com.google.gwt.typedarrays.server.ArrayBufferViewImpl Maven / Gradle / Ivy
/*
* Copyright 2012 Google Inc.
*
* 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.gwt.typedarrays.server;
import com.google.gwt.typedarrays.shared.ArrayBuffer;
import com.google.gwt.typedarrays.shared.ArrayBufferView;
/**
* Base class for {@link ArrayBufferView} implementations.
*/
public abstract class ArrayBufferViewImpl implements ArrayBufferView {
/**
* The spec lets the platform's native endianness come through, so we choose to
* expose little-endian regardless -- if apps care about the endianness but don't
* test for it, it is likely they assume little-endian.
*/
static final boolean USE_LITTLE_ENDIAN = true;
protected final ArrayBufferImpl arrayBuf;
protected final int byteLength;
protected final int byteOffset;
/**
* @param buffer
* @param byteOffset
* @param byteLength
*/
public ArrayBufferViewImpl(ArrayBuffer buffer, int byteOffset, int byteLength) {
if (!(buffer instanceof ArrayBufferImpl)) {
throw new UnsupportedOperationException("Unacceptable ArrayBuffer type");
}
this.arrayBuf = (ArrayBufferImpl) buffer;
this.byteOffset = byteOffset;
this.byteLength = byteLength;
}
@Override
public ArrayBuffer buffer() {
return arrayBuf;
}
@Override
public int byteLength() {
return byteLength;
}
@Override
public int byteOffset() {
return byteOffset;
}
/**
* Check the index range and throw an exception if out of range, if ok return the
* byte index of the specified element.
*
* @param index an element index
* @param bytesPerElement
* @return the byte index of the start of this element
*/
protected int checkRange(int index, int bytesPerElement) {
int byteIndex = index * bytesPerElement;
if (byteIndex < byteOffset || byteIndex + bytesPerElement > byteLength) {
throw new ArrayIndexOutOfBoundsException(index);
}
return byteIndex;
}
}