Drag and Drop example snippet: define my own data transfer type
/*
* Drag and Drop example snippet: define my own data transfer type
*
* For a list of all SWT example snippets see
* http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-swt-home/dev.html#snippets
*/
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.ByteArrayTransfer;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.dnd.TransferData;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
public class Snippet79 {
/*
* The data being transferred is an <bold>array of type MyType</bold> where
* MyType is define as:
*/
static class MyType {
String fileName;
long fileLength;
long lastModified;
}
static class MyTransfer extends ByteArrayTransfer {
private static final String MYTYPENAME = "name_for_my_type";
private static final int MYTYPEID = registerType(MYTYPENAME);
private static MyTransfer _instance = new MyTransfer();
public static MyTransfer getInstance() {
return _instance;
}
public void javaToNative(Object object, TransferData transferData) {
if (!checkMyType(object) || !isSupportedType(transferData)) {
DND.error(DND.ERROR_INVALID_DATA);
}
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 };
}
boolean checkMyType(Object object) {
if (object == null || !(object instanceof MyType[])
|| ((MyType[]) object).length == 0) {
return false;
}
MyType[] myTypes = (MyType[]) object;
for (int i = 0; i < myTypes.length; i++) {
if (myTypes[i] == null || myTypes[i].fileName == null
|| myTypes[i].fileName.length() == 0) {
return false;
}
}
return true;
}
protected boolean validate(Object object) {
return checkMyType(object);
}
}
public static void main(String[] args) {
Display display = new Display();
Shell shell = new Shell(display);
shell.setLayout(new FillLayout());
final Label label1 = new Label(shell, SWT.BORDER | SWT.WRAP);
label1.setText("Drag Source for MyData[]");
final Label label2 = new Label(shell, SWT.BORDER | SWT.WRAP);
label2.setText("Drop Target for MyData[]");
DragSource source = new DragSource(label1, DND.DROP_COPY);
source.setTransfer(new Transfer[] { MyTransfer.getInstance() });
source.addDragListener(new DragSourceAdapter() {
public void dragSetData(DragSourceEvent event) {
MyType myType1 = new MyType();
myType1.fileName = "C:\\abc.txt";
myType1.fileLength = 1000;
myType1.lastModified = 12312313;
MyType myType2 = new MyType();
myType2.fileName = "C:\\xyz.txt";
myType2.fileLength = 500;
myType2.lastModified = 12312323;
event.data = new MyType[] { myType1, myType2 };
}
});
DropTarget target = new DropTarget(label2, DND.DROP_COPY
| DND.DROP_DEFAULT);
target.setTransfer(new Transfer[] { MyTransfer.getInstance() });
target.addDropListener(new DropTargetAdapter() {
public void dragEnter(DropTargetEvent event) {
if (event.detail == DND.DROP_DEFAULT) {
event.detail = DND.DROP_COPY;
}
}
public void dragOperationChanged(DropTargetEvent event) {
if (event.detail == DND.DROP_DEFAULT) {
event.detail = DND.DROP_COPY;
}
}
public void drop(DropTargetEvent event) {
if (event.data != null) {
MyType[] myTypes = (MyType[]) event.data;
if (myTypes != null) {
String string = "";
for (int i = 0; i < myTypes.length; i++) {
string += myTypes[i].fileName + " ";
}
label2.setText(string);
}
}
}
});
shell.setSize(200, 200);
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch())
display.sleep();
}
display.dispose();
}
}
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