Create drag source and drop target extensions for tree grid (#9463)

Resolves #9372

13 files changed, 682 insertions, 5 deletions

diff --git a/client/src/main/java/com/vaadin/client/connectors/grid/GridDropTargetConnector.java b/client/src/main/java/com/vaadin/client/connectors/grid/GridDropTargetConnector.java
index 5b409e3174..9954134821 100644
--- a/client/src/main/java/com/vaadin/client/connectors/grid/GridDropTargetConnector.java
+++ b/client/src/main/java/com/vaadin/client/connectors/grid/GridDropTargetConnector.java
@@ -124,7 +124,14 @@ public class GridDropTargetConnector extends DropTargetExtensionConnector {
                 rowKey, dropLocation, mouseEventDetails);
     }
 
-    private JsonObject getRowData(TableRowElement row) {
+    /**
+     * Get the row data as json object for the given row.
+     *
+     * @param row
+     *         table row element
+     * @return row data as json object for the given row
+     */
+    protected JsonObject getRowData(TableRowElement row) {
         int rowIndex = ((Escalator.AbstractRowContainer) getGridBody())
                 .getLogicalRowIndex(row);
         return gridConnector.getDataSource().getRow(rowIndex);
@@ -132,8 +139,13 @@ public class GridDropTargetConnector extends DropTargetExtensionConnector {
 
     /**
      * Returns the location of the event within the row.
+     *
+     * @param target
+     *         drop target element
+     * @param event
+     *         drop event
      */
-    private DropLocation getDropLocation(Element target, NativeEvent event) {
+    protected DropLocation getDropLocation(Element target, NativeEvent event) {
         if (TableRowElement.is(target)) {
             if (getState().dropMode == DropMode.BETWEEN) {
                 if (getRelativeY(target,
@@ -241,7 +253,14 @@ public class GridDropTargetConnector extends DropTargetExtensionConnector {
         element.removeClassName(styleDragEmpty);
     }
 
