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/*
* Copyright (C) 2015 The Android Open Source Project
*
* 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.android.camera.ui.focus;
import android.annotation.TargetApi;
import android.hardware.camera2.CameraCharacteristics;
import android.os.Build.VERSION_CODES;
import com.android.camera.ui.motion.LinearScale;
/**
* Compute diopter range scale to convert lens focus distances into
* a ratio value.
*/
@TargetApi(VERSION_CODES.LOLLIPOP)
public class LensRangeCalculator {
/**
* A NoOp linear scale for computing diopter values will always return 0
*/
public static LinearScale getNoOp() {
return new LinearScale(0, 0, 0, 0);
}
/**
* Compute the focus range from the camera characteristics and build
* a linear scale model that maps a focus distance to a ratio between
* the min and max range.
*/
public static LinearScale getDiopterToRatioCalculator(CameraCharacteristics characteristics) {
// From the android documentation:
//
// 0.0f represents farthest focus, and LENS_INFO_MINIMUM_FOCUS_DISTANCE
// represents the nearest focus the device can achieve.
//
// Example:
//
// Infinity Hyperfocal Minimum Camera
// <----------|-----------------------------| |
// [0.0] [0.31] [14.29]
Float nearest = characteristics.get(CameraCharacteristics.LENS_INFO_MINIMUM_FOCUS_DISTANCE);
Float hyperfocal = characteristics.get(CameraCharacteristics.LENS_INFO_HYPERFOCAL_DISTANCE);
if (nearest == null && hyperfocal == null) {
return getNoOp();
}
nearest = (nearest == null) ? 0.0f : nearest;
hyperfocal = (hyperfocal == null) ? 0.0f : hyperfocal;
if (nearest > hyperfocal) {
return new LinearScale(hyperfocal, nearest, 0, 1);
}
return new LinearScale(nearest, hyperfocal, 0, 1);
}
}
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