ResourceValue.java

/*
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * 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.google.devrel.gmscore.tools.apk.arsc;

import com.google.auto.value.AutoValue;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMap.Builder;
import com.google.common.primitives.UnsignedBytes;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Map;

/** Represents a single typed resource value. */
@AutoValue
public abstract class ResourceValue implements SerializableResource {

  /** Resource type codes. */
  public enum Type {
    /** {@code data} is either 0 (undefined) or 1 (empty). */
    NULL(0x00),
    /** {@code data} holds a {@link ResourceTableChunk} entry reference. */
    REFERENCE(0x01),
    /** {@code data} holds an attribute resource identifier. */
    ATTRIBUTE(0x02),
    /** {@code data} holds an index into the containing resource table's string pool. */
    STRING(0x03),
    /** {@code data} holds a single-precision floating point number. */
    FLOAT(0x04),
    /** {@code data} holds a complex number encoding a dimension value, such as "100in". */
    DIMENSION(0x05),
    /** {@code data} holds a complex number encoding a fraction of a container. */
    FRACTION(0x06),
    /** {@code data} holds a dynamic {@link ResourceTableChunk} entry reference. */
    DYNAMIC_REFERENCE(0x07),
    /** {@code data} is a raw integer value of the form n..n. */
    INT_DEC(0x10),
    /** {@code data} is a raw integer value of the form 0xn..n. */
    INT_HEX(0x11),
    /** {@code data} is either 0 (false) or 1 (true). */
    INT_BOOLEAN(0x12),
    /** {@code data} is a raw integer value of the form #aarrggbb. */
    INT_COLOR_ARGB8(0x1c),
    /** {@code data} is a raw integer value of the form #rrggbb. */
    INT_COLOR_RGB8(0x1d),
    /** {@code data} is a raw integer value of the form #argb. */
    INT_COLOR_ARGB4(0x1e),
    /** {@code data} is a raw integer value of the form #rgb. */
    INT_COLOR_RGB4(0x1f);

    private final byte code;

    private static final Map<Byte, Type> FROM_BYTE;

    static {
      Builder<Byte, Type> builder = ImmutableMap.builder();
      for (Type type : values()) {
        builder.put(type.code(), type);
      }
      FROM_BYTE = builder.build();
    }

    Type(int code) {
      this.code = UnsignedBytes.checkedCast(code);
    }

    public byte code() {
      return code;
    }

    public static Type fromCode(byte code) {
      return Preconditions.checkNotNull(FROM_BYTE.get(code), "Unknown resource type: %s", code);
    }
  }

  /** The serialized size in bytes of a {@link ResourceValue}. */
  public static final int SIZE = 8;

  /** The length in bytes of this value. */
  public abstract int size();

  /** The raw data type of this value. */
  public abstract Type type();

  /** The actual 4-byte value; interpretation of the value depends on {@code dataType}. */
  public abstract int data();

  public static ResourceValue create(ByteBuffer buffer) {
    int size = (buffer.getShort() & 0xFFFF);
    buffer.get();  // Unused
    Type type = Type.fromCode(buffer.get());
    int data = buffer.getInt();
    return new AutoValue_ResourceValue(size, type, data);
  }

  @Override
  public byte[] toByteArray() {
    return toByteArray(false);
  }

  @Override
  public byte[] toByteArray(boolean shrink) {
    ByteBuffer buffer = ByteBuffer.allocate(SIZE).order(ByteOrder.LITTLE_ENDIAN);
    buffer.putShort((short) size());
    buffer.put((byte) 0);  // Unused
    buffer.put(type().code());
    buffer.putInt(data());
    return buffer.array();
  }
}