-    private Element getTargetElement(Element source) {
+    /**
+     * Gets the target element for a dragover or drop event.
+     *
+     * @param source
+     *         the event target of the event
+     * @return the element that should be handled as the target of the event
+     */
+    protected Element getTargetElement(Element source) {
         final Element tableWrapper = getDropTargetElement();
         final BodyRowContainer gridBody = getGridBody();
         final int rowCount = gridBody.getRowCount();
diff --git a/client/src/main/java/com/vaadin/client/connectors/grid/TreeGridDragSourceConnector.java b/client/src/main/java/com/vaadin/client/connectors/grid/TreeGridDragSourceConnector.java
new file mode 100644
index 0000000000..c2450bb9db
--- /dev/null
+++ b/client/src/main/java/com/vaadin/client/connectors/grid/TreeGridDragSourceConnector.java
@@ -0,0 +1,37 @@
+/*
+ * 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 com.vaadin.shared.ui.Connect;
+import com.vaadin.shared.ui.treegrid.TreeGridDragSourceState;
+import com.vaadin.ui.components.grid.TreeGridDragSource;
+
+/**
+ * Adds HTML5 drag and drop functionality to a TreeGrid's rows. This is the
+ * client side counterpart of {@link TreeGridDragSource}.
+ *
+ * @author Vaadin Ltd
+ * @since 8.1
+ */
+@Connect(TreeGridDragSource.class)
+public class TreeGridDragSourceConnector extends GridDragSourceConnector {
+
+    @Override
+    public TreeGridDragSourceState getState() {
+        return (TreeGridDragSourceState) super.getState();
+    }
+
+}
diff --git a/client/src/main/java/com/vaadin/client/connectors/grid/TreeGridDropTargetConnector.java b/client/src/main/java/com/vaadin/client/connectors/grid/TreeGridDropTargetConnector.java
new file mode 100644
index 0000000000..fd13426514
--- /dev/null
+++ b/client/src/main/java/com/vaadin/client/connectors/grid/TreeGridDropTargetConnector.java
@@ -0,0 +1,86 @@
+/*
+ * 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.List;
+import java.util.Map;
+
+import com.google.gwt.dom.client.Element;
+import com.google.gwt.dom.client.NativeEvent;
+import com.google.gwt.dom.client.TableRowElement;
+import com.vaadin.client.MouseEventDetailsBuilder;
+import com.vaadin.shared.MouseEventDetails;
+import com.vaadin.shared.data.HierarchicalDataCommunicatorConstants;
+import com.vaadin.shared.ui.Connect;
+import com.vaadin.shared.ui.grid.DropLocation;
+import com.vaadin.shared.ui.grid.GridState;
+import com.vaadin.shared.ui.treegrid.TreeGridDropTargetRpc;
+import com.vaadin.shared.ui.treegrid.TreeGridDropTargetState;
+import com.vaadin.ui.components.grid.TreeGridDropTarget;
+
+import elemental.json.JsonObject;
+
+/**
+ * Makes TreeGrid an HTML5 drop target. This is the client side counterpart of
+ * {@link TreeGridDropTarget}.
+ *
+ * @author Vaadin Ltd
+ * @since 8.1
+ */
+@Connect(TreeGridDropTarget.class)
+public class TreeGridDropTargetConnector extends GridDropTargetConnector {
+
+    @Override
+    protected void sendDropEventToServer(List<String> types,
+            Map<String, String> data, String dropEffect,
+            NativeEvent dropEvent) {
+        String rowKey = null;
+        DropLocation dropLocation = null;
+        Integer rowDepth = null;
+        Boolean rowCollapsed = null;
+
+        Element targetElement = getTargetElement(
+                (Element) dropEvent.getEventTarget().cast());
+        // the target element is either the tablewrapper or one of the body rows
+        if (TableRowElement.is(targetElement)) {
+            JsonObject rowData = getRowData(targetElement.cast());
+            rowKey = rowData.getString(GridState.JSONKEY_ROWKEY);
+            dropLocation = getDropLocation(targetElement, dropEvent);
+
+            // Collect hierarchy information
+            JsonObject hierarchyDescription = rowData.getObject(
+                    HierarchicalDataCommunicatorConstants.ROW_HIERARCHY_DESCRIPTION);
+            rowDepth = (int) hierarchyDescription
+                    .getNumber(HierarchicalDataCommunicatorConstants.ROW_DEPTH);
+            rowCollapsed = hierarchyDescription.getBoolean(
+                    HierarchicalDataCommunicatorConstants.ROW_COLLAPSED);
+        } else {
+            dropLocation = DropLocation.EMPTY;
+        }
+
+        MouseEventDetails mouseEventDetails = MouseEventDetailsBuilder
+                .buildMouseEventDetails(dropEvent, targetElement);
+
+        getRpcProxy(TreeGridDropTargetRpc.class).drop(types, data, dropEffect,
+                rowKey, rowDepth, rowCollapsed, dropLocation,
+                mouseEventDetails);
+    }
+
+    @Override
+    public TreeGridDropTargetState getState() {
+        return (TreeGridDropTargetState) super.getState();
+    }
+}
diff --git a/client/src/main/java/com/vaadin/client/widget/treegrid/TreeGrid.java b/client/src/main/java/com/vaadin/client/widget/treegrid/TreeGrid.java
index fb66bebb7d..328d594fe1 100644
--- a/client/src/main/java/com/vaadin/client/widget/treegrid/TreeGrid.java
+++ b/client/src/main/java/com/vaadin/client/widget/treegrid/TreeGrid.java
@@ -16,10 +16,14 @@
 package com.vaadin.client.widget.treegrid;
 
 import com.google.gwt.dom.client.Element;
+import com.google.gwt.dom.client.TableRowElement;
 import com.google.gwt.event.shared.HandlerRegistration;
+import com.vaadin.client.widget.escalator.EscalatorUpdater;
+import com.vaadin.client.widget.escalator.Row;
 import com.vaadin.client.widget.grid.events.BodyClickHandler;
 import com.vaadin.client.widget.treegrid.events.TreeGridClickEvent;
 import com.vaadin.client.widgets.Grid;
+import com.vaadin.shared.data.HierarchicalDataCommunicatorConstants;
 
 import elemental.json.JsonObject;
 
