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Vaadin is a web application framework for Rich Internet Applications (RIA).
Vaadin enables easy development and maintenance of fast and
secure rich web
applications with a stunning look and feel and a wide browser support.
It features a server-side architecture with the majority of the logic
running
on the server. Ajax technology is used at the browser-side to ensure a
rich
and interactive user experience.
/*
* Copyright 2000-2014 Vaadin Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.vaadin.client.ui.dd;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.dom.client.Node;
import com.google.gwt.dom.client.Style.Display;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.Event.NativePreviewEvent;
import com.vaadin.client.WidgetUtil;
import com.vaadin.client.ui.dd.VDragAndDropManager.DDManagerMediator;
/**
* Strategy to handle native preview events for VDragAndDropManager.
*
* The strategy could be overridden via GWT Deferred Binding mechanism.
*
* @author Vaadin Ltd
* @since 7.4.4
*/
public class DDEventHandleStrategy {
/**
* Returns {@code true} if {@code event} interrupts Drag and Drop.
*
* @param event
* GWT event to handle
* @param mediator
* VDragAndDropManager data accessor
* @return whether {@code true} interrupts DnD
*/
public boolean isDragInterrupted(NativePreviewEvent event,
DDManagerMediator mediator) {
int typeInt = event.getTypeInt();
if (typeInt == Event.ONKEYDOWN) {
int keyCode = event.getNativeEvent().getKeyCode();
if (keyCode == KeyCodes.KEY_ESCAPE) {
return true;
}
}
return false;
}
/**
* Handles key down {@code event}.
*
* Default implementation doesn't do anything.
*
* @param event
* key down GWT event
* @param mediator
* VDragAndDropManager data accessor
*/
public void handleKeyDownEvent(NativePreviewEvent event,
DDManagerMediator mediator) {
// no use for handling for any key down event
}
/**
* Get target element for {@code event}.
*
* @param event
* GWT event to find target
* @param mediator
* VDragAndDropManager data accessor
* @return target element for {@code event}
*/
public Element getTargetElement(NativePreviewEvent event,
DDManagerMediator mediator) {
NativeEvent gwtEvent = event.getNativeEvent();
Element targetElement;
if (WidgetUtil.isTouchEvent(gwtEvent)
|| mediator.getManager().getDragElement() != null) {
int x = WidgetUtil.getTouchOrMouseClientX(gwtEvent);
int y = WidgetUtil.getTouchOrMouseClientY(gwtEvent);
// Util.browserDebugger();
targetElement = WidgetUtil.getElementFromPoint(x, y);
} else {
Node targetNode = Node.as(gwtEvent.getEventTarget());
if (Element.is(targetNode)) {
targetElement = Element.as(targetNode);
} else {
targetElement = targetNode.getParentElement();
}
}
return targetElement;
}
/**
* Updates drag image DOM element. This method updates drag image position
* and adds additional styles. Default implementation hides drag element to
* be able to get target element by the point (see
* {@link #getTargetElement(NativePreviewEvent, DDManagerMediator)}. Method
* {@link #restoreDragImage(String, DDManagerMediator, NativePreviewEvent)}
* is used later on to restore the drag element in its state before
* temporary update. Returns "display" CSS style property of the original
* drag image. This value will be passed to the
* {@link #restoreDragImage(String, DDManagerMediator, NativePreviewEvent)}
* method.
*
* @param event
* GWT event for active DnD operation
* @param mediator
* VDragAndDropManager data accessor
* @return "display" CSS style property of drag image element to restore it
* later on
*/
public String updateDragImage(NativePreviewEvent event,
DDManagerMediator mediator) {
VDragAndDropManager manager = mediator.getManager();
manager.updateDragImagePosition(event.getNativeEvent(),
manager.getDragElement());
String display = null;
if (manager.getDragElement() != null) {
// to detect the "real" target, hide dragelement temporary and
// use elementFromPoint
display = manager.getDragElement().getStyle().getDisplay();
manager.getDragElement().getStyle().setDisplay(Display.NONE);
}
return display;
}
/**
* Restores drag image after temporary update by
* {@link #updateDragImage(NativePreviewEvent, DDManagerMediator)}.
