Make Grid rows draggable (#8690)

It is possible to customize the drag data for each row. (#8706)

Fixes #8396

4 files changed, 200 insertions, 12 deletions

diff --git a/client/src/main/java/com/vaadin/client/connectors/grid/GridDragSourceExtensionConnector.java b/client/src/main/java/com/vaadin/client/connectors/grid/GridDragSourceExtensionConnector.java
new file mode 100644
index 0000000000..f402f2396d
--- /dev/null
+++ b/client/src/main/java/com/vaadin/client/connectors/grid/GridDragSourceExtensionConnector.java
@@ -0,0 +1,119 @@
+/*
+ * 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.google.gwt.dom.client.NativeEvent;
+import com.google.gwt.dom.client.TableRowElement;
+import com.vaadin.client.ServerConnector;
+import com.vaadin.client.extensions.DragSourceExtensionConnector;
+import com.vaadin.client.widget.escalator.RowContainer;
+import com.vaadin.client.widgets.Escalator;
+import com.vaadin.shared.Range;
+import com.vaadin.shared.ui.Connect;
+import com.vaadin.shared.ui.grid.GridDragSourceExtensionState;
+import com.vaadin.ui.GridDragSourceExtension;
+
+import elemental.events.Event;
+import elemental.json.JsonObject;
+
+/**
+ * Adds HTML5 drag and drop functionality to a {@link com.vaadin.client.widgets.Grid
+ * Grid}'s rows. This is the client side counterpart of {@link
+ * GridDragSourceExtension}.
+ *
+ * @author Vaadin Ltd
+ * @since
+ */
+@Connect(GridDragSourceExtension.class)
+public class GridDragSourceExtensionConnector extends
+        DragSourceExtensionConnector {
+
+    private GridConnector gridConnector;
+
+    @Override
+    protected void extend(ServerConnector target) {
+        this.gridConnector = (GridConnector) target;
+
+        // Set newly added rows draggable
+        getGridBody().setNewEscalatorRowCallback(
+                rows -> rows.forEach(this::setDraggable));
+
+        // Add drag listeners to body element
+        addDragListeners(getGridBody().getElement());
+    }
+
+    @Override
+    protected void onDragStart(Event event) {
+        super.onDragStart(event);
+
+        if (event.getTarget() instanceof TableRowElement) {
+            TableRowElement row = (TableRowElement) event.getTarget();
+            int rowIndex = ((Escalator.AbstractRowContainer) getGridBody())
+                    .getLogicalRowIndex(row);
+
+            JsonObject rowData = gridConnector.getDataSource().getRow(rowIndex);
+
+            // Set drag data in DataTransfer object
+            ((NativeEvent) event).getDataTransfer()
+                    .setData(GridDragSourceExtensionState.DATA_TYPE_DRAG_DATA,
+                            getDragData(rowData).toJson());
+        }
+    }
+
+    /**
+     * Gets drag data from the row data if exists or returns complete row data
+     * otherwise.
+     *
+     * @param row
+     *         Row data.
+     * @return Drag data if present or row data otherwise.
+     */
+    private JsonObject getDragData(JsonObject row) {
+        return row.hasKey(GridDragSourceExtensionState.JSONKEY_DRAG_DATA)
+                ? row.getObject(GridDragSourceExtensionState.JSONKEY_DRAG_DATA)
+                : row;
+    }
+
+    @Override
+    public void onUnregister() {
+        super.onUnregister();
+
+        // Remove draggable from all row elements in the escalator
+        Range visibleRange = getEscalator().getVisibleRowRange();
+        for (int i = visibleRange.getStart(); i < visibleRange.getEnd(); i++) {
+            removeDraggable(getGridBody().getRowElement(i));
+        }
+
+        // Remove drag listeners from body element
+        removeDragListeners(getGridBody().getElement());
+
+        // Remove callback for newly added rows
+        getGridBody().setNewEscalatorRowCallback(null);
+    }
+
+    private Escalator getEscalator() {
+        return gridConnector.getWidget().getEscalator();
+    }
+
+    private RowContainer.BodyRowContainer getGridBody() {
+        return getEscalator().getBody();
+    }
+
+    @Override
+    public GridDragSourceExtensionState getState() {
+        return (GridDragSourceExtensionState) super.getState();
+    }
+}
diff --git a/client/src/main/java/com/vaadin/client/extensions/DragSourceExtensionConnector.java b/client/src/main/java/com/vaadin/client/extensions/DragSourceExtensionConnector.java
index 3094042826..23797ce886 100644
--- a/client/src/main/java/com/vaadin/client/extensions/DragSourceExtensionConnector.java
+++ b/client/src/main/java/com/vaadin/client/extensions/DragSourceExtensionConnector.java
@@ -56,29 +56,66 @@ public class DragSourceExtensionConnector extends AbstractExtensionConnector {
     protected void extend(ServerConnector target) {
         dragSourceWidget = ((ComponentConnector) target).getWidget();
 