@@ -27,14 +31,63 @@ import elemental.json.JsonObject;
  * An extension of the Grid widget, which supports displaying of hierarchical
  * data.
  *
- * @see Grid
- *
  * @author Vaadin Ltd
+ * @see Grid
  * @since 8.1
  */
 public class TreeGrid extends Grid<JsonObject> {
 
     /**
+     * Style name prefix for the row's depth in the hierarchy
+     */
+    private String depthStyleNamePrefix;
+
+    /**
+     * Body updater that adds additional style to each row containing depth
+     * information inside the hierarchy.
+     */
+    protected class BodyUpdater extends Grid.BodyUpdater {
+        @Override
+        public void update(Row row, Iterable cellsToUpdate) {
+            super.update(row, cellsToUpdate);
+
+            int rowIndex = row.getRow();
+            TableRowElement rowElement = row.getElement();
+
+            JsonObject rowData = getDataSource().getRow(rowIndex);
+            if (rowData != null) {
+                int depth = (int) rowData.getObject(
+                        HierarchicalDataCommunicatorConstants.ROW_HIERARCHY_DESCRIPTION)
+                        .getNumber(
+                                HierarchicalDataCommunicatorConstants.ROW_DEPTH);
+
+                // Add or replace style name containing depth information
+                String styleToBeReplaced = getFullClassName(
+                        depthStyleNamePrefix, rowElement.getClassName());
+                if (styleToBeReplaced == null) {
+                    rowElement.addClassName(depthStyleNamePrefix + depth);
+                } else {
+                    rowElement.replaceClassName(styleToBeReplaced,
+                            depthStyleNamePrefix + depth);
+                }
+            }
+        }
+
+        private String getFullClassName(String prefix, String classNameList) {
+            int start = classNameList.indexOf(prefix);
+            int end = start + prefix.length();
+            if (start > -1) {
+                while (end < classNameList.length()
+                        && classNameList.charAt(end) != ' ') {
+                    end++;
+                }
+                return classNameList.substring(start, end);
+            }
+            return null;
+        }
+    }
+
+    /**
      * Method for accessing the private {@link Grid#focusCell(int, int)} method
      * from this package
      */
@@ -50,8 +103,21 @@ public class TreeGrid extends Grid<JsonObject> {
         return this.@com.vaadin.client.widgets.Grid::isElementInChildWidget(*)(e);
     }-*/;
 
+
     @Override
     public HandlerRegistration addBodyClickHandler(BodyClickHandler handler) {
         return addHandler(handler, TreeGridClickEvent.TYPE);
     }
+
+    @Override
+    protected EscalatorUpdater createBodyUpdater() {
+        return new BodyUpdater();
+    }
+
+    @Override
+    public void setStylePrimaryName(String style) {
+        super.setStylePrimaryName(style);
+
+        depthStyleNamePrefix = getStylePrimaryName() + "-row-depth-";
+    }
 }
diff --git a/documentation/advanced/advanced-dragndrop.asciidoc b/documentation/advanced/advanced-dragndrop.asciidoc
index 8aa18b72ac..47f63a74d9 100644
--- a/documentation/advanced/advanced-dragndrop.asciidoc
+++ b/documentation/advanced/advanced-dragndrop.asciidoc
@@ -361,6 +361,11 @@ When dragging on top of a row, `v-grid-row-drag-center` indicates ON_TOP, `v-gri
 
 (((range="endofrange", startref="term.advanced.dragndrop")))
 
