Java tutorial
/* * 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.connectors.grid; import java.util.Objects; import java.util.Optional; import com.google.gwt.dom.client.Element; import com.google.gwt.dom.client.NativeEvent; import com.google.gwt.dom.client.TableRowElement; import com.google.gwt.user.client.Window; import com.vaadin.client.ServerConnector; import com.vaadin.client.WidgetUtil; import com.vaadin.client.extensions.DropTargetExtensionConnector; import com.vaadin.client.widget.escalator.RowContainer; import com.vaadin.client.widgets.Escalator; import com.vaadin.shared.ui.Connect; import com.vaadin.shared.ui.grid.DropLocation; import com.vaadin.shared.ui.grid.DropMode; import com.vaadin.shared.ui.grid.GridDropTargetRpc; import com.vaadin.shared.ui.grid.GridDropTargetState; import com.vaadin.shared.ui.grid.GridState; import com.vaadin.ui.GridDropTarget; import elemental.events.Event; import elemental.json.JsonObject; /** * Makes Grid an HTML5 drop target. This is the client side counterpart of * {@link GridDropTarget}. * * @author Vaadin Ltd * @since 8.1 */ @Connect(GridDropTarget.class) public class GridDropTargetConnector extends DropTargetExtensionConnector { /** * Current style name */ private String currentStyleName; private GridConnector gridConnector; /** * Class name to apply when an element is dragged over a row and the * location is {@link DropLocation#ON_TOP}. */ private String styleDragCenter; /** * Class name to apply when an element is dragged over a row and the * location is {@link DropLocation#ABOVE}. */ private String styleDragTop; /** * Class name to apply when an element is dragged over a row and the * location is {@link DropLocation#BELOW}. */ private String styleDragBottom; @Override protected void extend(ServerConnector target) { gridConnector = (GridConnector) target; super.extend(target); } @Override protected void sendDropEventToServer(String dataTransferText, Event dropEvent) { String rowKey = null; DropLocation dropLocation = null; Optional<TableRowElement> targetRow = getTargetRow((Element) dropEvent.getTarget()); if (targetRow.isPresent()) { rowKey = getRowData(targetRow.get()).getString(GridState.JSONKEY_ROWKEY); dropLocation = getDropLocation(targetRow.get(), (NativeEvent) dropEvent); } getRpcProxy(GridDropTargetRpc.class).drop(dataTransferText, rowKey, dropLocation); } private JsonObject getRowData(TableRowElement row) { int rowIndex = ((Escalator.AbstractRowContainer) getGridBody()).getLogicalRowIndex(row); return gridConnector.getDataSource().getRow(rowIndex); } /** * Returns the location of the event within the row. */ private DropLocation getDropLocation(Element target, NativeEvent event) { if (getState().dropMode == DropMode.BETWEEN) { if (getRelativeY(target, event) < (target.getOffsetHeight() / 2)) { return DropLocation.ABOVE; } else { return DropLocation.BELOW; } } else if (getState().dropMode == DropMode.ON_TOP_OR_BETWEEN) { if (getRelativeY(target, event) < getState().dropThreshold) { return DropLocation.ABOVE; } else if (target.getOffsetHeight() - getRelativeY(target, event) < getState().dropThreshold) { return DropLocation.BELOW; } else { return DropLocation.ON_TOP; } } return DropLocation.ON_TOP; } private int getRelativeY(Element element, NativeEvent event) { int relativeTop = element.getAbsoluteTop() - Window.getScrollTop(); return WidgetUtil.getTouchOrMouseClientY(event) - relativeTop; } @Override protected void onDragEnter(Event event) { // Generate style names for the drop target String styleRow = gridConnector.getWidget().getStylePrimaryName() + "-row"; styleDragCenter = styleRow + STYLE_SUFFIX_DRAG_CENTER; styleDragTop = styleRow + STYLE_SUFFIX_DRAG_TOP; styleDragBottom = styleRow + STYLE_SUFFIX_DRAG_BOTTOM; super.onDragEnter(event); } @Override protected void setTargetIndicator(Event event) { getTargetRow(((Element) event.getTarget())).ifPresent(target -> { // Get required class name String className = getTargetClassName(target, (NativeEvent) event); // Add or replace class name if changed if (!target.hasClassName(className)) { if (currentStyleName != null) { target.removeClassName(currentStyleName); } target.addClassName(className); currentStyleName = className; } }); } private String getTargetClassName(Element target, NativeEvent event) { String className; switch (getDropLocation(target, event)) { case ABOVE: className = styleDragTop; break; case BELOW: className = styleDragBottom; break; case ON_TOP: default: className = styleDragCenter; break; } return className; } @Override protected void removeTargetIndicator(Event event) { // Remove all possible style names getTargetRow((Element) event.getTarget()).ifPresent(e -> { e.removeClassName(styleDragCenter); e.removeClassName(styleDragTop); e.removeClassName(styleDragBottom); }); } private Optional<TableRowElement> getTargetRow(Element source) { while (!Objects.equals(source, getGridBody().getElement())) { if (TableRowElement.is(source)) { return Optional.of(source.cast()); } source = source.getParentElement(); } return Optional.empty(); } @Override protected Element getDropTargetElement() { return getGridBody().getElement(); } private Escalator getEscalator() { return gridConnector.getWidget().getEscalator(); } private RowContainer.BodyRowContainer getGridBody() { return getEscalator().getBody(); } @Override public GridDropTargetState getState() { return (GridDropTargetState) super.getState(); } }