Add an initial version of Tree component (#9212)

This patch introduces a Tree component, implemented as a Composite
using TreeGrid. As initial version of the component, some functionality
of the old Tree component has been left out for now.

Partly addresses #8617

2 files changed, 193 insertions, 0 deletions

diff --git a/server/src/main/java/com/vaadin/event/CollapseEvent.java b/server/src/main/java/com/vaadin/event/CollapseEvent.java
new file mode 100644
index 0000000000..ba740142e3
--- /dev/null
+++ b/server/src/main/java/com/vaadin/event/CollapseEvent.java
@@ -0,0 +1,97 @@
+/*
+ * 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.event;
+
+import java.io.Serializable;
+import java.lang.reflect.Method;
+
+import com.vaadin.ui.Component;
+import com.vaadin.util.ReflectTools;
+
+/**
+ * An event that is fired when an item is collapsed. Note that expanded subtrees
+ * of the collapsed item will not trigger collapse events.
+ *
+ * @author Vaadin Ltd
+ * @since 8.1
+ * @param <T>
+ *            collapsed item type
+ */
+public class CollapseEvent<T> extends Component.Event {
+
+    private final T collapsedItem;
+
+    private final boolean userOriginated;
+
+    /**
+     * Construct a collapse event.
+     *
+     * @param source
+     *            the hierarchical this event originated from
+     * @param collapsedItem
+     *            the item that was collapsed
+     * @param userOriginated
+     *            whether the collapse was triggered by a user interaction or
+     *            the server
+     */
+    public CollapseEvent(Component source, T collapsedItem,
+            boolean userOriginated) {
+        super(source);
+        this.collapsedItem = collapsedItem;
+        this.userOriginated = userOriginated;
+    }
+
+    /**
+     * Get the collapsed item that triggered this event.
+     *
+     * @return the collapsed item
+     */
+    public T getCollapsedItem() {
+        return collapsedItem;
+    }
+
+    /**
+     * Returns whether this event was triggered by user interaction, on the
+     * client side, or programmatically, on the server side.
+     *
+     * @return {@code true} if this event originates from the client,
+     *         {@code false} otherwise.
+     */
+    public boolean isUserOriginated() {
+        return userOriginated;
+    }
+
+    /**
+     * Item collapse event listener.
+     *
+     * @param <T>
+     *            the collapsed item's type
+     */
+    @FunctionalInterface
+    public interface CollapseListener<T> extends Serializable {
+
+        public static final Method COLLAPSE_METHOD = ReflectTools.findMethod(
+                CollapseListener.class, "itemCollapse", CollapseEvent.class);
+
+        /**
+         * Callback method for when an item has been collapsed.
+         *
+         * @param event
+         *            the collapse event
+         */
+        public void itemCollapse(CollapseEvent<T> event);
+    }
+}
diff --git a/server/src/main/java/com/vaadin/event/ExpandEvent.java b/server/src/main/java/com/vaadin/event/ExpandEvent.java
new file mode 100644
index 0000000000..775c368a12
--- /dev/null
+++ b/server/src/main/java/com/vaadin/event/ExpandEvent.java
@@ -0,0 +1,96 @@
+/*
+ * 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.event;
+
+import java.io.Serializable;
+import java.lang.reflect.Method;
+
+import com.vaadin.ui.Component;
+import com.vaadin.util.ReflectTools;
+
+/**
+ * An event that is fired when an item is expanded.
+ *
+ * @author Vaadin Ltd
+ * @since 8.1
+ * @param <T>
+ *            the expanded item's type
+ */
+public class ExpandEvent<T> extends Component.Event {
+
+    private final T expandedItem;
+
+    private final boolean userOriginated;
+
+    /**
+     * Construct an expand event.
+     *
+     * @param source
+     *            the hierarchical component this event originated from
+     * @param expandedItem
+     *            the item that was expanded
+     * @param userOriginated
+     *            whether the expand was triggered by a user interaction or the
+     *            server
+     */
+    public ExpandEvent(Component source, T expandedItem,
+            boolean userOriginated) {
+        super(source);
+        this.expandedItem = expandedItem;
+        this.userOriginated = userOriginated;
+    }
+
+    /**
+     * Get the expanded item that triggered this event.
+     *
+     * @return the expanded item
+     */
+    public T getExpandedItem() {
+        return expandedItem;
+    }
+
+    /**
+     * Returns whether this event was triggered by user interaction, on the
+     * client side, or programmatically, on the server side.
+     *
+     * @return {@code true} if this event originates from the client,
+     *         {@code false} otherwise.
+     */
+    public boolean isUserOriginated() {
+        return userOriginated;
+    }
+
+    /**
+     * Item expand event listener.
+     *
+     * @param <T>
+     *            the expanded item's type
+     */
+    @FunctionalInterface
+    public interface ExpandListener<T> extends Serializable {
+
+        public static final Method EXPAND_METHOD = ReflectTools.findMethod(
+                ExpandListener.class, "itemExpand", ExpandEvent.class);
+
+        /**
+         * Callback method for when an item has been expanded.
+         *
+         * @param event
+         *            the expand event
+         */
+        public void itemExpand(ExpandEvent<T> event);
+    }
+}