如何实现上标＆amp; Blackberry的下标

Question

Blackberry支持下标吗？我找到了BlackBerry论坛帖子"Subscript and superscript in RichTextField"，但我无法访问BlackBerry知识库文章。 我怎样才能实现上标＆amp; LabelField中的下标？

Answer 1

如果访问BlackBerry知识库（即来自某些国家/地区？）时出现问题，则该页面的内容（由@MSohm of RIM发布）：

  

RichTextField不能本地支持下标，上标或   多种颜色。多种字体，字体大小和字体格式   （例如，Bold，Italic，Underlined）受支持。下列   链接进一步解释了这一点。

     

操作方法 - 格式化RichTextField中的文本产品编号：DB-00124
  http://supportforums.blackberry.com/t5/Java-Development/Format-text-in-a-RichTextField/ta-p/445038

     

操作方法 - 更改字段的文本颜色产品编号：DB-00114
  http://supportforums.blackberry.com/t5/Java-Development/Change-the-text-color-of-a-field/ta-p/442951

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如果您仍想执行此操作，可以尝试继承RichTextField或LabelField，并覆盖paint()方法。在那里，您可以更改字体大小并移动文本的y坐标。这取决于您想要制定解决方案的通用程度。也许您可以发布有关您的问题的更多信息？

但是，作为一个非常简单的硬编码示例，以下代码将创建一个打印出来的LabelField：“ CO ₂ “

   private class SubscriptLabelField extends LabelField {

      private int _subscriptTop = 0;
      private int _subscriptFontSize = 0;

      public SubscriptLabelField(Object text, long style) {
         super(text, style);
         setFont(getFont());
      }

      public void setFont(Font newFont) {
         super.setFont(newFont);        

         // we use a subscript that's located at half the normal font's height,
         //   and is 2/3 as tall as the normal font
         int h = newFont.getHeight();
         _subscriptTop = h / 2;
         _subscriptFontSize = 2 * h / 3;
         super.invalidate();
      }

      protected void layout(int width, int height) {
         super.layout(width, height);

         // add more space at the bottom for the subscript
         int w = getExtent().width;
         int h = getExtent().height;
         int extraHeight = _subscriptFontSize - (getFont().getHeight() - _subscriptTop);
         setExtent(w, h + extraHeight);
      }

      public void paint(Graphics g) {
         // here we hardcode this method to simply draw the last char
         //  as a "subscript"
         String text = getText();
         String normalText = text.substring(0, text.length() - 1);
         g.drawText(normalText, 0, 0);

         // how much space will the normal text take up, horizontally?
         int advance = g.getFont().getAdvance(normalText);

         // make the subscript a smaller font
         Font oldFont = g.getFont();
         Font subscript = getFont().derive(Font.PLAIN, _subscriptFontSize);
         g.setFont(subscript);
         String subscriptText = text.substring(text.length() - 1);
         g.drawText(subscriptText, advance, _subscriptTop);

         // reset changes to graphics object just to be safe
         g.setFont(oldFont);
      }
   }

然后像这样使用它：

public SubscriptScreen() {
   super(MainScreen.VERTICAL_SCROLL | MainScreen.VERTICAL_SCROLLBAR);

   SubscriptLabelField textField = new SubscriptLabelField("C02", LabelField.NON_FOCUSABLE);

   // TODO: this line is just to show the adjusted boundaries of the field -> remove!
   textField.setBackground(BackgroundFactory.createSolidBackground(Color.LIGHTGRAY));

   add(textField);
}

给出：