Java tutorial
/** * Sencha GXT 4.0.0 - Sencha for GWT * Copyright (c) 2006-2015, Sencha Inc. * * licensing@sencha.com * http://www.sencha.com/products/gxt/license/ * * ================================================================================ * Open Source License * ================================================================================ * This version of Sencha GXT is licensed under the terms of the Open Source GPL v3 * license. You may use this license only if you are prepared to distribute and * share the source code of your application under the GPL v3 license: * http://www.gnu.org/licenses/gpl.html * * If you are NOT prepared to distribute and share the source code of your * application under the GPL v3 license, other commercial and oem licenses * are available for an alternate download of Sencha GXT. * * Please see the Sencha GXT Licensing page at: * http://www.sencha.com/products/gxt/license/ * * For clarification or additional options, please contact: * licensing@sencha.com * ================================================================================ * * * ================================================================================ * Disclaimer * ================================================================================ * THIS SOFTWARE IS DISTRIBUTED "AS-IS" WITHOUT ANY WARRANTIES, CONDITIONS AND * REPRESENTATIONS WHETHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE * IMPLIED WARRANTIES AND CONDITIONS OF MERCHANTABILITY, MERCHANTABLE QUALITY, * FITNESS FOR A PARTICULAR PURPOSE, DURABILITY, NON-INFRINGEMENT, PERFORMANCE AND * THOSE ARISING BY STATUTE OR FROM CUSTOM OR USAGE OF TRADE OR COURSE OF DEALING. * ================================================================================ */ package com.sencha.gxt.dnd.core.client; import java.util.ArrayList; import java.util.List; import com.google.gwt.dom.client.Element; import com.google.gwt.safehtml.shared.SafeHtmlBuilder; import com.google.gwt.safehtml.shared.SafeHtmlUtils; import com.sencha.gxt.core.client.util.Format; import com.sencha.gxt.core.shared.FastSet; import com.sencha.gxt.data.shared.ModelKeyProvider; import com.sencha.gxt.data.shared.TreeStore.TreeNode; import com.sencha.gxt.dnd.core.client.DND.Operation; import com.sencha.gxt.dnd.core.client.DND.TreeSource; import com.sencha.gxt.messages.client.DefaultMessages; import com.sencha.gxt.widget.core.client.tree.Tree; /** * Enables a {@link Tree} to act as the source of a drag and drop operation. * <p/> * Use {@link #setTreeSource(com.sencha.gxt.dnd.core.client.DND.TreeSource)} to specify whether leaf nodes, non-leaf * nodes or both types of nodes can be dragged (defaults to {@link TreeSource#BOTH}). The drag operation is cancelled * if the user attempts to drag a node type that is not permitted. * <p/> * The drag data consists of a list of items of type {@code <M>}. It is optimized to remove children of parents that are * also in the list (i.e. if a parent is the subject of a drag operation then all of its children are implicitly part of * the drag operation). * * @param <M> the model type */ public class TreeDragSource<M> extends DragSource { private TreeSource treeSource = TreeSource.BOTH; /** * Creates a drag source for the specified tree. * * @param tree the tree to enable as a drag source */ public TreeDragSource(Tree<M, ?> tree) { super(tree); setStatusText("{0} items selected"); } /** * Returns the tree associated with this drag source. * * @return the tree associated with this drag source */ public TreeSource getTreeSource() { return treeSource; } @SuppressWarnings("unchecked") @Override public Tree<M, ?> getWidget() { return (Tree<M, ?>) super.getWidget(); } /** * Sets the tree source (defaults to {@link TreeSource#BOTH}). * * @param treeSource the tree source */ public void setTreeSource(TreeSource treeSource) { this.treeSource = treeSource; } @Override protected void onDragDrop(DndDropEvent event) { if (event.getOperation() == Operation.MOVE) { @SuppressWarnings("unchecked") List<TreeNode<M>> sel = (List<TreeNode<M>>) event.getData(); for (TreeNode<M> s : sel) { getWidget().getStore().remove(s.getData()); } super.data = null; } } @Override protected void onDragStart(DndDragStartEvent event) { Element startTarget = event.getDragStartEvent().getStartElement().<Element>cast(); Tree.TreeNode<M> start = getWidget().findNode(startTarget); if (start == null || !getWidget().getView().isSelectableTarget(start.getModel(), startTarget)) { event.setCancelled(true); return; } List<M> selected = getWidget().getSelectionModel().getSelectedItems(); if (selected.size() == 0) { event.setCancelled(true); return; } List<TreeNode<M>> selectedSubTrees = new ArrayList<TreeNode<M>>(); if (getTreeSource() == TreeSource.LEAF) { for (M item : selected) { if (getWidget().isLeaf(item)) { selectedSubTrees.add(getWidget().getStore().getSubTree(item)); } else { // forget it, we've got a non-leaf event.setCancelled(true); return; } } } else { // If allowed to drop only nodes or both, then we need to remove items from the list // that also have their parents being dragged ModelKeyProvider<? super M> kp = getWidget().getStore().getKeyProvider(); // Start by looking for all selected non-leaf items FastSet nonLeafKeys = new FastSet(); for (M item : selected) { if (getWidget().isLeaf(item)) { // While we're at it, if we're only allowed nodes, cancel if we see a leaf if (treeSource == TreeSource.NODE) { event.setCancelled(true); return; } } else { nonLeafKeys.add(kp.getKey(item)); } } // Walking backward (so we can remove as we go) through the list of all selected items, for // each item, check if it has a parent already in the list. // Clearly that parent is a non-leaf, so will be in the set we established in the last loop // Note: see TreeGridDragSource it's similar for (int i = selected.size() - 1; i >= 0; i--) { // TODO consider tracking these parents, and if they are part of another // parent, adding them to the keyset M parent = selected.get(i); while ((parent = getWidget().getStore().getParent(parent)) != null) { // If we find that this item's parent is also selected, then we can skip this item if (nonLeafKeys.contains(kp.getKey(parent))) { selected.remove(i); break; } } } for (M item : selected) { selectedSubTrees.add(getWidget().getStore().getSubTree(item)); } } if (selectedSubTrees.size() > 0) { event.setData(selectedSubTrees); } else { event.setCancelled(true); } if (selected.size() > 0) { event.setCancelled(false); if (getStatusText() == null) { event.getStatusProxy().update(SafeHtmlUtils .fromString(DefaultMessages.getMessages().listField_itemsSelected(selected.size()))); } else { event.getStatusProxy() .update(SafeHtmlUtils.fromString(Format.substitute(getStatusText(), selected.size()))); } } } }