SelectionRectangle.java

package org.swtchart.ext.internal;

import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Point;

/**
 * Selection rectangle with mouse to zoom in/out.
 */
public class SelectionRectangle {

    /** the start point of selection */
    private Point startPoint;

    /** the end point of selection */
    private Point endPoint;

    /**
     * Sets the start point.
     * 
     * @param x
     *            the X coordinate of start point in pixels
     * @param y
     *            the Y coordinate of start point in pixels
     */
    public void setStartPoint(int x, int y) {
        startPoint = new Point(x, y);
    }

    /**
     * Sets the end point.
     * 
     * @param x
     *            the X coordinate of end point in pixels
     * @param y
     *            the X coordinate of end point in pixels
     */
    public void setEndPoint(int x, int y) {
        endPoint = new Point(x, y);
    }

    /**
     * Gets the horizontal selected range.
     * 
     * @return the horizontal selected range in pixels
     */
    public Point getHorizontalRange() {
        if (startPoint == null || endPoint == null) {
            return null;
        }

        return new Point(startPoint.x, endPoint.x);
    }

    /**
     * Gets the vertical selected range.
     * 
     * @return the vertical selected range in pixels
     */
    public Point getVerticalRange() {
        if (startPoint == null || endPoint == null) {
            return null;
        }

        return new Point(startPoint.y, endPoint.y);
    }

    /**
     * Check if selection is disposed.
     * 
     * @return true if selection is disposed.
     */
    public boolean isDisposed() {
        return startPoint == null;
    }

    /**
     * Disposes the resource.
     */
    public void dispose() {
        startPoint = null;
        endPoint = null;
    }

    /**
     * Draws the selection rectangle on chart panel.
     * 
     * @param gc
     *            the graphics context
     */
    public void draw(GC gc) {
        if (startPoint == null || endPoint == null) {
            return;
        }

        int minX;
        int maxX;
        if (startPoint.x > endPoint.x) {
            minX = endPoint.x;
            maxX = startPoint.x;
        } else {
            minX = startPoint.x;
            maxX = endPoint.x;
        }

        int minY;
        int maxY;
        if (startPoint.y > endPoint.y) {
            minY = endPoint.y;
            maxY = startPoint.y;
        } else {
            minY = startPoint.y;
            maxY = endPoint.y;
        }

        gc.drawRectangle(minX, minY, maxX - minX, maxY - minY);
    }

}