/**
   * Provides a mapping from the view coordinate space to the logical coordinate space of the model.
   *
   * @param v the view containing the view coordinates
   * @param x the X coordinate
   * @param y the Y coordinate
   * @param a the allocated region to render into
   * @param biasReturn either <code>Position.Bias.Forward</code> or <code>Position.Bias.Backward
   *     </code> is returned as the zero-th element of this array
   * @return the location within the model that best represents the given point of view
   * @see View#viewToModel
   */
  public int viewToModel(GlyphView v, float x, float y, Shape a, Position.Bias[] biasReturn) {

    Rectangle2D alloc = (a instanceof Rectangle2D) ? (Rectangle2D) a : a.getBounds2D();
    // Move the y co-ord of the hit onto the baseline.  This is because TextLayout supports
    // italic carets and we do not.
    TextHitInfo hit = layout.hitTestChar(x - (float) alloc.getX(), 0);
    int pos = hit.getInsertionIndex();

    if (pos == v.getEndOffset()) {
      pos--;
    }

    biasReturn[0] = hit.isLeadingEdge() ? Position.Bias.Forward : Position.Bias.Backward;
    return pos + v.getStartOffset();
  }
  /**
   * 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;
  }