#Drag & Drop

Webswing supports drag & drop functionality between swing components, drag & drop upload to file chooser and direct drag & drop of file from local system to swing component.

#File chooser upload

To upload a file using drag & drop to a file chooser, simply open file chooser and drop a file from local file system to the marked area. Note that transparentFileSave config should be false.

#Direct drag & drop

To use direct drag & drop you first need to register a swing component that should receive the uploaded file. Use WebswingApi method to do this:

if (WebswingUtil.isWebswing()) {
    WebswingApi api = WebswingUtil.getWebswingApi();
    api.registerDropComponent(pic1);
}

The registered component must have a valid TransferHandler:

pic1.setTransferHandler(picHandler);

This is an example of a simple TransferHandler:

class PictureTransferHandler extends TransferHandler {

    private static List<DataFlavor> supportedFlavors = Arrays.asList(DataFlavor.javaFileListFlavor);

    public boolean importData(JComponent c, Transferable t) {
        if (canImport(c, t.getTransferDataFlavors())) {
            if (t.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                try {
                    List<File> fileList = (List<File>) t.getTransferData(DataFlavor.javaFileListFlavor);
                    if (fileList != null && !fileList.isEmpty()) {
                        File droppedFile = fileList.get(0);
                        return true;
                    }
                } catch (IOException | UnsupportedFlavorException e) {
                    // log
                }
            }
        }
        return false;
    }

    public boolean canImport(JComponent c, DataFlavor[] flavors) {
        for (int i = 0; i < flavors.length; i++) {
            if (supportedFlavors.contains(flavors[i])) {
                return true;
            }
        }
        return false;
    }

}