Kernel: added DND utility class.

Issue-Ref: 3921
Issue-Url: https://af3-developer.fortiss.org/issues/3907Signed-off-by: Florian Hoelzl <hoelzl@fortiss.org>

org.fortiss.tooling.base.ui/src/org/fortiss/tooling/base/ui/editor/fx/controller/.ratings

 ContextMenuUtil.java 405387151d45b09dffb3b6ba44f980313c8edcaf GREEN
 CurvedLinkLayoutedContentAnchorangeController.java 67c20e31ddb82fe2fd499117193353b0545839a0 GREEN
-EObjectDiagramController.java 9af59e8e586c8251d174108a2ce2fcdee5e75782 GREEN
+EObjectDiagramController.java a34479522e68cd5f6dc64ca322eab3a56a95602a YELLOW
 EObjectEllipticResizableContentControllerBase.java 3494d4f0dcdff5eb35f22f0e21d04df81b32e494 GREEN
 EObjectModelChangeProvider.java f4b60cebb088a5c81ca92a41614e1a5d40030502 GREEN
 EObjectRectangularResizableContentControllerBase.java f4a967591a60fadb20550ec3eaabccf240c9ec0d GREEN

org.fortiss.tooling.base.ui/src/org/fortiss/tooling/base/ui/editor/fx/controller/EObjectDiagramController.java

@@ -18,6 +18,8 @@ import static java.util.Objects.requireNonNull;
 import static org.fortiss.tooling.base.ui.editor.fx.controller.ContextMenuUtil.createDisplayMenu;
 import static org.fortiss.tooling.base.ui.editor.fx.controller.ContextMenuUtil.createElementCompositionContext;
 import static org.fortiss.tooling.base.ui.editor.fx.controller.ContextMenuUtil.createPrototypeMenu;
+import static org.fortiss.tooling.base.ui.utils.FXDNDUtils.canCompose;
+import static org.fortiss.tooling.base.ui.utils.FXDNDUtils.compose;
 
 import java.util.List;
 
@@ -33,6 +35,7 @@ import org.fortiss.tooling.kernel.ui.service.IContextMenuService;
 
 import javafx.scene.Node;
 import javafx.scene.control.MenuItem;
+import javafx.scene.input.Dragboard;
 
 /**
  * Diagram controller that uses the {@link IElementCompositorService} to create context menu
@@ -41,7 +44,6 @@ import javafx.scene.control.MenuItem;
  * @author hoelzl
  */
 public class EObjectDiagramController<T extends EObject> extends ControllerBase {
-
 	/** The model change provider. */
 	private final EObjectModelChangeProvider modelChangeProvider;
 
@@ -85,4 +87,16 @@ public class EObjectDiagramController<T extends EObject> extends ControllerBase
 		result.add(createDisplayMenu(getViewer()));
 		return result;
 	}
+
+	/** {@inheritDoc} */
+	@Override
+	public boolean handleExternalDNDDragOver(Dragboard db, DiagramCoordinate diagramLocation) {
+		return canCompose(db, diagramLocation, getModelElement());
+	}
+
+	/** {@inheritDoc} */
+	@Override
+	public boolean handleExternalDNDDrop(Dragboard db, DiagramCoordinate diagramLocation) {
+		return compose(db, diagramLocation, getModelElement());
+	}
 }

org.fortiss.tooling.base.ui/src/org/fortiss/tooling/base/ui/utils/.ratings

@@ -2,6 +2,7 @@ AbstractNameEditingSupport.java c57336a0e0da18711a1610ca667dfea76728807f GREEN
 ActionUtils.java 322f43d4f92f992daef8ac88eb0f9197c840c89b GREEN
 DragAndDropBaseUtils.java d375377f9124f6113b2a295e6b0e09ac8966e564 GREEN
 EllipseLayoutUIUtils.java 4dd9dbd96a45e8c455c019caa19e4a50f18336af GREEN
+FXDNDUtils.java 5572358a950e932a65dfa053ca02e2fbbef5568e RED
 FontUtils.java a167a05bdaa8da9853705cc5134f30f6d81bc9f2 GREEN
 GCStateManager.java 983973a92376b5c757c1253b32e33d0666ccdf7b GREEN
 LWFXEditorUtils.java c624d3f0f6487b6d426b168dad048b2c39e71114 GREEN

org.fortiss.tooling.base.ui/src/org/fortiss/tooling/base/ui/utils/FXDNDUtils.java

+/*-------------------------------------------------------------------------+
+| Copyright 2020 fortiss GmbH                                              |
+|                                                                          |
+| 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 org.fortiss.tooling.base.ui.utils;
+
+import static org.fortiss.tooling.kernel.service.IPrototypeService.PROTOTYPE_DATA_FORMAT;
+
+import org.eclipse.emf.ecore.EObject;
+import org.fortiss.tooling.common.ui.javafx.lwfxef.DiagramCoordinate;
+import org.fortiss.tooling.kernel.extension.data.Prototype;
+import org.fortiss.tooling.kernel.service.ICommandStackService;
+import org.fortiss.tooling.kernel.service.IElementCompositorService;
+import org.fortiss.tooling.kernel.service.IPrototypeService;
+
+import javafx.scene.input.Dragboard;
+
+/**
+ * Utility methods for JavaFX drag-and-drop.
+ * 
+ * @author hoelzl
+ */
+public final class FXDNDUtils {
+	/** Returns whether element composition can be done via {@link IElementCompositorService}. */
+	public static boolean canCompose(Dragboard db, DiagramCoordinate location, EObject container) {
+		Prototype proto = extractPrototype(db);
+		if(proto != null) {
+			// FIXME: location
+			return IElementCompositorService.getInstance().canCompose(container,
+					proto.getPrototypeCopy(), null);
+		}
+		return false;
+	}
+
+	/** Extracts the prototype from the dragboard. */
+	private static Prototype extractPrototype(Dragboard db) {
+		Object data = db.getContent(PROTOTYPE_DATA_FORMAT);
+		if(data instanceof String) {
+			return IPrototypeService.getInstance().getPrototypeByUniqueID((String)data);
+		}
+		return null;
+	}
+
+	/** Composes the elements using {@link IElementCompositorService}. */
+	public static boolean compose(Dragboard db, DiagramCoordinate location, EObject container) {
+		Prototype proto = extractPrototype(db);
+		if(proto != null) {
+			IElementCompositorService ecs = IElementCompositorService.getInstance();
+			EObject copy = proto.getPrototypeCopy();
+			if(ecs.canCompose(container, copy, null)) {
+				// FIXME: location
+				ICommandStackService.getInstance().runAsCommand(container, () -> {
+					ecs.compose(container, copy, null);
+				});
+				return true;
+			}
+		}
+		return false;
+	}
+
+	/** Constructor. */
+	private FXDNDUtils() {
+		// prevent instantiation
+	}
+}