1 /*
2  * Copyright (C) 2014 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package android.hardware.camera2.marshal.impl;
17 
18 import android.hardware.camera2.marshal.Marshaler;
19 import android.hardware.camera2.marshal.MarshalQueryable;
20 import android.hardware.camera2.utils.TypeReference;
21 import android.util.Log;
22 
23 import java.nio.ByteBuffer;
24 import java.nio.charset.Charset;
25 
26 import static android.hardware.camera2.impl.CameraMetadataNative.*;
27 
28 /**
29  * Marshal {@link String} to/from {@link #TYPE_BYTE}.
30  */
31 public class MarshalQueryableString implements MarshalQueryable<String> {
32 
33     private static final String TAG = MarshalQueryableString.class.getSimpleName();
34     private static final boolean DEBUG = false;
35 
36     private static class PreloadHolder {
37         public static final Charset UTF8_CHARSET = Charset.forName("UTF-8");
38     }
39     private static final byte NUL = (byte)'\0'; // used as string terminator
40 
41     private class MarshalerString extends Marshaler<String> {
42 
MarshalerString(TypeReference<String> typeReference, int nativeType)43         protected MarshalerString(TypeReference<String> typeReference, int nativeType) {
44             super(MarshalQueryableString.this, typeReference, nativeType);
45         }
46 
47         @Override
marshal(String value, ByteBuffer buffer)48         public void marshal(String value, ByteBuffer buffer) {
49             byte[] arr = value.getBytes(PreloadHolder.UTF8_CHARSET);
50 
51             buffer.put(arr);
52             buffer.put(NUL); // metadata strings are NUL-terminated
53         }
54 
55         @Override
calculateMarshalSize(String value)56         public int calculateMarshalSize(String value) {
57             byte[] arr = value.getBytes(PreloadHolder.UTF8_CHARSET);
58 
59             return arr.length + 1; // metadata strings are NUL-terminated
60         }
61 
62         @Override
unmarshal(ByteBuffer buffer)63         public String unmarshal(ByteBuffer buffer) {
64             buffer.mark(); // save the current position
65 
66             boolean foundNull = false;
67             int stringLength = 0;
68             while (buffer.hasRemaining()) {
69                 if (buffer.get() == NUL) {
70                     foundNull = true;
71                     break;
72                 }
73 
74                 stringLength++;
75             }
76 
77             if (DEBUG) {
78                 Log.v(TAG,
79                         "unmarshal - scanned " + stringLength + " characters; found null? "
80                                 + foundNull);
81             }
82 
83             if (!foundNull) {
84                 throw new UnsupportedOperationException("Strings must be null-terminated");
85             }
86 
87             buffer.reset(); // go back to the previously marked position
88 
89             byte[] strBytes = new byte[stringLength + 1];
90             buffer.get(strBytes, /*dstOffset*/0, stringLength + 1); // including null character
91 
92             // not including null character
93             return new String(strBytes, /*offset*/0, stringLength, PreloadHolder.UTF8_CHARSET);
94         }
95 
96         @Override
getNativeSize()97         public int getNativeSize() {
98             return NATIVE_SIZE_DYNAMIC;
99         }
100     }
101 
102     @Override
createMarshaler( TypeReference<String> managedType, int nativeType)103     public Marshaler<String> createMarshaler(
104             TypeReference<String> managedType, int nativeType) {
105         return new MarshalerString(managedType, nativeType);
106     }
107 
108     @Override
isTypeMappingSupported(TypeReference<String> managedType, int nativeType)109     public boolean isTypeMappingSupported(TypeReference<String> managedType, int nativeType) {
110         return nativeType == TYPE_BYTE && String.class.equals(managedType.getType());
111     }
112 }
113