CircularViewModifier.java

/*
 ********************************************************************************
 * Copyright (c) 2012 Samsung Electronics, Inc.
 * All rights reserved.
 *
 * This software is a confidential and proprietary information of Samsung
 * Electronics, Inc. ("Confidential Information"). You shall not disclose such
 * Confidential Information and shall use it only in accordance with the terms
 * of the license agreement you entered into with Samsung Electronics.
 ********************************************************************************
 */

package com.sprc.circlelauncher.view;

import android.util.FloatMath;
import android.view.View;
import android.widget.AbsListView;
import android.widget.ListView;

/**
 * A simple implementation of the {@link ViewModifier} that rotates the {@link ListView} child {@link View Views} by an
 * angle.
 *
 * @author Artur Stepniewski <a.stepniewsk@samsung.com>
 *
 */
public class CircularViewModifier extends ViewModifier {

	private static final int CIRCLE_OFFSET = 500;
	private static final float DEGTORAD = 1.0f / 180.0f * (float) Math.PI;
	private static final float SCALING_RATIO = 0.001f;
	private static final float TRANSLATION_RATIO = 0.09f;

	@Override
	void applyToView(final View v, final AbsListView parent) {
		final float halfHeight = v.getHeight() * 0.5f;
		final float parentHalfHeight = parent.getHeight() * 0.5f;
		final float y = v.getY();
		final float rot = parentHalfHeight - halfHeight - y;

		v.setPivotX(0.0f);
		v.setPivotY(halfHeight);
		v.setRotation(rot * 0.05f);
		v.setTranslationX((-FloatMath.cos(rot * TRANSLATION_RATIO * DEGTORAD) + 1) * CIRCLE_OFFSET);

		final float scale = 1.0f - Math.abs(parentHalfHeight - halfHeight - y) * SCALING_RATIO;
		v.setScaleX(scale);
		v.setScaleY(scale);
	}
}