Recipe 9.15. Formatting a Portion of Existing Text

Problem

You want to add formatting to some, but not all, text in a text field, or you want to apply different formatting to various parts of a text field.

Solution

Create a TextFormat object and use it to format a substring of the text field by using one of the setTextFormat( ) method variations.

Discussion

You can format an entire text field as shown in Recipe 9.13, or you can use one of the versions of the setTextFormat( ) method to format just a portion of a text field. These variations allow you to apply formatting to the specified character range only.

You can set the formatting for a single character within a text field by invoking the setTextFormat( ) method and passing it two parameters:

index: The zero-relative index of the character to which the formatting should be applied.
textFormat: A reference to a TextFormat object.

This example applies the formatting to the first character only:

field.setTextFormat(0, formatter);

Alternatively, if you want to apply the formatting to a range of characters, you can invoke setTextFormat( ) with three parameters:

startIndex: The beginning, zero-relative character index.
endIndex: The index of the character after the last character in the desired range.
textFormat: A reference to a TextFormat object.

This example applies the formatting to the first 10 characters:

field.setTextFormat(0, 10, formatter);

You may notice that when you try to format portions of a text field, certain formatting options do not get applied under certain circumstances. For example, text alignment is applied only if the formatti ng is applied to the first character in the line.