Add events and functionality to Tree (#9318)

* Add ItemClick event to Tree
* Add collapse provider and style generator to Tree

1 files changed, 116 insertions, 0 deletions

diff --git a/server/src/main/java/com/vaadin/ui/Tree.java b/server/src/main/java/com/vaadin/ui/Tree.java
index 8f02c8c88f..97e1b94cec 100644
--- a/server/src/main/java/com/vaadin/ui/Tree.java
+++ b/server/src/main/java/com/vaadin/ui/Tree.java
@@ -15,6 +15,7 @@
  */
 package com.vaadin.ui;
 
+import java.lang.reflect.Method;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -30,15 +31,19 @@ import com.vaadin.data.provider.DataProvider;
 import com.vaadin.data.provider.HierarchicalDataProvider;
 import com.vaadin.event.CollapseEvent;
 import com.vaadin.event.CollapseEvent.CollapseListener;
+import com.vaadin.event.ConnectorEvent;
 import com.vaadin.event.ExpandEvent;
 import com.vaadin.event.ExpandEvent.ExpandListener;
+import com.vaadin.event.SerializableEventListener;
 import com.vaadin.event.selection.SelectionListener;
 import com.vaadin.server.Resource;
+import com.vaadin.server.SerializablePredicate;
 import com.vaadin.shared.Registration;
 import com.vaadin.shared.ui.grid.HeightMode;
 import com.vaadin.shared.ui.tree.TreeRendererState;
 import com.vaadin.ui.Grid.SelectionMode;
 import com.vaadin.ui.renderers.AbstractRenderer;
+import com.vaadin.util.ReflectTools;
 
 import elemental.json.JsonObject;
 
@@ -54,6 +59,72 @@ import elemental.json.JsonObject;
  */
 public class Tree<T> extends Composite implements HasDataProvider<T> {
 
+    @Deprecated
+    private static final Method ITEM_CLICK_METHOD = ReflectTools
+            .findMethod(ItemClickListener.class, "itemClick", ItemClick.class);
+
+    /**
+     * A listener for item click events.
+     *
+     * @param <T>
+     *            the tree item type
+     *
+     * @see ItemClick
+     * @see Registration
+     * @since 8.1
+     */
+    @FunctionalInterface
+    public interface ItemClickListener<T> extends SerializableEventListener {
+        /**
+         * Invoked when this listener receives a item click event from a Tree to
+         * which it has been added.
+         *
+         * @param event
+         *            the received event, not {@code null}
+         */
+        public void itemClick(Tree.ItemClick<T> event);
+    }
+
+    /**
+     * Tree item click event.
+     *
+     * @param <T>
+     *            the data type of tree
+     * @since 8.1
+     */
+    public static class ItemClick<T> extends ConnectorEvent {
+
+        private final T item;
+
+        /**
+         * Constructs a new item click.
+         *
+         * @param source
+         *            the tree component
+         * @param item
+         *            the clicked item
+         */
+        protected ItemClick(Tree<T> source, T item) {
+            super(source);
+            this.item = item;
+        }
+
+        /**
+         * Returns the clicked item.
+         *
+         * @return the clicked item
+         */
+        public T getItem() {
+            return item;
+        }
+
+        @SuppressWarnings("unchecked")
+        @Override
+        public Tree<T> getSource() {
+            return (Tree<T>) super.getSource();
+        }
+    }
+
     /**
      * String renderer that handles icon resources and stores their identifiers
      * into data objects.
@@ -142,6 +213,8 @@ public class Tree<T> extends Composite implements HasDataProvider<T> {
                 e.isUserOriginated()));
         treeGrid.addCollapseListener(e -> fireCollapseEvent(
                 e.getCollapsedItem(), e.isUserOriginated()));
+        treeGrid.addItemClickListener(
+                e -> fireEvent(new ItemClick<>(this, e.getItem())));
     }
 
     /**
@@ -389,6 +462,49 @@ public class Tree<T> extends Composite implements HasDataProvider<T> {
     }
 
     /**
+     * Sets the item collapse allowed provider for this Tree. The provider
+     * should return {@code true} for any item that the user can collapse.
+     * <p>
+     * <strong>Note:</strong> This callback will be accessed often when sending
+     * data to the client. The callback should not do any costly operations.
+     *
+     * @param provider
+     *            the item collapse allowed provider, not {@code null}
+     */
+    public void setItemCollapseAllowedProvider(
+            SerializablePredicate<T> provider) {
+        treeGrid.setItemCollapseAllowedProvider(provider);
+    }
+
+    /**
+     * Sets the style generator that is used for generating class names for
+     * items in this tree. Returning null from the generator results in no
+     * custom style name being set.
+     *
+     * @see StyleGenerator
+     *
+     * @param styleGenerator
+     *            the item style generator to set, not {@code null}
+     * @throws NullPointerException
+     *             if {@code styleGenerator} is {@code null}
+     */
+    public void setStyleGenerator(StyleGenerator<T> styleGenerator) {
+        treeGrid.setStyleGenerator(styleGenerator);
+    }
+
+    /**
+     * Adds an item click listener. The listener is called when an item of this
+     * {@code Tree} is clicked.
+     *
+     * @param listener
+     *            the item click listener, not null
+     * @return a registration for the listener
+     */
+    public Registration addItemClickListener(ItemClickListener<T> listener) {
+        return addListener(ItemClick.class, listener, ITEM_CLICK_METHOD);
+    }
+
+    /**
      * @deprecated This component's height is always set to be undefined.
      *             Calling this method will have no effect.
      */