Make it possible to drop things on top of Grid rows (#8747)

Fixes #8400

4 files changed, 198 insertions, 2 deletions

diff --git a/server/src/main/java/com/vaadin/event/dnd/DropTargetExtension.java b/server/src/main/java/com/vaadin/event/dnd/DropTargetExtension.java
index c4a5f981ff..fcca5efadb 100644
--- a/server/src/main/java/com/vaadin/event/dnd/DropTargetExtension.java
+++ b/server/src/main/java/com/vaadin/event/dnd/DropTargetExtension.java
@@ -43,14 +43,25 @@ public class DropTargetExtension<T extends AbstractComponent> extends
      *         Component to be extended.
      */
     public DropTargetExtension(T target) {
+
+        registerDropTargetRpc(target);
+
+        super.extend(target);
+    }
+
+    /**
+     * Register server RPC.
+     *
+     * @param target
+     *         Extended component.
+     */
+    protected void registerDropTargetRpc(T target) {
         registerRpc((DropTargetRpc) dataTransferText -> {
             DropEvent<T> event = new DropEvent<>(target, dataTransferText,
                     getUI().getActiveDragSource());
 
             fireEvent(event);
         });
-
-        super.extend(target);
     }
 
     /**
diff --git a/server/src/main/java/com/vaadin/event/dnd/grid/GridDropEvent.java b/server/src/main/java/com/vaadin/event/dnd/grid/GridDropEvent.java
new file mode 100644
index 0000000000..96017e3a1d
--- /dev/null
+++ b/server/src/main/java/com/vaadin/event/dnd/grid/GridDropEvent.java
@@ -0,0 +1,67 @@
+/*
+ * 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.dnd.grid;
+
+import com.vaadin.event.dnd.DragSourceExtension;
+import com.vaadin.event.dnd.DropEvent;
+import com.vaadin.ui.AbstractComponent;
+import com.vaadin.ui.Grid;
+
+/**
+ * Server side drop event on an HTML5 drop target {@link Grid} row.
+ *
+ * @param <T>
+ *         The Grid bean type.
+ * @author Vaadin Ltd.
+ * @see com.vaadin.ui.GridDropTargetExtension#addDropListener(GridDropListener)
+ * @since
+ */
+public class GridDropEvent<T> extends DropEvent<Grid<T>> {
+
+    private final T dropTargetRow;
+
+    /**
+     * Creates a server side Grid row drop event.
+     *
+     * @param target
+     *         Grid that received the drop.
+     * @param dataTransferText
+     *         Data of type {@code "text"} from the {@code DataTransfer}
+     *         object.
+     * @param dragSourceExtension
+     *         Drag source extension of the component that initiated the drop
+     *         event.
+     * @param dropTargetRowKey
+     *         Key of the target row that received the drop.
+     */
+    public GridDropEvent(Grid<T> target, String dataTransferText,
+            DragSourceExtension<? extends AbstractComponent> dragSourceExtension,
+            String dropTargetRowKey) {
+        super(target, dataTransferText, dragSourceExtension);
+
+        dropTargetRow = target.getDataCommunicator().getKeyMapper()
+                .get(dropTargetRowKey);
+    }
+
+    /**
+     * Get the row item source of this event.
+     *
+     * @return The row item this event was originated from.
+     */
+    public T getDropTargetRow() {
+        return dropTargetRow;
+    }
+}
diff --git a/server/src/main/java/com/vaadin/event/dnd/grid/GridDropListener.java b/server/src/main/java/com/vaadin/event/dnd/grid/GridDropListener.java
new file mode 100644
index 0000000000..e1e365fbeb
--- /dev/null
+++ b/server/src/main/java/com/vaadin/event/dnd/grid/GridDropListener.java
@@ -0,0 +1,46 @@
+/*
+ * 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.dnd.grid;
+
+import java.lang.reflect.Method;
+
+import com.vaadin.event.ConnectorEventListener;
+import com.vaadin.event.dnd.DropListener;
+import com.vaadin.event.dnd.DropTargetExtension;
+
+/**
+ * Drop listener for HTML5 drop on a Grid row.
+ *
+ * @param <T>
+ *         The Grid bean type.
+ * @author Vaadin Ltd.
+ * @see com.vaadin.ui.GridDropTargetExtension#addDropListener(GridDropListener)
+ * @since
+ */
+@FunctionalInterface
+public interface GridDropListener<T> extends ConnectorEventListener {
+
+    static final Method DROP_METHOD = GridDropListener.class
+            .getDeclaredMethods()[0];
+
+    /**
+     * Called when drop event is fired on a Grid row.
+     *
+     * @param event
+     *         Server side drop event.
+     */
+    void drop(GridDropEvent<T> event);
+}
diff --git a/server/src/main/java/com/vaadin/ui/GridDropTargetExtension.java b/server/src/main/java/com/vaadin/ui/GridDropTargetExtension.java
new file mode 100644
index 0000000000..bf75e26783
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/GridDropTargetExtension.java
@@ -0,0 +1,72 @@
+/*
+ * 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;
+
+import com.vaadin.event.dnd.DropTargetExtension;
+import com.vaadin.event.dnd.grid.GridDropEvent;
+import com.vaadin.event.dnd.grid.GridDropListener;
+import com.vaadin.shared.Registration;
+import com.vaadin.shared.ui.grid.GridDropTargetExtensionRpc;
+import com.vaadin.shared.ui.grid.GridDropTargetExtensionState;
+
+/**
+ * Makes the rows of a Grid HTML5 drop targets. This is the server side
+ * counterpart of GridDropTargetExtensionConnector.
+ *
+ * @param <T>
+ *         Type of the Grid bean.
+ * @author Vaadin Ltd
+ * @since
+ */
+public class GridDropTargetExtension<T> extends DropTargetExtension<Grid<T>> {
+    public GridDropTargetExtension(Grid<T> target) {
+        super(target);
+    }
+
+    @Override
+    protected void registerDropTargetRpc(Grid<T> target) {
+        registerRpc((GridDropTargetExtensionRpc) (dataTransferText, rowKey) -> {
+            GridDropEvent<T> event = new GridDropEvent<>(target,
+                    dataTransferText, getUI().getActiveDragSource(), rowKey);
+
+            fireEvent(event);
+        });
+    }
+
+    /**
+     * Attaches drop listener for the current drop target. {@link
+     * GridDropListener#drop(GridDropEvent)} 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 addDropListener(GridDropListener<T> listener) {
+        return addListener(GridDropEvent.class, listener,
+                GridDropListener.DROP_METHOD);
+    }
+
+    @Override
+    protected GridDropTargetExtensionState getState() {
+        return (GridDropTargetExtensionState) super.getState();
+    }
+
+    @Override
+    protected GridDropTargetExtensionState getState(boolean markAsDirty) {
+        return (GridDropTargetExtensionState) super.getState(markAsDirty);
+    }
+}