/** {@inheritDoc} */
  @Override
  public void mouseDragged(final MouseEvent aEvent) {
    final MouseEvent event = convertEvent(aEvent);
    final Point point = event.getPoint();

    // Update the selected channel while dragging...
    this.controller.setSelectedChannel(point);

    if (getModel().isCursorMode() && (this.movingCursor >= 0)) {
      this.controller.moveCursor(this.movingCursor, getCursorDropPoint(point));

      aEvent.consume();
    } else {
      if ((this.lastClickPosition == null)
          && ((aEvent.getModifiersEx() & InputEvent.BUTTON1_DOWN_MASK) != 0)) {
        this.lastClickPosition = new Point(point);
      }

      final JScrollPane scrollPane =
          getAncestorOfClass(JScrollPane.class, (Component) aEvent.getSource());
      if ((scrollPane != null) && (this.lastClickPosition != null)) {
        final JViewport viewPort = scrollPane.getViewport();
        final Component signalView = this.controller.getSignalDiagram().getSignalView();

        boolean horizontalOnly = (aEvent.getModifiersEx() & InputEvent.ALT_DOWN_MASK) != 0;
        boolean verticalOnly =
            horizontalOnly && ((aEvent.getModifiersEx() & InputEvent.SHIFT_DOWN_MASK) != 0);

        int dx = aEvent.getX() - this.lastClickPosition.x;
        int dy = aEvent.getY() - this.lastClickPosition.y;

        Point scrollPosition = viewPort.getViewPosition();
        int newX = scrollPosition.x;
        if (!verticalOnly) {
          newX -= dx;
        }
        int newY = scrollPosition.y;
        if (verticalOnly || !horizontalOnly) {
          newY -= dy;
        }

        int diagramWidth = signalView.getWidth();
        int viewportWidth = viewPort.getWidth();
        int maxX = diagramWidth - viewportWidth - 1;
        scrollPosition.x = Math.max(0, Math.min(maxX, newX));

        int diagramHeight = signalView.getHeight();
        int viewportHeight = viewPort.getHeight();
        int maxY = diagramHeight - viewportHeight;
        scrollPosition.y = Math.max(0, Math.min(maxY, newY));

        viewPort.setViewPosition(scrollPosition);
      }

      // Use UNCONVERTED/ORIGINAL mouse event!
      handleZoomRegion(aEvent, this.lastClickPosition);
    }
  }
  /**
   * Calculates the drop point for the cursor under the given coordinate.
   *
   * @param aCoordinate the coordinate to return the channel drop point for, cannot be <code>null
   *     </code>.
   * @return a drop point, never <code>null</code>.
   */
  private Point getCursorDropPoint(final Point aCoordinate) {
    Point dropPoint = new Point(aCoordinate);

    if (getModel().isSnapCursorMode()) {
      final MeasurementInfo signalHover = getModel().getSignalHover(aCoordinate);
      if ((signalHover != null) && !signalHover.isEmpty()) {
        dropPoint.x = signalHover.getMidSamplePos().intValue();
      }
    }
    dropPoint.y = 0;

    return dropPoint;
  }