diff --git a/android/ScratchJr/app/src/main/java/org/scratchjr/android/CameraExif.java b/android/ScratchJr/app/src/main/java/org/scratchjr/android/CameraExif.java new file mode 100644 index 0000000..af21cf7 --- /dev/null +++ b/android/ScratchJr/app/src/main/java/org/scratchjr/android/CameraExif.java @@ -0,0 +1,137 @@ +package org.scratchjr.android; + +import android.util.Log; + +/* + * 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. +*/ + +public class CameraExif { + 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; + } +} \ No newline at end of file