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- /*
- * Copyright 2000-2016 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.extensions;
-
- import com.google.gwt.dom.client.DataTransfer;
- import com.google.gwt.dom.client.Element;
- import com.google.gwt.dom.client.NativeEvent;
- import com.google.gwt.user.client.ui.Widget;
- import com.vaadin.client.ComponentConnector;
- import com.vaadin.client.ServerConnector;
- import com.vaadin.event.dnd.DragSourceExtension;
- import com.vaadin.shared.ui.Connect;
- import com.vaadin.shared.ui.dnd.DragSourceRpc;
- import com.vaadin.shared.ui.dnd.DragSourceState;
- import com.vaadin.shared.ui.dnd.DropEffect;
-
- import elemental.events.Event;
- import elemental.events.EventListener;
- import elemental.events.EventTarget;
-
- /**
- * Extension to add drag source functionality to a widget for using HTML5 drag
- * and drop. Client side counterpart of {@link DragSourceExtension}.
- *
- * @author Vaadin Ltd
- * @since 8.1
- */
- @Connect(DragSourceExtension.class)
- public class DragSourceExtensionConnector extends AbstractExtensionConnector {
-
- private static final String CLASS_DRAGGABLE = "v-draggable";
-
- // Create event listeners
- private final EventListener dragStartListener = this::onDragStart;
- private final EventListener dragEndListener = this::onDragEnd;
-
- /**
- * Widget of the drag source component.
- */
- private Widget dragSourceWidget;
-
- @Override
- protected void extend(ServerConnector target) {
- dragSourceWidget = ((ComponentConnector) target).getWidget();
-
- setDraggable(getDraggableElement());
- addDragListeners(getDraggableElement());
- }
-
- /**
- * Sets the given element draggable and adds class name.
- *
- * @param element
- * Element to be set draggable.
- */
- protected void setDraggable(Element element) {
- element.setDraggable(Element.DRAGGABLE_TRUE);
- element.addClassName(CLASS_DRAGGABLE);
- }
-
- /**
- * Removes draggable and class name from the given element.
- *
- * @param element
- * Element to remove draggable from.
- */
- protected void removeDraggable(Element element) {
- element.setDraggable(Element.DRAGGABLE_FALSE);
- element.removeClassName(CLASS_DRAGGABLE);
- }
-
- /**
- * Adds dragstart and dragend event listeners to the given DOM element.
- *
- * @param element
- * DOM element to attach event listeners to.
- */
- protected void addDragListeners(Element element) {
- EventTarget target = element.cast();
-
- target.addEventListener(Event.DRAGSTART, dragStartListener);
- target.addEventListener(Event.DRAGEND, dragEndListener);
- }
-
- /**
- * Removes dragstart and dragend event listeners from the given DOM element.
- *
- * @param element
- * DOM element to remove event listeners from.
- */
- protected void removeDragListeners(Element element) {
- EventTarget target = element.cast();
-
- target.removeEventListener(Event.DRAGSTART, dragStartListener);
- target.removeEventListener(Event.DRAGEND, dragEndListener);
- }
-
- @Override
- public void onUnregister() {
- super.onUnregister();
-
- Element dragSource = getDraggableElement();
-
- removeDraggable(dragSource);
- removeDragListeners(dragSource);
- }
-
- /**
- * Event handler for the {@code dragstart} event. Called when {@code
- * dragstart} event occurs.
- *
- * @param event
- * browser event to be handled
- */
- protected void onDragStart(Event event) {
- // Convert elemental event to have access to dataTransfer
- NativeEvent nativeEvent = (NativeEvent) event;
-
- // Set effectAllowed parameter
- if (getState().effectAllowed != null) {
- setEffectAllowed(nativeEvent.getDataTransfer(),
- getState().effectAllowed.getValue());
- }
-
- // Set text data parameter
- nativeEvent.getDataTransfer().setData(DragSourceState.DATA_TYPE_TEXT,
- createDataTransferText(event));
-
- // Initiate firing server side dragstart event when there is a
- // DragStartListener attached on the server side
- if (hasEventListener(DragSourceState.EVENT_DRAGSTART)) {
- sendDragStartEventToServer(event);
- }
-
- // Stop event bubbling
- nativeEvent.stopPropagation();
- }
-
- /**
- * Creates data of type {@code "text"} for the {@code DataTransfer} object
- * of the given event.
- *
- * @param dragStartEvent
- * Event to set the data for.
- * @return Textual data to be set for the event or {@literal null}.
- */
- protected String createDataTransferText(Event dragStartEvent) {
- return getState().dataTransferText;
- }
-
- /**
- * Initiates a server RPC for the drag start event.
- * <p>
- * This method is called only if there is a server side drag start event
- * handler attached.
- *
- * @param dragStartEvent
- * Client side dragstart event.
- */
- protected void sendDragStartEventToServer(Event dragStartEvent) {
- getRpcProxy(DragSourceRpc.class).dragStart();
- }
-
- /**
- * Event handler for the {@code dragend} event. Called when {@code dragend}
- * event occurs.
- *
- * @param event
- * browser event to be handled
- */
- protected void onDragEnd(Event event) {
- // Initiate server start dragend event when there is a DragEndListener
- // attached on the server side
- if (hasEventListener(DragSourceState.EVENT_DRAGEND)) {
- String dropEffect = getDropEffect(
- ((NativeEvent) event).getDataTransfer());
-
- assert dropEffect != null : "Drop effect should never be null";
-
- sendDragEndEventToServer(event,
- DropEffect.valueOf(dropEffect.toUpperCase()));
- }
- }
-
- /**
- * Initiates a server RPC for the drag end event.
- *
- * @param dragEndEvent
- * Client side dragend event.
- * @param dropEffect
- * Drop effect of the dragend event, extracted from {@code
- * DataTransfer.dropEffect} parameter.
- */
- protected void sendDragEndEventToServer(Event dragEndEvent,
- DropEffect dropEffect) {
- getRpcProxy(DragSourceRpc.class).dragEnd(dropEffect);
- }
-
- /**
- * Finds the draggable element within the widget. By default, returns the
- * topmost element.
- *
- * @return the draggable element in the parent widget.
- */
- protected Element getDraggableElement() {
- return dragSourceWidget.getElement();
- }
-
- private native void setEffectAllowed(DataTransfer dataTransfer,
- String effectAllowed)/*-{
- dataTransfer.effectAllowed = effectAllowed;
- }-*/;
-
- private native String getDropEffect(DataTransfer dataTransfer)/*-{
- return dataTransfer.dropEffect;
- }-*/;
-
- @Override
- public DragSourceState getState() {
- return (DragSourceState) super.getState();
- }
- }
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