*
* @param originalImageDisplay
* original "display" CSS style property of drag image element
* @param mediator
* VDragAndDropManager data accessor
* @param event
* GWT event for active DnD operation
*/
public void restoreDragImage(String originalImageDisplay,
DDManagerMediator mediator, NativePreviewEvent event) {
VDragAndDropManager manager = mediator.getManager();
if (manager.getDragElement() != null) {
manager.getDragElement().getStyle()
.setProperty("display", originalImageDisplay);
}
}
/**
* Handles event when drag image element (
* {@link VDragAndDropManager#getDragElement()} return value) is not null or
* {@code event} is touch event.
*
* If method returns {@code true} then event processing will be stoped.
*
* @param target
* target element over which DnD event has happened
* @param event
* GWT event for active DnD operation
* @param mediator
* VDragAndDropManager data accessor
* @return {@code true} is strategy handled the event and no further steps
* to handle required.
*/
public boolean handleDragImageEvent(Element target,
NativePreviewEvent event, DDManagerMediator mediator) {
VDragAndDropManager manager = mediator.getManager();
// ApplicationConnection.getConsole().log(
// "Event on dragImage, target changed");
// special handling for events over dragImage
// pretty much all events are mousemove althout below
// kind of happens mouseover
switch (event.getTypeInt()) {
case Event.ONMOUSEOVER:
case Event.ONMOUSEOUT:
// ApplicationConnection
// .getConsole()
// .log(
// "IGNORING proxy image event, fired because of hack or not significant");
return true;
case Event.ONMOUSEMOVE:
case Event.ONTOUCHMOVE:
VDropHandler findDragTarget = findDragTarget(target, mediator);
if (findDragTarget != manager.getCurrentDropHandler()) {
// dragleave on old
handleDragLeave(mediator, true);
// dragenter on new
manager.setCurrentDropHandler(findDragTarget);
handleDragEnter(target, mediator);
} else if (findDragTarget != null) {
handleDragOver(target, mediator);
}
// prevent text selection on IE
event.getNativeEvent().preventDefault();
return true;
}
return false;
}
/**
* Handles drag enter on new element.
*
* @param mediator
* VDragAndDropManager data accessor
* @param target
* target element over which DnD event has happened
*/
protected void handleDragEnter(Element target, DDManagerMediator mediator) {
VDragAndDropManager manager = mediator.getManager();
if (manager.getCurrentDropHandler() != null) {
mediator.getDragEvent().setElementOver(target);
manager.getCurrentDropHandler().dragEnter(mediator.getDragEvent());
}
}
/**
* Handles drag over on element.
*
* @param mediator
* VDragAndDropManager data accessor
* @param target
* target element over which DnD event has happened
*/
protected void handleDragOver(Element target, DDManagerMediator mediator) {
mediator.getDragEvent().setElementOver(target);
mediator.getManager().getCurrentDropHandler()
.dragOver(mediator.getDragEvent());
}
/**
* Final phase of event handling.
*
* @param targetElement
* target element over which DnD event has happened
* @param event
* GWT event for active DnD operation
* @param mediator
* VDragAndDropManager data accessor
*/
public void handleEvent(Element targetElement, NativePreviewEvent event,
DDManagerMediator mediator) {
switch (event.getTypeInt()) {
case Event.ONMOUSEOVER:
handleMouseOver(targetElement, event, mediator);
break;
case Event.ONMOUSEOUT:
handleMouseOut(targetElement, event, mediator);
break;
case Event.ONMOUSEMOVE:
case Event.ONTOUCHMOVE:
handleMouseMove(targetElement, event, mediator);
break;
case Event.ONTOUCHEND:
handleTouchEnd(targetElement, event, mediator);
break;
case Event.ONMOUSEUP:
handleMouseUp(targetElement, event, mediator);
break;
}
}
/**
* Called to handle {@link Event#ONMOUSEMOVE} event.
