Drag and drop allows data transfer between various components in your javafx application. It allows transferring data in between your internal nodes or between two applications.
A drag-and-drop gesture happens as follows: The user click a mouse button on a gesture source, drags the mouse, and releases the mouse button on a gesture target. While dragging the data, the user gets visual feedback, which denotes locations that do not accept the data and, when over a target that accepts the data, gives a hint where to drop the data.
The data is transferred using a dragboard, which has the same interface as a system clipboard but is only used for the drag-and-drop data transfer.Various types of data can be transferred such as text, images, URLs, files, bytes, and strings.
1. Receiving Data From other applications
Receiving data from other applications through drag and drop is very simple in JavaFX. The method setOnDragOver of node allows controlling what happens when something is dragged over the node. For example, as you can see in the top image, I have added a simple ImageView and implemented setOnDragOver to accept when files are dragged over it. Let’s see the code.
imageView.setOnDragOver(new EventHandler() {
public void handle(DragEvent event) {
if (event.getDragboard().hasFiles()) {
event.acceptTransferModes(TransferMode.ANY);
}
event.consume();
}
});
event.acceptTransferModes(TransferMode.ANY);
imageView.setOnDragDropped(new EventHandler<DragEvent>() {
public void handle(DragEvent event) {
List<File> files = event.getDragboard().getFiles();
System.out.println("Got " + files.size() + " files");
imageView.setImage(new Image(new FileInputStream(files.get(0))));
event.consume();
}
});
In this code, the list of incoming files is taken using event.getDragboard().getFiles() method. So we can send a list of file instead of a single one. From the received files, we have to create an image and set it as the image for the imageview.
2. Drag and Drop between two internal components
source.setOnDragDetected(new EventHandler<MouseEvent>() {
public void handle(MouseEvent event) {
Dragboard db = source.startDragAndDrop(TransferMode.ANY);
ClipboardContent content = new ClipboardContent();
content.putString(source.getText());
db.setContent(content);
event.consume();
}
});
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