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## java.awt.dnd
Class DragSourceContext

    java.lang.Object
      |
      +--java.awt.dnd.DragSourceContext

All Implemented Interfaces:
  DragSourceListener, DragSourceMotionListener, EventListener, Serializable

public class DragSourceContext
extends Object
implements DragSourceListener, DragSourceMotionListener, Serializable

The `DragSourceContext` class is responsible for managing the initiator side of the Drag and Drop protocol. In particular, it is responsible for managing drag event notifications to the `DragSourceListener`s and `DragSourceMotionListener`s, and providing the `Transferable` representing the source data for the drag operation.

Note that the `DragSourceContext` itself implements the `DragSourceListener` and `DragSourceMotionListener` interfaces. This is to allow the platform peer (the `DragSourceContextPeer` instance) created by the `DragSource` to notify the `DragSourceContext` of state changes in the ongoing operation. This allows the `DragSourceContext` to interpose itself between the platform and the listeners provided by the initiator of the drag operation.

Since:
  1.2
See Also:
  `DragSourceListener`, `DragSourceMotionListener`, Serialized Form

Field Summary
`protected static int` | `CHANGED` An `int` used by updateCurrentCursor() indicating that the user operation has changed.
`protected static int` | `DEFAULT` An `int` used by updateCurrentCursor() indicating that the `Cursor` should change to the default (no drop) `Cursor`.
`protected static int` | `ENTER` An `int` used by updateCurrentCursor() indicating that the `Cursor` has entered a `DropTarget`.
`protected static int` | `OVER` An `int` used by updateCurrentCursor() indicating that the `Cursor` is over a `DropTarget`.

Constructor Summary
`DragSourceContext(java.awt.dnd.peer.DragSourceContextPeer dscp, DragGestureEvent trigger, Cursor dragCursor, Image dragImage, Point offset, Transferable t, DragSourceListener dsl)` Called from `DragSource`, this constructor creates a new `DragSourceContext` given the `DragSourceContextPeer` for this Drag, the `DragGestureEvent` that triggered the Drag, the initial `Cursor` to use for the Drag, an (optional) `Image` to display while the Drag is taking place, the offset of the `Image` origin from the hotspot at the instant of the triggering event, the `Transferable` subject data, and the `DragSourceListener` to use during the Drag and Drop operation.

Method Summary
`void` | `addDragSourceListener(DragSourceListener dsl)` Add a `DragSourceListener` to this `DragSourceContext` if one has not already been added.
`void` | `dragDropEnd(DragSourceDropEvent dsde)` Calls `dragDropEnd` on the `DragSourceListener`s registered with this `DragSourceContext` and with the associated `DragSource`, and passes them the specified `DragSourceDropEvent`.
`void` | `dragEnter(DragSourceDragEvent dsde)` Calls `dragEnter` on the `DragSourceListener`s registered with this `DragSourceContext` and with the associated `DragSource`, and passes them the specified `DragSourceDragEvent`.
`void` | `dragExit(DragSourceEvent dse)` Calls `dragExit` on the `DragSourceListener`s registered with this `DragSourceContext` and with the associated `DragSource`, and passes them the specified `DragSourceEvent`.
`void` | `dragMouseMoved(DragSourceDragEvent dsde)` Calls `dragMouseMoved` on the `DragSourceMotionListener`s registered with the `DragSource` associated with this `DragSourceContext`, and them passes the specified `DragSourceDragEvent`.
`void` | `dragOver(DragSourceDragEvent dsde)` Calls `dragOver` on the `DragSourceListener`s registered with this `DragSourceContext` and with the associated `DragSource`, and passes them the specified `DragSourceDragEvent`.
`void` | `dropActionChanged(DragSourceDragEvent dsde)` Calls `dropActionChanged` on the `DragSourceListener`s registered with this `DragSourceContext` and with the associated `DragSource`, and passes them the specified `DragSourceDragEvent`.
`Component` | `getComponent()` Returns the `Component` associated with this `DragSourceContext`.
`Cursor` | `getCursor()` Returns the current drag `Cursor`.
`DragSource` | `getDragSource()` Returns the `DragSource` that instantiated this `DragSourceContext`.
`int` | `getSourceActions()` Returns a bitwise mask of `DnDConstants` that represent the set of drop actions supported by the drag source for the drag operation associated with this `DragSourceContext`.
`Transferable` | `getTransferable()` Returns the `Transferable` associated with this `DragSourceContext`.
`DragGestureEvent` | `getTrigger()` Returns the `DragGestureEvent` that initially triggered the drag.
`void` | `removeDragSourceListener(DragSourceListener dsl)` Removes the specified `DragSourceListener` from this `DragSourceContext`.
`void` | `setCursor(Cursor c)` Sets the cursor for this drag operation to the specified `Cursor`.
`void` | `transferablesFlavorsChanged()` Notifies the peer that the `Transferable`'s `DataFlavor`s have changed.
`protected void` | `updateCurrentCursor(int dropOp, int targetAct, int status)` If the default drag cursor behavior is active, this method sets the default drag cursor for the specified selected operation, supported actions and status, otherwise this method does nothing.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### DEFAULT

