Textview多行時,最後結尾處顯示省略號
阿新 • • 發佈:2019-02-19
一般情況寫,在設定Textview最大行數和結尾處顯示省略號以後,預設是會在結尾處顯示省略號的。這裡不用系統預設的,而是自己拼省略號,以滿足某些實際需求。文章最後附onWindowFocusChanged()生命週期。
效果圖:
程式碼實現(2種方式):
佈局是一樣的:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:id="@+id/activity_main"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width ="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="30dp"
android:lineSpacingMultiplier ="1.4"
android:textSize="20sp"
/>
<TextView
android:id="@+id/result_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="30dp"
android:lineSpacingMultiplier="1.4"
android:textSize ="20sp"
/>
</LinearLayout>
程式碼實現:
第一種方法:
package com.chen.animdemo;
import android.app.Activity;
import android.os.Bundle;
import android.text.TextPaint;
import android.text.TextUtils;
import android.util.Log;
import android.widget.TextView;
public class MainActivity extends Activity {
private TextView textview;
private TextView result_tv;
private String s;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
s = "0123456789012345678901234567890123456789012345678901234567890123456789";
textview = (TextView) findViewById(R.id.textview);
result_tv = (TextView) findViewById(R.id.result_tv);
textview.setText(s);
}
@Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
TextPaint paint = textview.getPaint();
int paddingLeft = textview.getPaddingLeft();
int paddingRight = textview.getPaddingRight();
//給省略號留的長度(但是,因為字元佔位問題,獲取的這個長度,要比省略號的三個點的長度大一些)
float moreText = textview.getTextSize() * 3;
//乘2,是代表2行的意思,減去moreText,是給省略號預留一點位置
float availableTextWidth = (textview.getWidth() - paddingLeft - paddingRight) * 2 - moreText;
/**
* TextUtils中public static CharSequence ellipsize(CharSequence text,TextPaint p,float avail, TruncateAt where)說明
*
* Returns the original(原始) text if it fits(適合、符合) in the specified(指定) width
* given the properties(性質) of the specified(指定) Paint,
* or, if it does not fit, a truncated(縮短了的,被刪截的)
* copy with ellipsis(省略、省略符號) character added at the specified(指定) edge(邊緣) or center.
*/
CharSequence ellipsizeStr = TextUtils.ellipsize(s, paint, availableTextWidth, TextUtils.TruncateAt.END);
Log.e("textview.getTextSize()", textview.getTextSize() + "");
Log.e("moreText", moreText + "");
Log.e("textview.getWidth()", textview.getWidth() + "");
Log.e("paddingLeft", paddingLeft + "");
Log.e("paddingRight", paddingRight + "");
Log.e("availableTextWidth", availableTextWidth + "");
Log.e("ellipsizeStr", ellipsizeStr + "");
result_tv.setText(ellipsizeStr);
}
}
第二種方法:
package com.chen.animdemo;
import android.app.Activity;
import android.os.Bundle;
import android.text.TextPaint;
import android.text.TextUtils;
import android.util.Log;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.widget.TextView;
public class MainActivity2 extends Activity {
private TextView textview;
private TextView result_tv;
private String s;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
s = "0123456789012345678901234567890123456789012345678901234567890123456789";
textview = (TextView) findViewById(R.id.textview);
result_tv = (TextView) findViewById(R.id.result_tv);
textview.setText(s);
textview.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
//一般用完之後,立即移除該監聽
textview.getViewTreeObserver().removeGlobalOnLayoutListener(this);
TextPaint paint = textview.getPaint();
int paddingLeft = textview.getPaddingLeft();
int paddingRight = textview.getPaddingRight();
//給省略號留的長度(但是,因為字元佔位問題,獲取的這個長度,要比省略號的三個點的長度大一些)
float moreText = textview.getTextSize() * 3;
//乘2,是代表2行的意思,減去moreText,是給省略號預留一點位置
float availableTextWidth = (textview.getWidth() - paddingLeft - paddingRight) * 2 - moreText;
/**
* TextUtils中public static CharSequence ellipsize(CharSequence text,TextPaint p,float avail, TruncateAt where)說明
*
* Returns the original(原始) text if it fits(適合、符合) in the specified(指定) width
* given the properties(性質) of the specified(指定) Paint,
* or, if it does not fit, a truncated(縮短了的,被刪截的)
* copy with ellipsis(省略、省略符號) character added at the specified(指定) edge(邊緣) or center.
