sketcher2/src/com/jotuntech/sketcher/client/Smoother.java

package com.jotuntech.sketcher.client;

import java.util.ArrayList;
import java.util.List;

import com.jotuntech.sketcher.common.Input;

/**
 * Static singleton for input interpolation.
 *
 * @author Thor Harald Johansen
 */
public class Smoother {
	/* Smoothing threshold */
	private static float threshold = 4f;
	private static float smoothness = 1.5f;
	private static boolean enabled = true;

	Input[] cursor = new Input[] {new Input(), new Input(), new Input()};

	/**
	 * Sets all points to given input
	 * @param d input to add.
	 */

	public void set(Input d) {
		cursor[0] = d;
		cursor[1] = cursor[0];
		cursor[2] = cursor[1];
	}

	public void setPressure(int pressure) {
		//cursor[0].pressure = pressure;
		//cursor[1].pressure = pressure;
		//cursor[2].pressure = pressure;
	}

	/**
	 * Adds a new input for smoothing.
	 *
	 * @param d input to add.
	 */

	public void add(Input d) {
		float dx = d.x - cursor[2].x;
		float dy = d.y - cursor[2].y;
		float dd = d.pressure - cursor[2].pressure;

		float h = (float)Math.hypot(dx, dy);

		float d2 = h - smoothness;

		if(d2 > 0) {
			float sx = dx * d2 / h;
			float sy = dy * d2 / h;
			float sd = dd * d2 / h;

			cursor[0] = cursor[1];
			cursor[1] = cursor[2];
			cursor[2] = new Input(cursor[2].x + sx, cursor[2].y + sy, (int)(cursor[2].pressure + sd));
		}
	}

	/**
	 * Return a list of smoothed inputs.
	 *
	 * @return List of smoothed inputs.
	 */

	public List<Input> get() {
		/* Create list for inputs. */
		List<Input> inputs = new ArrayList<Input>();

		if(enabled) {
			/* Segment cursor. */
			segment(inputs, cursor[0], cursor[1], cursor[2]);
		} else {
			inputs.add(cursor[2]);
		}

		return inputs;
	}

	public Input getIndex(int index) {
		return cursor[index];
	}

	// uses a, b and c to interpolate inputs between b and c, store in inputs.
	void segment(List<Input> inputs, Input a, Input b, Input c) {
		// difference AB & BC
		Input dab = a.difference(b);
		Input dbc = b.difference(c);

		// magnitude AB & BC
		float mab = (float)Math.hypot(dab.x, dab.y);
		float mbc = (float)Math.hypot(dbc.x, dbc.y);

		// orientation AB & BC
		float oab = (float)Math.acos(dab.x / mab) * (dab.y < 0 ? -1 : 1);
		float obc = (float)Math.acos(dbc.x / mbc) * (dbc.y < 0 ? -1 : 1);

		// normalize
		if(obc - oab > Math.PI || obc - oab < -Math.PI) {
			obc -= Math.PI * 2;
		}

		// angle ABC
		float abc = Math.abs(obc - oab);

		// threshold of operation
		if(mbc * abc > threshold && abc < Math.PI / 2) {
			// three-quarter of angle ABC
			float angle = (oab + (obc * 3)) / 4;

			// half of magnitude BC
			Input d = new Input(b.x + ((float)Math.cos(angle) * mbc / 2), b.y
					+ ((float)Math.sin(angle) * mbc / 2), (b.pressure + c.pressure) / 2);

			segment(inputs, a, b, d);
			inputs.add(d);
			segment(inputs, b, d, c);
		} else {
			inputs.add(c);
		}
	}

	public static void setThreshold(float threshold) {
		Smoother.threshold = threshold;
	}

	public static float getThreshold() {
		return threshold;
	}

	public static void setSmoothness(float smoothness) {
		Smoother.smoothness = smoothness;
	}

	public static float getSmoothness() {
		return smoothness;
	}

	public static void setEnabled(boolean enabled) {
		Smoother.enabled = enabled;
	}

	public static boolean isEnabled() {
		return enabled;
	}
}