+=== Drag and Drop Rows in TreeGrid
+
+To make the rows of a TreeGrid component draggable or to make them a drop target, apply [classname]#TreeGridDragSource# or [classname]#TreeGridDropTarget# extensions to the component, respectively.
+In addition to the drag and drop features for Grid above, [classname]#TreeGridDropEvent# provides information about the status of the node (expanded or collapsed) and its depth in the hierarchy.
+
 == Drag and Drop Files
 
 Files can be uploaded to the server by dropping them onto a file drop target. To make a component a file drop target, apply the [classname]#FileDropTarget# extension to it by creating a new instance and passing the component as first constructor parameter to it.
diff --git a/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDragSource.java b/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDragSource.java
new file mode 100644
index 0000000000..68d0c68b13
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDragSource.java
@@ -0,0 +1,54 @@
+/*
+ * 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 com.vaadin.shared.ui.treegrid.TreeGridDragSourceState;
+import com.vaadin.ui.TreeGrid;
+
+/**
+ * Makes a TreeGrid'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 and the subtree belonging to a
+ * selected row is not dragged either.
+ *
+ * @param <T>
+ *            The TreeGrid bean type.
+ * @author Vaadin Ltd.
+ * @since 8.1
+ */
+public class TreeGridDragSource<T> extends GridDragSource<T> {
+
+    /**
+     * Extends a TreeGrid and makes it's rows draggable.
+     *
+     * @param target
+     *            TreeGrid to be extended.
+     */
+    public TreeGridDragSource(TreeGrid<T> target) {
+        super(target);
+    }
+
+    @Override
+    protected TreeGridDragSourceState getState() {
+        return (TreeGridDragSourceState) super.getState();
+    }
+
+    @Override
+    protected TreeGridDragSourceState getState(boolean markAsDirty) {
+        return (TreeGridDragSourceState) super.getState(markAsDirty);
+    }
+}
diff --git a/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDropEvent.java b/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDropEvent.java
new file mode 100644
index 0000000000..015f6169d5
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDropEvent.java
@@ -0,0 +1,99 @@
+/*
+ * 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.Map;
+import java.util.Optional;
+
+import com.vaadin.shared.MouseEventDetails;
+import com.vaadin.shared.ui.dnd.DropEffect;
+import com.vaadin.shared.ui.grid.DropLocation;
+import com.vaadin.ui.AbstractComponent;
+import com.vaadin.ui.TreeGrid;
+import com.vaadin.ui.dnd.DragSourceExtension;
+
+/**
+ * Drop event on an HTML5 drop target {@link TreeGrid} row.
+ *
+ * @param <T>
+ *         The TreeGrid bean type.
+ * @author Vaadin Ltd.
+ * @see TreeGridDropTarget#addTreeGridDropListener(TreeGridDropListener)
+ * @since 8.1
+ */
+public class TreeGridDropEvent<T> extends GridDropEvent<T> {
+
+    private Integer depth;
+    private Boolean collapsed;
+
+    /**
+     * Creates a TreeGrid row drop event.
+     *
+     * @param target
+     *         TreeGrid that received the drop.
+     * @param data
+     *         Map containing all types and corresponding data from the {@code
+     *         DataTransfer} object.
+     * @param dropEffect
+     *         the desired drop effect
+     * @param dragSourceExtension
+     *         Drag source extension of the component that initiated the drop
+     *         event.
+     * @param dropTargetRow
+     *         Target row that received the drop, or {@code null} if dropped on
+     *         empty grid
+     * @param dropLocation
+     *         Location of the drop within the target row.
+     * @param mouseEventDetails
