/** @see IPainter#deactivate */
 public final void deactivate(final boolean redraw) {
   if (mIsActive) {
     mIsActive = false;
     mTextWidget.removePaintListener(this);
     if (mPositionManager != null) {
       mPositionManager.unmanagePosition(mBracketPosition);
     }
     if (redraw) {
       handleDrawRequest(null);
     }
   }
 }
  private final void draw(final GC gc, final int offset, final int length) {
    if (gc != null) {
      Point left = mTextWidget.getLocationAtOffset(offset);
      Point right = mTextWidget.getLocationAtOffset(offset + length);
      Color color = mMismatch ? mMismatchColor : mColor;

      if (mBox) {
        gc.setForeground(color);
        int x = left.x;
        int y = left.y;
        int w = right.x - left.x - 1;
        int h = gc.getFontMetrics().getHeight();
        gc.drawRectangle(x, y, w, h);
      } else {
        gc.setForeground(mDefaultColor);
        gc.setBackground(color);
        gc.drawString(mTextWidget.getTextRange(offset, 1), left.x, left.y, false);
      }
    } else {
      mTextWidget.redrawRange(offset, length, true);
    }
  }
  /** @see IPainter#paint(int) */
  public final void paint(final int reason) {
    Point selection = mSourceViewer.getSelectedRange();
    if (selection.y > 0) {
      deactivate(true);
      return;
    }

    SexpNavigator explorer = mEditor.getExplorer();

    boolean backward = true;
    boolean closeToParen = false;
    int offset = selection.x;
    IDocument document = mEditor.getDocument();
    try {
      char previousChar = '\0';
      char nextChar = '\0';

      if (selection.x > 0) previousChar = document.getChar(selection.x - 1);

      if (selection.x > 0
          && SchemeScannerUtilities.isClosingParenthesis(previousChar)
          && SchemeTextUtilities.getPartition(document, selection.x - 1).getType()
              == IDocument.DEFAULT_CONTENT_TYPE) {
        closeToParen = true;
      } else {
        nextChar = document.getChar(selection.x);
        if (selection.x < document.getLength() - 1
            && SchemeScannerUtilities.isOpeningParenthesis(nextChar)
            && SchemeTextUtilities.getPartition(document, selection.x).getType()
                == IDocument.DEFAULT_CONTENT_TYPE) {
          closeToParen = true;
          backward = false;
        }
      }

      if (closeToParen && backward && explorer.backwardSexpression(selection.x)) {
        offset = explorer.getListStart();
        char matchingChar = document.getChar(offset);
        mMismatch =
            SchemeScannerUtilities.getParenthesisType(previousChar)
                != SchemeScannerUtilities.getParenthesisType(matchingChar);
      } else {
        if (closeToParen && !backward && explorer.forwardSexpression(selection.x)) {
          offset = explorer.getSexpEnd() - 1;
          char matchingChar = document.getChar(offset);
          mMismatch =
              SchemeScannerUtilities.getParenthesisType(nextChar)
                  != SchemeScannerUtilities.getParenthesisType(matchingChar);
        } else {
          deactivate(true);
          return;
        }
      }

    } catch (BadLocationException exception) {
      deactivate(true);
      return;
    }

    if (mIsActive) {
      // only if different
      if (offset != mBracketPosition.getOffset()) {
        // remove old highlighting
        handleDrawRequest(null);
        // update position
        mBracketPosition.isDeleted = false;
        mBracketPosition.offset = offset;
        mBracketPosition.length = 1;
        // apply new highlighting
        handleDrawRequest(null);
      }
    } else {
      mIsActive = true;

      mBracketPosition.isDeleted = false;
      mBracketPosition.offset = offset;
      mBracketPosition.length = 1;

      mTextWidget.addPaintListener(this);
      mPositionManager.managePosition(mBracketPosition);
      handleDrawRequest(null);
    }
  }