Make it possible to drop things between Grid rows (#8979)

Fixes #8401

2 files changed, 74 insertions, 15 deletions

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
index 07ba1327a6..98d1b3495b 100644
--- a/server/src/main/java/com/vaadin/event/dnd/grid/GridDropEvent.java
+++ b/server/src/main/java/com/vaadin/event/dnd/grid/GridDropEvent.java
@@ -17,11 +17,12 @@ package com.vaadin.event.dnd.grid;
 
 import com.vaadin.event.dnd.DragSourceExtension;
 import com.vaadin.event.dnd.DropEvent;
+import com.vaadin.shared.ui.grid.DropLocation;
 import com.vaadin.ui.AbstractComponent;
 import com.vaadin.ui.Grid;
 
 /**
- * Server side drop event on an HTML5 drop target {@link Grid} row.
+ * Drop event on an HTML5 drop target {@link Grid} row.
  *
  * @param <T>
  *         The Grid bean type.
@@ -32,9 +33,10 @@ import com.vaadin.ui.Grid;
 public class GridDropEvent<T> extends DropEvent<Grid<T>> {
 
     private final T dropTargetRow;
+    private final DropLocation dropLocation;
 
     /**
-     * Creates a server side Grid row drop event.
+     * Creates a Grid row drop event.
      *
      * @param target
      *         Grid that received the drop.
@@ -44,16 +46,18 @@ public class GridDropEvent<T> extends DropEvent<Grid<T>> {
      * @param dragSourceExtension
      *         Drag source extension of the component that initiated the drop
      *         event.
-     * @param dropTargetRowKey
-     *         Key of the target row that received the drop.
+     * @param dropTargetRow
+     *         Target row that received the drop.
+     * @param dropLocation
+     *         Location of the drop within the target row.
      */
     public GridDropEvent(Grid<T> target, String dataTransferText,
             DragSourceExtension<? extends AbstractComponent> dragSourceExtension,
-            String dropTargetRowKey) {
+            T dropTargetRow, DropLocation dropLocation) {
         super(target, dataTransferText, dragSourceExtension);
 
-        dropTargetRow = target.getDataCommunicator().getKeyMapper()
-                .get(dropTargetRowKey);
+        this.dropTargetRow = dropTargetRow;
+        this.dropLocation = dropLocation;
     }
 
     /**
@@ -64,4 +68,13 @@ public class GridDropEvent<T> extends DropEvent<Grid<T>> {
     public T getDropTargetRow() {
         return dropTargetRow;
     }
+
+    /**
+     * Get the location of the drop within the row.
+     *
+     * @return Location of the drop within the row.
+     */
+    public DropLocation getDropLocation() {
+        return dropLocation;
+    }
 }
diff --git a/server/src/main/java/com/vaadin/ui/GridDropTargetExtension.java b/server/src/main/java/com/vaadin/ui/GridDropTargetExtension.java
index 1fcb7160f4..17633fa5ce 100644
--- a/server/src/main/java/com/vaadin/ui/GridDropTargetExtension.java
+++ b/server/src/main/java/com/vaadin/ui/GridDropTargetExtension.java
@@ -19,6 +19,7 @@ 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.DropMode;
 import com.vaadin.shared.ui.grid.GridDropTargetExtensionRpc;
 import com.vaadin.shared.ui.grid.GridDropTargetExtensionState;
 
@@ -32,18 +33,47 @@ import com.vaadin.shared.ui.grid.GridDropTargetExtensionState;
  * @since
  */
 public class GridDropTargetExtension<T> extends DropTargetExtension<Grid<T>> {
-    public GridDropTargetExtension(Grid<T> target) {
+
+    /**
+     * Extends a Grid and makes it's rows drop targets for HTML5 drag and drop.
+     *
+     * @param target
+     *         Grid to be extended.
+     * @param dropMode
+     *         Drop mode that describes the allowed drop locations within the
+     *         Grid's row.
+     * @see GridDropEvent#getDropLocation()
+     */
+    public GridDropTargetExtension(Grid<T> target, DropMode dropMode) {
         super(target);
+
+        setDropMode(dropMode);
     }
 
-    @Override
-    protected void registerDropTargetRpc(Grid<T> target) {
-        registerRpc((GridDropTargetExtensionRpc) (dataTransferText, rowKey) -> {
-            GridDropEvent<T> event = new GridDropEvent<>(target,
-                    dataTransferText, getUI().getActiveDragSource(), rowKey);
+    /**
+     * Sets the drop mode of this drop target.
+     *
+     * @param dropMode
+     *         Drop mode that describes the allowed drop locations within the
+     *         Grid's row.
+     * @see GridDropEvent#getDropLocation()
+     */
+    public void setDropMode(DropMode dropMode) {
+        if (dropMode == null) {
+            throw new IllegalArgumentException("Drop mode cannot be null");
+        }
+
+        getState().dropMode = dropMode;
+    }
 
-            fireEvent(event);
-        });
+    /**
+     * Gets the drop mode of this drop target.
+     *
+     * @return Drop mode that describes the allowed drop locations within the
+     *         Grid's row.
+     */
+    public DropMode getDropMode() {
+        return getState(false).dropMode;
     }
 
     /**
@@ -61,6 +91,22 @@ public class GridDropTargetExtension<T> extends DropTargetExtension<Grid<T>> {
     }
 
     @Override
+    protected void registerDropTargetRpc(Grid<T> target) {
+        registerRpc(
+                (GridDropTargetExtensionRpc) (dataTransferText, rowKey, dropLocation) -> {
+
+                    T dropTargetRow = target.getDataCommunicator()
+                            .getKeyMapper().get(rowKey);
+
+                    GridDropEvent<T> event = new GridDropEvent<>(target,
+                            dataTransferText, getUI().getActiveDragSource(),
+                            dropTargetRow, dropLocation);
+
+                    fireEvent(event);
+                });
+    }
+
+    @Override
     protected GridDropTargetExtensionState getState() {
         return (GridDropTargetExtensionState) super.getState();
     }