Android实现可以展开的TextView

本文实例为大家分享了一个可以展开的textview的具体代码，供大家参考，具体内容如下

原理是通过点击的时候设置 setmaxlines(linenum)来实现:

public class expandabletextview extends textview { 
 private static int min_line_num = 2; 
 private static int max_line_num = 20; 
 private int linenum = min_line_num; 
 private boolean misexpanded = false; 
 bitmap bitmapdown; 
 bitmap bitmapup; 
 int w, h; 
 /** 点击事件listener */ 
 private onclicklistener monclicklistener; 
 
 public expandabletextview(context context, attributeset attrs) { 
  super(context, attrs); 
  init(context, attrs); 
 } 
 
 private void init(context context, attributeset attrs) { 
  setmaxlines(linenum); 
  bitmapdown = bitmapfactory.decoderesource(getresources(), r.drawable.update_detail_down); 
  bitmapup = bitmapfactory.decoderesource(getresources(), r.drawable.update_detail_up); 
  w = bitmapdown.getwidth() + (int) context.getresources().getdimension(r.dimen.expand_textview_right); 
  h = bitmapdown.getheight() + (int) context.getresources().getdimension(r.dimen.expand_textview_bottom); 
   
  super.setonclicklistener(new onclicklistener() { 
   @override 
   public void onclick(view v) { 
    if (linenum == min_line_num) { 
     linenum = max_line_num; 
     setmaxlines(linenum); 
    } else { 
     linenum = min_line_num; 
     setmaxlines(linenum); 
    } 
    if (monclicklistener != null) { 
     monclicklistener.onclick(v); 
    } 
   } 
  }); 
 } 
 
 @override 
 public void setonclicklistener(onclicklistener listener) { 
  if (!isclickable()) { 
   setclickable(true); 
  } 
  monclicklistener = listener; 
 } 
 
 @override 
 public void setmaxlines(int maxlines) { 
  super.setmaxlines(maxlines); 
 
  if (linenum == max_line_num) { 
   misexpanded = true; 
  } else { 
   misexpanded = false; 
  } 
 } 
 
 public boolean isexpanded() { 
  return misexpanded; 
 } 
 
 @override 
 protected void ondraw(canvas canvas) { 
  if (getlinecount() <= min_line_num) { 
   super.ondraw(canvas); 
   return; 
  } 
  if (linenum == min_line_num) { 
   canvas.drawbitmap(bitmapdown, getwidth() - w, getheight() - h, null); 
  } else { 
   canvas.drawbitmap(bitmapup, getwidth() - w, getheight() - h, null); 
  } 
  super.ondraw(canvas); 
 } 
 
 
 public void setmaxline(int line) { 
  linenum = line; 
  setmaxlines(line); 
 } 
} 

这样来写layout:

<relativelayout xmlns:android="http://schemas.android.com/apk/res/android" 
 xmlns:tools="http://schemas.android.com/tools" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" 
 android:background="#ffffff" > 
 
 <textview 
  android:id="@+id/detail_action" 
  android:textcolor="#000000" 
  android:textsize="11sp" 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
  android:layout_alignparenttop="true" 
  android:layout_marginright="8dip" 
  android:drawablepadding="4dip" 
  android:paddingbottom="10dip" 
  android:paddingtop="10dip" 
  android:singleline="true" 
  android:text="sdfkljsfiosjdfiosfjsiofjsdifsd" /> 
 
 <com.example.view.expandabletextview 
  android:id="@+id/textview" 
  android:layout_width="100dp" 
  android:layout_height="wrap_content" 
  android:layout_below="@id/detail_action" 
  android:linespacingextra="4dip" 
  android:paddingbottom="-40dip" 
  android:paddingright="48dip" 
  android:text="adfsfsfewrwerwerwerqrwgdffdfdfersafsdfsdfsdd" 
  android:layout_margintop="-5dip" 
  android:textcolor="#000000" > 
 </com.example.view.expandabletextview> 
  
  
  <textview 
  android:id="@+id/detail_action1" 
  android:textcolor="#000000" 
  android:textsize="11sp" 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
  android:layout_below="@id/textview" 
  android:layout_marginright="8dip" 
  android:drawablepadding="4dip" 
  android:paddingbottom="10dip" 
  android:paddingtop="10dip" 
  android:singleline="true" 
  android:text="sdfkljsfiosjdfiosfjsiofjsdifsd" /> 
 
</relativelayout> 

效果图：

代码：一个可以展开的textview

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。