Fixes DragAndDropWrapper does not support choosing a custom component as the drag image (#13836)

Amend : Fixes the comments for the last commit.
Amend 2: Fixes a nullpointer found in a certain test scenario

Change-Id: I72327f5f8ab9e46d88e1ebed8f1db3a7da39d7d8

2 files changed, 52 insertions, 1 deletions

diff --git a/client/src/com/vaadin/client/ui/VDragAndDropWrapper.java b/client/src/com/vaadin/client/ui/VDragAndDropWrapper.java
index 4010ffd542..7bf341a387 100644
--- a/client/src/com/vaadin/client/ui/VDragAndDropWrapper.java
+++ b/client/src/com/vaadin/client/ui/VDragAndDropWrapper.java
@@ -114,7 +114,8 @@ public class VDragAndDropWrapper extends VCustomComponent implements
      * @return true if the event was handled as a drag start event
      */
     private boolean startDrag(NativeEvent event) {
-        if (dragStartMode == WRAPPER || dragStartMode == COMPONENT) {
+        if (dragStartMode == WRAPPER || dragStartMode == COMPONENT
+                || dragStartMode == COMPONENT_OTHER) {
             VTransferable transferable = new VTransferable();
             transferable.setDragSource(getConnector());
 
@@ -130,6 +131,10 @@ public class VDragAndDropWrapper extends VCustomComponent implements
 
             if (dragStartMode == WRAPPER) {
                 dragEvent.createDragImage(getElement(), true);
+            } else if (dragStartMode == COMPONENT_OTHER
+                    && getDragImageWidget() != null) {
+                dragEvent.createDragImage(getDragImageWidget().getElement(),
+                        true);
             } else {
                 dragEvent.createDragImage(widget.getElement(), true);
             }
@@ -142,6 +147,7 @@ public class VDragAndDropWrapper extends VCustomComponent implements
     protected final static int COMPONENT = 1;
     protected final static int WRAPPER = 2;
     protected final static int HTML5 = 3;
+    protected final static int COMPONENT_OTHER = 4;
 
     /** For internal use only. May be removed or replaced in the future. */
     public int dragStartMode;
@@ -458,6 +464,7 @@ public class VDragAndDropWrapper extends VCustomComponent implements
      * Flag used by html5 dd
      */
     private boolean currentlyValid;
+    private Widget dragImageWidget;
 
     private static final String OVER_STYLE = "v-ddwrapper-over";
 
@@ -661,4 +668,22 @@ public class VDragAndDropWrapper extends VCustomComponent implements
         notifySizePotentiallyChanged();
     }
 
+    /**
+     * Set the widget that will be used as the drag image when using
+     * DragStartMode {@link COMPONENT_OTHER} .
+     * 
+     * @param widget
+     */
+    public void setDragAndDropWidget(Widget widget) {
+        dragImageWidget = widget;
+    }
+
+    /**
+     * @return the widget used as drag image. Returns <code>null</code> if no
+     *         widget is set.
+     */
+    public Widget getDragImageWidget() {
+        return dragImageWidget;
+    }
+
 }
diff --git a/client/src/com/vaadin/client/ui/draganddropwrapper/DragAndDropWrapperConnector.java b/client/src/com/vaadin/client/ui/draganddropwrapper/DragAndDropWrapperConnector.java
index afb521b141..f222721e24 100644
--- a/client/src/com/vaadin/client/ui/draganddropwrapper/DragAndDropWrapperConnector.java
+++ b/client/src/com/vaadin/client/ui/draganddropwrapper/DragAndDropWrapperConnector.java
@@ -17,8 +17,12 @@ package com.vaadin.client.ui.draganddropwrapper;
 
 import java.util.HashMap;
 import java.util.Set;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 import com.vaadin.client.ApplicationConnection;
+import com.vaadin.client.ComponentConnector;
+import com.vaadin.client.ConnectorMap;
 import com.vaadin.client.Paintable;
 import com.vaadin.client.UIDL;
 import com.vaadin.client.VConsole;
@@ -81,6 +85,25 @@ public class DragAndDropWrapperConnector extends CustomComponentConnector
 
             getWidget().dragStartMode = uidl
                     .getIntAttribute(DragAndDropWrapperConstants.DRAG_START_MODE);
+
+            String dragImageComponentConnectorId = uidl
+                    .getStringAttribute(DragAndDropWrapperConstants.DRAG_START_COMPONENT_ATTRIBUTE);
+
+            ComponentConnector connector = null;
+            if (dragImageComponentConnectorId != null) {
+                connector = (ComponentConnector) ConnectorMap.get(client)
+                        .getConnector(dragImageComponentConnectorId);
+
+                if (connector == null) {
+                    getLogger().log(
+                            Level.WARNING,
+                            "DragAndDropWrapper drag image component"
+                                    + " connector now found. Make sure the"
+                                    + " component is attached.");
+                } else {
+                    getWidget().setDragAndDropWidget(connector.getWidget());
+                }
+            }
             getWidget().initDragStartMode();
             getWidget().html5DataFlavors = uidl
                     .getMapAttribute(DragAndDropWrapperConstants.HTML5_DATA_FLAVORS);
@@ -95,4 +118,7 @@ public class DragAndDropWrapperConnector extends CustomComponentConnector
         return (VDragAndDropWrapper) super.getWidget();
     }
 
+    private static Logger getLogger() {
+        return Logger.getLogger(DragAndDropWrapperConnector.class.getName());
+    }
 }