ShadowWidth.java

/*
 * Copyright (C) 2016 eschao <esc.chao@gmail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.eschao.android.widget.pageflip;

/**
 * Shadow width
 *
 * @author eschao
 */

final class ShadowWidth {

    // minimal shadow width
    float mMin;

    // maximal shadow width
    float mMax;

    // the shadow width ratio based on fold cylinder radius
    // shadow width will be dynamically computed upon fold cylinder radius
    float mRatio;

    public ShadowWidth(float min, float max, float ratio) {
        set(min, max, ratio);
    }

    /**
     * Set minimal, maximal and ratio value of shadow width
     *
     * @param min minimal value
     * @param max maximal value
     * @param ratio width ratio based on fold cylinder radius
     */
    public void set(float min, float max, float ratio) {
        if (min < 0 || max < 0 || min > max ||
            ratio <= 0 || ratio > 1) {
            throw new IllegalArgumentException("One of Min(" + min + ") Max(" +
                                               max + ") Ration(" + ratio + ")" +
                                               "is invalid!");
        }

        mMin = min;
        mMax = max;
        mRatio = ratio;
    }

    /**
     * Compute shadow width upon fold cylinder radius
     * <p>if width is out of (min, max), one of them will be returned</p>
     *
     * @param r fold cylinder radius
     * @return shadow width
     */
    public float width(float r) {
        float w = r * mRatio;
        if (w < mMin) {
            return mMin;
        }
        else if (w > mMax) {
            return mMax;
        }
        else {
            return w;
        }
    }
}