*
* @param target
* target element over which DnD event has happened
* @param event
* ONMOUSEMOVE GWT event for active DnD operation
* @param mediator
* VDragAndDropManager data accessor
*/
protected void handleMouseMove(Element target, NativePreviewEvent event,
DDManagerMediator mediator) {
VDragAndDropManager manager = mediator.getManager();
if (manager.getCurrentDropHandler() != null) {
handleDragOver(target, mediator);
}
event.getNativeEvent().preventDefault();
}
/**
* Called to handle {@link Event#ONTOUCHEND} event.
*
* @param target
* target element over which DnD event has happened
* @param event
* ONTOUCHEND GWT event for active DnD operation
* @param mediator
* VDragAndDropManager data accessor
*/
protected void handleTouchEnd(Element target, NativePreviewEvent event,
DDManagerMediator mediator) {
/* Avoid simulated event on drag end */
event.getNativeEvent().preventDefault();
handleMouseUp(target, event, mediator);
}
/**
* Called to handle {@link Event#ONMOUSEUP} event.
*
* @param target
* target element over which DnD event has happened
* @param event
* ONMOUSEUP GWT event for active DnD operation
* @param mediator
* VDragAndDropManager data accessor
*/
protected void handleMouseUp(Element target, NativePreviewEvent event,
DDManagerMediator mediator) {
mediator.getManager().endDrag();
}
/**
* Called to handle {@link Event#ONMOUSEOUT} event.
*
* @param target
* target element over which DnD event has happened
* @param event
* ONMOUSEOUT GWT event for active DnD operation
* @param mediator
* VDragAndDropManager data accessor
*/
protected void handleMouseOut(Element target, NativePreviewEvent event,
DDManagerMediator mediator) {
VDragAndDropManager manager = mediator.getManager();
Element relatedTarget = Element.as(event.getNativeEvent()
.getRelatedEventTarget());
VDropHandler newDragHanler = findDragTarget(relatedTarget, mediator);
if (manager.getDragElement() != null
&& manager.getDragElement().isOrHasChild(relatedTarget)) {
// ApplicationConnection.getConsole().log(
// "Mouse out of dragImage, ignored");
return;
}
if (manager.getCurrentDropHandler() != newDragHanler) {
handleDragLeave(mediator, true);
manager.setCurrentDropHandler(null);
}
}
/**
* Handles drag leave on old element.
*
* @param mediator
* VDragAndDropManager data accessor
*/
protected void handleDragLeave(DDManagerMediator mediator,
boolean clearServerCallback) {
VDragAndDropManager manager = mediator.getManager();
if (manager.getCurrentDropHandler() != null) {
manager.getCurrentDropHandler().dragLeave(mediator.getDragEvent());
mediator.getDragEvent().getDropDetails().clear();
if (clearServerCallback) {
mediator.clearServerCallback();
}
}
}
/**
* Called to handle {@link Event#ONMOUSEOVER} event.
*
* @param target
* target element over which DnD event has happened
* @param event
* ONMOUSEOVER GWT event for active DnD operation
* @param mediator
* VDragAndDropManager data accessor
*/
protected void handleMouseOver(Element target, NativePreviewEvent event,
DDManagerMediator mediator) {
VDragAndDropManager manager = mediator.getManager();
VDropHandler dragHandler = findDragTarget(target, mediator);
if (dragHandler != null
&& dragHandler != manager.getCurrentDropHandler()) {
handleDragLeave(mediator, false);
manager.setCurrentDropHandler(dragHandler);
// ApplicationConnection.getConsole().log(
// "DropHandler now"
// + currentDropHandler.getPaintable());
handleDragEnter(target, mediator);
} else if (dragHandler == null
&& manager.getCurrentDropHandler() != null) {
// ApplicationConnection.getConsole().log("Invalid state!?");
handleDragLeave(mediator, false);
manager.setCurrentDropHandler(null);
}
}
/**
* Find drag handler for the {@code target} element.
*
* @param target
* target element over which DnD event has happened
* @param mediator
* VDragAndDropManager data accessor
* @return drop handler of target element
*/
protected VDropHandler findDragTarget(Element target,
DDManagerMediator mediator) {
return mediator.getManager().findDragTarget(target);
}
}