import com.google.gwt.dom.client.Style.Position;
import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.event.shared.HandlerRegistration;
+import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.EventListener;
import com.google.gwt.user.client.Event.NativePreviewEvent;
*/
public class VDragAndDropManager {
+ private final class DefaultDragAndDropEventHandler implements
+ NativePreviewHandler {
+ public void onPreviewNativeEvent(NativePreviewEvent event) {
+ updateCurrentEvent(event.getNativeEvent());
+ updateDragImagePosition();
+
+ NativeEvent nativeEvent = event.getNativeEvent();
+ Element targetElement = (Element) nativeEvent.getEventTarget()
+ .cast();
+ if (dragElement != null && targetElement.isOrHasChild(dragElement)) {
+ ApplicationConnection.getConsole().log(
+ "Event on dragImage, ignored");
+ event.cancel();
+ nativeEvent.stopPropagation();
+ return;
+ }
+
+ int typeInt = event.getTypeInt();
+ switch (typeInt) {
+ case Event.ONMOUSEOVER:
+ ApplicationConnection.getConsole().log(
+ event.getNativeEvent().getType());
+ VDropHandler target = findDragTarget(targetElement);
+ if (target != null && target != currentDrag) {
+ currentDropHandler = target;
+ target.dragEnter(currentDrag);
+ } else if (target == null && currentDropHandler != null) {
+ ApplicationConnection.getConsole().log("Invalid state!?");
+ currentDropHandler = null;
+ }
+ break;
+ case Event.ONMOUSEOUT:
+ ApplicationConnection.getConsole().log(
+ event.getNativeEvent().getType());
+
+ Element relatedTarget = (Element) nativeEvent
+ .getRelatedEventTarget().cast();
+ VDropHandler newDragHanler = findDragTarget(relatedTarget);
+ if (dragElement != null
+ && dragElement.isOrHasChild(relatedTarget)) {
+ ApplicationConnection.getConsole().log(
+ "Mouse out of dragImage, ignored");
+ return;
+ }
+
+ if (currentDropHandler != null
+ && currentDropHandler != newDragHanler) {
+ currentDropHandler.dragLeave(currentDrag);
+ currentDropHandler = null;
+ acceptCallback = null;
+ }
+ break;
+ case Event.ONMOUSEMOVE:
+ if (currentDropHandler != null) {
+ currentDropHandler.dragOver(currentDrag);
+ }
+ nativeEvent.preventDefault();
+
+ break;
+
+ case Event.ONMOUSEUP:
+ endDrag();
+ break;
+
+ default:
+ break;
+ }
+
+ }
+ }
+
public enum DragEventType {
ENTER, LEAVE, OVER, DROP
}
/**
* If drag and drop operation is not handled by {@link VDragAndDropManager}s
- * internal handler, this can be used to update current {@link VDropHandler}.
+ * internal handler, this can be used to update current {@link VDropHandler}
+ * .
*
* @param currentDropHandler
*/
private VAcceptCallback acceptCallback;
+ private HandlerRegistration deferredStartRegistration;
+
public static VDragAndDropManager get() {
if (instance == null) {
instance = new VDragAndDropManager();
private VDragAndDropManager() {
}
+ private NativePreviewHandler defaultDragAndDropEventHandler = new DefaultDragAndDropEventHandler();
+
/**
* This method is used to start Vaadin client side drag and drop operation.
* Operation may be started by virtually any Widget.
* Cancels possible existing drag. TODO figure out if this is always a bug
* if one is active. Maybe a good and cheap lifesaver thought.
* <p>
- * If possible, method automatically detects current {@link VDropHandler} and
- * fires {@link VDropHandler#dragEnter(VDragEvent)} event on it.
+ * If possible, method automatically detects current {@link VDropHandler}
+ * and fires {@link VDropHandler#dragEnter(VDragEvent)} event on it.
* <p>
* May also be used to control the drag and drop operation. If this option
* is used, {@link VDropHandler} is searched on mouse events and appropriate
* @return
*/
public VDragEvent startDrag(VTransferable transferable,
- NativeEvent startEvent, boolean handleDragEvents) {
+ final NativeEvent startEvent, final boolean handleDragEvents) {
interruptDrag();
currentDrag = new VDragEvent(transferable, startEvent);
- VDropHandler dh = null;
- if (startEvent != null) {
- dh = findDragTarget((Element) startEvent.getEventTarget().cast());
- }
- if (dh != null) {
- // drag has started on a DropHandler, kind of drag over happens
- currentDropHandler = dh;
- updateCurrentEvent(startEvent);
- dh.dragEnter(currentDrag);
- }
+ updateCurrentEvent(startEvent);
- if (handleDragEvents) {
+ final Command startDrag = new Command() {
- handlerRegistration = Event
- .addNativePreviewHandler(new NativePreviewHandler() {
-
- public void onPreviewNativeEvent(
- NativePreviewEvent event) {
- updateCurrentEvent(event.getNativeEvent());
- updateDragImagePosition();
-
- NativeEvent nativeEvent = event.getNativeEvent();
- Element targetElement = (Element) nativeEvent
- .getEventTarget().cast();
- if (dragElement != null
- && targetElement.isOrHasChild(dragElement)) {
- ApplicationConnection.getConsole().log(
- "Event on dragImage, ignored");
- event.cancel();
- nativeEvent.stopPropagation();
- return;
- }
+ public void execute() {
+ VDropHandler dh = null;
+ if (startEvent != null) {
+ dh = findDragTarget((Element) currentDrag.currentGwtEvent
+ .getEventTarget().cast());
+ }
+ if (dh != null) {
+ // drag has started on a DropHandler, kind of drag over
+ // happens
+ currentDropHandler = dh;
+ dh.dragEnter(currentDrag);
+ }
- int typeInt = event.getTypeInt();
- switch (typeInt) {
- case Event.ONMOUSEOVER:
- ApplicationConnection.getConsole().log(
- event.getNativeEvent().getType());
- VDropHandler target = findDragTarget(targetElement);
- if (target != null && target != currentDrag) {
- currentDropHandler = target;
- target.dragEnter(currentDrag);
- } else if (target == null
- && currentDropHandler != null) {
- ApplicationConnection.getConsole().log(
- "Invalid state!?");
- currentDropHandler = null;
- }
- break;
- case Event.ONMOUSEOUT:
- ApplicationConnection.getConsole().log(
- event.getNativeEvent().getType());
-
- Element relatedTarget = (Element) nativeEvent
- .getRelatedEventTarget().cast();
- VDropHandler newDragHanler = findDragTarget(relatedTarget);
- if (dragElement != null
- && dragElement
- .isOrHasChild(relatedTarget)) {
- ApplicationConnection.getConsole().log(
- "Mouse out of dragImage, ignored");
- return;
- }
+ if (handleDragEvents) {
+ handlerRegistration = Event
+ .addNativePreviewHandler(defaultDragAndDropEventHandler);
+ }
+ }
+ };
- if (currentDropHandler != null
- && currentDropHandler != newDragHanler) {
- currentDropHandler.dragLeave(currentDrag);
- currentDropHandler = null;
- acceptCallback = null;
- }
- break;
- case Event.ONMOUSEMOVE:
- if (currentDropHandler != null) {
- currentDropHandler.dragOver(currentDrag);
+ if (handleDragEvents) {
+ // only really start drag event on mousemove
+ if (Event.as(startEvent).getTypeInt() == Event.ONMOUSEDOWN) {
+
+ deferredStartRegistration = Event
+ .addNativePreviewHandler(new NativePreviewHandler() {
+
+ public void onPreviewNativeEvent(
+ NativePreviewEvent event) {
+ int typeInt = event.getTypeInt();
+ switch (typeInt) {
+ case Event.ONKEYDOWN:
+ case Event.ONKEYPRESS:
+ case Event.ONKEYUP:
+ // don't cancel possible drag start
+ break;
+ case Event.ONMOUSEMOVE:
+ deferredStartRegistration.removeHandler();
+ deferredStartRegistration = null;
+ updateCurrentEvent(event.getNativeEvent());
+ startDrag.execute();
+ default:
+ // on any other events, clean up the
+ // deferred drag start
+
+ deferredStartRegistration.removeHandler();
+ deferredStartRegistration = null;
+ break;
}
- nativeEvent.preventDefault();
-
- break;
- case Event.ONMOUSEUP:
- endDrag();
- break;
-
- default:
- break;
}
+ });
- }
+ } else {
+ startDrag.execute();
+ }
- });
+ } else {
+ startDrag.execute();
}
+
return currentDrag;
}
* @return
*/
private VDropHandler findDragTarget(Element element) {
-
EventListener eventListener = Event.getEventListener(element);
while (eventListener == null) {
element = element.getParentElement();
if (element == null) {
break;
}
- eventListener = Event.getEventListener(element);
+ try {
+ eventListener = Event.getEventListener(element);
+ } catch (Exception e) {
+ // CCE Should not happen but it does to me // MT 1.2.2010
+ e.printStackTrace();
+ }
}
if (eventListener == null) {
ApplicationConnection.getConsole().log(
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