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 
17 package com.android.camera.ui.focus;
18 
19 import android.annotation.TargetApi;
20 import android.hardware.camera2.CameraCharacteristics;
21 import android.os.Build.VERSION_CODES;
22 
23 import com.android.camera.ui.motion.LinearScale;
24 
25 /**
26  * Compute diopter range scale to convert lens focus distances into
27  * a ratio value.
28  */
29 @TargetApi(VERSION_CODES.LOLLIPOP)
30 public class LensRangeCalculator {
31 
32     /**
33      * A NoOp linear scale for computing diopter values will always return 0
34      */
getNoOp()35     public static LinearScale getNoOp() {
36         return new LinearScale(0, 0, 0, 0);
37     }
38 
39     /**
40      * Compute the focus range from the camera characteristics and build
41      * a linear scale model that maps a focus distance to a ratio between
42      * the min and max range.
43      */
getDiopterToRatioCalculator(CameraCharacteristics characteristics)44     public static LinearScale getDiopterToRatioCalculator(CameraCharacteristics characteristics) {
45         // From the android documentation:
46         //
47         // 0.0f represents farthest focus, and LENS_INFO_MINIMUM_FOCUS_DISTANCE
48         // represents the nearest focus the device can achieve.
49         //
50         // Example:
51         //
52         // Infinity    Hyperfocal                 Minimum   Camera
53         //  <----------|-----------------------------|         |
54         // [0.0]     [0.31]                       [14.29]
55         Float nearest = characteristics.get(CameraCharacteristics.LENS_INFO_MINIMUM_FOCUS_DISTANCE);
56         Float hyperfocal = characteristics.get(CameraCharacteristics.LENS_INFO_HYPERFOCAL_DISTANCE);
57 
58         if (nearest == null && hyperfocal == null) {
59             return getNoOp();
60         }
61 
62         nearest = (nearest == null) ? 0.0f : nearest;
63         hyperfocal = (hyperfocal == null) ? 0.0f : hyperfocal;
64 
65         if (nearest > hyperfocal) {
66             return new LinearScale(hyperfocal, nearest, 0, 1);
67         }
68 
69         return new LinearScale(nearest, hyperfocal, 0, 1);
70     }
71 }
72