Java tutorial
/* * Copyright (C) 2014 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 android.hardware.camera2.params; import static com.android.internal.util.Preconditions.*; import android.hardware.camera2.CameraMetadata; import android.hardware.camera2.utils.HashCodeHelpers; import android.util.Rational; import java.util.Arrays; /** * Immutable class for describing a 3x3 matrix of {@link Rational} values in row-major order. * * <p>This matrix maps a transform from one color space to another. For the particular color space * source and target, see the appropriate camera metadata documentation for the key that provides * this value.</p> * * @see CameraMetadata */ public final class ColorSpaceTransform { /** The number of rows in this matrix. */ private static final int ROWS = 3; /** The number of columns in this matrix. */ private static final int COLUMNS = 3; /** The number of total Rational elements in this matrix. */ private static final int COUNT = ROWS * COLUMNS; /** Number of int elements in a rational. */ private static final int RATIONAL_SIZE = 2; /** Numerator offset inside a rational (pair). */ private static final int OFFSET_NUMERATOR = 0; /** Denominator offset inside a rational (pair). */ private static final int OFFSET_DENOMINATOR = 1; /** Number of int elements in this matrix. */ private static final int COUNT_INT = ROWS * COLUMNS * RATIONAL_SIZE; /** * Create a new immutable {@link ColorSpaceTransform} instance from a {@link Rational} array. * * <p>The elements must be stored in a row-major order.</p> * * @param elements An array of {@code 9} elements * * @throws IllegalArgumentException * if the count of {@code elements} is not {@code 9} * @throws NullPointerException * if {@code elements} or any sub-element is {@code null} */ public ColorSpaceTransform(Rational[] elements) { checkNotNull(elements, "elements must not be null"); if (elements.length != COUNT) { throw new IllegalArgumentException("elements must be " + COUNT + " length"); } mElements = new int[COUNT_INT]; for (int i = 0; i < elements.length; ++i) { checkNotNull(elements, "element[" + i + "] must not be null"); mElements[i * RATIONAL_SIZE + OFFSET_NUMERATOR] = elements[i].getNumerator(); mElements[i * RATIONAL_SIZE + OFFSET_DENOMINATOR] = elements[i].getDenominator(); } } /** * Create a new immutable {@link ColorSpaceTransform} instance from an {@code int} array. * * <p>The elements must be stored in a row-major order. Each rational is stored * contiguously as a {@code (numerator, denominator)} pair.</p> * * <p>In particular:<pre>{@code * int[] elements = new int[ * N11, D11, N12, D12, N13, D13, * N21, D21, N22, D22, N23, D23, * N31, D31, N32, D32, N33, D33 * ]; * * new ColorSpaceTransform(elements)}</pre> * * where {@code Nij} and {@code Dij} is the numerator and denominator for row {@code i} and * column {@code j}.</p> * * @param elements An array of {@code 18} elements * * @throws IllegalArgumentException * if the count of {@code elements} is not {@code 18} * @throws NullPointerException * if {@code elements} is {@code null} */ public ColorSpaceTransform(int[] elements) { checkNotNull(elements, "elements must not be null"); if (elements.length != COUNT_INT) { throw new IllegalArgumentException("elements must be " + COUNT_INT + " length"); } for (int i = 0; i < elements.length; ++i) { checkNotNull(elements, "element " + i + " must not be null"); } mElements = Arrays.copyOf(elements, elements.length); } /** * Get an element of this matrix by its row and column. * * <p>The rows must be within the range [0, 3), * and the column must be within the range [0, 3).</p> * * @return element (non-{@code null}) * * @throws IllegalArgumentException if column or row was out of range */ public Rational getElement(int column, int row) { if (column < 0 || column >= COLUMNS) { throw new IllegalArgumentException("column out of range"); } else if (row < 0 || row >= ROWS) { throw new IllegalArgumentException("row out of range"); } int numerator = mElements[(row * COLUMNS + column) * RATIONAL_SIZE + OFFSET_NUMERATOR]; int denominator = mElements[(row * COLUMNS + column) * RATIONAL_SIZE + OFFSET_DENOMINATOR]; return new Rational(numerator, denominator); } /** * Copy the {@link Rational} elements in row-major order from this matrix into the destination. * * @param destination * an array big enough to hold at least {@code 9} elements after