The RichTextArea control (JDK-8301121), or any custom control that need to render custom text decorations (such as selection blocks, squiggly lines, strike-through lines, to name a few) can benefit from a better public API representing the range.

Currently, the range is represented by an array of PathElements in an undocumented fashion; the reverse engineering shows that it is typically a sequence of [MoveTo,LineTo] for single lines, or [MoveTo,LineTo,LineTo,LineTo, LineTo] for blocks.

One possibility is to add a new method to Text / TextFlow:
  public RangeInfo getRangeInfo(int start, int end, RangeType type)
or possibly
  public RangeInfo getRangeInfo(int start, int end, RangeType type, boolean includeLineSpacing)
to address
JDK-8317120 RFE: TextFlow.rangeShape() ignores lineSpacing
JDK-8317122 RFE: TextFlow.preferredHeight ignores lineSpacing

The RangeInfo class would provide the following data points:
- PathElement[] getRangeShape() // to be used by the legacy rangeShape() method
- PathElement[] getUnderlineShape() // to be used by the legacy underlineShape() method
- PathElement[] getStrikeThroughShape()
- getPartCount // the number of "parts", i.e. lines or rectangular blocks
- getBounds(int part) // the bounds of each part

The RichTextArea requires such a public API in TextFlow only, but we'll basically get the same functionality for Text node for free.

NOTE: this API is somewhat derivative of JDK-8341670 [Text,TextFlow] Public API for Text Layout, it might be possible to roll the requested functionality into LayoutInfo class.