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