    protected static final int DEFAULT

  An `int` used by updateCurrentCursor() indicating that the `Cursor` should change to the default (no drop) `Cursor`.

  See Also:
    Constant Field Values

### ENTER

    protected static final int ENTER

  An `int` used by updateCurrentCursor() indicating that the `Cursor` has entered a `DropTarget`.

  See Also:
    Constant Field Values

### OVER

    protected static final int OVER

  An `int` used by updateCurrentCursor() indicating that the `Cursor` is over a `DropTarget`.

  See Also:
    Constant Field Values

### CHANGED

    protected static final int CHANGED

  An `int` used by updateCurrentCursor() indicating that the user operation has changed.

  See Also:
    Constant Field Values

Constructor Detail

### DragSourceContext

    public DragSourceContext(java.awt.dnd.peer.DragSourceContextPeer dscp,
                             DragGestureEvent trigger,
                             Cursor dragCursor,
                             Image dragImage,
                             Point offset,
                             Transferable t,
                             DragSourceListener dsl)

  Called from `DragSource`, this constructor creates a new `DragSourceContext` given the `DragSourceContextPeer` for this Drag, the `DragGestureEvent` that triggered the Drag, the initial `Cursor` to use for the Drag, an (optional) `Image` to display while the Drag is taking place, the offset of the `Image` origin from the hotspot at the instant of the triggering event, the `Transferable` subject data, and the `DragSourceListener` to use during the Drag and Drop operation.
  If `DragSourceContextPeer` is `null` `NullPointerException` is thrown.
  If `DragGestureEvent` is `null` `NullPointerException` is thrown.
  If `Cursor` is `null` no exception is thrown and the default drag cursor behavior is activated for this drag operation.
  If `Image` is `null` no exception is thrown.
  If `Image` is not `null` and the offset is `null` `NullPointerException` is thrown.
  If `Transferable` is `null` `NullPointerException` is thrown.
  If `DragSourceListener` is `null` no exception is thrown.

Parameters:
  `dscp` - the `DragSourceContextPeer` for this drag
  `trigger` - the triggering event
  `dragCursor` - the initial `Cursor`
  `dragImage` - the `Image` to drag (or `null`)
  `offset` - the offset of the image origin from the hotspot at the instant of the triggering event
  `t` - the `Transferable`
  `dsl` - the `DragSourceListener`
Throws:
  `IllegalArgumentException` - if the `Component` associated with the trigger event is `null`.
  `IllegalArgumentException` - if the `DragSource` for the trigger event is `null`.
  `IllegalArgumentException` - if the drag action for the trigger event is `DnDConstants.ACTION_NONE`.
  `IllegalArgumentException` - if the source actions for the `DragGestureRecognizer` associated with the trigger event are equal to `DnDConstants.ACTION_NONE`.
  `NullPointerException` - if dscp, trigger, or t are null, or if dragImage is non-null and offset is null

Method Detail

### getDragSource

    public DragSource getDragSource()

  Returns the `DragSource` that instantiated this `DragSourceContext`.

  Returns:
    the `DragSource` that instantiated this `DragSourceContext`

### getComponent

    public Component getComponent()

  Returns the `Component` associated with this `DragSourceContext`.

  Returns:
    the `Component` that started the drag

### getTrigger

    public DragGestureEvent getTrigger()

  Returns the `DragGestureEvent` that initially triggered the drag.

  Returns:
    the Event that triggered the drag

### getSourceActions

    public int getSourceActions()

  Returns a bitwise mask of `DnDConstants` that represent the set of drop actions supported by the drag source for the drag operation associated with this `DragSourceContext`.

