1 files changed, 161 insertions, 0 deletions
diff --git a/src/main/java/eu/siacs/conversations/utils/ExifHelper.java b/src/main/java/eu/siacs/conversations/utils/ExifHelper.java
new file mode 100644
index 00000000..5e465e94
--- /dev/null
+++ b/src/main/java/eu/siacs/conversations/utils/ExifHelper.java
@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2011 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 eu.siacs.conversations.utils;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import de.thedevstack.android.logcat.Logging;
+
+public class ExifHelper {
+    private static final String TAG = "CameraExif";
+
+    public static int getOrientation(InputStream is) {
+        if (is == null) {
+            return 0;
+        }
+
+        byte[] buf = new byte[8];
+        int length = 0;
+
+        // ISO/IEC 10918-1:1993(E)
+        while (read(is, buf, 2) && (buf[0] & 0xFF) == 0xFF) {
+            int marker = buf[1] & 0xFF;
+
+            // Check if the marker is a padding.
+            if (marker == 0xFF) {
+                continue;
+            }
+
+            // 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) {
+                return 0;
+            }
+
+            // Get the length and check if it is reasonable.
+            if (!read(is, buf, 2)) {
+                return 0;
+            }
+            length = pack(buf, 0, 2, false);
+            if (length < 2) {
+                Logging.e(TAG, "Invalid length");
+                return 0;
+            }
+            length -= 2;
+
+            // Break if the marker is EXIF in APP1.
+            if (marker == 0xE1 && length >= 6) {
+                if (!read(is, buf, 6)) return 0;
+                length -= 6;
+                if (pack(buf, 0, 4, false) == 0x45786966 &&
+                    pack(buf, 4, 2, false) == 0) {
+                    break;
+                }
+            }
+
+            // Skip other markers.
+            try {
+                is.skip(length);
+            } catch (IOException ex) {
+                return 0;
+            }
+            length = 0;
+        }
+
+        // JEITA CP-3451 Exif Version 2.2
+        if (length > 8) {
+            int offset = 0;
+            byte[] jpeg = new byte[length];
+            if (!read(is, jpeg, length)) {
+                return 0;
+            }
+
+            // Identify the byte order.
+            int tag = pack(jpeg, offset, 4, false);
+            if (tag != 0x49492A00 && tag != 0x4D4D002A) {
+                Logging.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) {
+                Logging.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;
+                    }
+                    Logging.i(TAG, "Unsupported orientation");
+                    return 0;
+                }
+                offset += 12;
+                length -= 12;
+            }
+        }
+
+        Logging.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;
+    }
+
+    private static boolean read(InputStream is, byte[] buf, int length) {
+        try {
+            return is.read(buf, 0, length) == length;
+        } catch (IOException ex) {
+            return false;
+        }
+    }
+}