今天在项目中遇到一个问题:在一段文字如果超过3行就将文件阶段并在第三行结尾显示 ...阅读全文
这个要怎么去处理呢,使用 TextView 去处理结尾只能是 ...
啊. 更何况 阅读全文
我还要去做点击事件,点击后展示全文.这个要怎么去处理呢?
思考好久无果,突然灵光一闪,那么 TextView.ellipsize()
是怎么处理的呢?
if (singleLine && getKeyListener() == null && ellipsize < 0) {
ellipsize = 3; // END
}
switch (ellipsize) {
case 1:
setEllipsize(TextUtils.TruncateAt.START);
break;
case 2:
setEllipsize(TextUtils.TruncateAt.MIDDLE);
break;
case 3:
setEllipsize(TextUtils.TruncateAt.END);
break;
case 4:
if (ViewConfiguration.get(context).isFadingMarqueeEnabled()) {
setHorizontalFadingEdgeEnabled(true);
mMarqueeFadeMode = MARQUEE_FADE_NORMAL;
} else {
setHorizontalFadingEdgeEnabled(false);
mMarqueeFadeMode = MARQUEE_FADE_SWITCH_SHOW_ELLIPSIS;
}
setEllipsize(TextUtils.TruncateAt.MARQUEE);
break;
}
这里对传递进来的 ellipsize 进行分类,这里我只看为 END 时:
public void setEllipsize(TextUtils.TruncateAt where) {
// TruncateAt is an enum. != comparison is ok between these singleton objects.
if (mEllipsize != where) {
mEllipsize = where;
if (mLayout != null) {
nullLayouts();
requestLayout();
invalidate();
}
}
}
这里看到将值传递给了 mEllipsize
并且 shouldEllipsize = mEllipsize != null;
传递给了 shouldEllipsize
;
继续看下竟然都是使用了 TextUtils.ellipsize()
方法
来来我们在看看 TextUtils.ellipsize()
是干了什么
/**
* Returns the original text if it fits in the specified width
* given the properties of the specified Paint,
* or, if it does not fit, a copy with ellipsis character added
* at the specified edge or center.
* If <code>preserveLength</code> is specified, the returned copy
* will be padded with zero-width spaces to preserve the original
* length and offsets instead of truncating.
* If <code>callback</code> is non-null, it will be called to
* report the start and end of the ellipsized range. TextDirection
* is determined by the first strong directional character.
*/
public static CharSequence ellipsize(CharSequence text,
TextPaint paint,
float avail, TruncateAt where,
boolean preserveLength,
EllipsizeCallback callback) {
return ellipsize(text, paint, avail, where, preserveLength, callback,
TextDirectionHeuristics.FIRSTSTRONG_LTR,
(where == TruncateAt.END_SMALL) ? ELLIPSIS_TWO_DOTS_STRING : ELLIPSIS_STRING);
}
/**
* Returns the original text if it fits in the specified width
* given the properties of the specified Paint,
* or, if it does not fit, a copy with ellipsis character added
* at the specified edge or center.
* If <code>preserveLength</code> is specified, the returned copy
* will be padded with zero-width spaces to preserve the original
* length and offsets instead of truncating.
* If <code>callback</code> is non-null, it will be called to
* report the start and end of the ellipsized range.
*
* @hide
*/
public static CharSequence ellipsize(CharSequence text,
TextPaint paint,
float avail, TruncateAt where,
boolean preserveLength,
EllipsizeCallback callback,
TextDirectionHeuristic textDir, String ellipsis) {
int len = text.length();
MeasuredText mt = MeasuredText.obtain();
try {
float width = setPara(mt, paint, text, 0, text.length(), textDir);
if (width <= avail) {
if (callback != null) {
callback.ellipsized(0, 0);
}
return text;
}
// XXX assumes ellipsis string does not require shaping and
// is unaffected by style
float ellipsiswid = paint.measureText(ellipsis);
avail -= ellipsiswid;
int left = 0;
int right = len;
if (avail < 0) {
// it all goes
} else if (where == TruncateAt.START) {
right = len - mt.breakText(len, false, avail);
} else if (where == TruncateAt.END || where == TruncateAt.END_SMALL) {
left = mt.breakText(len, true, avail);
} else {
right = len - mt.breakText(len, false, avail / 2);
avail -= mt.measure(right, len);
left = mt.breakText(right, true, avail);
}
if (callback != null) {
callback.ellipsized(left, right);
}
char[] buf = mt.mChars;
Spanned sp = text instanceof Spanned ? (Spanned) text : null;
int remaining = len - (right - left);
if (preserveLength) {
if (remaining > 0) { // else eliminate the ellipsis too
buf[left++] = ellipsis.charAt(0);
}
for (int i = left; i < right; i++) {
buf[i] = ZWNBS_CHAR;
}
String s = new String(buf, 0, len);
if (sp == null) {
return s;
}
SpannableString ss = new SpannableString(s);
copySpansFrom(sp, 0, len, Object.class, ss, 0);
return ss;
}
if (remaining == 0) {
return "";
}
if (sp == null) {
StringBuilder sb = new StringBuilder(remaining + ellipsis.length());
sb.append(buf, 0, left);
sb.append(ellipsis);
sb.append(buf, right, len - right);
return sb.toString();
}
SpannableStringBuilder ssb = new SpannableStringBuilder();
ssb.append(text, 0, left);
ssb.append(ellipsis);
ssb.append(text, right, len);
return ssb;
} finally {
MeasuredText.recycle(mt);
}
}
代码写的简单明了,不过我在来说一下吧:
先看传递进来的参数是用来干什么的:
参数 | 作用 |
---|---|
CharSequence text | 完整的文字 |
TextPaint paint | TextView 的 paint 你可以使用 TextView.getPaint() 来获取 |
float avail | 你显示区域的的宽度需要将 Padding 和 margin 减去 |
TruncateAt where | 如何删减(这里是 TextUtils 中的枚举类) |
boolean preserveLength | 返回被截取后的文字还是在控件中的容纳的文字 |
EllipsizeCallback callback | 回调返回截取开始和结束位置 |
TextDirectionHeuristic textDir | 我没搞懂,好像表示是截取的方向,正序还是倒叙??(被隐藏) |
String ellipsis | 省略的符号默认 ... 和 .. (被隐藏) |
剩下的就好解决了,方法有了那就开始实现功能了.
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