对于一个单行TextView,当字符串超出一行时,如何获取未显示的部分字符串?

wswsl
  • 123

想要获取textview某行实际显示的字数,而不是整行的字数,这该怎么弄呢?
求大神


问题修正:
textview设定最大行数为1后,文本超出了textview,textView末尾显示省略号,我就想知道省略号代表的内容

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li21
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✓ 已被采纳

假设TextView的宽度是在xml内设置的具体数值,比如300dp,
(目的是为了简化这个问题,如果设置为match_parent或者wrap_content,需要在程序运行时计算其宽度,而直接getWidth总是返回0,比较麻烦。)

比如是这样配置的:

    <TextView
        android:id="@+id/textView"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:ellipsize="end"
        android:singleLine="true" />

然后填充了一个超长的字符串,比如这样:

String str = "If you really want to hear about it, the first thing you'll probably want to know";

这样就会导致显示不全,像这样:
If you really want to hear about it, the first thin...

所以,如果你想得到已显示的字符个数,或者未显示的字符个数,那么其中的关键是如何计算每一个字符的宽度
然后遍历这个字符串,当前n个字符宽度总和,超过TextView宽度时,就得到了已显示的字符个数。

String str = "If you really want to hear about it, the first thing you'll probably want to know";
mTextView = (TextView) findViewById(R.id.textView);

// 计算TextView宽度:xml中定义的宽度300dp,转换成px
float textViewWidth = convertDpToPixel(300);
float dotWidth = getCharWidth(mTextView, '.');
Log.d(TAG, "TextView width " + textViewWidth);

int sumWidth = 0;
for (int index=0; index<str.length(); index++) {
    // 计算每一个字符的宽度
    char c = str.charAt(index);
    float charWidth = getCharWidth(mTextView, c);
    sumWidth += charWidth;
    Log.d(TAG, "#" + index + ": " + c + ", width=" + charWidth + ", sum=" + sumWidth);
    
    if (sumWidth + dotWidth*3 >= textViewWidth) {
        Log.d(TAG, "TextView shows #" + index + " char: " + str.substring(0, index));
        break;
    }
}

// Dp转Px
private float convertDpToPixel(float dp){
    Resources resources = getResources();
    DisplayMetrics metrics = resources.getDisplayMetrics();
    float px = dp * (metrics.densityDpi / 160f);
    return px;
}

// 计算每一个字符的宽度
public float getCharWidth(TextView textView, char c) {
    textView.setText(String.valueOf(c));
    textView.measure(0, 0);
    return textView.getMeasuredWidth();
}  

结果如下,在荣耀3C和LG G3上测试通过(G3比计算的结果,多显示了一个字符)

10-22 01:17:42.046: D/Text(21495): TextView width 600.0
10-22 01:17:42.048: D/Text(21495): #0: I, width=8.0, sum=8
10-22 01:17:42.049: D/Text(21495): #1: f, width=9.0, sum=17
10-22 01:17:42.049: D/Text(21495): #2:  , width=7.0, sum=24
10-22 01:17:42.049: D/Text(21495): #3: y, width=14.0, sum=38
......
10-22 01:17:42.053: D/Text(21495): #17: t, width=9.0, sum=213
10-22 01:17:42.053: D/Text(21495): #18:  , width=7.0, sum=220
10-22 01:17:42.053: D/Text(21495): #19: t, width=9.0, sum=229
......

10-22 01:17:42.061: D/Text(21495): #50: n, width=16.0, sum=575
10-22 01:17:42.061: D/Text(21495): #51: g, width=16.0, sum=591
10-22 01:17:42.061: D/Text(21495): TextView shows #51 char: If you really want to hear about it, the first thin

就是这样。

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