*/
CharSequence ellipsizeStr = TextUtils.ellipsize(s, paint, availableTextWidth, TextUtils.TruncateAt.END);
Log.e("textview.getTextSize()", textview.getTextSize() + "");
Log.e("moreText", moreText + "");
Log.e("textview.getWidth()", textview.getWidth() + "");
Log.e("paddingLeft", paddingLeft + "");
Log.e("paddingRight", paddingRight + "");
Log.e("availableTextWidth", availableTextWidth + "");
Log.e("ellipsizeStr", ellipsizeStr + "");
result_tv.setText(ellipsizeStr);
}
});
}
}
資料列印:
E/textview.getTextSize(): 55.0
E/moreText: 165.0
E/textview.getWidth(): 1080
E/paddingLeft: 0
E/paddingRight: 0
E/availableTextWidth: 1995.0
E/ellipsizeStr: 012345678901234567890123456789012345678901234567890123456789012…
說明:
在上面的計算方法中,有這樣一句:
float availableTextWidth = (textview.getWidth() - paddingLeft - paddingRight) * 2 - moreText;
最後為什麼要減去 moreText呢?
將上述任一方法的該句改為:
float availableTextWidth = (textview.getWidth() - paddingLeft - paddingRight) * 2
效果圖如下(注意省略號的出現位置):
資料列印如下:
E/textview.getTextSize(): 55.0
E/moreText: 165.0
E/textview.getWidth(): 1080
E/paddingLeft: 0
E/paddingRight: 0
E/availableTextWidth: 2160.0
E/ellipsizeStr: 01234567890123456789012345678901234567890123456789012345678901234567…
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onWindowFocusChanged()宣告週期:
啟動
03-20 10:49:00.608 3392-3392/com.chen.animdemo E/chen: onCreate
03-20 10:49:00.609 3392-3392/com.chen.animdemo E/chen: onStart
03-20 10:49:00.611 3392-3392/com.chen.animdemo E/chen: onResume
03-20 10:49:00.654 3392-3392/com.chen.animdemo E/chen: onWindowFocusChanged
home鍵
03-20 10:49:21.899 3392-3392/com.chen.animdemo E/chen: onWindowFocusChanged
03-20 10:49:21.902 3392-3392/com.chen.animdemo E/chen: onPause
03-20 10:49:22.232 3392-3392/com.chen.animdemo E/chen: onStop
回來
03-20 10:49:47.842 3392-3392/com.chen.animdemo E/chen: onRestart
03-20 10:49:47.846 3392-3392/com.chen.animdemo E/chen: onStart
03-20 10:49:47.847 3392-3392/com.chen.animdemo E/chen: onResume
03-20 10:49:47.860 3392-3392/com.chen.animdemo E/chen: onWindowFocusChanged
鎖屏
03-20 10:50:01.250 3392-3392/com.chen.animdemo E/chen: onPause
03-20 10:50:01.326 3392-3392/com.chen.animdemo E/chen: onStop
03-20 10:50:02.788 3392-3392/com.chen.animdemo E/chen: onWindowFocusChanged
開屏
03-20 10:50:21.452 3392-3392/com.chen.animdemo E/chen: onRestart
03-20 10:50:21.471 3392-3392/com.chen.animdemo E/chen: onStart
03-20 10:50:21.472 3392-3392/com.chen.animdemo E/chen: onResume
03-20 10:50:21.515 3392-3392/com.chen.animdemo E/chen: onWindowFocusChanged
注:
在這個方法中,可以獲得任何介面上任何控制元件的寬高資料,且不用再次測量,因為走到這個方法裡,就是已經測量並擺放完畢的。但是,如果實際需求中,你剛剛進入這個介面,就需要獲取一些控制元件的寬高去做一些操作,就不要用這個方法了,因為通過它獲取控制元件寬高資料,有延時