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July 14, 2017 10:35
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| /* | |
| * Copyright (C) 2010 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; | |
| import android.util.Log; | |
| public class Exif { | |
| private static final String TAG = "CameraExif"; | |
| // Returns the degrees in clockwise. Values are 0, 90, 180, or 270. | |
| public static int getOrientation(byte[] jpeg) { | |
| if (jpeg == null) { | |
| return 0; | |
| } | |
| int offset = 0; | |
| int length = 0; | |
| // ISO/IEC 10918-1:1993(E) | |
| while (offset + 3 < jpeg.length && (jpeg[offset++] & 0xFF) == 0xFF) { | |
| int marker = jpeg[offset] & 0xFF; | |
| // Check if the marker is a padding. | |
| if (marker == 0xFF) { | |
| continue; | |
| } | |
| offset++; | |
| // Check if the marker is SOI or TEM. | |
| if (marker == 0xD8 || marker == 0x01) { | |
| continue; | |
| } | |
| // Check if the marker is EOI or SOS. | |
| if (marker == 0xD9 || marker == 0xDA) { | |
| break; | |
| } | |
| // Get the length and check if it is reasonable. | |
| length = pack(jpeg, offset, 2, false); | |
| if (length < 2 || offset + length > jpeg.length) { | |
| Log.e(TAG, "Invalid length"); | |
| return 0; | |
| } | |
| // Break if the marker is EXIF in APP1. | |
| if (marker == 0xE1 && length >= 8 && | |
| pack(jpeg, offset + 2, 4, false) == 0x45786966 && | |
| pack(jpeg, offset + 6, 2, false) == 0) { | |
| offset += 8; | |
| length -= 8; | |
| break; | |
| } | |
| // Skip other markers. | |
| offset += length; | |
| length = 0; | |
| } | |
| // JEITA CP-3451 Exif Version 2.2 | |
| if (length > 8) { | |
| // Identify the byte order. | |
| int tag = pack(jpeg, offset, 4, false); | |
| if (tag != 0x49492A00 && tag != 0x4D4D002A) { | |
| Log.e(TAG, "Invalid byte order"); | |
| return 0; | |
| } | |
| boolean littleEndian = (tag == 0x49492A00); | |
| // Get the offset and check if it is reasonable. | |
| int count = pack(jpeg, offset + 4, 4, littleEndian) + 2; | |
| if (count < 10 || count > length) { | |
| Log.e(TAG, "Invalid offset"); | |
| return 0; | |
| } | |
| offset += count; | |
| length -= count; | |
| // Get the count and go through all the elements. | |
| count = pack(jpeg, offset - 2, 2, littleEndian); | |
| while (count-- > 0 && length >= 12) { | |
| // Get the tag and check if it is orientation. | |
| tag = pack(jpeg, offset, 2, littleEndian); | |
| if (tag == 0x0112) { | |
| // We do not really care about type and count, do we? | |
| int orientation = pack(jpeg, offset + 8, 2, littleEndian); | |
| switch (orientation) { | |
| case 1: | |
| return 0; | |
| case 3: | |
| return 180; | |
| case 6: | |
| return 90; | |
| case 8: | |
| return 270; | |
| } | |
| Log.i(TAG, "Unsupported orientation"); | |
| return 0; | |
| } | |
| offset += 12; | |
| length -= 12; | |
| } | |
| } | |
| Log.i(TAG, "Orientation not found"); | |
| return 0; | |
| } | |
| private static int pack(byte[] bytes, int offset, int length, | |
| boolean littleEndian) { | |
| int step = 1; | |
| if (littleEndian) { | |
| offset += length - 1; | |
| step = -1; | |
| } | |
| int value = 0; | |
| while (length-- > 0) { | |
| value = (value << 8) | (bytes[offset] & 0xFF); | |
| offset += step; | |
| } | |
| return value; | |
| } | |
| } |
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