Added holding down ctrl for creating mapping edges functionality

- needed to specify ctrl key instead of shortcut key, might be because
of the menu item accelerators

scopviz/src/main/java/de/tu_darmstadt/informatik/tk/scopviz/ui/handlers/KeyboardShortcuts.java

@@ -1,5 +1,9 @@
 package de.tu_darmstadt.informatik.tk.scopviz.ui.handlers;
 
+import de.tu_darmstadt.informatik.tk.scopviz.debug.Debug;
+import de.tu_darmstadt.informatik.tk.scopviz.main.CreationMode;
+import de.tu_darmstadt.informatik.tk.scopviz.main.Layer;
+import de.tu_darmstadt.informatik.tk.scopviz.main.Main;
 import javafx.event.EventHandler;
 import javafx.scene.input.KeyCode;
 import javafx.scene.input.KeyCodeCombination;
@@ -18,8 +22,8 @@ import javafx.stage.Stage;
 public final class KeyboardShortcuts {
 
 	// example of keycombinations
-	final static KeyCombination rCtrl = new KeyCodeCombination(KeyCode.M, KeyCombination.CONTROL_DOWN);
-	final static KeyCombination rCtrlShift = new KeyCodeCombination(KeyCode.R, KeyCombination.CONTROL_DOWN,
+	final static KeyCombination mShift = new KeyCodeCombination(KeyCode.M, KeyCombination.SHIFT_DOWN);
+	final static KeyCombination rAltShift = new KeyCodeCombination(KeyCode.R, KeyCombination.ALT_DOWN,
 			KeyCombination.SHIFT_DOWN);
 
 	/**
@@ -36,7 +40,8 @@ public final class KeyboardShortcuts {
 	 */
 	public static void initialize(Stage primaryStage) {
 
-		primaryStage.addEventFilter(KeyEvent.KEY_RELEASED, buttonsPressed);
+		primaryStage.addEventFilter(KeyEvent.KEY_PRESSED, buttonsPressed);
+		primaryStage.addEventFilter(KeyEvent.KEY_RELEASED, buttonsReleased);
 
 	}
 
@@ -47,13 +52,45 @@ public final class KeyboardShortcuts {
 
 		@Override
 		public void handle(KeyEvent event) {
+			
+			if(event.getCode() == KeyCode.CONTROL){
+				
+				//for functionality of holding down ctrl for creating mapping edges
+				if(Main.getInstance().getGraphManager().getGraph().getAttribute("layer") == Layer.MAPPING){
+					Main.getInstance().setCreationMode(CreationMode.CREATE_DIRECTED_EDGE);
+					Debug.out("Ctrl pressed");
+				}
+				
+			}
 
-			if (rCtrl.match(event)) {
-				System.out.println("Ctrl+M pressed");
+		}
+	};
+	
+	/**
+	 * A general Handler for any Button releases
+	 */
+	private static EventHandler<KeyEvent> buttonsReleased = new EventHandler<KeyEvent>() {
+
+		@Override
+		public void handle(KeyEvent event) {
+			
+			if (mShift.match(event)) {
+				Debug.out("M+Shift released");
 			}
 
-			else if (rCtrlShift.match(event)) {
-				System.out.println("Ctrl+Shift+R pressed");
+			else if (rAltShift.match(event)) {
+				Debug.out("Alt+Shift+R released");
+			}
+			
+			else if(event.getCode() == KeyCode.CONTROL){
+				
+				//for functionality of holding down ctrl for creating mapping edges
+				if(Main.getInstance().getGraphManager().getGraph().getAttribute("layer") == Layer.MAPPING){
+					Main.getInstance().setCreationMode(CreationMode.CREATE_NONE);
+					Main.getInstance().getGraphManager().deselectEdgeCreationNodes();
+					Debug.out("Ctrl released");
+				}
+				
 			}
 
 		}