LinearScale.java revision aca904e29aea542b6e6a4fcc837759a57a270a49 
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        mScale = (mRangeB - mRangeA) / (mDomainB - mDomainA);
38    }
39
40    /**
41     * Clamp a given domain value to the given domain.
42     */
43    public float clamp(float domainValue) {
44        if (mDomainA > mDomainB) {
45            return Math.max(mDomainB, Math.min(mDomainA, domainValue));
46        }
47
48        return Math.max(mDomainA, Math.min(mDomainB, domainValue));
49    }
50
51    /**
52     * Returns true if the value is within the domain.
53     */
54    public boolean isInDomain(float domainValue) {
55        if (mDomainA > mDomainB) {
56            return domainValue >= mDomainA && domainValue <= mDomainB;
57        }
58        return domainValue >= mDomainB && domainValue <= mDomainA;
59    }
60
61    /**
62     * Linearly scale a given domain value into the output range.
63     */
64    public float scale(float domainValue) {
65        return mRangeA + (domainValue - mDomainA) * mScale;
66    }
67
68    /**
69     * For the current domain and range parameters produce a new scale function
70     * that is the inverse of the current scale function.
71     */
72    public LinearScale inverse() {
73        return new LinearScale(mRangeA, mRangeB, mDomainA, mDomainB);
74    }
75}