DragHandler (com.iamsoft:iamsoft-fxutils 8.0.1 API)

java.lang.Object
- furbelow.DragHandler

All Implemented Interfaces:

DragGestureListener, DragSourceListener, DragSourceMotionListener, EventListener
```
public abstract class DragHandler
extends Object
implements DragSourceListener, DragSourceMotionListener, DragGestureListener
```
Provides simplified drag handling for a component. Usage:
```
 int actions = DnDConstants.MOVE_OR_COPY;
 Component component = ...;
 DragHandler handler = new DragHandler(component, actions);
 
```
- Supports painting an arbitrary Icon with transparency to represent the item being dragged (restricted to the Window of the drag source if the platform doesn't support drag images).
- Disallow starting a drag if the user requests an unsupported action.
- Adjusts the cursor on drags with no modifier for which the default action is disallowed but where one or more non-default actions are allowed, e.g. a drag (with no modifiers) to a target which supports "link" should change the cursor to "link" (prior to 1.6, the JRE behavior is to display a "not allowed" cursor, even though the action actually depends on how the drop target responds). The bug is fixed in java 1.6.
- Disallow drops to targets if the non-default (user-requested) action is not supported by the target, e.g. the user requests a "copy" when the target only supports "move". This is generally the responsibility of the drop handler, which decides whether or not to accept a drag. The DragHandler provides static modifier state information since the drop handler doesn't have access to it.
NOTE: Fundamentally, the active action is determined by the drop handler in DropTargetDragEvent.acceptDrag(int), but often client code simply relies on DropTargetDragEvent.getDropAction().

Field Summary

Fields
Modifier and Type	Field and Description
`protected static int`	`COPY` Convenience to reference `DnDConstants.ACTION_COPY`.
`static float`	`DEFAULT_GHOST_ALPHA` Default transparency for ghosting.
`protected static int`	`LINK` Convenience to reference `DnDConstants.ACTION_LINK`.
`static Dimension`	`MAX_GHOST_SIZE` Default maximum size for ghosted images.
`protected static int`	`MOVE` Convenience to reference `DnDConstants.ACTION_MOVE`.
`protected static int`	`NONE` Convenience to reference `DnDConstants.ACTION_NONE`.
`static int`	`UNKNOWN_MODIFIERS` `getModifiers()` returns this value when the current modifiers state is unknown.
`static Transferable`	`UNKNOWN_TRANSFERABLE` `#getTransferable(DropTargetDragEvent)` returns this value when the current `Transferable` is unknown.

Constructor Summary

Constructors
Modifier	Constructor and Description
`protected`	`DragHandler(Component dragSource, int actions)` Enable drags from the given component, supporting the actions in the given action mask.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`protected int`	`adjustDropAction(DragSourceEvent ev)` Pick a different drop action if the target doesn't support the current one and there are no modifiers.
`protected boolean`	`canDrag(DragGestureEvent e)` Override to control whether a drag is started.
`protected Image`	`createDragImage(Icon icon)` Create an image from the given icon.
`protected GhostedDragImage`	`createGhostedDragImage(JComponent dragSource, Point screen, Icon dragIcon, Point dragIconOffset)` Create a ghosted drag image.
`void`	`dragDropEnd(DragSourceDropEvent e)`
`void`	`dragEnter(DragSourceDragEvent e)`
`void`	`dragExit(DragSourceEvent e)`
`void`	`dragGestureRecognized(DragGestureEvent e)` Called when a user drag gesture is recognized.
`void`	`dragMouseMoved(DragSourceDragEvent e)`
`void`	`dragOver(DragSourceDragEvent e)`
`protected void`	`dragStarted(DragGestureEvent e)` Override to perform any decoration of the target at the start of a drag, if desired.
`void`	`dropActionChanged(DragSourceDragEvent e)`
`protected int`	`getAcceptableDropAction(int targetActions)` Returns the first available action supported by source and target.
`protected Cursor`	`getCursorForAction(int actualAction)`
`protected Icon`	`getDragIcon(DragGestureEvent e, Point srcOffset)` Override this to provide a custom image.
`protected int`	`getDropAction(DragSourceEvent ev)` Get the currently requested drop action.
`protected abstract Transferable`	`getTransferable(DragGestureEvent e)` Override to provide an appropriate `Transferable` representing the data being dragged.
`static Transferable`	`getTransferable(DropTargetEvent e)` Used to communicate the current `Transferable` during a drag, if available.
`protected Icon`	`scaleDragIcon(Icon dragIcon, Point offset)` Reduce the size of the given drag icon, if appropriate.
`protected void`	`setModifiers(int mods)` Update the modifiers hint.
`protected void`	`updateCursor(DragSourceEvent ev)`

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

- Field Detail
  - MAX_GHOST_SIZE
```
public static final Dimension MAX_GHOST_SIZE
```
    Default maximum size for ghosted images.
  - DEFAULT_GHOST_ALPHA
```
public static final float DEFAULT_GHOST_ALPHA
```
    Default transparency for ghosting.
    
    See Also:
    
    Constant Field Values
  - UNKNOWN_MODIFIERS
```
public static final int UNKNOWN_MODIFIERS
```
    getModifiers() returns this value when the current modifiers state is unknown.
    
