How to implement Superscript & Subscript in Blackberry - blackberry

Question

Does Blackberry support subscript superscript? I found the BlackBerry Forum thread "Subscript and superscript in RichTextField", but I am not able to access the BlackBerry knowledge base article.
How can I implement superscript & subscript in a LabelField?

Answer 1

If there's a problem accessing the BlackBerry knowledge base (i.e. from some countries?), here is the content of that page (posted by #MSohm of RIM):
A RichTextField does not nativly support subscript, superscript or
multiple colours. Multiple fonts, font sizes, and font formatting
(for example, Bold, Italic, Underlined) are supported. The following
links explain this further.
How To - Format text in a RichTextField Article Number: DB-00124
http://supportforums.blackberry.com/t5/Java-Development/Format-text-in-a-RichTextField/ta-p/445038
How To - Change the text color of a field Article Number: DB-00114
http://supportforums.blackberry.com/t5/Java-Development/Change-the-text-color-of-a-field/ta-p/442951
If you still want to do this, you could try subclassing RichTextField, or LabelField, and overriding the paint() method. There, you could change the font size and shift the y coordinate of the text. It depends how generic you want to make the solution. Perhaps you could post more information about your problem?
But, as a very simple, hardcoded example, the following code will create a LabelField that prints out: "CO2"
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);
}
}
And then use it like this:
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);
}
which gives: