BeamRules.java

package com.xenoage.zong.musiclayout.notator.beam.lines;

import static com.xenoage.zong.musiclayout.notator.beam.lines.Beam128thRules.beam128thRules;
import static com.xenoage.zong.musiclayout.notator.beam.lines.Beam16thRules.beam16thRules;
import static com.xenoage.zong.musiclayout.notator.beam.lines.Beam32ndRules.beam32ndRules;
import static com.xenoage.zong.musiclayout.notator.beam.lines.Beam64thRules.beam64thRules;
import static com.xenoage.zong.musiclayout.notator.beam.lines.Beam8thRules.beam8thRules;
import static java.lang.Math.min;

import com.xenoage.zong.core.music.beam.Beam;
import com.xenoage.zong.musiclayout.notation.BeamNotation;

/**
 * Beam rules, dependent on the number of beam lines.
 * 
 * @author Andreas Wenger
 */
public abstract class BeamRules {
	
	private static BeamRules[] allBeamRules = { beam8thRules, beam16thRules,
		beam32ndRules, beam64thRules, beam128thRules };
	
	/**
	 * Gets the appropriate {@link BeamRules} for the given {@link Beam}.
	 */
	public static BeamRules getRules(Beam beam) {
		return getRules(beam.getMaxLinesCount());
	}

	/**
	 * Gets the appropriate {@link BeamRules} for a{@link Beam} with the given
	 * maximum number of beam lines.
	 */
	public static BeamRules getRules(int maxBeamLinesCount) {
		return allBeamRules[min(maxBeamLinesCount - 1, allBeamRules.length - 1)];
	}
	
	/**
	 * Gets the maximum number of beam lines, e.g. 1 for a beam
	 * which contains at maximum 8th notes, 2 for 16th notes and so on.
	 */
	public abstract int getBeamLinesCount();
	
	/**
	 * Gets the minimum absolute length of a stem in IS,
	 * from the outermost note at the stem side up to
	 * the end of the stem.
	 */
	public abstract float getMinimumStemLengthIs();

	/**
	 * Returns the vertical distance between two beam lines in IS, that is
	 * the "white space" between two beam lines.
	 * Normally this is {@link BeamNotation#normalGapIs}, but it can be up to
	 * {@link BeamNotation#largeGapIs} for a beam with more than three lines.
	 */
	public abstract float getGapIs();
	
	/**
	 * Like {@link #getGapIs()}, but for beams with four or more lines
	 * at the special case when only up to three beam lines fall inside the staff.
	 * See Ross, p. 126, at the top.
	 */
	public float getGapOutsideStaffIs() {
		return getGapIs();
	}
	
}