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/* Copyright © 2000 Free Software Foundation
This file is part of libgcj.
This software is copyrighted work licensed under the terms of the
Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
details. */
package gnu.gcj.awt;
import java.awt.image.*;
/**
* Utility class for creating and accessing data buffers of arbitrary
* data types.
*/
public final class Buffers
{
/**
* Create a data buffer of a particular type.
*
* @param dataType the desired data type of the buffer.
* @param data an array containing data, or null
* @param size the size of the data buffer bank
*/
public static DataBuffer createBuffer(int dataType, Object data,
int size)
{
if (data == null) return createBuffer(dataType, size, 1);
return createBufferFromData(dataType, data, size);
}
/**
* Create a data buffer of a particular type.
*
* @param dataType the desired data type of the buffer.
* @param size the size of the data buffer bank
*/
public static DataBuffer createBuffer(int dataType, int size) {
return createBuffer(dataType, size, 1);
}
/**
* Create a data buffer of a particular type.
*
* @param dataType the desired data type of the buffer.
* @param size the size of the data buffer bank
* @param numBanks the number of banks the buffer should have
*/
public static DataBuffer createBuffer(int dataType, int size, int numBanks)
{
switch (dataType)
{
case DataBuffer.TYPE_BYTE:
return new DataBufferByte(size, numBanks);
case DataBuffer.TYPE_USHORT:
return new DataBufferUShort(size, numBanks);
case DataBuffer.TYPE_INT:
return new DataBufferInt(size, numBanks);
default:
throw new UnsupportedOperationException();
}
}
/**
* Create a data buffer of a particular type.
*
* @param dataType the desired data type of the buffer
* @param data an array containing the data
* @param size the size of the data buffer bank
*/
public static DataBuffer createBufferFromData(int dataType, Object data,
int size)
{
switch (dataType)
{
case DataBuffer.TYPE_BYTE:
return new DataBufferByte((byte[]) data, size);
case DataBuffer.TYPE_USHORT:
return new DataBufferUShort((short[]) data, size);
case DataBuffer.TYPE_INT:
return new DataBufferInt((int[]) data, size);
default:
throw new UnsupportedOperationException();
}
}
/**
* Return the data array of a data buffer, regardless of the data
* type.
*
* @return an array of primitive values. The actual array type
* depends on the data type of the buffer.
*/
public static Object getData(DataBuffer buffer)
{
if (buffer instanceof DataBufferByte)
return ((DataBufferByte) buffer).getData();
if (buffer instanceof DataBufferUShort)
return ((DataBufferUShort) buffer).getData();
if (buffer instanceof DataBufferInt)
return ((DataBufferInt) buffer).getData();
throw new ClassCastException("Unknown data buffer type");
}
/**
* Copy data from array contained in data buffer, much like
* System.arraycopy. Create a suitable destination array if the
* given destination array is null.
*/
public static Object getData(DataBuffer src, int srcOffset,
Object dest, int destOffset,
int length)
{
Object from;
if (src instanceof DataBufferByte)
{
from = ((DataBufferByte) src).getData();
if (dest == null) dest = new byte[length+destOffset];
}
else if (src instanceof DataBufferUShort)
{
from = ((DataBufferUShort) src).getData();
if (dest == null) dest = new short[length+destOffset];
}
else if (src instanceof DataBufferInt)
{
from = ((DataBufferInt) src).getData();
if (dest == null) dest = new int[length+destOffset];
}
else
{
throw new ClassCastException("Unknown data buffer type");
}
System.arraycopy(from, srcOffset, dest, destOffset, length);
return dest;
}
/**
* @param bits the width of a data element measured in bits
*
* @return the smallest data type that can store data elements of
* the given number of bits, without any truncation.
*/
public static int smallestAppropriateTransferType(int bits)
{
if (bits <= 8)
{
return DataBuffer.TYPE_BYTE;
}
else if (bits <= 16)
{
return DataBuffer.TYPE_USHORT;
}
else if (bits <= 32)
{
return DataBuffer.TYPE_INT;
}
else
{
return DataBuffer.TYPE_UNDEFINED;
}
}
}
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