Remove support for transfer data type (#8910)

* Remove API for setting arbitrary drag data
* Store the drag source component in the UI

Fixes #8893 

2 files changed, 7 insertions, 40 deletions

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 051554f913..da14466666 100644
--- a/client/src/main/java/com/vaadin/client/extensions/DragSourceExtensionConnector.java
+++ b/client/src/main/java/com/vaadin/client/extensions/DragSourceExtensionConnector.java
@@ -15,9 +15,6 @@
  */
 package com.vaadin.client.extensions;
 
-import java.util.List;
-import java.util.Map;
-
 import com.google.gwt.dom.client.DataTransfer;
 import com.google.gwt.dom.client.Element;
 import com.google.gwt.dom.client.NativeEvent;
@@ -45,11 +42,6 @@ public class DragSourceExtensionConnector extends AbstractExtensionConnector {
 
     private static final String CLASS_DRAGGABLE = "v-draggable";
 
-    /**
-     * Data type for storing drag source extension connector's ID
-     */
-    static final String DATA_TYPE_DRAG_SOURCE_ID = "drag-source-id";
-
     // Create event listeners
     private final EventListener dragStartListener = this::onDragStart;
     private final EventListener dragEndListener = this::onDragEnd;
@@ -105,16 +97,9 @@ public class DragSourceExtensionConnector extends AbstractExtensionConnector {
                     getState().effectAllowed.getValue());
         }
 
-        // Set data parameter
-        List<String> types = getState().types;
-        Map<String, String> data = getState().data;
-        for (String format : types) {
-            nativeEvent.getDataTransfer().setData(format, data.get(format));
-        }
-
-        // Store the extension's connector ID in DataTransfer.data
-        nativeEvent.getDataTransfer()
-                .setData(DATA_TYPE_DRAG_SOURCE_ID, getConnectorId());
+        // Set text data parameter
+        nativeEvent.getDataTransfer().setData(DragSourceState.DATA_TYPE_TEXT,
+                getState().dataTransferText);
 
         // Initiate firing server side dragstart event when there is a
         // DragStartListener attached on the server side
diff --git a/client/src/main/java/com/vaadin/client/extensions/DropTargetExtensionConnector.java b/client/src/main/java/com/vaadin/client/extensions/DropTargetExtensionConnector.java
index a8e25f261c..a1ac662987 100644
--- a/client/src/main/java/com/vaadin/client/extensions/DropTargetExtensionConnector.java
+++ b/client/src/main/java/com/vaadin/client/extensions/DropTargetExtensionConnector.java
@@ -15,12 +15,6 @@
  */
 package com.vaadin.client.extensions;
 
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
-import com.google.gwt.core.client.JsArrayString;
 import com.google.gwt.dom.client.BrowserEvents;
 import com.google.gwt.dom.client.DataTransfer;
 import com.google.gwt.dom.client.Element;
@@ -30,6 +24,7 @@ import com.vaadin.client.ComponentConnector;
 import com.vaadin.client.ServerConnector;
 import com.vaadin.event.dnd.DropTargetExtension;
 import com.vaadin.shared.ui.Connect;
+import com.vaadin.shared.ui.dnd.DragSourceState;
 import com.vaadin.shared.ui.dnd.DropTargetRpc;
 import com.vaadin.shared.ui.dnd.DropTargetState;
 
@@ -184,20 +179,11 @@ public class DropTargetExtensionConnector extends AbstractExtensionConnector {
             nativeEvent.preventDefault();
             nativeEvent.stopPropagation();
 
-            // Initiate firing server side drop event
-            JsArrayString typesJsArray = getTypes(
-                    nativeEvent.getDataTransfer());
-            List<String> types = new ArrayList<>();
-            Map<String, String> data = new HashMap<>();
-            for (int i = 0; i < typesJsArray.length(); i++) {
-                types.add(typesJsArray.get(i));
-                data.put(typesJsArray.get(i), nativeEvent.getDataTransfer()
-                        .getData(typesJsArray.get(i)));
-            }
+            String dataTransferText = nativeEvent.getDataTransfer().getData(
+                    DragSourceState.DATA_TYPE_TEXT);
 
             getRpcProxy(DropTargetRpc.class)
-                    .drop(types, data, getState().dropEffect, data.get(
-                            DragSourceExtensionConnector.DATA_TYPE_DRAG_SOURCE_ID));
+                    .drop(dataTransferText, getState().dropEffect);
         }
 
         removeTargetIndicator(getDropTargetElement());
@@ -224,10 +210,6 @@ public class DropTargetExtensionConnector extends AbstractExtensionConnector {
         return new Function('event', script)(event);
     }-*/;
 
-    private native JsArrayString getTypes(DataTransfer dataTransfer)/*-{
-        return dataTransfer.types;
-    }-*/;
-
     @Override
     public DropTargetState getState() {
         return (DropTargetState) super.getState();