1.引言
在開發過程中經常需要使用文本,有時候需要對一段文字中的部分文字進行特殊的處理,如改變其中部分文字的大小、顏色、加下劃線等,這個時候使用Span就能方便地解決這些問題。本文將主要介紹SpannableStringBuilder和各種Span的使用。
2.SpannableStringBuilder的基本用法
新建一個SpannableStringBuilder對象的操作如下:
SpannableStringBuilder builder = new SpannableStringBuilder("Hello World!");
SpannableStringBuilder的setSpan()方法如下:
//what:各種文本Span,如BackgroundColorSpan、ForegroundColorSpan等
//start:應用Span的文本的開始位置索引
//end:應用Span的文本的結束位置索引
//flags:標誌
public void setSpan(Object what, int start, int end, int flags) {
setSpan(true, what, start, end, flags, true/*enforceParagraph*/);
}
3.使用Span給文本添加效果
3.1 AbsoluteSizeSpan
此Span用來改變文本的絕對大小,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用來改變文本的背景顏色大小,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用來給文本添加點擊效果,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用來給段落添加drawable和padding,這個padding指的是drawable和文本之間的距離,默認值是0,Span要從文本的起始位置設置,否則Span將不會渲染或者錯誤地渲染,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替換文本內容,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可以用來改變文本的顏色,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可以在文本開始的地方添加位圖,而且可以在位圖和文本之間設置padding,padding的默認值是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替換文本,創建ImageSpan的構造方法有很多,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可以給文本設置MaskFilter,例如給文本設置模糊效果,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可以在文本開始的地方添加一個垂直的線條,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可以按一定的比例縮放文本的大小,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以一定的係數在水平方向縮放文本的大小,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劃線,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可以設置文本的樣式,可用的樣式有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可以將文本的基線移動到更低的地方,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可以將文本的基線移動到更高的地方,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劃線,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.多個Span組合使用
Span不但可以單獨使用,還可以組合在一起使用,以下示例演示瞭如何同時加粗文字,改變文字的顏色和添加下滑線:
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.總結
Span的功能相當豐富,如改變文本顏色、大小、添加點擊效果、加下劃線等功能,本文介紹了經常用到的各種Span,Span支持單獨使用和組合使用,使用它能夠對文本進行各種靈活的操作,去實現個性化的需求。