#49 Fixed bar width

[yoshitaka]

In current design, bar width can be configured only by setting a padding between bars in percentage of bar interval.

It should be also possible to configure the bar width with a fixed value in pixels.

[yoshitaka]

The bar axis width can be configured with certain pixel width with following APIs.

public interface IBarSeries extends ISeries {

    /**
     * Bar width style.
     */
    public enum BarWidthStyle {

        /** the style stretching the bar width depending on interval of bars. */
        STRETCHED,

        /** the style fixing the bar width regardless of interval of bars. */
        FIXED;
    }

    /**
     * Gets the bar width style.
     * 
     * @param style
     *            the bar width style
     * @return the bar width style
     */
    BarWidthStyle getBarWidthStyle(BarWidthStyle style);

    /**
     * Sets the bar width style. The default is <tt>BarWidthStyle.STRETCHED</tt>
     * .
     * 
     * @param style
     *            the bar width style
     */
    void setBarWidthStyle(BarWidthStyle style);

    /**
     * Gets the bar width in pixels.
     * 
     * @return the bar width in pixels
     */
    int getBarWidth();

    /**
     * Sets the bar width in pixels. The specified bar width is active only when
     * the bar width style is set to <tt>BarWidthStyle.FIXED</tt>.
     * 
     * @param width
     *            the bar width in pixels
     */
    void setBarWidth(int width);
}