  Returns:
    the drop actions supported by the drag source

### setCursor

    public void setCursor(Cursor c)

  Sets the cursor for this drag operation to the specified `Cursor`. If the specified `Cursor` is `null`, the default drag cursor behavior is activated for this drag operation, otherwise it is deactivated.

  Parameters:
    `c` - the `Cursor` to display, or `null` to activate the default drag cursor behavior

### getCursor

    public Cursor getCursor()

  Returns the current drag `Cursor`.

  Returns:
    the current drag `Cursor`

### addDragSourceListener

    public void addDragSourceListener(DragSourceListener dsl)
                               throws TooManyListenersException

  Add a `DragSourceListener` to this `DragSourceContext` if one has not already been added. If a `DragSourceListener` already exists, this method throws a `TooManyListenersException`.

  Parameters:
    `dsl` - the `DragSourceListener` to add. Note that while `null` is not prohibited, it is not acceptable as a parameter.

  Throws:
    ``TooManyListenersException`` - if a `DragSourceListener` has already been added
    `TooManyListenersException`

### removeDragSourceListener

    public void removeDragSourceListener(DragSourceListener dsl)

  Removes the specified `DragSourceListener` from this `DragSourceContext`.

  Parameters:
    `dsl` - the `DragSourceListener` to remove; note that while `null` is not prohibited, it is not acceptable as a parameter

### transferablesFlavorsChanged

    public void transferablesFlavorsChanged()

  Notifies the peer that the `Transferable`'s `DataFlavor`s have changed.

### dragEnter

    public void dragEnter(DragSourceDragEvent dsde)

  Calls `dragEnter` on the `DragSourceListener`s registered with this `DragSourceContext` and with the associated `DragSource`, and passes them the specified `DragSourceDragEvent`.

  Specified by:
    `dragEnter` in interface `DragSourceListener`
  Parameters:
    `dsde` - the `DragSourceDragEvent`

### dragOver

    public void dragOver(DragSourceDragEvent dsde)

  Calls `dragOver` on the `DragSourceListener`s registered with this `DragSourceContext` and with the associated `DragSource`, and passes them the specified `DragSourceDragEvent`.

  Specified by:
    `dragOver` in interface `DragSourceListener`
  Parameters:
    `dsde` - the `DragSourceDragEvent`

### dragExit

    public void dragExit(DragSourceEvent dse)

  Calls `dragExit` on the `DragSourceListener`s registered with this `DragSourceContext` and with the associated `DragSource`, and passes them the specified `DragSourceEvent`.

  Specified by:
    `dragExit` in interface `DragSourceListener`
  Parameters:
    `dse` - the `DragSourceEvent`

### dropActionChanged

    public void dropActionChanged(DragSourceDragEvent dsde)

  Calls `dropActionChanged` on the `DragSourceListener`s registered with this `DragSourceContext` and with the associated `DragSource`, and passes them the specified `DragSourceDragEvent`.

  Specified by:
    `dropActionChanged` in interface `DragSourceListener`
  Parameters:
    `dsde` - the `DragSourceDragEvent`

### dragDropEnd

    public void dragDropEnd(DragSourceDropEvent dsde)

  Calls `dragDropEnd` on the `DragSourceListener`s registered with this `DragSourceContext` and with the associated `DragSource`, and passes them the specified `DragSourceDropEvent`.

  Specified by:
    `dragDropEnd` in interface `DragSourceListener`
  Parameters:
    `dsde` - the `DragSourceDropEvent`

### dragMouseMoved

    public void dragMouseMoved(DragSourceDragEvent dsde)

  Calls `dragMouseMoved` on the `DragSourceMotionListener`s registered with the `DragSource` associated with this `DragSourceContext`, and them passes the specified `DragSourceDragEvent`.

  Specified by:
    `dragMouseMoved` in interface `DragSourceMotionListener`
  Parameters:
    `dsde` - the `DragSourceDragEvent`
  Since:
    1.4

### getTransferable

    public Transferable getTransferable()

  Returns the `Transferable` associated with this `DragSourceContext`.

  Returns:
    the `Transferable`

### updateCurrentCursor

    protected void updateCurrentCursor(int dropOp,
                                       int targetAct,
                                       int status)

  If the default drag cursor behavior is active, this method sets the default drag cursor for the specified selected operation, supported actions and status, otherwise this method does nothing.

  Parameters:
    `dropOp` - the user's currently selected operation
    `targetAct` - the current target's supported actions
    `status` - the constant

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