/*
* 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.ui.components.grid;
import java.util.List;
import java.util.Optional;
import java.util.Set;
import java.util.stream.Collectors;
import com.vaadin.data.provider.DataGenerator;
import com.vaadin.server.SerializableFunction;
import com.vaadin.shared.Registration;
import com.vaadin.shared.ui.dnd.DragSourceState;
import com.vaadin.shared.ui.dnd.DropEffect;
import com.vaadin.shared.ui.grid.GridDragSourceRpc;
import com.vaadin.shared.ui.grid.GridDragSourceState;
import com.vaadin.ui.Grid;
import com.vaadin.ui.dnd.DragSourceExtension;
import elemental.json.JsonObject;
/**
* Makes a Grid's rows draggable for HTML5 drag and drop functionality.
* <p>
* When dragging a selected row, all the visible selected rows are dragged. Note
* that ONLY visible rows are taken into account.
*
* @param <T>
* The Grid bean type.
* @author Vaadin Ltd.
* @since 8.1
*/
public class GridDragSource<T> extends DragSourceExtension<Grid<T>> {
/**
* Drag data generator that appends drag data to each row.
*/
private DataGenerator<T> dragDataGenerator;
/**
* Drag data generator function that is executed for each row.
*/
private SerializableFunction<T, JsonObject> generatorFunction;
/**
* Extends a Grid and makes it's rows draggable.
*
* @param target
* Grid to be extended.
*/
public GridDragSource(Grid<T> target) {
super(target);
// Create drag data generator
dragDataGenerator = this::generateDragData;
// Add drag data generator to Grid
target.getDataCommunicator().addDataGenerator(dragDataGenerator);
}
@Override
protected void registerDragSourceRpc() {
registerRpc(new GridDragSourceRpc() {
@Override
public void dragStart(List<String> draggedItemKeys) {
GridDragStartEvent<T> event = new GridDragStartEvent<>(
getParent(), getState(false).effectAllowed,
getDraggedItems(getParent(), draggedItemKeys));
fireEvent(event);
}
@Override
public void dragEnd(DropEffect dropEffect,
List<String> draggedItemKeys) {
GridDragEndEvent<T> event = new GridDragEndEvent<>(getParent(),
dropEffect,
getDraggedItems(getParent(), draggedItemKeys));
fireEvent(event);
}
});
}
/**
* Collects the dragged items of a Grid given the list of item keys.
*/
private Set<T> getDraggedItems(Grid<T> grid, List<String> draggedItemKeys) {
if (draggedItemKeys == null || draggedItemKeys.isEmpty()) {
throw new IllegalStateException(
"The drag event does not contain dragged items");
}
return draggedItemKeys.stream()
.map(key -> grid.getDataCommunicator().getKeyMapper().get(key))
.collect(Collectors.toSet());
}
/**
* Drag data generator. Appends drag data to row data json if generator
* function is set by the user of this extension.
*
* @param item
* Row item for data generation.
* @param jsonObject
* Row data in json format.
*/
private void generateDragData(T item, JsonObject jsonObject) {
Optional.ofNullable(generatorFunction)
.ifPresent(generator -> jsonObject.put(
GridDragSourceState.JSONKEY_DRAG_DATA,
generator.apply(item)));
}
/**
* Sets a generator function for customizing drag data. The function is
* executed for each item in the Grid during data generation. Return a
* {@link JsonObject} to be appended to the row data.
* <p>
* Example:
*
* <pre>
* dragSourceExtension.setDragDataGenerator(item -> {
* JsonObject dragData = Json.createObject();
* dragData.put("someKey", item.getValue());
* return dragData;
* });
* </pre>
*
* @param generator
* Function to be executed on row data generation.
*/
public void setDragDataGenerator(
SerializableFunction<T, JsonObject> generator) {
generatorFunction = generator;
}
/**
* Setting the data transfer text for this drag source is not supported.
*
* @throws UnsupportedOperationException
* Setting dataTransferText is not supported, since the drag
* data is set for each row based on the data provided by the
* generator.
* @see #setDragDataGenerator(SerializableFunction)
*/
@Override
public void setDataTransferText(String data)
throws UnsupportedOperationException {
throw new UnsupportedOperationException(
"Setting dataTransferText is not supported");
}
/**
* Attaches dragstart listener for the current drag source grid.
*
* @param listener
* Listener to handle the dragstart event.
* @return Handle to be used to remove this listener.
* @see GridDragStartEvent
*/
public Registration addGridDragStartListener(
GridDragStartListener<T> listener) {
return addListener(DragSourceState.EVENT_DRAGSTART,
GridDragStartEvent.class, listener,
GridDragStartListener.DRAG_START_METHOD);
}
/**
* Attaches dragend listener for the current drag source grid.
*
* @param listener
* Listener to handle the dragend event.
* @return Handle to be used to remove this listener.
* @see GridDragEndEvent
*/
public Registration addGridDragEndListener(
GridDragEndListener<T> listener) {
return addListener(DragSourceState.EVENT_DRAGEND,
GridDragEndEvent.class, listener,
GridDragEndListener.DRAG_END_METHOD);
}
/**
* Returns the generator function for customizing drag data.
*
* @return Drag data generator function.
*/
public SerializableFunction<T, JsonObject> getDragDataGenerator() {
return generatorFunction;
}
@Override
public void remove() {
super.remove();
getParent().getDataCommunicator()
.removeDataGenerator(dragDataGenerator);
}
@Override
protected GridDragSourceState getState() {
return (GridDragSourceState) super.getState();
}
@Override
protected GridDragSourceState getState(boolean markAsDirty) {
return (GridDragSourceState) super.getState(markAsDirty);
}
}