/**
* Reports whether or not drag <code>Image</code> support is available on the underlying platform.
*
* <p>
*
* @return if the Drag Image support is available on this platform
*/
public static boolean isDragImageSupported() {
Toolkit t = Toolkit.getDefaultToolkit();
Boolean supported;
try {
supported =
(Boolean) Toolkit.getDefaultToolkit().getDesktopProperty("DnD.isDragImageSupported");
return supported.booleanValue();
} catch (Exception e) {
return false;
}
}
/**
* Start a drag, given the <code>DragGestureEvent</code> that initiated the drag, the initial
* <code>Cursor</code> to use, the <code>Image</code> to drag, the offset of the <code>Image
* </code> origin from the hotspot of the <code>Cursor</code> at the instant of the trigger, the
* <code>Transferable</code> subject data of the drag, the <code>DragSourceListener</code>, and
* the <code>FlavorMap</code>.
*
* <p>
*
* @param trigger the <code>DragGestureEvent</code> that initiated the drag
* @param dragCursor the initial {@code Cursor} for this drag operation or {@code null} for the
* default cursor handling; see <a
* href="DragSourceContext.html#defaultCursor">DragSourceContext</a> for more details on the
* cursor handling mechanism during drag and drop
* @param dragImage the image to drag or {@code null}
* @param imageOffset the offset of the <code>Image</code> origin from the hotspot of the <code>
* Cursor</code> at the instant of the trigger
* @param transferable the subject data of the drag
* @param dsl the <code>DragSourceListener</code>
* @param flavorMap the <code>FlavorMap</code> to use, or <code>null</code>
* <p>
* @throws ae.java.awt.dnd.InvalidDnDOperationException if the Drag and Drop system is unable to
* initiate a drag operation, or if the user attempts to start a drag while an existing drag
* operation is still executing
*/
public void startDrag(
DragGestureEvent trigger,
Cursor dragCursor,
Image dragImage,
Point imageOffset,
Transferable transferable,
DragSourceListener dsl,
FlavorMap flavorMap)
throws InvalidDnDOperationException {
SunDragSourceContextPeer.setDragDropInProgress(true);
try {
if (flavorMap != null) this.flavorMap = flavorMap;
DragSourceContextPeer dscp = Toolkit.getDefaultToolkit().createDragSourceContextPeer(trigger);
DragSourceContext dsc =
createDragSourceContext(
dscp, trigger, dragCursor, dragImage, imageOffset, transferable, dsl);
if (dsc == null) {
throw new InvalidDnDOperationException();
}
dscp.startDrag(dsc, dsc.getCursor(), dragImage, imageOffset); // may throw
} catch (RuntimeException e) {
SunDragSourceContextPeer.setDragDropInProgress(false);
throw e;
}
}
private static Cursor load(String name) {
if (GraphicsEnvironment.isHeadless()) {
return null;
}
try {
return (Cursor) Toolkit.getDefaultToolkit().getDesktopProperty(name);
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException("failed to load system cursor: " + name + " : " + e.getMessage());
}
}
/**
* Returns the drag gesture motion threshold. The drag gesture motion threshold defines the
* recommended behavior for {@link MouseDragGestureRecognizer}s.
*
* <p>If the system property <code>awt.dnd.drag.threshold</code> is set to a positive integer,
* this method returns the value of the system property; otherwise if a pertinent desktop property
* is available and supported by the implementation of the Java platform, this method returns the
* value of that property; otherwise this method returns some default value. The pertinent desktop
* property can be queried using <code>
* ae.java.awt.Toolkit.getDesktopProperty("DnD.gestureMotionThreshold")</code>.
*
* @return the drag gesture motion threshold
* @see MouseDragGestureRecognizer
* @since 1.5
*/
public static int getDragThreshold() {
int ts =
((Integer) AccessController.doPrivileged(new GetIntegerAction("awt.dnd.drag.threshold", 0)))
.intValue();
if (ts > 0) {
return ts;
} else {
Integer td =
(Integer) Toolkit.getDefaultToolkit().getDesktopProperty("DnD.gestureMotionThreshold");
if (td != null) {
return td.intValue();
}
}
return 5;
}
/**
* Creates a new <code>DragGestureRecognizer</code> that implements the default abstract subclass
* of <code>DragGestureRecognizer</code> for this <code>DragSource</code>, and sets the specified
* <code>Component</code> and <code>DragGestureListener</code> on the newly created object.
*
* <p>For this <code>DragSource</code> the default is <code>MouseDragGestureRecognizer</code>.
*
* <p>
*
* @param c the <code>Component</code> target for the recognizer
* @param actions the permitted source actions
* @param dgl the <code>DragGestureListener</code> to notify
* <p>
* @return the new <code>DragGestureRecognizer</code> or <code>null</code> if the <code>
* Toolkit.createDragGestureRecognizer</code> method has no implementation available for the
* requested <code>DragGestureRecognizer</code> subclass and returns <code>null</code>
*/
public DragGestureRecognizer createDefaultDragGestureRecognizer(
Component c, int actions, DragGestureListener dgl) {
return Toolkit.getDefaultToolkit()
.createDragGestureRecognizer(MouseDragGestureRecognizer.class, this, c, actions, dgl);
}
/**
* Creates a new <code>DragGestureRecognizer</code> that implements the specified abstract
* subclass of <code>DragGestureRecognizer</code>, and sets the specified <code>Component</code>
* and <code>DragGestureListener</code> on the newly created object.
*
* <p>
*
* @param recognizerAbstractClass the requested abstract type
* @param actions the permitted source drag actions
* @param c the <code>Component</code> target
* @param dgl the <code>DragGestureListener</code> to notify
* <p>
* @return the new <code>DragGestureRecognizer</code> or <code>null</code> if the <code>
* Toolkit.createDragGestureRecognizer</code> method has no implementation available for the
* requested <code>DragGestureRecognizer</code> subclass and returns <code>null</code>
*/
public <T extends DragGestureRecognizer> T createDragGestureRecognizer(
Class<T> recognizerAbstractClass, Component c, int actions, DragGestureListener dgl) {
return Toolkit.getDefaultToolkit()
.createDragGestureRecognizer(recognizerAbstractClass, this, c, actions, dgl);
}