the * {@code offset} * @param offset * a non-negative offset into the array * @throws NullPointerException * If {@code destination} was {@code null} * @throws ArrayIndexOutOfBoundsException * If there's not enough room to write the elements at the specified destination and * offset. */ public void copyElements(Rational[] destination, int offset) { checkArgumentNonnegative(offset, "offset must not be negative"); checkNotNull(destination, "destination must not be null"); if (destination.length - offset < COUNT) { throw new ArrayIndexOutOfBoundsException("destination too small to fit elements"); } for (int i = 0, j = 0; i < COUNT; ++i, j += RATIONAL_SIZE) { int numerator = mElements[j + OFFSET_NUMERATOR]; int denominator = mElements[j + OFFSET_DENOMINATOR]; destination[i + offset] = new Rational(numerator, denominator); } } /** * Copy the {@link Rational} elements in row-major order from this matrix into the destination. * * <p>Each element is stored as a contiguous rational packed as a * {@code (numerator, denominator)} pair of ints, identical to the * {@link ColorSpaceTransform#ColorSpaceTransform(int[]) constructor}.</p> * * @param destination * an array big enough to hold at least {@code 18} elements after the * {@code offset} * @param offset * a non-negative offset into the array * @throws NullPointerException * If {@code destination} was {@code null} * @throws ArrayIndexOutOfBoundsException * If there's not enough room to write the elements at the specified destination and * offset. * * @see ColorSpaceTransform#ColorSpaceTransform(int[]) */ public void copyElements(int[] destination, int offset) { checkArgumentNonnegative(offset, "offset must not be negative"); checkNotNull(destination, "destination must not be null"); if (destination.length - offset < COUNT_INT) { throw new ArrayIndexOutOfBoundsException("destination too small to fit elements"); } // Manual copy faster than System#arraycopy for very small loops for (int i = 0; i < COUNT_INT; ++i) { destination[i + offset] = mElements[i]; } } /** * Check if this {@link ColorSpaceTransform} is equal to another {@link ColorSpaceTransform}. * * <p>Two color space transforms are equal if and only if all of their elements are * {@link Object#equals equal}.</p> * * @return {@code true} if the objects were equal, {@code false} otherwise */ @Override public boolean equals(final Object obj) { if (obj == null) { return false; } if (this == obj) { return true; } if (obj instanceof ColorSpaceTransform) { final ColorSpaceTransform other = (ColorSpaceTransform) obj; for (int i = 0, j = 0; i < COUNT; ++i, j += RATIONAL_SIZE) { int numerator = mElements[j + OFFSET_NUMERATOR]; int denominator = mElements[j + OFFSET_DENOMINATOR]; int numeratorOther = other.mElements[j + OFFSET_NUMERATOR]; int denominatorOther = other.mElements[j + OFFSET_DENOMINATOR]; Rational r = new Rational(numerator, denominator); Rational rOther = new Rational(numeratorOther, denominatorOther); if (!r.equals(rOther)) { return false; } } return true; } return false; } /** * {@inheritDoc} */ @Override public int hashCode() { return HashCodeHelpers.hashCode(mElements); } /** * Return the color space transform as a string representation. * * <p> Example: * {@code "ColorSpaceTransform([1/1, 0/1, 0/1], [0/1, 1/1, 0/1], [0/1, 0/1, 1/1])"} is an * identity transform. Elements are printed in row major order. </p> * * @return string representation of color space transform */ @Override public String toString() { return String.format("ColorSpaceTransform%s", toShortString()); } /** * Return the color space transform as a compact string representation. * * <p> Example: * {@code "([1/1, 0/1, 0/1], [0/1, 1/1, 0/1], [0/1, 0/1, 1/1])"} is an identity transform. * Elements are printed in row major order. </p> * * @return compact string representation of color space transform */ private String toShortString() { StringBuilder sb = new StringBuilder("("); for (int row = 0, i = 0; row < ROWS; row++) { sb.append("["); for (int col = 0; col < COLUMNS; col++, i += RATIONAL_SIZE) { int numerator = mElements[i + OFFSET_NUMERATOR]; int denominator = mElements[i + OFFSET_DENOMINATOR]; sb.append(numerator); sb.append("/"); sb.append(denominator); if (col < COLUMNS - 1) { sb.append(", "); } } sb.append("]"); if (row < ROWS - 1) { sb.append(", "); } } sb.append(")"); return sb.toString(); } private final int[] mElements; }