org.eclipse.swt.dnd

Class Transfer

java.lang.Object

org.eclipse.swt.dnd.Transfer

Direct Known Subclasses:

ByteArrayTransfer

public abstract class Transfer
extends java.lang.Object

Transfer provides a mechanism for converting between a java representation of data and a platform specific representation of data and vice versa. It is used in data transfer operations such as drag and drop and clipboard copy/paste.

You should only need to become familiar with this class if you are implementing a Transfer subclass and you are unable to subclass the ByteArrayTransfer class.

See Also:

ByteArrayTransfer, Drag and Drop snippets, SWT Example: DNDExample, Sample code and further information

Structure Diagram

Field Summary

Fields

Modifier and Type	Field and Description
private static int	RETRY_LIMIT

Constructor Summary

Constructors

Constructor and Description
Transfer()

Method Summary

Methods

Modifier and Type	Method and Description
(package private) int	getData(IDataObject dataObject, FORMATETC pFormatetc, STGMEDIUM pmedium)
abstract TransferData[]	getSupportedTypes() Returns a list of the platform specific data types that can be converted using this transfer agent.
protected abstract int[]	getTypeIds() Returns the platform specific ids of the data types that can be converted using this transfer agent.
protected abstract java.lang.String[]	getTypeNames() Returns the platform specific names of the data types that can be converted using this transfer agent.
abstract boolean	isSupportedType(TransferData transferData) Returns true if the TransferData data type can be converted using this transfer agent, or false otherwise (including if transferData is null).
protected abstract void	javaToNative(java.lang.Object object, TransferData transferData) Converts a java representation of data to a platform specific representation of the data.
protected abstract java.lang.Object	nativeToJava(TransferData transferData) Converts a platform specific representation of data to a java representation.
static int	registerType(java.lang.String formatName) Registers a name for a data type and returns the associated unique identifier.
protected boolean	validate(java.lang.Object object) Test that the object is of the correct format for this Transfer class.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

RETRY_LIMIT

private static final int RETRY_LIMIT

See Also:

Constant Field Values

Constructor Detail

Transfer

public Transfer()

Method Detail

getData

int getData(IDataObject dataObject,
          FORMATETC pFormatetc,
          STGMEDIUM pmedium)

getSupportedTypes

public abstract TransferData[] getSupportedTypes()

Returns a list of the platform specific data types that can be converted using this transfer agent.

Only the data type fields of the TransferData objects are filled in.

Returns:

a list of the data types that can be converted using this transfer agent

isSupportedType

public abstract boolean isSupportedType(TransferData transferData)

Returns true if the TransferData data type can be converted using this transfer agent, or false otherwise (including if transferData is null).

Parameters:

transferData - a platform specific description of a data type; only the data type fields of the TransferData object need to be filled in

Returns:

true if the transferData data type can be converted using this transfer agent

getTypeIds

protected abstract int[] getTypeIds()

Returns the platform specific ids of the data types that can be converted using this transfer agent.

Returns:

the platform specific ids of the data types that can be converted using this transfer agent

getTypeNames

protected abstract java.lang.String[] getTypeNames()

Returns the platform specific names of the data types that can be converted using this transfer agent.

Returns:

the platform specific names of the data types that can be converted using this transfer agent.

javaToNative

protected abstract void javaToNative(java.lang.Object object,
                TransferData transferData)

Converts a java representation of data to a platform specific representation of the data.

On a successful conversion, the transferData.result field will be set as follows:

• Windows: COM.S_OK
• Motif: 1
• GTK: 1
• Photon: 1

If this transfer agent is unable to perform the conversion, the transferData.result field will be set to a failure value as follows:

• Windows: COM.DV_E_TYMED or COM.E_FAIL
• Motif: 0
• GTK: 0
• Photon: 0

Parameters:

object - a java representation of the data to be converted; the type of Object that is passed in is dependent on the Transfer subclass.

transferData - an empty TransferData object; this object will be filled in on return with the platform specific representation of the data

Throws:

SWTException -

• ERROR_INVALID_DATA - if object does not contain data in a valid format or is null

nativeToJava

protected abstract java.lang.Object nativeToJava(TransferData transferData)

Converts a platform specific representation of data to a java representation.

Parameters:

transferData - the platform specific representation of the data to be converted

Returns:

a java representation of the converted data if the conversion was successful; otherwise null. If transferData is null then null is returned. The type of Object that is returned is dependent on the Transfer subclass.

registerType

public static int registerType(java.lang.String formatName)

Registers a name for a data type and returns the associated unique identifier.

You may register the same type more than once, the same unique identifier will be returned if the type has been previously registered.

Note: On windows, do not call this method with pre-defined Clipboard Format types such as CF_TEXT or CF_BITMAP because the pre-defined identifier will not be returned

Parameters:

formatName - the name of a data type

Returns:

the unique identifier associated with this data type

validate

protected boolean validate(java.lang.Object object)

Test that the object is of the correct format for this Transfer class.

Parameters:

object - a java representation of the data to be converted

Returns:

true if object is of the correct form for this transfer type

Since:

3.1