+     *         Mouse event details object containing information about the drop
+     *         event
+     * @param depth
+     *         depth of the row in the hierarchy
+     * @param collapsed
+     *         whether the target row is collapsed
+     */
+    public TreeGridDropEvent(TreeGrid<T> target, Map<String, String> data,
+            DropEffect dropEffect,
+            DragSourceExtension<? extends AbstractComponent> dragSourceExtension,
+            T dropTargetRow, DropLocation dropLocation,
+            MouseEventDetails mouseEventDetails, Integer depth,
+            Boolean collapsed) {
+        super(target, data, dropEffect, dragSourceExtension, dropTargetRow,
+                dropLocation, mouseEventDetails);
+
+        this.depth = depth;
+        this.collapsed = collapsed;
+    }
+
+    /**
+     * Gets the depth of the drop target row in the hierarchy.
+     *
+     * @return the depth of the drop target row in the hierarchy
+     */
+    public Optional<Integer> getDropTargetRowDepth() {
+        return Optional.ofNullable(depth);
+    }
+
+    /**
+     * Tells whether the drop target row is collapsed.
+     *
+     * @return {@code true} if the drop target row is collapsed, {@code false}
+     * otherwise
+     */
+    public Optional<Boolean> isDropTargetRowCollapsed() {
+        return Optional.ofNullable(collapsed);
+    }
+}
diff --git a/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDropListener.java b/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDropListener.java
new file mode 100644
index 0000000000..d413a7b42b
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDropListener.java
@@ -0,0 +1,44 @@
+/*
+ * 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.lang.reflect.Method;
+
+import com.vaadin.event.ConnectorEventListener;
+
+/**
+ * Drop listener for HTML5 drop on a TreeGrid row.
+ *
+ * @param <T>
+ *            The Grid bean type.
+ * @author Vaadin Ltd.
+ * @see TreeGridDropTarget#addTreeGridDropListener(TreeGridDropListener)
+ * @since 8.1
+ */
+@FunctionalInterface
+public interface TreeGridDropListener<T> extends ConnectorEventListener {
+
+    static final Method DROP_METHOD = TreeGridDropListener.class
+            .getDeclaredMethods()[0];
+
+    /**
+     * Called when drop event is fired on a Grid row.
+     *
+     * @param event
+     *            Server side drop event.
+     */
+    void drop(TreeGridDropEvent<T> event);
+}
diff --git a/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDropTarget.java b/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDropTarget.java
new file mode 100644
index 0000000000..1d440b5fec
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/components/grid/TreeGridDropTarget.java
@@ -0,0 +1,104 @@
+/*
+ * 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.LinkedHashMap;
+import java.util.Map;
+
+import com.vaadin.shared.Registration;
+import com.vaadin.shared.ui.dnd.DropEffect;
+import com.vaadin.shared.ui.grid.DropMode;
+import com.vaadin.shared.ui.treegrid.TreeGridDropTargetRpc;
+import com.vaadin.shared.ui.treegrid.TreeGridDropTargetState;
+import com.vaadin.ui.TreeGrid;
+
+/**
+ * Makes the rows of a TreeGrid HTML5 drop targets. This is the server side
+ * counterpart of GridDropTargetExtensionConnector.
+ *
+ * @param <T>
+ *         Type of the TreeGrid bean.
+ * @author Vaadin Ltd
+ * @since 8.1
+ */
+public class TreeGridDropTarget<T> extends GridDropTarget<T> {
+
+    /**
+     * Extends a TreeGrid and makes it's rows drop targets for HTML5 drag and
+     * drop.
+     *
+     * @param target
+     *         TreeGrid to be extended.
+     * @param dropMode
+     *         Drop mode that describes the allowed drop locations within the
+     *         TreeGrid's row.
+     */
