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Android Span文本

i小灰 人气:0

1.引言

在开发过程中经常需要使用文本,有时候需要对一段文字中的部分文字进行特殊的处理,如改变其中部分文字的大小、颜色、加下划线等,这个时候使用Span就能方便地解决这些问题。本文将主要介绍SpannableStringBuilder和各种Span的使用。

2.SpannableStringBuilder的基本用法

新建一个SpannableStringBuilder对象的操作如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");

SpannableStringBuilder的setSpan()方法如下:

//what:各种文本Span,如BackgroundColorSpan、ForegroundColorSpan等
//start:应用Span的文本的开始位置索引
//end:应用Span的文本的结束位置索引
//flags:标志
public void setSpan(Object what, int start, int end, int flags) {
    setSpan(true, what, start, end, flags, true/*enforceParagraph*/);
}

3.使用Span给文本添加效果

3.1 AbsoluteSizeSpan

此Span用来改变文本的绝对大小,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new AbsoluteSizeSpan(60),3,9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder); 

3.2 BackgroundColorSpan

此Span用来改变文本的背景颜色大小,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new BackgroundColorSpan(Color.GREEN),3,9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.3 ClickableSpan

此Span用来给文本添加点击效果,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new ClickableSpan() {
    @Override
    public void onClick(@NonNull View widget) {
        Toast.makeText(MainActivity.this,"ClickableSpan",Toast.LENGTH_SHORT).show();
    }
}, 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);
tv_content.setMovementMethod(LinkMovementMethod.getInstance());
tv_content.setHighlightColor(Color.TRANSPARENT);

3.4 DrawableMarginSpan

此Span用来给段落添加drawable和padding,这个padding指的是drawable和文本之间的距离,默认值是0,Span要从文本的起始位置设置,否则Span将不会渲染或者错误地渲染,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
Drawable drawable = AppCompatResources.getDrawable(MainActivity.this,R.drawable.ic_launcher);
builder.setSpan(new DrawableMarginSpan(drawable,30), 0, builder.length(), Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.5 DynamicDrawableSpan

此Span使用drawable替换文本内容,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new DynamicDrawableSpan() {
    @Override
    public Drawable getDrawable() {
       Drawable drawable =             
       AppCompatResources.getDrawable(MainActivity.this,R.drawable.ic_launcher);              
       drawable.setBounds(0,0,drawable.getIntrinsicWidth(),drawable.getIntrinsicHeight());
       return drawable;
    }
}, 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.6 ForegroundColorSpan

此Span可以用来改变文本的颜色,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new ForegroundColorSpan(Color.GREEN), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.7 IconMarginSpan

此Span可以在文本开始的地方添加位图,而且可以在位图和文本之间设置padding,padding的默认值是0px,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
builder.setSpan(new IconMarginSpan(bitmap,30), 0, builder.length(), Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.8 ImageSpan

此Span可以使用Drawable替换文本,创建ImageSpan的构造方法有很多,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new ImageSpan(MainActivity.this,R.drawable.ic_launcher), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.9 MaskFilterSpan

此Span可以给文本设置MaskFilter,例如给文本设置模糊效果,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
MaskFilter maskFilter = new BlurMaskFilter(10f, BlurMaskFilter.Blur.NORMAL);
builder.setSpan(new MaskFilterSpan(maskFilter), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.10 QuoteSpan

此Span可以在文本开始的地方添加一个垂直的线条,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new QuoteSpan(Color.GREEN), 0, builder.length(), Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.11 RelativeSizeSpan

此Span可以按一定的比例缩放文本的大小,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new RelativeSizeSpan(2.0f), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.12 ScaleXSpan

此Span以一定的系数在水平方向缩放文本的大小,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new ScaleXSpan(2.5f), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.13 StrikethroughSpan

此Span可以在文本上添加下划线,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new StrikethroughSpan(), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.14 StyleSpan

此Span可以设置文本的样式,可用的样式有Typeface.NORMAL、Typeface.BOLD、Typeface.ITALIC、Typeface.BOLD_ITALIC,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new StyleSpan(Typeface.BOLD), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.15 SubscriptSpan

此Span可以将文本的基线移动到更低的地方,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new SubscriptSpan(), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.16 SuperscriptSpan

此Span可以将文本的基线移动到更高的地方,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new SuperscriptSpan(), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

3.17 UnderlineSpan()

此Span可以在文本下面添加下划线,示例如下:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new UnderlineSpan(), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

4.多个Span组合使用

Span不但可以单独使用,还可以组合在一起使用,以下示例演示了如何同时加粗文字,改变文字的颜色和添加下滑线:

SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
builder.setSpan(new UnderlineSpan(), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
builder.setSpan(new ForegroundColorSpan(Color.GREEN), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
builder.setSpan(new StyleSpan(Typeface.BOLD), 3, 9, Spannable.SPAN_EXCLUSIVE_INCLUSIVE);
tv_content.setText(builder);

5.总结

Span的功能相当丰富,如改变文本颜色、大小、添加点击效果、加下划线等功能,本文介绍了经常用到的各种Span,Span支持单独使用和组合使用,使用它能够对文本进行各种灵活的操作,去实现个性化的需求。

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