Refactoring: Remove the dependency of ExifInterface.

Since we only need the orientation information from Exif, it is
fairly simple to implement one by ourselves. This will avoid
disk access and JNI overhead, and save some CPU time since other
tags are not touched.

Change-Id: I962e2f19ec88a082bfd8eb438e255bffad2a5365

1 files changed, 136 insertions, 0 deletions

diff --git a/src/com/android/camera/Exif.java b/src/com/android/camera/Exif.java
new file mode 100644
index 0000000..d1df3e3
--- /dev/null
+++ b/src/com/android/camera/Exif.java
@@ -0,0 +1,136 @@
+/*
+ * 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;
+
+class Exif {
+    private static final String TAG = "CameraExif";
+
+    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;
+    }
+}