Better ZoomChart zooming

public void mouseDragged(final MouseEvent e) {
        if (this.m_lastPressedButton != MouseEvent.BUTTON1) {
            return;
        }

        double x;   // Rectangle start x without chart bounds
        double y;   // Rectangle start y without chart bounds
        double x2;  // Rectangle end x without chart bounds
        double y2;  // Rectangle end y without chart bounds
        double startX;
        double endX;
        double dimX;
        double dimY;
        double startY;
        double endY;
        double chartStartX = this.getXChartStart();
        double chartEndX = this.getXChartEnd();
        // Switched these around because I think the window's top as y starting coordinates
        double chartStartY = this.getYChartEnd();
        double chartEndY = this.getYChartStart();

        // Checking which coordinates will be rectangles starting and ending points
        x = Math.min(this.m_startPoint.getX(), e.getX());
        x2 = Math.max(this.m_startPoint.getX(), e.getX());
        y = Math.min(this.m_startPoint.getY(), e.getY());
        y2 = Math.max(this.m_startPoint.getY(), e.getY());


        // Bounding rectangle to chart area only
        // x-coordinate
        startX = Math.min(chartEndX, x);
        startX = Math.max(chartStartX, startX);
        endX = Math.min(chartEndX, x2);
        endX = Math.max(chartStartX, endX);

        // y-coordinate
        startY = Math.min(chartEndY, y);
        startY = Math.max(chartStartY, startY);
        endY = Math.min(chartEndY, y2);
        endY = Math.max(chartStartY, endY);


        dimX = endX - startX;
        dimY = endY - startY;

        this.m_zoomArea = new Rectangle2D.Double(startX, startY, dimX, dimY);

        this.setRequestedRepaint(true);
  }