill_parent"
??????android:layout_height="wrap_content"
??????android:text="?"
??????android:textColor="@color/black"
??????android:singleLine="true"
??????android:ellipsize="marquee"
??????android:marqueeRepeatLimit="3"
??????android:textSize="18sp"
??/>
??<TextView?
??????android:id="@+id/date_text"
??????android:layout_width="fill_parent"
??????android:layout_height="wrap_content"
??????android:layout_gravity="bottom"
??????android:textColor="@color/gray"
??????android:text="2010/05/28"
??????android:textSize="12sp"
??/>
</LinearLayout>