content: /*
   * Copyright (C) 2014 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 android.hardware.camera2.marshal.impl;
  
  import android.hardware.camera2.marshal.Marshaler;
  import android.hardware.camera2.marshal.MarshalQueryable;
  import android.hardware.camera2.utils.TypeReference;
  import android.util.Log;
  
  import java.nio.ByteBuffer;
  import java.nio.charset.Charset;
  
  import static android.hardware.camera2.impl.CameraMetadataNative.*;
  
  /**
   * Marshal {@link String} to/from {@link #TYPE_BYTE}.
   */
  public class MarshalQueryableString implements MarshalQueryable<String> {
  
      private static final String TAG = MarshalQueryableString.class.getSimpleName();
      private static final boolean DEBUG = false;
  
      private static class PreloadHolder {
          public static final Charset UTF8_CHARSET = Charset.forName("UTF-8");
      }
      private static final byte NUL = (byte)'\0'; // used as string terminator
  
      private class MarshalerString extends Marshaler<String> {
  
          protected MarshalerString(TypeReference<String> typeReference, int nativeType) {
              super(MarshalQueryableString.this, typeReference, nativeType);
          }
  
          @Override
          public void marshal(String value, ByteBuffer buffer) {
              byte[] arr = value.getBytes(PreloadHolder.UTF8_CHARSET);
  
              buffer.put(arr);
              buffer.put(NUL); // metadata strings are NUL-terminated
          }
  
          @Override
          public int calculateMarshalSize(String value) {
              byte[] arr = value.getBytes(PreloadHolder.UTF8_CHARSET);
  
              return arr.length + 1; // metadata strings are NUL-terminated
          }
  
          @Override
          public String unmarshal(ByteBuffer buffer) {
              buffer.mark(); // save the current position
  
              boolean foundNull = false;
              int stringLength = 0;
              while (buffer.hasRemaining()) {
                  if (buffer.get() == NUL) {
                      foundNull = true;
                      break;
                  }
  
                  stringLength++;
              }
  
              if (DEBUG) {
                  Log.v(TAG,
                          "unmarshal - scanned " + stringLength + " characters; found null? "
                                  + foundNull);
              }
  
              if (!foundNull) {
                  throw new UnsupportedOperationException("Strings must be null-terminated");
              }
  
              buffer.reset(); // go back to the previously marked position
  
              byte[] strBytes = new byte[stringLength + 1];
              buffer.get(strBytes, /*dstOffset*/0, stringLength + 1); // including null character
  
              // not including null character
              return new String(strBytes, /*offset*/0, stringLength, PreloadHolder.UTF8_CHARSET);
          }
  
          @Override
          public int getNativeSize() {
              return NATIVE_SIZE_DYNAMIC;
          }
      }
  
      @Override
      public Marshaler<String> createMarshaler(
              TypeReference<String> managedType, int nativeType) {
          return new MarshalerString(managedType, nativeType);
      }
  
      @Override
      public boolean isTypeMappingSupported(TypeReference<String> managedType, int nativeType) {
          return nativeType == TYPE_BYTE && String.class.equals(managedType.getType());
      }
  }
  