public Shape modelToView(GlyphView v, int pos, Position.Bias bias, Shape a)
      throws BadLocationException {
    int offs = pos - v.getStartOffset();
    Rectangle2D alloc = a.getBounds2D();
    TextHitInfo hit =
        (bias == Position.Bias.Forward)
            ? TextHitInfo.afterOffset(offs)
            : TextHitInfo.beforeOffset(offs);
    float[] locs = layout.getCaretInfo(hit);

    // vertical at the baseline, should use slope and check if glyphs
    // are being rendered vertically.
    alloc.setRect(alloc.getX() + locs[0], alloc.getY(), 1, alloc.getHeight());
    return alloc;
  }
  /**
   * Determine the span the glyphs given a start location (for tab expansion). This implementation
   * assumes it has no tabs (i.e. TextLayout doesn't deal with tab expansion).
   */
  public float getSpan(GlyphView v, int p0, int p1, TabExpander e, float x) {

    if ((p0 == v.getStartOffset()) && (p1 == v.getEndOffset())) {
      return layout.getAdvance();
    }
    int p = v.getStartOffset();
    int index0 = p0 - p;
    int index1 = p1 - p;

    TextHitInfo hit0 = TextHitInfo.afterOffset(index0);
    TextHitInfo hit1 = TextHitInfo.beforeOffset(index1);
    float[] locs = layout.getCaretInfo(hit0);
    float x0 = locs[0];
    locs = layout.getCaretInfo(hit1);
    float x1 = locs[0];
    return (x1 > x0) ? x1 - x0 : x0 - x1;
  }
  /**
   * Provides a way to determine the next visually represented model location that one might place a
   * caret. Some views may not be visible, they might not be in the same order found in the model,
   * or they just might not allow access to some of the locations in the model.
   *
   * @param v the view to use
   * @param pos the position to convert >= 0
   * @param a the allocated region to render into
   * @param direction the direction from the current position that can be thought of as the arrow
   *     keys typically found on a keyboard. This may be SwingConstants.WEST, SwingConstants.EAST,
   *     SwingConstants.NORTH, or SwingConstants.SOUTH.
   * @return the location within the model that best represents the next location visual position.
   * @exception BadLocationException
   * @exception IllegalArgumentException for an invalid direction
   */
  public int getNextVisualPositionFrom(
      GlyphView v, int pos, Position.Bias b, Shape a, int direction, Position.Bias[] biasRet)
      throws BadLocationException {

    int startOffset = v.getStartOffset();
    int endOffset = v.getEndOffset();
    Segment text;
    AbstractDocument doc;
    boolean viewIsLeftToRight;
    TextHitInfo currentHit, nextHit;

    switch (direction) {
      case View.NORTH:
        break;
      case View.SOUTH:
        break;
      case View.EAST:
        doc = (AbstractDocument) v.getDocument();
        viewIsLeftToRight = doc.isLeftToRight(startOffset, endOffset);

        if (startOffset == doc.getLength()) {
          if (pos == -1) {
            biasRet[0] = Position.Bias.Forward;
            return startOffset;
          }
          // End case for bidi text where newline is at beginning
          // of line.
          return -1;
        }
        if (pos == -1) {
          // Entering view from the left.
          if (viewIsLeftToRight) {
            biasRet[0] = Position.Bias.Forward;
            return startOffset;
          } else {
            text = v.getText(endOffset - 1, endOffset);
            char c = text.array[text.offset];
            SegmentCache.releaseSharedSegment(text);
            if (c == '\n') {
              biasRet[0] = Position.Bias.Forward;
              return endOffset - 1;
            }
            biasRet[0] = Position.Bias.Backward;
            return endOffset;
          }
        }
        if (b == Position.Bias.Forward) currentHit = TextHitInfo.afterOffset(pos - startOffset);
        else currentHit = TextHitInfo.beforeOffset(pos - startOffset);
        nextHit = layout.getNextRightHit(currentHit);
        if (nextHit == null) {
          return -1;
        }
        if (viewIsLeftToRight != layout.isLeftToRight()) {
          // If the layout's base direction is different from
          // this view's run direction, we need to use the weak
          // carrat.
          nextHit = layout.getVisualOtherHit(nextHit);
        }
        pos = nextHit.getInsertionIndex() + startOffset;

        if (pos == endOffset) {
          // A move to the right from an internal position will
          // only take us to the endOffset in a left to right run.
          text = v.getText(endOffset - 1, endOffset);
          char c = text.array[text.offset];
          SegmentCache.releaseSharedSegment(text);
          if (c == '\n') {
            return -1;
          }
          biasRet[0] = Position.Bias.Backward;
        } else {
          biasRet[0] = Position.Bias.Forward;
        }
        return pos;
      case View.WEST:
        doc = (AbstractDocument) v.getDocument();
        viewIsLeftToRight = doc.isLeftToRight(startOffset, endOffset);

        if (startOffset == doc.getLength()) {
          if (pos == -1) {
            biasRet[0] = Position.Bias.Forward;
            return startOffset;
          }
          // End case for bidi text where newline is at beginning
          // of line.
          return -1;
        }
        if (pos == -1) {
          // Entering view from the right
          if (viewIsLeftToRight) {
            text = v.getText(endOffset - 1, endOffset);
            char c = text.array[text.offset];
            SegmentCache.releaseSharedSegment(text);
            if ((c == '\n') || Character.isSpaceChar(c)) {
              biasRet[0] = Position.Bias.Forward;
              return endOffset - 1;
            }
            biasRet[0] = Position.Bias.Backward;
            return endOffset;
          } else {
            biasRet[0] = Position.Bias.Forward;
            return startOffset;
          }
        }
        if (b == Position.Bias.Forward) currentHit = TextHitInfo.afterOffset(pos - startOffset);
        else currentHit = TextHitInfo.beforeOffset(pos - startOffset);
        nextHit = layout.getNextLeftHit(currentHit);
        if (nextHit == null) {
          return -1;
        }
        if (viewIsLeftToRight != layout.isLeftToRight()) {
          // If the layout's base direction is different from
          // this view's run direction, we need to use the weak
          // carrat.
          nextHit = layout.getVisualOtherHit(nextHit);
        }
        pos = nextHit.getInsertionIndex() + startOffset;

        if (pos == endOffset) {
          // A move to the left from an internal position will
          // only take us to the endOffset in a right to left run.
          text = v.getText(endOffset - 1, endOffset);
          char c = text.array[text.offset];
          SegmentCache.releaseSharedSegment(text);
          if (c == '\n') {
            return -1;
          }
          biasRet[0] = Position.Bias.Backward;
        } else {
          biasRet[0] = Position.Bias.Forward;
        }
        return pos;
      default:
        throw new IllegalArgumentException("Bad direction: " + direction);
    }
    return pos;
  }