+    public TreeGridDropTarget(TreeGrid<T> target, DropMode dropMode) {
+        super(target, dropMode);
+    }
+
+    /**
+     * Attaches drop listener for the current drop target. {@link
+     * TreeGridDropListener#drop(TreeGridDropEvent)} is called when drop event
+     * happens on the client side.
+     *
+     * @param listener
+     *         Listener to handle drop event.
+     * @return Handle to be used to remove this listener.
+     */
+    public Registration addTreeGridDropListener(
+            TreeGridDropListener<T> listener) {
+        return addListener(TreeGridDropEvent.class, listener,
+                TreeGridDropListener.DROP_METHOD);
+    }
+
+    @Override
+    protected void registerDropTargetRpc() {
+        registerRpc((TreeGridDropTargetRpc) (types, data, dropEffect, rowKey,
+                depth, collapsed, dropLocation, mouseEventDetails) -> {
+
+            // Create a linked map that preserves the order of types
+            Map<String, String> dataPreserveOrder = new LinkedHashMap<>();
+            types.forEach(type -> dataPreserveOrder.put(type, data.get(type)));
+
+            T dropTargetRow = getParent().getDataCommunicator().getKeyMapper()
+                    .get(rowKey);
+
+            TreeGridDropEvent<T> event = new TreeGridDropEvent<>(getParent(),
+                    dataPreserveOrder,
+                    DropEffect.valueOf(dropEffect.toUpperCase()),
+                    getUI().getActiveDragSource(), dropTargetRow, dropLocation,
+                    mouseEventDetails, depth, collapsed);
+
+            fireEvent(event);
+        });
+    }
+
+    @Override
+    public TreeGrid<T> getParent() {
+        return (TreeGrid<T>) super.getParent();
+    }
+
+    @Override
+    protected TreeGridDropTargetState getState() {
+        return (TreeGridDropTargetState) super.getState();
+    }
+
+    @Override
+    protected TreeGridDropTargetState getState(boolean markAsDirty) {
+        return (TreeGridDropTargetState) super.getState(markAsDirty);
+    }
+}
diff --git a/shared/src/main/java/com/vaadin/shared/ui/treegrid/TreeGridDragSourceState.java b/shared/src/main/java/com/vaadin/shared/ui/treegrid/TreeGridDragSourceState.java
new file mode 100644
index 0000000000..f3ea4cf900
--- /dev/null
+++ b/shared/src/main/java/com/vaadin/shared/ui/treegrid/TreeGridDragSourceState.java
@@ -0,0 +1,28 @@
+/*
+ * 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.shared.ui.treegrid;
+
+import com.vaadin.shared.ui.grid.GridDragSourceState;
+
+/**
+ * State class containing parameters for TreeGridDragSource.
+ *
+ * @author Vaadin Ltd
+ * @since 8.1
+ */
+public class TreeGridDragSourceState extends GridDragSourceState {
+
+}
diff --git a/shared/src/main/java/com/vaadin/shared/ui/treegrid/TreeGridDropTargetRpc.java b/shared/src/main/java/com/vaadin/shared/ui/treegrid/TreeGridDropTargetRpc.java
new file mode 100644
index 0000000000..0ce81c80dd
--- /dev/null
+++ b/shared/src/main/java/com/vaadin/shared/ui/treegrid/TreeGridDropTargetRpc.java
@@ -0,0 +1,59 @@
+/*
+ * 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.shared.ui.treegrid;
+
+import java.util.List;
+import java.util.Map;
+
+import com.vaadin.shared.MouseEventDetails;
+import com.vaadin.shared.communication.ServerRpc;
+import com.vaadin.shared.ui.grid.DropLocation;
+
+/**
+ * RPC for firing server side drop event when client side drop event happens on
+ * drop target TreeGrid.
+ *
+ * @author Vaadin Ltd.
+ * @since 8.1
+ */
+public interface TreeGridDropTargetRpc extends ServerRpc {
+
+    /**
+     * Called when drop event happens on client side.
+     *
+     * @param types
+     *         list of data types from {@code DataTransfer.types} object
+     * @param data
+     *         map containing all types and corresponding data from the {@code