-        Element dragSourceElement = getDraggableElement();
+        setDraggable(getDraggableElement());
+        addDragListeners(getDraggableElement());
+    }
+
+    /**
+     * Sets the given element draggable and adds class name.
+     *
+     * @param element
+     *         Element to be set draggable.
+     */
+    protected void setDraggable(Element element) {
+        element.setDraggable(Element.DRAGGABLE_TRUE);
+        element.addClassName(CLASS_DRAGGABLE);
+    }
+
+    /**
+     * Removes draggable and class name from the given element.
+     *
+     * @param element
+     *         Element to remove draggable from.
+     */
+    protected void removeDraggable(Element element) {
+        element.setDraggable(Element.DRAGGABLE_FALSE);
+        element.removeClassName(CLASS_DRAGGABLE);
+    }
 
-        dragSourceElement.setDraggable(Element.DRAGGABLE_TRUE);
-        dragSourceElement.addClassName(CLASS_DRAGGABLE);
+    /**
+     * Adds dragstart and dragend event listeners to the given DOM element.
+     *
+     * @param element
+     *         DOM element to attach event listeners to.
+     */
+    protected void addDragListeners(Element element) {
+        EventTarget target = element.cast();
 
-        EventTarget dragSource = dragSourceElement.cast();
+        target.addEventListener(Event.DRAGSTART, dragStartListener);
+        target.addEventListener(Event.DRAGEND, dragEndListener);
+    }
 
-        // dragstart
-        dragSource.addEventListener(Event.DRAGSTART, dragStartListener);
+    /**
+     * Removes dragstart and dragend event listeners from the given DOM element.
+     *
+     * @param element
+     *         DOM element to remove event listeners from.
+     */
+    protected void removeDragListeners(Element element) {
+        EventTarget target = element.cast();
 
-        // dragend
-        dragSource.addEventListener(Event.DRAGEND, dragEndListener);
+        target.removeEventListener(Event.DRAGSTART, dragStartListener);
+        target.removeEventListener(Event.DRAGEND, dragEndListener);
     }
 
     @Override
     public void onUnregister() {
         super.onUnregister();
 
-        EventTarget dragSource = (EventTarget) getDraggableElement();
+        Element dragSource = getDraggableElement();
 
-        // Remove listeners
-        dragSource.removeEventListener(Event.DRAGSTART, dragStartListener);
-        dragSource.removeEventListener(Event.DRAGEND, dragEndListener);
+        removeDraggable(dragSource);
+        removeDragListeners(dragSource);
     }
 
     /**
diff --git a/client/src/main/java/com/vaadin/client/widget/escalator/RowContainer.java b/client/src/main/java/com/vaadin/client/widget/escalator/RowContainer.java
index 0105aa687c..ca00ca9b63 100644
--- a/client/src/main/java/com/vaadin/client/widget/escalator/RowContainer.java
+++ b/client/src/main/java/com/vaadin/client/widget/escalator/RowContainer.java
@@ -16,6 +16,9 @@
 
 package com.vaadin.client.widget.escalator;
 
+import java.util.List;
+import java.util.function.Consumer;
+
 import com.google.gwt.dom.client.Element;
 import com.google.gwt.dom.client.TableRowElement;
 import com.google.gwt.dom.client.TableSectionElement;
@@ -116,6 +119,17 @@ public interface RowContainer {
         @Override
         public void removeRows(int index, int numberOfRows)
                 throws IndexOutOfBoundsException, IllegalArgumentException;
+
+        /**
+         * Sets a callback function that is executed when new rows are added to
+         * the escalator.
+         *
+         * @param consumer
+         *         A Consumer function that receives the newly added table row
+         *         elements.
+         */
+        public void setNewEscalatorRowCallback(
+                Consumer<List<TableRowElement>> consumer);
     }
 
     /**
diff --git a/client/src/main/java/com/vaadin/client/widgets/Escalator.java b/client/src/main/java/com/vaadin/client/widgets/Escalator.java
index 7bb078a94a..1f223c1d85 100644
--- a/client/src/main/java/com/vaadin/client/widgets/Escalator.java
+++ b/client/src/main/java/com/vaadin/client/widgets/Escalator.java
@@ -25,7 +25,9 @@ import java.util.List;
 import java.util.ListIterator;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Optional;
 import java.util.TreeMap;
+import java.util.function.Consumer;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -2401,6 +2403,12 @@ public class Escalator extends Widget
         @Deprecated
         private int topRowLogicalIndex = 0;
 
+        /**
+         * A callback function to be executed after new rows are added to the
+         * escalator.
+         */
+        private Consumer<List<TableRowElement>> newEscalatorRowCallback;
+
         private void setTopRowLogicalIndex(int topRowLogicalIndex) {
             if (LogConfiguration.loggingIsEnabled(Level.INFO)) {
                 Logger.getLogger("Escalator.BodyRowContainer")
@@ -2992,6 +3000,10 @@ public class Escalator extends Widget
                     y += spacerContainer.getSpacerHeight(i);
                 }
 
+                // Execute the registered callback function for newly created rows
+                Optional.ofNullable(newEscalatorRowCallback)
+                        .ifPresent(callback -> callback.accept(addedRows));
+
                 return addedRows;
             } else {
                 return Collections.emptyList();
@@ -3982,6 +3994,12 @@ public class Escalator extends Widget
                 int padding) {
             spacerContainer.scrollToSpacer(spacerIndex, destination, padding);
         }
+
+        @Override
+        public void setNewEscalatorRowCallback(
+                Consumer<List<TableRowElement>> callback) {
+            this.newEscalatorRowCallback = callback;
+        }
     }
 
     private class ColumnConfigurationImpl implements ColumnConfiguration {