    See Also:
    
    Constant Field Values
  - UNKNOWN_TRANSFERABLE
```
public static final Transferable UNKNOWN_TRANSFERABLE
```
    #getTransferable(DropTargetDragEvent) returns this value when the current Transferable is unknown.
  - MOVE
```
protected static final int MOVE
```
    Convenience to reference DnDConstants.ACTION_MOVE.
    
    See Also:
    
    Constant Field Values
  - COPY
```
protected static final int COPY
```
    Convenience to reference DnDConstants.ACTION_COPY.
    
    See Also:
    
    Constant Field Values
  - LINK
```
protected static final int LINK
```
    Convenience to reference DnDConstants.ACTION_LINK.
    
    See Also:
    
    Constant Field Values
  - NONE
```
protected static final int NONE
```
    Convenience to reference DnDConstants.ACTION_NONE.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - DragHandler
```
protected DragHandler(Component dragSource,
                      int actions)
```
    Enable drags from the given component, supporting the actions in the given action mask.
- Method Detail
  - getTransferable
```
public static Transferable getTransferable(DropTargetEvent e)
```
    Used to communicate the current Transferable during a drag, if available. Work around absence of access to the data when dragging pre-1.5.
  - canDrag
```
protected boolean canDrag(DragGestureEvent e)
```
    Override to control whether a drag is started. The default implementation disallows the drag if the user is applying modifiers and the user-requested action is not supported.
  - setModifiers
```
protected void setModifiers(int mods)
```
    Update the modifiers hint.
  - getTransferable
```
protected abstract Transferable getTransferable(DragGestureEvent e)
```
    Override to provide an appropriate Transferable representing the data being dragged.
  - getDragIcon
```
protected Icon getDragIcon(DragGestureEvent e,
                           Point srcOffset)
```
    Override this to provide a custom image. The Icon returned by this method by default is null, which results in no drag image.
    
    Parameters:
    
    srcOffset - set this to be the offset from the drag source component's upper left corner to the image's upper left corner. For example, when dragging a row from a list, the offset would be the row's bounding rectangle's (x,y) coordinate.
    The default value is (0,0), so if unchanged, the image is will use the same origin as the drag source component.
  - dragStarted
```
protected void dragStarted(DragGestureEvent e)
```
    Override to perform any decoration of the target at the start of a drag, if desired.
  - dragGestureRecognized
```
public void dragGestureRecognized(DragGestureEvent e)
```
    Called when a user drag gesture is recognized. This method is responsible for initiating the drag operation.
    
    Specified by:
    
    dragGestureRecognized in interface DragGestureListener
  - scaleDragIcon
```
protected Icon scaleDragIcon(Icon dragIcon,
                             Point offset)
```
    Reduce the size of the given drag icon, if appropriate. When using a smaller drag icon, we also need to adjust the offset.
  - createGhostedDragImage
```
protected GhostedDragImage createGhostedDragImage(JComponent dragSource,
                                                  Point screen,
                                                  Icon dragIcon,
                                                  Point dragIconOffset)
```
    Create a ghosted drag image.
  - createDragImage
```
protected Image createDragImage(Icon icon)
```
    Create an image from the given icon. The image is provided to the native handler if drag images are supported natively.
  - getCursorForAction
```
protected Cursor getCursorForAction(int actualAction)
```
  - getAcceptableDropAction
```
protected int getAcceptableDropAction(int targetActions)
```
    Returns the first available action supported by source and target.
  - getDropAction
```
protected int getDropAction(DragSourceEvent ev)
```
    Get the currently requested drop action.
  - adjustDropAction
```
protected int adjustDropAction(DragSourceEvent ev)
```
    Pick a different drop action if the target doesn't support the current one and there are no modifiers.
  - updateCursor
```
protected void updateCursor(DragSourceEvent ev)
```
  - dragDropEnd
```
public void dragDropEnd(DragSourceDropEvent e)
```
    Specified by:
    
    dragDropEnd in interface DragSourceListener
  - dragEnter
```
public void dragEnter(DragSourceDragEvent e)
```
    Specified by:
    
    dragEnter in interface DragSourceListener
  - dragMouseMoved
```
public void dragMouseMoved(DragSourceDragEvent e)
```
    Specified by:
    
    dragMouseMoved in interface DragSourceMotionListener
  - dragOver
```
public void dragOver(DragSourceDragEvent e)
```
    Specified by:
    
    dragOver in interface DragSourceListener
  - dragExit
```
public void dragExit(DragSourceEvent e)
```
    Specified by:
    
    dragExit in interface DragSourceListener
  - dropActionChanged
```
public void dropActionChanged(DragSourceDragEvent e)
```
    Specified by:
    
    dropActionChanged in interface DragSourceListener

Class DragHandler

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

MAX_GHOST_SIZE

DEFAULT_GHOST_ALPHA

UNKNOWN_MODIFIERS

UNKNOWN_TRANSFERABLE

MOVE

COPY

LINK

NONE

Constructor Detail

DragHandler

Method Detail

getTransferable

canDrag

setModifiers

getTransferable

getDragIcon

dragStarted

dragGestureRecognized

scaleDragIcon

createGhostedDragImage

createDragImage

getCursorForAction

getAcceptableDropAction

getDropAction

adjustDropAction

updateCursor

dragDropEnd

dragEnter

dragMouseMoved

dragOver

dragExit

dropActionChanged