+     *         DataTransfer} object
+     * @param dropEffect
+     *         the desired drop effect
+     * @param rowKey
+     *         key of the row on which the drop event occurred
+     * @param depth
+     *         depth of the row in the hierarchy
+     * @param collapsed
+     *         whether the target row is collapsed
+     * @param dropLocation
+     *         location of the drop within the row
+     * @param mouseEventDetails
+     *         Mouse event details object containing information about the drop
+     *         event
+     */
+    public void drop(List<String> types, Map<String, String> data,
+            String dropEffect, String rowKey, Integer depth, Boolean collapsed,
+            DropLocation dropLocation, MouseEventDetails mouseEventDetails);
+}
diff --git a/shared/src/main/java/com/vaadin/shared/ui/treegrid/TreeGridDropTargetState.java b/shared/src/main/java/com/vaadin/shared/ui/treegrid/TreeGridDropTargetState.java
new file mode 100644
index 0000000000..29fea79c98
--- /dev/null
+++ b/shared/src/main/java/com/vaadin/shared/ui/treegrid/TreeGridDropTargetState.java
@@ -0,0 +1,28 @@
+/*
+ * 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.shared.ui.treegrid;
+
+import com.vaadin.shared.ui.grid.GridDropTargetState;
+
+/**
+ * State class containing parameters for TreeGridDropTarget.
+ *
+ * @author Vaadin Ltd
+ * @since 8.1
+ */
+public class TreeGridDropTargetState extends GridDropTargetState {
+
+}
diff --git a/uitest/src/main/java/com/vaadin/tests/components/treegrid/TreeGridDragAndDrop.java b/uitest/src/main/java/com/vaadin/tests/components/treegrid/TreeGridDragAndDrop.java
new file mode 100644
index 0000000000..2ed2c4f1f4
--- /dev/null
+++ b/uitest/src/main/java/com/vaadin/tests/components/treegrid/TreeGridDragAndDrop.java
@@ -0,0 +1,48 @@
+package com.vaadin.tests.components.treegrid;
+
+import com.vaadin.annotations.Theme;
+import com.vaadin.annotations.Widgetset;
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.shared.ui.grid.DropMode;
+import com.vaadin.tests.components.AbstractTestUIWithLog;
+import com.vaadin.tests.data.bean.HierarchicalTestBean;
+import com.vaadin.ui.TreeGrid;
+import com.vaadin.ui.components.grid.TreeGridDragSource;
+import com.vaadin.ui.components.grid.TreeGridDropTarget;
+
+@Theme("valo")
+@Widgetset("com.vaadin.DefaultWidgetSet")
+public class TreeGridDragAndDrop extends AbstractTestUIWithLog {
+    @Override
+    protected void setup(VaadinRequest request) {
+        getUI().setMobileHtml5DndEnabled(true);
+
+        TreeGrid<HierarchicalTestBean> grid;
+        grid = new TreeGrid<>();
+        grid.setSizeFull();
+        grid.addColumn(HierarchicalTestBean::toString).setCaption("String")
+                .setId("string");
+        grid.addColumn(HierarchicalTestBean::getDepth).setCaption("Depth")
+                .setId("depth").setDescriptionGenerator(
+                t -> "Hierarchy depth: " + t.getDepth());
+        grid.addColumn(HierarchicalTestBean::getIndex)
+                .setCaption("Index on this depth").setId("index");
+        grid.setHierarchyColumn("string");
+        grid.setDataProvider(new LazyHierarchicalDataProvider(3, 2));
+
+        grid.setId("testComponent");
+
+        TreeGridDragSource<HierarchicalTestBean> dragSource = new TreeGridDragSource<>(
+                grid);
+        TreeGridDropTarget<HierarchicalTestBean> dropTarget = new TreeGridDropTarget<>(
+                grid, DropMode.ON_TOP_OR_BETWEEN);
+
+        dropTarget.addTreeGridDropListener(event -> {
+            log("depth=" + event.getDropTargetRowDepth().orElse(null)
+                    + ", collapsed=" + event.isDropTargetRowCollapsed()
+                    .orElse(null));
+        });
+
+        addComponent(grid);
+    }
+}