Add drag and drop support for files in General Tab

CHANGELOG.md

@@ -18,6 +18,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - We increased the size of the keywords and file text areas in the entry editor
 - When the entry that is currently shown in the entry editor is deleted externally, the editor is now closed automatically [#2946](https://github.com/JabRef/jabref/issues/2946)
 - We added reordering of file and link entries in the `General`-Tab [3165, comment](https://github.com/JabRef/jabref/issues/3165#issuecomment-326269715)
+- We added drag and drop support for adding files directly in the `General`-Tab. The dragged files are currently only linked from their existing directory. For more advanced features use the `Add files` dialog. [#koppor#244](https://github.com/koppor/jabref/issues/244)
 
 ### Fixed
 

src/main/java/org/jabref/gui/fieldeditors/LinkedFilesEditor.java

@@ -1,6 +1,9 @@
 package org.jabref.gui.fieldeditors;
 
+import java.io.File;
+import java.util.List;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 import javafx.beans.binding.Bindings;
 import javafx.collections.ObservableList;
@@ -63,14 +66,40 @@ public LinkedFilesEditor(String fieldName, DialogService dialogService, BibDatab
 
         listView.setCellFactory(cellFactory);
 
+        setUpFilesDragAndDrop();
         Bindings.bindContentBidirectional(listView.itemsProperty().get(), viewModel.filesProperty());
         setUpKeyBindings();
     }
 
+    private void setUpFilesDragAndDrop() {
+        listView.setOnDragOver(event -> {
+            if (event.getDragboard().hasFiles()) {
+                event.acceptTransferModes(TransferMode.COPY, TransferMode.LINK);
+            }
+        });
+
+        listView.setOnDragDropped(event -> {
+            Dragboard dragboard = event.getDragboard();
+            boolean success = false;
+            ObservableList<LinkedFileViewModel> items = listView.itemsProperty().get();
+
+            if (dragboard.hasFiles()) {
+                List<LinkedFileViewModel> linkedFiles = dragboard.getFiles().stream().map(File::toPath).map(viewModel::fromFile).collect(Collectors.toList());
+                items.addAll(linkedFiles);
+            }
+            event.setDropCompleted(success);
+            event.consume();
+        });
+
+    }
+
     private void handleOnDragOver(LinkedFileViewModel originalItem, DragEvent event) {
         if ((event.getGestureSource() != originalItem) && event.getDragboard().hasContent(DragAndDropDataFormats.LINKED_FILE)) {
             event.acceptTransferModes(TransferMode.MOVE);
         }
+        if (event.getDragboard().hasFiles()) {
+            event.acceptTransferModes(TransferMode.COPY, TransferMode.LINK);
+        }
     }
 
     private void handleOnDragDetected(@SuppressWarnings("unused") LinkedFileViewModel linkedFile, MouseEvent event) {
@@ -103,15 +132,15 @@ private void handleOnDragDropped(LinkedFileViewModel originalItem, DragEvent eve
                     break;
                 }
             }
-
             int thisIdx = items.indexOf(originalItem);
             items.set(draggedIdx, originalItem);
             items.set(thisIdx, transferedItem);
-
-            event.setDropCompleted(success);
-            event.consume();
             success = true;
         }
+        if (dragboard.hasFiles()) {
+            List<LinkedFileViewModel> linkedFiles = dragboard.getFiles().stream().map(File::toPath).map(viewModel::fromFile).collect(Collectors.toList());
+            items.addAll(linkedFiles);
+        }
         event.setDropCompleted(success);
         event.consume();
 

src/main/java/org/jabref/gui/fieldeditors/LinkedFilesEditorViewModel.java

@@ -95,6 +95,14 @@ private static LinkedFile fromFile(Path file, List<Path> fileDirectories) {
         return new LinkedFile("", relativePath.toString(), suggestedFileType.getName());
     }
 
+    public LinkedFileViewModel fromFile(Path file) {
+        List<Path> fileDirectories = databaseContext.getFileDirectoriesAsPaths(Globals.prefs.getFileDirectoryPreferences());
+
+        LinkedFile linkedFile = fromFile(file, fileDirectories);
+        return new LinkedFileViewModel(linkedFile, entry, databaseContext);
+
+    }
+
     public boolean isFulltextLookupInProgress() {
         return fulltextLookupInProgress.get();
     }