基于String中语言的TextView自定义字体 [英] Custom fonts for TextView based on languages inside String

问题描述

基于String中的语言，我有两个必须在TextView上应用的字体ttf文件.所以考虑以下示例文本:

I have two font ttf files that must be applied on a TextView based on languages inside String. So e.g. consider this sample text:

嘿，怎么了ضعيف

hey what's up ضعيف

我可以应用字体跨度基于语言，但是它需要在从我们的服务器中获取的每个字符串中进行自定义标记，例如

I can just apply a typeface span based on language but it requires custom markup in every string that is fetched from our server e.g.

 <ttf1>hey what's up <ttf1><ttf2>ضعيف</ttf2>

，并且在运行时解析每个String都会对性能产生影响.还有其他方法可以实现这一目标吗?

And parsing every String at run time will give a performance hit. Is there any other approach to achieve this?

首先要说的是我只需要针对文本的方向(即RTL和LTR)执行此操作，因此在上面的示例中，英语是LTR，阿拉伯语是RTL.这会有所不同吗?

For start lets say I need to do this just for direction of text i.e. RTL and LTR so in above example English is LTR and Arabic is RTL. Will this be any different?

我曾尝试合并这两个字体文件，但是存在行高问题，如果我将其修复为一个字体文件，则其他文件会损坏.

I have tried merging those two font files but there are line height issues and if I fix it for one font file it gets broken for other file.

推荐答案

在某人的帮助下，我发现了比手动标记更优雅的解决方案:

I found a more elegant solution than manual markup with help of someone:

String paragraph = "hey what's up ضعيف";
int NO_FLAG = 0;
Bidi bidi = new Bidi(paragraph, NO_FLAG);
int runCount = bidi.getRunCount();
for (int i = 0; i < runCount; i++) {
    String ltrtl = bidi.getRunLevel(i) % 2 == 0 ? "ltr" : "rtl";
    String subString = paragraph.substring(bidi.getRunStart(i), bidi.getRunLimit(i));
    Log.d(">>bidi:" + i,  subString+" is "+ltrtl);
}

打印:

嘿，这是ltr

hey what's up is ltr

ضعيف是rtl

因此，现在人们可以像这样根据语言方向轻松构建TypefaceSpan或MetricAffectingSpan:

So now one can easily build TypefaceSpan or MetricAffectingSpan based on language direction like this:

SpannableString spanString = new SpannableString(paragraph);
for (int i = 0; i < runCount; i++) {
    Object span = bidi.getRunLevel(i) % 2 == 0 ? ltrFontSpan : rtlFontSpan;
    spanString.setSpan(span, bidi.getRunStart(i), bidi.getRunLimit(i), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE); 
}
textView.setText(spanString);

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