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SWT is an open source widget toolkit for Java designed to provide efficient, portable access to the user-interface facilities of the operating systems on which it is implemented.
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/*******************************************************************************
* Copyright (c) 2000, 2012 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.swt.dnd;
import org.eclipse.swt.internal.ole.win32.*;
import org.eclipse.swt.internal.win32.*;
/**
* The class ByteArrayTransfer provides a platform specific
* mechanism for converting a java byte[] to a platform
* specific representation of the byte array and vice versa.
*
* ByteArrayTransfer is never used directly but is sub-classed
* by transfer agents that convert between data in a java format such as a
* String and a platform specific byte array.
*
*
If the data you are converting does not map to a
* byte[], you should sub-class Transfer directly
* and do your own mapping to a platform data type.
*
* The following snippet shows a subclass of ByteArrayTransfer that transfers
* data defined by the class MyType.
*
*
* public class MyType {
* public String fileName;
* public long fileLength;
* public long lastModified;
* }
*
*
*
* public class MyTypeTransfer extends ByteArrayTransfer {
*
* private static final String MYTYPENAME = "my_type_name";
* private static final int MYTYPEID = registerType(MYTYPENAME);
* private static MyTypeTransfer _instance = new MyTypeTransfer();
*
* private MyTypeTransfer() {}
*
* public static MyTypeTransfer getInstance () {
* return _instance;
* }
* public void javaToNative (Object object, TransferData transferData) {
* if (object == null || !(object instanceof MyType[])) return;
*
* if (isSupportedType(transferData)) {
* MyType[] myTypes = (MyType[]) object;
* try {
* // write data to a byte array and then ask super to convert to pMedium
* ByteArrayOutputStream out = new ByteArrayOutputStream();
* DataOutputStream writeOut = new DataOutputStream(out);
* for (int i = 0, length = myTypes.length; i < length; i++){
* byte[] buffer = myTypes[i].fileName.getBytes();
* writeOut.writeInt(buffer.length);
* writeOut.write(buffer);
* writeOut.writeLong(myTypes[i].fileLength);
* writeOut.writeLong(myTypes[i].lastModified);
* }
* byte[] buffer = out.toByteArray();
* writeOut.close();
*
* super.javaToNative(buffer, transferData);
*
* } catch (IOException e) {
* }
* }
* }
* public Object nativeToJava(TransferData transferData){
*
* if (isSupportedType(transferData)) {
*
* byte[] buffer = (byte[])super.nativeToJava(transferData);
* if (buffer == null) return null;
*
* MyType[] myData = new MyType[0];
* try {
* ByteArrayInputStream in = new ByteArrayInputStream(buffer);
* DataInputStream readIn = new DataInputStream(in);
* while(readIn.available() > 20) {
* MyType datum = new MyType();
* int size = readIn.readInt();
* byte[] name = new byte[size];
* readIn.read(name);
* datum.fileName = new String(name);
* datum.fileLength = readIn.readLong();
* datum.lastModified = readIn.readLong();
* MyType[] newMyData = new MyType[myData.length + 1];
* System.arraycopy(myData, 0, newMyData, 0, myData.length);
* newMyData[myData.length] = datum;
* myData = newMyData;
* }
* readIn.close();
* } catch (IOException ex) {
* return null;
* }
* return myData;
* }
*
* return null;
* }
* protected String[] getTypeNames(){
* return new String[]{MYTYPENAME};
* }
* protected int[] getTypeIds(){
* return new int[] {MYTYPEID};
* }
* }
*
*
* @see Transfer
*/
public abstract class ByteArrayTransfer extends Transfer {
public TransferData[] getSupportedTypes() {
int[] types = getTypeIds();
TransferData[] data = new TransferData[types.length];
for (int i = 0; i < types.length; i++) {
data[i] = new TransferData();
data[i].type = types[i];
data[i].formatetc = new FORMATETC();
data[i].formatetc.cfFormat = types[i];
data[i].formatetc.dwAspect = COM.DVASPECT_CONTENT;
data[i].formatetc.lindex = -1;
data[i].formatetc.tymed = COM.TYMED_HGLOBAL;
}
return data;
}
public boolean isSupportedType(TransferData transferData){
if (transferData == null) return false;
int[] types = getTypeIds();
for (int i = 0; i < types.length; i++) {
FORMATETC format = transferData.formatetc;
if (format.cfFormat == types[i] &&
(format.dwAspect & COM.DVASPECT_CONTENT) == COM.DVASPECT_CONTENT &&
(format.tymed & COM.TYMED_HGLOBAL) == COM.TYMED_HGLOBAL )
return true;
}
return false;
}
/**
* This implementation of javaToNative converts a java
* byte[] to a platform specific representation.
*
* @param object a java byte[] containing the data to be converted
* @param transferData an empty TransferData object that will
* be filled in on return with the platform specific format of the data
*
* @see Transfer#nativeToJava
*/
protected void javaToNative (Object object, TransferData transferData) {
if (!checkByteArray(object) || !isSupportedType(transferData)) {
DND.error(DND.ERROR_INVALID_DATA);
}
// Allocate the memory because the caller (DropTarget) has not handed it in
// The caller of this method must release the data when it is done with it.
byte[] data = (byte[])object;
int size = data.length;
int /*long*/ newPtr = OS.GlobalAlloc(OS.GMEM_FIXED | OS.GMEM_ZEROINIT, size);
OS.MoveMemory(newPtr, data, size);
transferData.stgmedium = new STGMEDIUM();
transferData.stgmedium.tymed = COM.TYMED_HGLOBAL;
transferData.stgmedium.unionField = newPtr;
transferData.stgmedium.pUnkForRelease = 0;
transferData.result = COM.S_OK;
}
/**
* This implementation of nativeToJava converts a platform specific
* representation of a byte array to a java byte[].
*
* @param transferData the platform specific representation of the data to be converted
* @return a java byte[] containing the converted data if the conversion was
* successful; otherwise null
*
* @see Transfer#javaToNative
*/
protected Object nativeToJava(TransferData transferData) {
if (!isSupportedType(transferData) || transferData.pIDataObject == 0) return null;
IDataObject data = new IDataObject(transferData.pIDataObject);
data.AddRef();
FORMATETC formatetc = transferData.formatetc;
STGMEDIUM stgmedium = new STGMEDIUM();
stgmedium.tymed = COM.TYMED_HGLOBAL;
transferData.result = getData(data, formatetc, stgmedium);
data.Release();
if (transferData.result != COM.S_OK) return null;
int /*long*/ hMem = stgmedium.unionField;
int size = OS.GlobalSize(hMem);
byte[] buffer = new byte[size];
int /*long*/ ptr = OS.GlobalLock(hMem);
OS.MoveMemory(buffer, ptr, size);
OS.GlobalUnlock(hMem);
OS.GlobalFree(hMem);
return buffer;
}
boolean checkByteArray(Object object) {
return (object != null && object instanceof byte[] && ((byte[])object).length > 0);
}
}