1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.camera.ui.motion;
18
19/**
20 * Represents a discrete linear scale function.
21 */
22public final class LinearScale {
23    private final float mDomainA;
24    private final float mDomainB;
25    private final float mRangeA;
26    private final float mRangeB;
27
28    private final float mScale;
29
30    public LinearScale(float domainA, float domainB, float rangeA, float rangeB) {
31        mDomainA = domainA;
32        mDomainB = domainB;
33        mRangeA = rangeA;
34        mRangeB = rangeB;
35
36        // Precomputed ratio between input domain and output range.
37        float scale = (mRangeB - mRangeA) / (mDomainB - mDomainA);
38        mScale = Float.isNaN(scale) ? 0.0f : scale;
39    }
40
41    /**
42     * Clamp a given domain value to the given domain.
43     */
44    public float clamp(float domainValue) {
45        if (mDomainA > mDomainB) {
46            return Math.max(mDomainB, Math.min(mDomainA, domainValue));
47        }
48
49        return Math.max(mDomainA, Math.min(mDomainB, domainValue));
50    }
51
52    /**
53     * Returns true if the value is within the domain.
54     */
55    public boolean isInDomain(float domainValue) {
56        if (mDomainA > mDomainB) {
57            return domainValue <= mDomainA && domainValue >= mDomainB;
58        }
59        return domainValue >= mDomainA && domainValue <= mDomainB;
60    }
61
62    /**
63     * Linearly scale a given domain value into the output range.
64     */
65    public float scale(float domainValue) {
66        return mRangeA + (domainValue - mDomainA) * mScale;
67    }
68
69    /**
70     * For the current domain and range parameters produce a new scale function
71     * that is the inverse of the current scale function.
72     */
73    public LinearScale inverse() {
74        return new LinearScale(mRangeA, mRangeB, mDomainA, mDomainB);
75    }
76
77    @Override
78    public String toString() {
79        return "LinearScale{" +
80              "mDomainA=" + mDomainA +
81              ", mDomainB=" + mDomainB +
82              ", mRangeA=" + mRangeA +
83              ", mRangeB=" + mRangeB + "}";
84    }
85}