目录
目录
效果展示
image
实现原理
原理很简单，需要用3个TextView，其中一个是展示文字的，一个是用来计算文字的行数，一个是用来展开和收起的：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- 展示文字-->
<TextView
android:id="@+id/view_seemore_tvcontent"
android:textColor="#000"
android:maxLines="2"
android:ellipsize="end"
android:textSize="15sp"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
<!-- 占位置的隐藏，并且高度设置的很小，用来获取行数-->
<TextView
android:id="@+id/view_seemore_tvlinecount"
android:textColor="#000"
android:visibility="invisible"
android:textSize="15sp"
android:layout_width="match_parent"
android:layout_height="1dp"/>
<!-- 显示更多和收起-->
<TextView
android:id="@+id/view_seemore_tv_seemore"
android:layout_marginTop="5dp"
android:text="查看更多"
android:textColor="#00f"
android:visibility="gone"
android:maxLines="2"
android:ellipsize="end"
android:textSize="15sp"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
然后需要在自定义控件的类中做相应的处理：
class SeeMoreView:FrameLayout {
//是否展开和收起的标记
private var mIsShowAll:Boolean = false
constructor(context: Context) : this(context,null)
constructor(context: Context, attrs: AttributeSet?) : this(context, attrs,0)
constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(
context,
attrs,
defStyleAttr
){
View.inflate(context, R.layout.view_seemore,this)
initListener()
}
private fun initListener() {
//查看更多的点击事件
view_seemore_tv_seemore.setOnClickListener {
if(mIsShowAll){
//这是收起的关键代码，将最大行数设置为你想展示的最小行数即可
view_seemore_tvcontent.maxLines = 2
view_seemore_tv_seemore.text = "查看更多"
}else{
//这是查看更多的关键代码，将最大行数设置一个大数即可
view_seemore_tvcontent.maxLines = 20
view_seemore_tv_seemore.text = "收起"
}
mIsShowAll = !mIsShowAll
}
//attachedToWindow之后执行操作
post {
//这里必须这样写，这是在attachedToWindow之后执行操作，否则获取行数会出问题
Log.e("测试","OnLayout${view_seemore_tvlinecount.lineCount}")
if(view_seemore_tvlinecount.lineCount>2){
view_seemore_tv_seemore.visibility = View.VISIBLE
}else{
view_seemore_tv_seemore.visibility = View.GONE
}
}
}
/**
* 设置文字
*/
fun setText(text:String){
//每次设置文字后都要进行重置
view_seemore_tvcontent.text = text
view_seemore_tvlinecount.text = text
view_seemore_tv_seemore.text = "查看更多"
view_seemore_tvcontent.maxLines = 2
mIsShowAll = false
if(view_seemore_tvlinecount.lineCount>2){
view_seemore_tv_seemore.visibility = View.VISIBLE
}else{
view_seemore_tv_seemore.visibility = View.GONE
}
}
}
