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